branchcache: use an explicit class for the v2 version

This prepare the introduction of an experimental v3 format version.

In the process, we move the description of the format in that new class.

contrib/perf.py

@@ -1,4664 +1,4676 b''
 # perf.py - performance test routines
 '''helper extension to measure performance
 
 Configurations
 ==============
 
 ``perf``
 --------
 
 ``all-timing``
     When set, additional statistics will be reported for each benchmark: best,
     worst, median average. If not set only the best timing is reported
     (default: off).
 
 ``presleep``
   number of second to wait before any group of runs (default: 1)
 
 ``pre-run``
   number of run to perform before starting measurement.
 
 ``profile-benchmark``
   Enable profiling for the benchmarked section.
   (The first iteration is benchmarked)
 
 ``run-limits``
   Control the number of runs each benchmark will perform. The option value
   should be a list of `<time>-<numberofrun>` pairs. After each run the
   conditions are considered in order with the following logic:
 
       If benchmark has been running for <time> seconds, and we have performed
       <numberofrun> iterations, stop the benchmark,
 
   The default value is: `3.0-100, 10.0-3`
 
 ``stub``
     When set, benchmarks will only be run once, useful for testing
     (default: off)
 '''
 
 # "historical portability" policy of perf.py:
 #
 # We have to do:
 # - make perf.py "loadable" with as wide Mercurial version as possible
 #   This doesn't mean that perf commands work correctly with that Mercurial.
 #   BTW, perf.py itself has been available since 1.1 (or eb240755386d).
 # - make historical perf command work correctly with as wide Mercurial
 #   version as possible
 #
 # We have to do, if possible with reasonable cost:
 # - make recent perf command for historical feature work correctly
 #   with early Mercurial
 #
 # We don't have to do:
 # - make perf command for recent feature work correctly with early
 #   Mercurial
 
 import contextlib
 import functools
 import gc
 import os
 import random
 import shutil
 import struct
 import sys
 import tempfile
 import threading
 import time
 
 import mercurial.revlog
 from mercurial import (
     changegroup,
     cmdutil,
     commands,
     copies,
     error,
     extensions,
     hg,
     mdiff,
     merge,
     util,
 )
 
 # for "historical portability":
 # try to import modules separately (in dict order), and ignore
 # failure, because these aren't available with early Mercurial
 try:
     from mercurial import branchmap  # since 2.5 (or bcee63733aad)
 except ImportError:
     pass
 try:
     from mercurial import obsolete  # since 2.3 (or ad0d6c2b3279)
 except ImportError:
     pass
 try:
     from mercurial import registrar  # since 3.7 (or 37d50250b696)
 
     dir(registrar)  # forcibly load it
 except ImportError:
     registrar = None
 try:
     from mercurial import repoview  # since 2.5 (or 3a6ddacb7198)
 except ImportError:
     pass
 try:
     from mercurial.utils import repoviewutil  # since 5.0
 except ImportError:
     repoviewutil = None
 try:
     from mercurial import scmutil  # since 1.9 (or 8b252e826c68)
 except ImportError:
     pass
 try:
     from mercurial import setdiscovery  # since 1.9 (or cb98fed52495)
 except ImportError:
     pass
 
 try:
     from mercurial import profiling
 except ImportError:
     profiling = None
 
 try:
     from mercurial.revlogutils import constants as revlog_constants
 
     perf_rl_kind = (revlog_constants.KIND_OTHER, b'created-by-perf')
 
     def revlog(opener, *args, **kwargs):
         return mercurial.revlog.revlog(opener, perf_rl_kind, *args, **kwargs)
 
 
 except (ImportError, AttributeError):
     perf_rl_kind = None
 
     def revlog(opener, *args, **kwargs):
         return mercurial.revlog.revlog(opener, *args, **kwargs)
 
 
 def identity(a):
     return a
 
 
 try:
     from mercurial import pycompat
 
     getargspec = pycompat.getargspec  # added to module after 4.5
     _byteskwargs = pycompat.byteskwargs  # since 4.1 (or fbc3f73dc802)
     _sysstr = pycompat.sysstr  # since 4.0 (or 2219f4f82ede)
     _bytestr = pycompat.bytestr  # since 4.2 (or b70407bd84d5)
     _xrange = pycompat.xrange  # since 4.8 (or 7eba8f83129b)
     fsencode = pycompat.fsencode  # since 3.9 (or f4a5e0e86a7e)
     if pycompat.ispy3:
         _maxint = sys.maxsize  # per py3 docs for replacing maxint
     else:
         _maxint = sys.maxint
 except (NameError, ImportError, AttributeError):
     import inspect
 
     getargspec = inspect.getargspec
     _byteskwargs = identity
     _bytestr = str
     fsencode = identity  # no py3 support
     _maxint = sys.maxint  # no py3 support
     _sysstr = lambda x: x  # no py3 support
     _xrange = xrange
 
 try:
     # 4.7+
     queue = pycompat.queue.Queue
 except (NameError, AttributeError, ImportError):
     # <4.7.
     try:
         queue = pycompat.queue
     except (NameError, AttributeError, ImportError):
         import Queue as queue
 
 try:
     from mercurial import logcmdutil
 
     makelogtemplater = logcmdutil.maketemplater
 except (AttributeError, ImportError):
     try:
         makelogtemplater = cmdutil.makelogtemplater
     except (AttributeError, ImportError):
         makelogtemplater = None
 
 # for "historical portability":
 # define util.safehasattr forcibly, because util.safehasattr has been
 # available since 1.9.3 (or 94b200a11cf7)
 _undefined = object()
 
 
 def safehasattr(thing, attr):
     return getattr(thing, _sysstr(attr), _undefined) is not _undefined
 
 
 setattr(util, 'safehasattr', safehasattr)
 
 # for "historical portability":
 # define util.timer forcibly, because util.timer has been available
 # since ae5d60bb70c9
 if safehasattr(time, 'perf_counter'):
     util.timer = time.perf_counter
 elif os.name == b'nt':
     util.timer = time.clock
 else:
     util.timer = time.time
 
 # for "historical portability":
 # use locally defined empty option list, if formatteropts isn't
 # available, because commands.formatteropts has been available since
 # 3.2 (or 7a7eed5176a4), even though formatting itself has been
 # available since 2.2 (or ae5f92e154d3)
 formatteropts = getattr(
     cmdutil, "formatteropts", getattr(commands, "formatteropts", [])
 )
 
 # for "historical portability":
 # use locally defined option list, if debugrevlogopts isn't available,
 # because commands.debugrevlogopts has been available since 3.7 (or
 # 5606f7d0d063), even though cmdutil.openrevlog() has been available
 # since 1.9 (or a79fea6b3e77).
 revlogopts = getattr(
     cmdutil,
     "debugrevlogopts",
     getattr(
         commands,
         "debugrevlogopts",
         [
             (b'c', b'changelog', False, b'open changelog'),
             (b'm', b'manifest', False, b'open manifest'),
             (b'', b'dir', False, b'open directory manifest'),
         ],
     ),
 )
 
 cmdtable = {}
 
 
 # for "historical portability":
 # define parsealiases locally, because cmdutil.parsealiases has been
 # available since 1.5 (or 6252852b4332)
 def parsealiases(cmd):
     return cmd.split(b"|")
 
 
 if safehasattr(registrar, 'command'):
     command = registrar.command(cmdtable)
 elif safehasattr(cmdutil, 'command'):
     command = cmdutil.command(cmdtable)
     if 'norepo' not in getargspec(command).args:
         # for "historical portability":
         # wrap original cmdutil.command, because "norepo" option has
         # been available since 3.1 (or 75a96326cecb)
         _command = command
 
         def command(name, options=(), synopsis=None, norepo=False):
             if norepo:
                 commands.norepo += b' %s' % b' '.join(parsealiases(name))
             return _command(name, list(options), synopsis)
 
 
 else:
     # for "historical portability":
     # define "@command" annotation locally, because cmdutil.command
     # has been available since 1.9 (or 2daa5179e73f)
     def command(name, options=(), synopsis=None, norepo=False):
         def decorator(func):
             if synopsis:
                 cmdtable[name] = func, list(options), synopsis
             else:
                 cmdtable[name] = func, list(options)
             if norepo:
                 commands.norepo += b' %s' % b' '.join(parsealiases(name))
             return func
 
         return decorator
 
 
 try:
     import mercurial.registrar
     import mercurial.configitems
 
     configtable = {}
     configitem = mercurial.registrar.configitem(configtable)
     configitem(
         b'perf',
         b'presleep',
         default=mercurial.configitems.dynamicdefault,
         experimental=True,
     )
     configitem(
         b'perf',
         b'stub',
         default=mercurial.configitems.dynamicdefault,
         experimental=True,
     )
     configitem(
         b'perf',
         b'parentscount',
         default=mercurial.configitems.dynamicdefault,
         experimental=True,
     )
     configitem(
         b'perf',
         b'all-timing',
         default=mercurial.configitems.dynamicdefault,
         experimental=True,
     )
     configitem(
         b'perf',
         b'pre-run',
         default=mercurial.configitems.dynamicdefault,
     )
     configitem(
         b'perf',
         b'profile-benchmark',
         default=mercurial.configitems.dynamicdefault,
     )
     configitem(
         b'perf',
         b'run-limits',
         default=mercurial.configitems.dynamicdefault,
         experimental=True,
     )
 except (ImportError, AttributeError):
     pass
 except TypeError:
     # compatibility fix for a11fd395e83f
     # hg version: 5.2
     configitem(
         b'perf',
         b'presleep',
         default=mercurial.configitems.dynamicdefault,
     )
     configitem(
         b'perf',
         b'stub',
         default=mercurial.configitems.dynamicdefault,
     )
     configitem(
         b'perf',
         b'parentscount',
         default=mercurial.configitems.dynamicdefault,
     )
     configitem(
         b'perf',
         b'all-timing',
         default=mercurial.configitems.dynamicdefault,
     )
     configitem(
         b'perf',
         b'pre-run',
         default=mercurial.configitems.dynamicdefault,
     )
     configitem(
         b'perf',
         b'profile-benchmark',
         default=mercurial.configitems.dynamicdefault,
     )
     configitem(
         b'perf',
         b'run-limits',
         default=mercurial.configitems.dynamicdefault,
     )
 
 
 def getlen(ui):
     if ui.configbool(b"perf", b"stub", False):
         return lambda x: 1
     return len
 
 
 class noop:
     """dummy context manager"""
 
     def __enter__(self):
         pass
 
     def __exit__(self, *args):
         pass
 
 
 NOOPCTX = noop()
 
 
 def gettimer(ui, opts=None):
     """return a timer function and formatter: (timer, formatter)
 
     This function exists to gather the creation of formatter in a single
     place instead of duplicating it in all performance commands."""
 
     # enforce an idle period before execution to counteract power management
     # experimental config: perf.presleep
     time.sleep(getint(ui, b"perf", b"presleep", 1))
 
     if opts is None:
         opts = {}
     # redirect all to stderr unless buffer api is in use
     if not ui._buffers:
         ui = ui.copy()
         uifout = safeattrsetter(ui, b'fout', ignoremissing=True)
         if uifout:
             # for "historical portability":
             # ui.fout/ferr have been available since 1.9 (or 4e1ccd4c2b6d)
             uifout.set(ui.ferr)
 
     # get a formatter
     uiformatter = getattr(ui, 'formatter', None)
     if uiformatter:
         fm = uiformatter(b'perf', opts)
     else:
         # for "historical portability":
         # define formatter locally, because ui.formatter has been
         # available since 2.2 (or ae5f92e154d3)
         from mercurial import node
 
         class defaultformatter:
             """Minimized composition of baseformatter and plainformatter"""
 
             def __init__(self, ui, topic, opts):
                 self._ui = ui
                 if ui.debugflag:
                     self.hexfunc = node.hex
                 else:
                     self.hexfunc = node.short
 
             def __nonzero__(self):
                 return False
 
             __bool__ = __nonzero__
 
             def startitem(self):
                 pass
 
             def data(self, **data):
                 pass
 
             def write(self, fields, deftext, *fielddata, **opts):
                 self._ui.write(deftext % fielddata, **opts)
 
             def condwrite(self, cond, fields, deftext, *fielddata, **opts):
                 if cond:
                     self._ui.write(deftext % fielddata, **opts)
 
             def plain(self, text, **opts):
                 self._ui.write(text, **opts)
 
             def end(self):
                 pass
 
         fm = defaultformatter(ui, b'perf', opts)
 
     # stub function, runs code only once instead of in a loop
     # experimental config: perf.stub
     if ui.configbool(b"perf", b"stub", False):
         return functools.partial(stub_timer, fm), fm
 
     # experimental config: perf.all-timing
     displayall = ui.configbool(b"perf", b"all-timing", True)
 
     # experimental config: perf.run-limits
     limitspec = ui.configlist(b"perf", b"run-limits", [])
     limits = []
     for item in limitspec:
         parts = item.split(b'-', 1)
         if len(parts) < 2:
             ui.warn((b'malformatted run limit entry, missing "-": %s\n' % item))
             continue
         try:
             time_limit = float(_sysstr(parts[0]))
         except ValueError as e:
             ui.warn(
                 (
                     b'malformatted run limit entry, %s: %s\n'
                     % (_bytestr(e), item)
                 )
             )
             continue
         try:
             run_limit = int(_sysstr(parts[1]))
         except ValueError as e:
             ui.warn(
                 (
                     b'malformatted run limit entry, %s: %s\n'
                     % (_bytestr(e), item)
                 )
             )
             continue
         limits.append((time_limit, run_limit))
     if not limits:
         limits = DEFAULTLIMITS
 
     profiler = None
     if profiling is not None:
         if ui.configbool(b"perf", b"profile-benchmark", False):
             profiler = profiling.profile(ui)
 
     prerun = getint(ui, b"perf", b"pre-run", 0)
     t = functools.partial(
         _timer,
         fm,
         displayall=displayall,
         limits=limits,
         prerun=prerun,
         profiler=profiler,
     )
     return t, fm
 
 
 def stub_timer(fm, func, setup=None, title=None):
     if setup is not None:
         setup()
     func()
 
 
 @contextlib.contextmanager
 def timeone():
     r = []
     ostart = os.times()
     cstart = util.timer()
     yield r
     cstop = util.timer()
     ostop = os.times()
     a, b = ostart, ostop
     r.append((cstop - cstart, b[0] - a[0], b[1] - a[1]))
 
 
 # list of stop condition (elapsed time, minimal run count)
 DEFAULTLIMITS = (
     (3.0, 100),
     (10.0, 3),
 )
 
 
 @contextlib.contextmanager
 def noop_context():
     yield
 
 
 def _timer(
     fm,
     func,
     setup=None,
     context=noop_context,
     title=None,
     displayall=False,
     limits=DEFAULTLIMITS,
     prerun=0,
     profiler=None,
 ):
     gc.collect()
     results = []
     begin = util.timer()
     count = 0
     if profiler is None:
         profiler = NOOPCTX
     for i in range(prerun):
         if setup is not None:
             setup()
         with context():
             func()
     keepgoing = True
     while keepgoing:
         if setup is not None:
             setup()
         with context():
             with profiler:
                 with timeone() as item:
                     r = func()
         profiler = NOOPCTX
         count += 1
         results.append(item[0])
         cstop = util.timer()
         # Look for a stop condition.
         elapsed = cstop - begin
         for t, mincount in limits:
             if elapsed >= t and count >= mincount:
                 keepgoing = False
                 break
 
     formatone(fm, results, title=title, result=r, displayall=displayall)
 
 
 def formatone(fm, timings, title=None, result=None, displayall=False):
     count = len(timings)
 
     fm.startitem()
 
     if title:
         fm.write(b'title', b'! %s\n', title)
     if result:
         fm.write(b'result', b'! result: %s\n', result)
 
     def display(role, entry):
         prefix = b''
         if role != b'best':
             prefix = b'%s.' % role
         fm.plain(b'!')
         fm.write(prefix + b'wall', b' wall %f', entry[0])
         fm.write(prefix + b'comb', b' comb %f', entry[1] + entry[2])
         fm.write(prefix + b'user', b' user %f', entry[1])
         fm.write(prefix + b'sys', b' sys %f', entry[2])
         fm.write(prefix + b'count', b' (%s of %%d)' % role, count)
         fm.plain(b'\n')
 
     timings.sort()
     min_val = timings[0]
     display(b'best', min_val)
     if displayall:
         max_val = timings[-1]
         display(b'max', max_val)
         avg = tuple([sum(x) / count for x in zip(*timings)])
         display(b'avg', avg)
         median = timings[len(timings) // 2]
         display(b'median', median)
 
 
 # utilities for historical portability
 
 
 def getint(ui, section, name, default):
     # for "historical portability":
     # ui.configint has been available since 1.9 (or fa2b596db182)
     v = ui.config(section, name, None)
     if v is None:
         return default
     try:
         return int(v)
     except ValueError:
         raise error.ConfigError(
             b"%s.%s is not an integer ('%s')" % (section, name, v)
         )
 
 
 def safeattrsetter(obj, name, ignoremissing=False):
     """Ensure that 'obj' has 'name' attribute before subsequent setattr
 
     This function is aborted, if 'obj' doesn't have 'name' attribute
     at runtime. This avoids overlooking removal of an attribute, which
     breaks assumption of performance measurement, in the future.
 
     This function returns the object to (1) assign a new value, and
     (2) restore an original value to the attribute.
 
     If 'ignoremissing' is true, missing 'name' attribute doesn't cause
     abortion, and this function returns None. This is useful to
     examine an attribute, which isn't ensured in all Mercurial
     versions.
     """
     if not util.safehasattr(obj, name):
         if ignoremissing:
             return None
         raise error.Abort(
             (
                 b"missing attribute %s of %s might break assumption"
                 b" of performance measurement"
             )
             % (name, obj)
         )
 
     origvalue = getattr(obj, _sysstr(name))
 
     class attrutil:
         def set(self, newvalue):
             setattr(obj, _sysstr(name), newvalue)
 
         def restore(self):
             setattr(obj, _sysstr(name), origvalue)
 
     return attrutil()
 
 
 # utilities to examine each internal API changes
 
 
 def getbranchmapsubsettable():
     # for "historical portability":
     # subsettable is defined in:
     # - branchmap since 2.9 (or 175c6fd8cacc)
     # - repoview since 2.5 (or 59a9f18d4587)
     # - repoviewutil since 5.0
     for mod in (branchmap, repoview, repoviewutil):
         subsettable = getattr(mod, 'subsettable', None)
         if subsettable:
             return subsettable
 
     # bisecting in bcee63733aad::59a9f18d4587 can reach here (both
     # branchmap and repoview modules exist, but subsettable attribute
     # doesn't)
     raise error.Abort(
         b"perfbranchmap not available with this Mercurial",
         hint=b"use 2.5 or later",
     )
 
 
 def getsvfs(repo):
     """Return appropriate object to access files under .hg/store"""
     # for "historical portability":
     # repo.svfs has been available since 2.3 (or 7034365089bf)
     svfs = getattr(repo, 'svfs', None)
     if svfs:
         return svfs
     else:
         return getattr(repo, 'sopener')
 
 
 def getvfs(repo):
     """Return appropriate object to access files under .hg"""
     # for "historical portability":
     # repo.vfs has been available since 2.3 (or 7034365089bf)
     vfs = getattr(repo, 'vfs', None)
     if vfs:
         return vfs
     else:
         return getattr(repo, 'opener')
 
 
 def repocleartagscachefunc(repo):
     """Return the function to clear tags cache according to repo internal API"""
     if util.safehasattr(repo, b'_tagscache'):  # since 2.0 (or 9dca7653b525)
         # in this case, setattr(repo, '_tagscache', None) or so isn't
         # correct way to clear tags cache, because existing code paths
         # expect _tagscache to be a structured object.
         def clearcache():
             # _tagscache has been filteredpropertycache since 2.5 (or
             # 98c867ac1330), and delattr() can't work in such case
             if '_tagscache' in vars(repo):
                 del repo.__dict__['_tagscache']
 
         return clearcache
 
     repotags = safeattrsetter(repo, b'_tags', ignoremissing=True)
     if repotags:  # since 1.4 (or 5614a628d173)
         return lambda: repotags.set(None)
 
     repotagscache = safeattrsetter(repo, b'tagscache', ignoremissing=True)
     if repotagscache:  # since 0.6 (or d7df759d0e97)
         return lambda: repotagscache.set(None)
 
     # Mercurial earlier than 0.6 (or d7df759d0e97) logically reaches
     # this point, but it isn't so problematic, because:
     # - repo.tags of such Mercurial isn't "callable", and repo.tags()
     #   in perftags() causes failure soon
     # - perf.py itself has been available since 1.1 (or eb240755386d)
     raise error.Abort(b"tags API of this hg command is unknown")
 
 
 # utilities to clear cache
 
 
 def clearfilecache(obj, attrname):
     unfiltered = getattr(obj, 'unfiltered', None)
     if unfiltered is not None:
         obj = obj.unfiltered()
     if attrname in vars(obj):
         delattr(obj, attrname)
     obj._filecache.pop(attrname, None)
 
 
 def clearchangelog(repo):
     if repo is not repo.unfiltered():
         object.__setattr__(repo, '_clcachekey', None)
         object.__setattr__(repo, '_clcache', None)
     clearfilecache(repo.unfiltered(), 'changelog')
 
 
 # perf commands
 
 
 @command(b'perf::walk|perfwalk', formatteropts)
 def perfwalk(ui, repo, *pats, **opts):
     opts = _byteskwargs(opts)
     timer, fm = gettimer(ui, opts)
     m = scmutil.match(repo[None], pats, {})
     timer(
         lambda: len(
             list(
                 repo.dirstate.walk(m, subrepos=[], unknown=True, ignored=False)
             )
         )
     )
     fm.end()
 
 
 @command(b'perf::annotate|perfannotate', formatteropts)
 def perfannotate(ui, repo, f, **opts):
     opts = _byteskwargs(opts)
     timer, fm = gettimer(ui, opts)
     fc = repo[b'.'][f]
     timer(lambda: len(fc.annotate(True)))
     fm.end()
 
 
 @command(
     b'perf::status|perfstatus',
     [
         (b'u', b'unknown', False, b'ask status to look for unknown files'),
         (b'', b'dirstate', False, b'benchmark the internal dirstate call'),
     ]
     + formatteropts,
 )
 def perfstatus(ui, repo, **opts):
     """benchmark the performance of a single status call
 
     The repository data are preserved between each call.
 
     By default, only the status of the tracked file are requested. If
     `--unknown` is passed, the "unknown" files are also tracked.
     """
     opts = _byteskwargs(opts)
     # m = match.always(repo.root, repo.getcwd())
     # timer(lambda: sum(map(len, repo.dirstate.status(m, [], False, False,
     #                                                False))))
     timer, fm = gettimer(ui, opts)
     if opts[b'dirstate']:
         dirstate = repo.dirstate
         m = scmutil.matchall(repo)
         unknown = opts[b'unknown']
 
         def status_dirstate():
             s = dirstate.status(
                 m, subrepos=[], ignored=False, clean=False, unknown=unknown
             )
             sum(map(bool, s))
 
         if util.safehasattr(dirstate, 'running_status'):
             with dirstate.running_status(repo):
                 timer(status_dirstate)
                 dirstate.invalidate()
         else:
             timer(status_dirstate)
     else:
         timer(lambda: sum(map(len, repo.status(unknown=opts[b'unknown']))))
     fm.end()
 
 
 @command(b'perf::addremove|perfaddremove', formatteropts)
 def perfaddremove(ui, repo, **opts):
     opts = _byteskwargs(opts)
     timer, fm = gettimer(ui, opts)
     try:
         oldquiet = repo.ui.quiet
         repo.ui.quiet = True
         matcher = scmutil.match(repo[None])
         opts[b'dry_run'] = True
         if 'uipathfn' in getargspec(scmutil.addremove).args:
             uipathfn = scmutil.getuipathfn(repo)
             timer(lambda: scmutil.addremove(repo, matcher, b"", uipathfn, opts))
         else:
             timer(lambda: scmutil.addremove(repo, matcher, b"", opts))
     finally:
         repo.ui.quiet = oldquiet
         fm.end()
 
 
 def clearcaches(cl):
     # behave somewhat consistently across internal API changes
     if util.safehasattr(cl, b'clearcaches'):
         cl.clearcaches()
     elif util.safehasattr(cl, b'_nodecache'):
         # <= hg-5.2
         from mercurial.node import nullid, nullrev
 
         cl._nodecache = {nullid: nullrev}
         cl._nodepos = None
 
 
 @command(b'perf::heads|perfheads', formatteropts)
 def perfheads(ui, repo, **opts):
     """benchmark the computation of a changelog heads"""
     opts = _byteskwargs(opts)
     timer, fm = gettimer(ui, opts)
     cl = repo.changelog
 
     def s():
         clearcaches(cl)
 
     def d():
         len(cl.headrevs())
 
     timer(d, setup=s)
     fm.end()
 
 
 def _default_clear_on_disk_tags_cache(repo):
     from mercurial import tags
 
     repo.cachevfs.tryunlink(tags._filename(repo))
 
 
 def _default_clear_on_disk_tags_fnodes_cache(repo):
     from mercurial import tags
 
     repo.cachevfs.tryunlink(tags._fnodescachefile)
 
 
 def _default_forget_fnodes(repo, revs):
     """function used by the perf extension to prune some entries from the
     fnodes cache"""
     from mercurial import tags
 
     missing_1 = b'\xff' * 4
     missing_2 = b'\xff' * 20
     cache = tags.hgtagsfnodescache(repo.unfiltered())
     for r in revs:
         cache._writeentry(r * tags._fnodesrecsize, missing_1, missing_2)
     cache.write()
 
 
 @command(
     b'perf::tags|perftags',
     formatteropts
     + [
         (b'', b'clear-revlogs', False, b'refresh changelog and manifest'),
         (
             b'',
             b'clear-on-disk-cache',
             False,
             b'clear on disk tags cache (DESTRUCTIVE)',
         ),
         (
             b'',
             b'clear-fnode-cache-all',
             False,
             b'clear on disk file node cache (DESTRUCTIVE),',
         ),
         (
             b'',
             b'clear-fnode-cache-rev',
             [],
             b'clear on disk file node cache (DESTRUCTIVE),',
             b'REVS',
         ),
         (
             b'',
             b'update-last',
             b'',
             b'simulate an update over the last N revisions (DESTRUCTIVE),',
             b'N',
         ),
     ],
 )
 def perftags(ui, repo, **opts):
     """Benchmark tags retrieval in various situation
 
     The option marked as (DESTRUCTIVE) will alter the on-disk cache, possibly
     altering performance after the command was run. However, it does not
     destroy any stored data.
     """
     from mercurial import tags
 
     opts = _byteskwargs(opts)
     timer, fm = gettimer(ui, opts)
     repocleartagscache = repocleartagscachefunc(repo)
     clearrevlogs = opts[b'clear_revlogs']
     clear_disk = opts[b'clear_on_disk_cache']
     clear_fnode = opts[b'clear_fnode_cache_all']
 
     clear_fnode_revs = opts[b'clear_fnode_cache_rev']
     update_last_str = opts[b'update_last']
     update_last = None
     if update_last_str:
         try:
             update_last = int(update_last_str)
         except ValueError:
             msg = b'could not parse value for update-last: "%s"'
             msg %= update_last_str
             hint = b'value should be an integer'
             raise error.Abort(msg, hint=hint)
 
     clear_disk_fn = getattr(
         tags,
         "clear_cache_on_disk",
         _default_clear_on_disk_tags_cache,
     )
     if getattr(tags, 'clear_cache_fnodes_is_working', False):
         clear_fnodes_fn = tags.clear_cache_fnodes
     else:
         clear_fnodes_fn = _default_clear_on_disk_tags_fnodes_cache
     clear_fnodes_rev_fn = getattr(
         tags,
         "forget_fnodes",
         _default_forget_fnodes,
     )
 
     clear_revs = []
     if clear_fnode_revs:
         clear_revs.extend(scmutil.revrange(repo, clear_fnode_revs))
 
     if update_last:
         revset = b'last(all(), %d)' % update_last
         last_revs = repo.unfiltered().revs(revset)
         clear_revs.extend(last_revs)
 
         from mercurial import repoview
 
         rev_filter = {(b'experimental', b'extra-filter-revs'): revset}
         with repo.ui.configoverride(rev_filter, source=b"perf"):
             filter_id = repoview.extrafilter(repo.ui)
 
         filter_name = b'%s%%%s' % (repo.filtername, filter_id)
         pre_repo = repo.filtered(filter_name)
         pre_repo.tags()  # warm the cache
         old_tags_path = repo.cachevfs.join(tags._filename(pre_repo))
         new_tags_path = repo.cachevfs.join(tags._filename(repo))
 
     clear_revs = sorted(set(clear_revs))
 
     def s():
         if update_last:
             util.copyfile(old_tags_path, new_tags_path)
         if clearrevlogs:
             clearchangelog(repo)
             clearfilecache(repo.unfiltered(), 'manifest')
         if clear_disk:
             clear_disk_fn(repo)
         if clear_fnode:
             clear_fnodes_fn(repo)
         elif clear_revs:
             clear_fnodes_rev_fn(repo, clear_revs)
         repocleartagscache()
 
     def t():
         len(repo.tags())
 
     timer(t, setup=s)
     fm.end()
 
 
 @command(b'perf::ancestors|perfancestors', formatteropts)
 def perfancestors(ui, repo, **opts):
     opts = _byteskwargs(opts)
     timer, fm = gettimer(ui, opts)
     heads = repo.changelog.headrevs()
 
     def d():
         for a in repo.changelog.ancestors(heads):
             pass
 
     timer(d)
     fm.end()
 
 
 @command(b'perf::ancestorset|perfancestorset', formatteropts)
 def perfancestorset(ui, repo, revset, **opts):
     opts = _byteskwargs(opts)
     timer, fm = gettimer(ui, opts)
     revs = repo.revs(revset)
     heads = repo.changelog.headrevs()
 
     def d():
         s = repo.changelog.ancestors(heads)
         for rev in revs:
             rev in s
 
     timer(d)
     fm.end()
 
 
 @command(
     b'perf::delta-find',
     revlogopts + formatteropts,
     b'-c|-m|FILE REV',
 )
 def perf_delta_find(ui, repo, arg_1, arg_2=None, **opts):
     """benchmark the process of finding a valid delta for a revlog revision
 
     When a revlog receives a new revision (e.g. from a commit, or from an
     incoming bundle), it searches for a suitable delta-base to produce a delta.
     This perf command measures how much time we spend in this process. It
     operates on an already stored revision.
 
     See `hg help debug-delta-find` for another related command.
     """
     from mercurial import revlogutils
     import mercurial.revlogutils.deltas as deltautil
 
     opts = _byteskwargs(opts)
     if arg_2 is None:
         file_ = None
         rev = arg_1
     else:
         file_ = arg_1
         rev = arg_2
 
     repo = repo.unfiltered()
 
     timer, fm = gettimer(ui, opts)
 
     rev = int(rev)
 
     revlog = cmdutil.openrevlog(repo, b'perf::delta-find', file_, opts)
 
     deltacomputer = deltautil.deltacomputer(revlog)
 
     node = revlog.node(rev)
     p1r, p2r = revlog.parentrevs(rev)
     p1 = revlog.node(p1r)
     p2 = revlog.node(p2r)
     full_text = revlog.revision(rev)
     textlen = len(full_text)
     cachedelta = None
     flags = revlog.flags(rev)
 
     revinfo = revlogutils.revisioninfo(
         node,
         p1,
         p2,
         [full_text],  # btext
         textlen,
         cachedelta,
         flags,
     )
 
     # Note: we should probably purge the potential caches (like the full
     # manifest cache) between runs.
     def find_one():
         with revlog._datafp() as fh:
             deltacomputer.finddeltainfo(revinfo, fh, target_rev=rev)
 
     timer(find_one)
     fm.end()
 
 
 @command(b'perf::discovery|perfdiscovery', formatteropts, b'PATH')
 def perfdiscovery(ui, repo, path, **opts):
     """benchmark discovery between local repo and the peer at given path"""
     repos = [repo, None]
     timer, fm = gettimer(ui, opts)
 
     try:
         from mercurial.utils.urlutil import get_unique_pull_path_obj
 
         path = get_unique_pull_path_obj(b'perfdiscovery', ui, path)
     except ImportError:
         try:
             from mercurial.utils.urlutil import get_unique_pull_path
 
             path = get_unique_pull_path(b'perfdiscovery', repo, ui, path)[0]
         except ImportError:
             path = ui.expandpath(path)
 
     def s():
         repos[1] = hg.peer(ui, opts, path)
 
     def d():
         setdiscovery.findcommonheads(ui, *repos)
 
     timer(d, setup=s)
     fm.end()
 
 
 @command(
     b'perf::bookmarks|perfbookmarks',
     formatteropts
     + [
         (b'', b'clear-revlogs', False, b'refresh changelog and manifest'),
     ],
 )
 def perfbookmarks(ui, repo, **opts):
     """benchmark parsing bookmarks from disk to memory"""
     opts = _byteskwargs(opts)
     timer, fm = gettimer(ui, opts)
 
     clearrevlogs = opts[b'clear_revlogs']
 
     def s():
         if clearrevlogs:
             clearchangelog(repo)
         clearfilecache(repo, b'_bookmarks')
 
     def d():
         repo._bookmarks
 
     timer(d, setup=s)
     fm.end()
 
 
 @command(
     b'perf::bundle',
     [
         (
             b'r',
             b'rev',
             [],
             b'changesets to bundle',
             b'REV',
         ),
         (
             b't',
             b'type',
             b'none',
             b'bundlespec to use (see `hg help bundlespec`)',
             b'TYPE',
         ),
     ]
     + formatteropts,
     b'REVS',
 )
 def perfbundle(ui, repo, *revs, **opts):
     """benchmark the creation of a bundle from a repository
 
     For now, this only supports "none" compression.
     """
     try:
         from mercurial import bundlecaches
 
         parsebundlespec = bundlecaches.parsebundlespec
     except ImportError:
         from mercurial import exchange
 
         parsebundlespec = exchange.parsebundlespec
 
     from mercurial import discovery
     from mercurial import bundle2
 
     opts = _byteskwargs(opts)
     timer, fm = gettimer(ui, opts)
 
     cl = repo.changelog
     revs = list(revs)
     revs.extend(opts.get(b'rev', ()))
     revs = scmutil.revrange(repo, revs)
     if not revs:
         raise error.Abort(b"not revision specified")
     # make it a consistent set (ie: without topological gaps)
     old_len = len(revs)
     revs = list(repo.revs(b"%ld::%ld", revs, revs))
     if old_len != len(revs):
         new_count = len(revs) - old_len
         msg = b"add %d new revisions to make it a consistent set\n"
         ui.write_err(msg % new_count)
 
     targets = [cl.node(r) for r in repo.revs(b"heads(::%ld)", revs)]
     bases = [cl.node(r) for r in repo.revs(b"heads(::%ld - %ld)", revs, revs)]
     outgoing = discovery.outgoing(repo, bases, targets)
 
     bundle_spec = opts.get(b'type')
 
     bundle_spec = parsebundlespec(repo, bundle_spec, strict=False)
 
     cgversion = bundle_spec.params.get(b"cg.version")
     if cgversion is None:
         if bundle_spec.version == b'v1':
             cgversion = b'01'
         if bundle_spec.version == b'v2':
             cgversion = b'02'
     if cgversion not in changegroup.supportedoutgoingversions(repo):
         err = b"repository does not support bundle version %s"
         raise error.Abort(err % cgversion)
 
     if cgversion == b'01':  # bundle1
         bversion = b'HG10' + bundle_spec.wirecompression
         bcompression = None
     elif cgversion in (b'02', b'03'):
         bversion = b'HG20'
         bcompression = bundle_spec.wirecompression
     else:
         err = b'perf::bundle: unexpected changegroup version %s'
         raise error.ProgrammingError(err % cgversion)
 
     if bcompression is None:
         bcompression = b'UN'
 
     if bcompression != b'UN':
         err = b'perf::bundle: compression currently unsupported: %s'
         raise error.ProgrammingError(err % bcompression)
 
     def do_bundle():
         bundle2.writenewbundle(
             ui,
             repo,
             b'perf::bundle',
             os.devnull,
             bversion,
             outgoing,
             bundle_spec.params,
         )
 
     timer(do_bundle)
     fm.end()
 
 
 @command(b'perf::bundleread|perfbundleread', formatteropts, b'BUNDLE')
 def perfbundleread(ui, repo, bundlepath, **opts):
     """Benchmark reading of bundle files.
 
     This command is meant to isolate the I/O part of bundle reading as
     much as possible.
     """
     from mercurial import (
         bundle2,
         exchange,
         streamclone,
     )
 
     opts = _byteskwargs(opts)
 
     def makebench(fn):
         def run():
             with open(bundlepath, b'rb') as fh:
                 bundle = exchange.readbundle(ui, fh, bundlepath)
                 fn(bundle)
 
         return run
 
     def makereadnbytes(size):
         def run():
             with open(bundlepath, b'rb') as fh:
                 bundle = exchange.readbundle(ui, fh, bundlepath)
                 while bundle.read(size):
                     pass
 
         return run
 
     def makestdioread(size):
         def run():
             with open(bundlepath, b'rb') as fh:
                 while fh.read(size):
                     pass
 
         return run
 
     # bundle1
 
     def deltaiter(bundle):
         for delta in bundle.deltaiter():
             pass
 
     def iterchunks(bundle):
         for chunk in bundle.getchunks():
             pass
 
     # bundle2
 
     def forwardchunks(bundle):
         for chunk in bundle._forwardchunks():
             pass
 
     def iterparts(bundle):
         for part in bundle.iterparts():
             pass
 
     def iterpartsseekable(bundle):
         for part in bundle.iterparts(seekable=True):
             pass
 
     def seek(bundle):
         for part in bundle.iterparts(seekable=True):
             part.seek(0, os.SEEK_END)
 
     def makepartreadnbytes(size):
         def run():
             with open(bundlepath, b'rb') as fh:
                 bundle = exchange.readbundle(ui, fh, bundlepath)
                 for part in bundle.iterparts():
                     while part.read(size):
                         pass
 
         return run
 
     benches = [
         (makestdioread(8192), b'read(8k)'),
         (makestdioread(16384), b'read(16k)'),
         (makestdioread(32768), b'read(32k)'),
         (makestdioread(131072), b'read(128k)'),
     ]
 
     with open(bundlepath, b'rb') as fh:
         bundle = exchange.readbundle(ui, fh, bundlepath)
 
         if isinstance(bundle, changegroup.cg1unpacker):
             benches.extend(
                 [
                     (makebench(deltaiter), b'cg1 deltaiter()'),
                     (makebench(iterchunks), b'cg1 getchunks()'),
                     (makereadnbytes(8192), b'cg1 read(8k)'),
                     (makereadnbytes(16384), b'cg1 read(16k)'),
                     (makereadnbytes(32768), b'cg1 read(32k)'),
                     (makereadnbytes(131072), b'cg1 read(128k)'),
                 ]
             )
         elif isinstance(bundle, bundle2.unbundle20):
             benches.extend(
                 [
                     (makebench(forwardchunks), b'bundle2 forwardchunks()'),
                     (makebench(iterparts), b'bundle2 iterparts()'),
                     (
                         makebench(iterpartsseekable),
                         b'bundle2 iterparts() seekable',
                     ),
                     (makebench(seek), b'bundle2 part seek()'),
                     (makepartreadnbytes(8192), b'bundle2 part read(8k)'),
                     (makepartreadnbytes(16384), b'bundle2 part read(16k)'),
                     (makepartreadnbytes(32768), b'bundle2 part read(32k)'),
                     (makepartreadnbytes(131072), b'bundle2 part read(128k)'),
                 ]
             )
         elif isinstance(bundle, streamclone.streamcloneapplier):
             raise error.Abort(b'stream clone bundles not supported')
         else:
             raise error.Abort(b'unhandled bundle type: %s' % type(bundle))
 
     for fn, title in benches:
         timer, fm = gettimer(ui, opts)
         timer(fn, title=title)
         fm.end()
 
 
 @command(
     b'perf::changegroupchangelog|perfchangegroupchangelog',
     formatteropts
     + [
         (b'', b'cgversion', b'02', b'changegroup version'),
         (b'r', b'rev', b'', b'revisions to add to changegroup'),
     ],
 )
 def perfchangegroupchangelog(ui, repo, cgversion=b'02', rev=None, **opts):
     """Benchmark producing a changelog group for a changegroup.
 
     This measures the time spent processing the changelog during a
     bundle operation. This occurs during `hg bundle` and on a server
     processing a `getbundle` wire protocol request (handles clones
     and pull requests).
 
     By default, all revisions are added to the changegroup.
     """
     opts = _byteskwargs(opts)
     cl = repo.changelog
     nodes = [cl.lookup(r) for r in repo.revs(rev or b'all()')]
     bundler = changegroup.getbundler(cgversion, repo)
 
     def d():
         state, chunks = bundler._generatechangelog(cl, nodes)
         for chunk in chunks:
             pass
 
     timer, fm = gettimer(ui, opts)
 
     # Terminal printing can interfere with timing. So disable it.
     with ui.configoverride({(b'progress', b'disable'): True}):
         timer(d)
 
     fm.end()
 
 
 @command(b'perf::dirs|perfdirs', formatteropts)
 def perfdirs(ui, repo, **opts):
     opts = _byteskwargs(opts)
     timer, fm = gettimer(ui, opts)
     dirstate = repo.dirstate
     b'a' in dirstate
 
     def d():
         dirstate.hasdir(b'a')
         try:
             del dirstate._map._dirs
         except AttributeError:
             pass
 
     timer(d)
     fm.end()
 
 
 @command(
     b'perf::dirstate|perfdirstate',
     [
         (
             b'',
             b'iteration',
             None,
             b'benchmark a full iteration for the dirstate',
         ),
         (
             b'',
             b'contains',
             None,
             b'benchmark a large amount of `nf in dirstate` calls',
         ),
     ]
     + formatteropts,
 )
 def perfdirstate(ui, repo, **opts):
     """benchmap the time of various distate operations
 
     By default benchmark the time necessary to load a dirstate from scratch.
     The dirstate is loaded to the point were a "contains" request can be
     answered.
     """
     opts = _byteskwargs(opts)
     timer, fm = gettimer(ui, opts)
     b"a" in repo.dirstate
 
     if opts[b'iteration'] and opts[b'contains']:
         msg = b'only specify one of --iteration or --contains'
         raise error.Abort(msg)
 
     if opts[b'iteration']:
         setup = None
         dirstate = repo.dirstate
 
         def d():
             for f in dirstate:
                 pass
 
     elif opts[b'contains']:
         setup = None
         dirstate = repo.dirstate
         allfiles = list(dirstate)
         # also add file path that will be "missing" from the dirstate
         allfiles.extend([f[::-1] for f in allfiles])
 
         def d():
             for f in allfiles:
                 f in dirstate
 
     else:
 
         def setup():
             repo.dirstate.invalidate()
 
         def d():
             b"a" in repo.dirstate
 
     timer(d, setup=setup)
     fm.end()
 
 
 @command(b'perf::dirstatedirs|perfdirstatedirs', formatteropts)
 def perfdirstatedirs(ui, repo, **opts):
     """benchmap a 'dirstate.hasdir' call from an empty `dirs` cache"""
     opts = _byteskwargs(opts)
     timer, fm = gettimer(ui, opts)
     repo.dirstate.hasdir(b"a")
 
     def setup():
         try:
             del repo.dirstate._map._dirs
         except AttributeError:
             pass
 
     def d():
         repo.dirstate.hasdir(b"a")
 
     timer(d, setup=setup)
     fm.end()
 
 
 @command(b'perf::dirstatefoldmap|perfdirstatefoldmap', formatteropts)
 def perfdirstatefoldmap(ui, repo, **opts):
     """benchmap a `dirstate._map.filefoldmap.get()` request
 
     The dirstate filefoldmap cache is dropped between every request.
     """
     opts = _byteskwargs(opts)
     timer, fm = gettimer(ui, opts)
     dirstate = repo.dirstate
     dirstate._map.filefoldmap.get(b'a')
 
     def setup():
         del dirstate._map.filefoldmap
 
     def d():
         dirstate._map.filefoldmap.get(b'a')
 
     timer(d, setup=setup)
     fm.end()
 
 
 @command(b'perf::dirfoldmap|perfdirfoldmap', formatteropts)
 def perfdirfoldmap(ui, repo, **opts):
     """benchmap a `dirstate._map.dirfoldmap.get()` request
 
     The dirstate dirfoldmap cache is dropped between every request.
     """
     opts = _byteskwargs(opts)
     timer, fm = gettimer(ui, opts)
     dirstate = repo.dirstate
     dirstate._map.dirfoldmap.get(b'a')
 
     def setup():
         del dirstate._map.dirfoldmap
         try:
             del dirstate._map._dirs
         except AttributeError:
             pass
 
     def d():
         dirstate._map.dirfoldmap.get(b'a')
 
     timer(d, setup=setup)
     fm.end()
 
 
 @command(b'perf::dirstatewrite|perfdirstatewrite', formatteropts)
 def perfdirstatewrite(ui, repo, **opts):
     """benchmap the time it take to write a dirstate on disk"""
     opts = _byteskwargs(opts)
     timer, fm = gettimer(ui, opts)
     ds = repo.dirstate
     b"a" in ds
 
     def setup():
         ds._dirty = True
 
     def d():
         ds.write(repo.currenttransaction())
 
     with repo.wlock():
         timer(d, setup=setup)
     fm.end()
 
 
 def _getmergerevs(repo, opts):
     """parse command argument to return rev involved in merge
 
     input: options dictionnary with `rev`, `from` and `bse`
     output: (localctx, otherctx, basectx)
     """
     if opts[b'from']:
         fromrev = scmutil.revsingle(repo, opts[b'from'])
         wctx = repo[fromrev]
     else:
         wctx = repo[None]
         # we don't want working dir files to be stat'd in the benchmark, so
         # prime that cache
         wctx.dirty()
     rctx = scmutil.revsingle(repo, opts[b'rev'], opts[b'rev'])
     if opts[b'base']:
         fromrev = scmutil.revsingle(repo, opts[b'base'])
         ancestor = repo[fromrev]
     else:
         ancestor = wctx.ancestor(rctx)
     return (wctx, rctx, ancestor)
 
 
 @command(
     b'perf::mergecalculate|perfmergecalculate',
     [
         (b'r', b'rev', b'.', b'rev to merge against'),
         (b'', b'from', b'', b'rev to merge from'),
         (b'', b'base', b'', b'the revision to use as base'),
     ]
     + formatteropts,
 )
 def perfmergecalculate(ui, repo, **opts):
     opts = _byteskwargs(opts)
     timer, fm = gettimer(ui, opts)
 
     wctx, rctx, ancestor = _getmergerevs(repo, opts)
 
     def d():
         # acceptremote is True because we don't want prompts in the middle of
         # our benchmark
         merge.calculateupdates(
             repo,
             wctx,
             rctx,
             [ancestor],
             branchmerge=False,
             force=False,
             acceptremote=True,
             followcopies=True,
         )
 
     timer(d)
     fm.end()
 
 
 @command(
     b'perf::mergecopies|perfmergecopies',
     [
         (b'r', b'rev', b'.', b'rev to merge against'),
         (b'', b'from', b'', b'rev to merge from'),
         (b'', b'base', b'', b'the revision to use as base'),
     ]
     + formatteropts,
 )
 def perfmergecopies(ui, repo, **opts):
     """measure runtime of `copies.mergecopies`"""
     opts = _byteskwargs(opts)
     timer, fm = gettimer(ui, opts)
     wctx, rctx, ancestor = _getmergerevs(repo, opts)
 
     def d():
         # acceptremote is True because we don't want prompts in the middle of
         # our benchmark
         copies.mergecopies(repo, wctx, rctx, ancestor)
 
     timer(d)
     fm.end()
 
 
 @command(b'perf::pathcopies|perfpathcopies', [], b"REV REV")
 def perfpathcopies(ui, repo, rev1, rev2, **opts):
     """benchmark the copy tracing logic"""
     opts = _byteskwargs(opts)
     timer, fm = gettimer(ui, opts)
     ctx1 = scmutil.revsingle(repo, rev1, rev1)
     ctx2 = scmutil.revsingle(repo, rev2, rev2)
 
     def d():
         copies.pathcopies(ctx1, ctx2)
 
     timer(d)
     fm.end()
 
 
 @command(
     b'perf::phases|perfphases',
     [
         (b'', b'full', False, b'include file reading time too'),
     ]
     + formatteropts,
     b"",
 )
 def perfphases(ui, repo, **opts):
     """benchmark phasesets computation"""
     opts = _byteskwargs(opts)
     timer, fm = gettimer(ui, opts)
     _phases = repo._phasecache
     full = opts.get(b'full')
     tip_rev = repo.changelog.tiprev()
 
     def d():
         phases = _phases
         if full:
             clearfilecache(repo, b'_phasecache')
             phases = repo._phasecache
         phases.invalidate()
         phases.phase(repo, tip_rev)
 
     timer(d)
     fm.end()
 
 
 @command(b'perf::phasesremote|perfphasesremote', [], b"[DEST]")
 def perfphasesremote(ui, repo, dest=None, **opts):
     """benchmark time needed to analyse phases of the remote server"""
     from mercurial.node import bin
     from mercurial import (
         exchange,
         hg,
         phases,
     )
 
     opts = _byteskwargs(opts)
     timer, fm = gettimer(ui, opts)
 
     path = ui.getpath(dest, default=(b'default-push', b'default'))
     if not path:
         raise error.Abort(
             b'default repository not configured!',
             hint=b"see 'hg help config.paths'",
         )
     if util.safehasattr(path, 'main_path'):
         path = path.get_push_variant()
         dest = path.loc
     else:
         dest = path.pushloc or path.loc
     ui.statusnoi18n(b'analysing phase of %s\n' % util.hidepassword(dest))
     other = hg.peer(repo, opts, dest)
 
     # easier to perform discovery through the operation
     op = exchange.pushoperation(repo, other)
     exchange._pushdiscoverychangeset(op)
 
     remotesubset = op.fallbackheads
 
     with other.commandexecutor() as e:
         remotephases = e.callcommand(
             b'listkeys', {b'namespace': b'phases'}
         ).result()
     del other
     publishing = remotephases.get(b'publishing', False)
     if publishing:
         ui.statusnoi18n(b'publishing: yes\n')
     else:
         ui.statusnoi18n(b'publishing: no\n')
 
     has_node = getattr(repo.changelog.index, 'has_node', None)
     if has_node is None:
         has_node = repo.changelog.nodemap.__contains__
     nonpublishroots = 0
     for nhex, phase in remotephases.iteritems():
         if nhex == b'publishing':  # ignore data related to publish option
             continue
         node = bin(nhex)
         if has_node(node) and int(phase):
             nonpublishroots += 1
     ui.statusnoi18n(b'number of roots: %d\n' % len(remotephases))
     ui.statusnoi18n(b'number of known non public roots: %d\n' % nonpublishroots)
 
     def d():
         phases.remotephasessummary(repo, remotesubset, remotephases)
 
     timer(d)
     fm.end()
 
 
 @command(
     b'perf::manifest|perfmanifest',
     [
         (b'm', b'manifest-rev', False, b'Look up a manifest node revision'),
         (b'', b'clear-disk', False, b'clear on-disk caches too'),
     ]
     + formatteropts,
     b'REV|NODE',
 )
 def perfmanifest(ui, repo, rev, manifest_rev=False, clear_disk=False, **opts):
     """benchmark the time to read a manifest from disk and return a usable
     dict-like object
 
     Manifest caches are cleared before retrieval."""
     opts = _byteskwargs(opts)
     timer, fm = gettimer(ui, opts)
     if not manifest_rev:
         ctx = scmutil.revsingle(repo, rev, rev)
         t = ctx.manifestnode()
     else:
         from mercurial.node import bin
 
         if len(rev) == 40:
             t = bin(rev)
         else:
             try:
                 rev = int(rev)
 
                 if util.safehasattr(repo.manifestlog, b'getstorage'):
                     t = repo.manifestlog.getstorage(b'').node(rev)
                 else:
                     t = repo.manifestlog._revlog.lookup(rev)
             except ValueError:
                 raise error.Abort(
                     b'manifest revision must be integer or full node'
                 )
 
     def d():
         repo.manifestlog.clearcaches(clear_persisted_data=clear_disk)
         repo.manifestlog[t].read()
 
     timer(d)
     fm.end()
 
 
 @command(b'perf::changeset|perfchangeset', formatteropts)
 def perfchangeset(ui, repo, rev, **opts):
     opts = _byteskwargs(opts)
     timer, fm = gettimer(ui, opts)
     n = scmutil.revsingle(repo, rev).node()
 
     def d():
         repo.changelog.read(n)
         # repo.changelog._cache = None
 
     timer(d)
     fm.end()
 
 
 @command(b'perf::ignore|perfignore', formatteropts)
 def perfignore(ui, repo, **opts):
     """benchmark operation related to computing ignore"""
     opts = _byteskwargs(opts)
     timer, fm = gettimer(ui, opts)
     dirstate = repo.dirstate
 
     def setupone():
         dirstate.invalidate()
         clearfilecache(dirstate, b'_ignore')
 
     def runone():
         dirstate._ignore
 
     timer(runone, setup=setupone, title=b"load")
     fm.end()
 
 
 @command(
     b'perf::index|perfindex',
     [
         (b'', b'rev', [], b'revision to be looked up (default tip)'),
         (b'', b'no-lookup', None, b'do not revision lookup post creation'),
     ]
     + formatteropts,
 )
 def perfindex(ui, repo, **opts):
     """benchmark index creation time followed by a lookup
 
     The default is to look `tip` up. Depending on the index implementation,
     the revision looked up can matters. For example, an implementation
     scanning the index will have a faster lookup time for `--rev tip` than for
     `--rev 0`. The number of looked up revisions and their order can also
     matters.
 
     Example of useful set to test:
 
     * tip
     * 0
     * -10:
     * :10
     * -10: + :10
     * :10: + -10:
     * -10000:
     * -10000: + 0
 
     It is not currently possible to check for lookup of a missing node. For
     deeper lookup benchmarking, checkout the `perfnodemap` command."""
     import mercurial.revlog
 
     opts = _byteskwargs(opts)
     timer, fm = gettimer(ui, opts)
     mercurial.revlog._prereadsize = 2 ** 24  # disable lazy parser in old hg
     if opts[b'no_lookup']:
         if opts['rev']:
             raise error.Abort('--no-lookup and --rev are mutually exclusive')
         nodes = []
     elif not opts[b'rev']:
         nodes = [repo[b"tip"].node()]
     else:
         revs = scmutil.revrange(repo, opts[b'rev'])
         cl = repo.changelog
         nodes = [cl.node(r) for r in revs]
 
     unfi = repo.unfiltered()
     # find the filecache func directly
     # This avoid polluting the benchmark with the filecache logic
     makecl = unfi.__class__.changelog.func
 
     def setup():
         # probably not necessary, but for good measure
         clearchangelog(unfi)
 
     def d():
         cl = makecl(unfi)
         for n in nodes:
             cl.rev(n)
 
     timer(d, setup=setup)
     fm.end()
 
 
 @command(
     b'perf::nodemap|perfnodemap',
     [
         (b'', b'rev', [], b'revision to be looked up (default tip)'),
         (b'', b'clear-caches', True, b'clear revlog cache between calls'),
     ]
     + formatteropts,
 )
 def perfnodemap(ui, repo, **opts):
     """benchmark the time necessary to look up revision from a cold nodemap
 
     Depending on the implementation, the amount and order of revision we look
     up can varies. Example of useful set to test:
     * tip
     * 0
     * -10:
     * :10
     * -10: + :10
     * :10: + -10:
     * -10000:
     * -10000: + 0
 
     The command currently focus on valid binary lookup. Benchmarking for
     hexlookup, prefix lookup and missing lookup would also be valuable.
     """
     import mercurial.revlog
 
     opts = _byteskwargs(opts)
     timer, fm = gettimer(ui, opts)
     mercurial.revlog._prereadsize = 2 ** 24  # disable lazy parser in old hg
 
     unfi = repo.unfiltered()
     clearcaches = opts[b'clear_caches']
     # find the filecache func directly
     # This avoid polluting the benchmark with the filecache logic
     makecl = unfi.__class__.changelog.func
     if not opts[b'rev']:
         raise error.Abort(b'use --rev to specify revisions to look up')
     revs = scmutil.revrange(repo, opts[b'rev'])
     cl = repo.changelog
     nodes = [cl.node(r) for r in revs]
 
     # use a list to pass reference to a nodemap from one closure to the next
     nodeget = [None]
 
     def setnodeget():
         # probably not necessary, but for good measure
         clearchangelog(unfi)
         cl = makecl(unfi)
         if util.safehasattr(cl.index, 'get_rev'):
             nodeget[0] = cl.index.get_rev
         else:
             nodeget[0] = cl.nodemap.get
 
     def d():
         get = nodeget[0]
         for n in nodes:
             get(n)
 
     setup = None
     if clearcaches:
 
         def setup():
             setnodeget()
 
     else:
         setnodeget()
         d()  # prewarm the data structure
     timer(d, setup=setup)
     fm.end()
 
 
 @command(b'perf::startup|perfstartup', formatteropts)
 def perfstartup(ui, repo, **opts):
     opts = _byteskwargs(opts)
     timer, fm = gettimer(ui, opts)
 
     def d():
         if os.name != 'nt':
             os.system(
                 b"HGRCPATH= %s version -q > /dev/null" % fsencode(sys.argv[0])
             )
         else:
             os.environ['HGRCPATH'] = r' '
             os.system("%s version -q > NUL" % sys.argv[0])
 
     timer(d)
     fm.end()
 
 
 def _find_stream_generator(version):
     """find the proper generator function for this stream version"""
     import mercurial.streamclone
 
     available = {}
 
     # try to fetch a v1 generator
     generatev1 = getattr(mercurial.streamclone, "generatev1", None)
     if generatev1 is not None:
 
         def generate(repo):
             entries, bytes, data = generatev2(repo, None, None, True)
             return data
 
         available[b'v1'] = generatev1
     # try to fetch a v2 generator
     generatev2 = getattr(mercurial.streamclone, "generatev2", None)
     if generatev2 is not None:
 
         def generate(repo):
             entries, bytes, data = generatev2(repo, None, None, True)
             return data
 
         available[b'v2'] = generate
     # try to fetch a v3 generator
     generatev3 = getattr(mercurial.streamclone, "generatev3", None)
     if generatev3 is not None:
 
         def generate(repo):
             entries, bytes, data = generatev3(repo, None, None, True)
             return data
 
         available[b'v3-exp'] = generate
 
     # resolve the request
     if version == b"latest":
         # latest is the highest non experimental version
         latest_key = max(v for v in available if b'-exp' not in v)
         return available[latest_key]
     elif version in available:
         return available[version]
     else:
         msg = b"unkown or unavailable version: %s"
         msg %= version
         hint = b"available versions: %s"
         hint %= b', '.join(sorted(available))
         raise error.Abort(msg, hint=hint)
 
 
 @command(
     b'perf::stream-locked-section',
     [
         (
             b'',
             b'stream-version',
             b'latest',
             b'stream version to use ("v1", "v2", "v3" or "latest", (the default))',
         ),
     ]
     + formatteropts,
 )
 def perf_stream_clone_scan(ui, repo, stream_version, **opts):
     """benchmark the initial, repo-locked, section of a stream-clone"""
 
     opts = _byteskwargs(opts)
     timer, fm = gettimer(ui, opts)
 
     # deletion of the generator may trigger some cleanup that we do not want to
     # measure
     result_holder = [None]
 
     def setupone():
         result_holder[0] = None
 
     generate = _find_stream_generator(stream_version)
 
     def runone():
         # the lock is held for the duration the initialisation
         result_holder[0] = generate(repo)
 
     timer(runone, setup=setupone, title=b"load")
     fm.end()
 
 
 @command(
     b'perf::stream-generate',
     [
         (
             b'',
             b'stream-version',
             b'latest',
             b'stream version to us ("v1", "v2" or "latest", (the default))',
         ),
     ]
     + formatteropts,
 )
 def perf_stream_clone_generate(ui, repo, stream_version, **opts):
     """benchmark the full generation of a stream clone"""
 
     opts = _byteskwargs(opts)
     timer, fm = gettimer(ui, opts)
 
     # deletion of the generator may trigger some cleanup that we do not want to
     # measure
 
     generate = _find_stream_generator(stream_version)
 
     def runone():
         # the lock is held for the duration the initialisation
         for chunk in generate(repo):
             pass
 
     timer(runone, title=b"generate")
     fm.end()
 
 
 @command(
     b'perf::stream-consume',
     formatteropts,
 )
 def perf_stream_clone_consume(ui, repo, filename, **opts):
     """benchmark the full application of a stream clone
 
     This include the creation of the repository
     """
     # try except to appease check code
     msg = b"mercurial too old, missing necessary module: %s"
     try:
         from mercurial import bundle2
     except ImportError as exc:
         msg %= _bytestr(exc)
         raise error.Abort(msg)
     try:
         from mercurial import exchange
     except ImportError as exc:
         msg %= _bytestr(exc)
         raise error.Abort(msg)
     try:
         from mercurial import hg
     except ImportError as exc:
         msg %= _bytestr(exc)
         raise error.Abort(msg)
     try:
         from mercurial import localrepo
     except ImportError as exc:
         msg %= _bytestr(exc)
         raise error.Abort(msg)
 
     opts = _byteskwargs(opts)
     timer, fm = gettimer(ui, opts)
 
     # deletion of the generator may trigger some cleanup that we do not want to
     # measure
     if not (os.path.isfile(filename) and os.access(filename, os.R_OK)):
         raise error.Abort("not a readable file: %s" % filename)
 
     run_variables = [None, None]
 
     @contextlib.contextmanager
     def context():
         with open(filename, mode='rb') as bundle:
             with tempfile.TemporaryDirectory() as tmp_dir:
                 tmp_dir = fsencode(tmp_dir)
                 run_variables[0] = bundle
                 run_variables[1] = tmp_dir
                 yield
                 run_variables[0] = None
                 run_variables[1] = None
 
     def runone():
         bundle = run_variables[0]
         tmp_dir = run_variables[1]
         # only pass ui when no srcrepo
         localrepo.createrepository(
             repo.ui, tmp_dir, requirements=repo.requirements
         )
         target = hg.repository(repo.ui, tmp_dir)
         gen = exchange.readbundle(target.ui, bundle, bundle.name)
         # stream v1
         if util.safehasattr(gen, 'apply'):
             gen.apply(target)
         else:
             with target.transaction(b"perf::stream-consume") as tr:
                 bundle2.applybundle(
                     target,
                     gen,
                     tr,
                     source=b'unbundle',
                     url=filename,
                 )
 
     timer(runone, context=context, title=b"consume")
     fm.end()
 
 
 @command(b'perf::parents|perfparents', formatteropts)
 def perfparents(ui, repo, **opts):
     """benchmark the time necessary to fetch one changeset's parents.
 
     The fetch is done using the `node identifier`, traversing all object layers
     from the repository object. The first N revisions will be used for this
     benchmark. N is controlled by the ``perf.parentscount`` config option
     (default: 1000).
     """
     opts = _byteskwargs(opts)
     timer, fm = gettimer(ui, opts)
     # control the number of commits perfparents iterates over
     # experimental config: perf.parentscount
     count = getint(ui, b"perf", b"parentscount", 1000)
     if len(repo.changelog) < count:
         raise error.Abort(b"repo needs %d commits for this test" % count)
     repo = repo.unfiltered()
     nl = [repo.changelog.node(i) for i in _xrange(count)]
 
     def d():
         for n in nl:
             repo.changelog.parents(n)
 
     timer(d)
     fm.end()
 
 
 @command(b'perf::ctxfiles|perfctxfiles', formatteropts)
 def perfctxfiles(ui, repo, x, **opts):
     opts = _byteskwargs(opts)
     x = int(x)
     timer, fm = gettimer(ui, opts)
 
     def d():
         len(repo[x].files())
 
     timer(d)
     fm.end()
 
 
 @command(b'perf::rawfiles|perfrawfiles', formatteropts)
 def perfrawfiles(ui, repo, x, **opts):
     opts = _byteskwargs(opts)
     x = int(x)
     timer, fm = gettimer(ui, opts)
     cl = repo.changelog
 
     def d():
         len(cl.read(x)[3])
 
     timer(d)
     fm.end()
 
 
 @command(b'perf::lookup|perflookup', formatteropts)
 def perflookup(ui, repo, rev, **opts):
     opts = _byteskwargs(opts)
     timer, fm = gettimer(ui, opts)
     timer(lambda: len(repo.lookup(rev)))
     fm.end()
 
 
 @command(
     b'perf::linelogedits|perflinelogedits',
     [
         (b'n', b'edits', 10000, b'number of edits'),
         (b'', b'max-hunk-lines', 10, b'max lines in a hunk'),
     ],
     norepo=True,
 )
 def perflinelogedits(ui, **opts):
     from mercurial import linelog
 
     opts = _byteskwargs(opts)
 
     edits = opts[b'edits']
     maxhunklines = opts[b'max_hunk_lines']
 
     maxb1 = 100000
     random.seed(0)
     randint = random.randint
     currentlines = 0
     arglist = []
     for rev in _xrange(edits):
         a1 = randint(0, currentlines)
         a2 = randint(a1, min(currentlines, a1 + maxhunklines))
         b1 = randint(0, maxb1)
         b2 = randint(b1, b1 + maxhunklines)
         currentlines += (b2 - b1) - (a2 - a1)
         arglist.append((rev, a1, a2, b1, b2))
 
     def d():
         ll = linelog.linelog()
         for args in arglist:
             ll.replacelines(*args)
 
     timer, fm = gettimer(ui, opts)
     timer(d)
     fm.end()
 
 
 @command(b'perf::revrange|perfrevrange', formatteropts)
 def perfrevrange(ui, repo, *specs, **opts):
     opts = _byteskwargs(opts)
     timer, fm = gettimer(ui, opts)
     revrange = scmutil.revrange
     timer(lambda: len(revrange(repo, specs)))
     fm.end()
 
 
 @command(b'perf::nodelookup|perfnodelookup', formatteropts)
 def perfnodelookup(ui, repo, rev, **opts):
     opts = _byteskwargs(opts)
     timer, fm = gettimer(ui, opts)
     import mercurial.revlog
 
     mercurial.revlog._prereadsize = 2 ** 24  # disable lazy parser in old hg
     n = scmutil.revsingle(repo, rev).node()
 
     try:
         cl = revlog(getsvfs(repo), radix=b"00changelog")
     except TypeError:
         cl = revlog(getsvfs(repo), indexfile=b"00changelog.i")
 
     def d():
         cl.rev(n)
         clearcaches(cl)
 
     timer(d)
     fm.end()
 
 
 @command(
     b'perf::log|perflog',
     [(b'', b'rename', False, b'ask log to follow renames')] + formatteropts,
 )
 def perflog(ui, repo, rev=None, **opts):
     opts = _byteskwargs(opts)
     if rev is None:
         rev = []
     timer, fm = gettimer(ui, opts)
     ui.pushbuffer()
     timer(
         lambda: commands.log(
             ui, repo, rev=rev, date=b'', user=b'', copies=opts.get(b'rename')
         )
     )
     ui.popbuffer()
     fm.end()
 
 
 @command(b'perf::moonwalk|perfmoonwalk', formatteropts)
 def perfmoonwalk(ui, repo, **opts):
     """benchmark walking the changelog backwards
 
     This also loads the changelog data for each revision in the changelog.
     """
     opts = _byteskwargs(opts)
     timer, fm = gettimer(ui, opts)
 
     def moonwalk():
         for i in repo.changelog.revs(start=(len(repo) - 1), stop=-1):
             ctx = repo[i]
             ctx.branch()  # read changelog data (in addition to the index)
 
     timer(moonwalk)
     fm.end()
 
 
 @command(
     b'perf::templating|perftemplating',
     [
         (b'r', b'rev', [], b'revisions to run the template on'),
     ]
     + formatteropts,
 )
 def perftemplating(ui, repo, testedtemplate=None, **opts):
     """test the rendering time of a given template"""
     if makelogtemplater is None:
         raise error.Abort(
             b"perftemplating not available with this Mercurial",
             hint=b"use 4.3 or later",
         )
 
     opts = _byteskwargs(opts)
 
     nullui = ui.copy()
     nullui.fout = open(os.devnull, 'wb')
     nullui.disablepager()
     revs = opts.get(b'rev')
     if not revs:
         revs = [b'all()']
     revs = list(scmutil.revrange(repo, revs))
 
     defaulttemplate = (
         b'{date|shortdate} [{rev}:{node|short}]'
         b' {author|person}: {desc|firstline}\n'
     )
     if testedtemplate is None:
         testedtemplate = defaulttemplate
     displayer = makelogtemplater(nullui, repo, testedtemplate)
 
     def format():
         for r in revs:
             ctx = repo[r]
             displayer.show(ctx)
             displayer.flush(ctx)
 
     timer, fm = gettimer(ui, opts)
     timer(format)
     fm.end()
 
 
 def _displaystats(ui, opts, entries, data):
     # use a second formatter because the data are quite different, not sure
     # how it flies with the templater.
     fm = ui.formatter(b'perf-stats', opts)
     for key, title in entries:
         values = data[key]
         nbvalues = len(data)
         values.sort()
         stats = {
             'key': key,
             'title': title,
             'nbitems': len(values),
             'min': values[0][0],
             '10%': values[(nbvalues * 10) // 100][0],
             '25%': values[(nbvalues * 25) // 100][0],
             '50%': values[(nbvalues * 50) // 100][0],
             '75%': values[(nbvalues * 75) // 100][0],
             '80%': values[(nbvalues * 80) // 100][0],
             '85%': values[(nbvalues * 85) // 100][0],
             '90%': values[(nbvalues * 90) // 100][0],
             '95%': values[(nbvalues * 95) // 100][0],
             '99%': values[(nbvalues * 99) // 100][0],
             'max': values[-1][0],
         }
         fm.startitem()
         fm.data(**stats)
         # make node pretty for the human output
         fm.plain('### %s (%d items)\n' % (title, len(values)))
         lines = [
             'min',
             '10%',
             '25%',
             '50%',
             '75%',
             '80%',
             '85%',
             '90%',
             '95%',
             '99%',
             'max',
         ]
         for l in lines:
             fm.plain('%s: %s\n' % (l, stats[l]))
     fm.end()
 
 
 @command(
     b'perf::helper-mergecopies|perfhelper-mergecopies',
     formatteropts
     + [
         (b'r', b'revs', [], b'restrict search to these revisions'),
         (b'', b'timing', False, b'provides extra data (costly)'),
         (b'', b'stats', False, b'provides statistic about the measured data'),
     ],
 )
 def perfhelpermergecopies(ui, repo, revs=[], **opts):
     """find statistics about potential parameters for `perfmergecopies`
 
     This command find (base, p1, p2) triplet relevant for copytracing
     benchmarking in the context of a merge.  It reports values for some of the
     parameters that impact merge copy tracing time during merge.
 
     If `--timing` is set, rename detection is run and the associated timing
     will be reported. The extra details come at the cost of slower command
     execution.
 
     Since rename detection is only run once, other factors might easily
     affect the precision of the timing. However it should give a good
     approximation of which revision triplets are very costly.
     """
     opts = _byteskwargs(opts)
     fm = ui.formatter(b'perf', opts)
     dotiming = opts[b'timing']
     dostats = opts[b'stats']
 
     output_template = [
         ("base", "%(base)12s"),
         ("p1", "%(p1.node)12s"),
         ("p2", "%(p2.node)12s"),
         ("p1.nb-revs", "%(p1.nbrevs)12d"),
         ("p1.nb-files", "%(p1.nbmissingfiles)12d"),
         ("p1.renames", "%(p1.renamedfiles)12d"),
         ("p1.time", "%(p1.time)12.3f"),
         ("p2.nb-revs", "%(p2.nbrevs)12d"),
         ("p2.nb-files", "%(p2.nbmissingfiles)12d"),
         ("p2.renames", "%(p2.renamedfiles)12d"),
         ("p2.time", "%(p2.time)12.3f"),
         ("renames", "%(nbrenamedfiles)12d"),
         ("total.time", "%(time)12.3f"),
     ]
     if not dotiming:
         output_template = [
             i
             for i in output_template
             if not ('time' in i[0] or 'renames' in i[0])
         ]
     header_names = [h for (h, v) in output_template]
     output = ' '.join([v for (h, v) in output_template]) + '\n'
     header = ' '.join(['%12s'] * len(header_names)) + '\n'
     fm.plain(header % tuple(header_names))
 
     if not revs:
         revs = ['all()']
     revs = scmutil.revrange(repo, revs)
 
     if dostats:
         alldata = {
             'nbrevs': [],
             'nbmissingfiles': [],
         }
         if dotiming:
             alldata['parentnbrenames'] = []
             alldata['totalnbrenames'] = []
             alldata['parenttime'] = []
             alldata['totaltime'] = []
 
     roi = repo.revs('merge() and %ld', revs)
     for r in roi:
         ctx = repo[r]
         p1 = ctx.p1()
         p2 = ctx.p2()
         bases = repo.changelog._commonancestorsheads(p1.rev(), p2.rev())
         for b in bases:
             b = repo[b]
             p1missing = copies._computeforwardmissing(b, p1)
             p2missing = copies._computeforwardmissing(b, p2)
             data = {
                 b'base': b.hex(),
                 b'p1.node': p1.hex(),
                 b'p1.nbrevs': len(repo.revs('only(%d, %d)', p1.rev(), b.rev())),
                 b'p1.nbmissingfiles': len(p1missing),
                 b'p2.node': p2.hex(),
                 b'p2.nbrevs': len(repo.revs('only(%d, %d)', p2.rev(), b.rev())),
                 b'p2.nbmissingfiles': len(p2missing),
             }
             if dostats:
                 if p1missing:
                     alldata['nbrevs'].append(
                         (data['p1.nbrevs'], b.hex(), p1.hex())
                     )
                     alldata['nbmissingfiles'].append(
                         (data['p1.nbmissingfiles'], b.hex(), p1.hex())
                     )
                 if p2missing:
                     alldata['nbrevs'].append(
                         (data['p2.nbrevs'], b.hex(), p2.hex())
                     )
                     alldata['nbmissingfiles'].append(
                         (data['p2.nbmissingfiles'], b.hex(), p2.hex())
                     )
             if dotiming:
                 begin = util.timer()
                 mergedata = copies.mergecopies(repo, p1, p2, b)
                 end = util.timer()
                 # not very stable timing since we did only one run
                 data['time'] = end - begin
                 # mergedata contains five dicts: "copy", "movewithdir",
                 # "diverge", "renamedelete" and "dirmove".
                 # The first 4 are about renamed file so lets count that.
                 renames = len(mergedata[0])
                 renames += len(mergedata[1])
                 renames += len(mergedata[2])
                 renames += len(mergedata[3])
                 data['nbrenamedfiles'] = renames
                 begin = util.timer()
                 p1renames = copies.pathcopies(b, p1)
                 end = util.timer()
                 data['p1.time'] = end - begin
                 begin = util.timer()
                 p2renames = copies.pathcopies(b, p2)
                 end = util.timer()
                 data['p2.time'] = end - begin
                 data['p1.renamedfiles'] = len(p1renames)
                 data['p2.renamedfiles'] = len(p2renames)
 
                 if dostats:
                     if p1missing:
                         alldata['parentnbrenames'].append(
                             (data['p1.renamedfiles'], b.hex(), p1.hex())
                         )
                         alldata['parenttime'].append(
                             (data['p1.time'], b.hex(), p1.hex())
                         )
                     if p2missing:
                         alldata['parentnbrenames'].append(
                             (data['p2.renamedfiles'], b.hex(), p2.hex())
                         )
                         alldata['parenttime'].append(
                             (data['p2.time'], b.hex(), p2.hex())
                         )
                     if p1missing or p2missing:
                         alldata['totalnbrenames'].append(
                             (
                                 data['nbrenamedfiles'],
                                 b.hex(),
                                 p1.hex(),
                                 p2.hex(),
                             )
                         )
                         alldata['totaltime'].append(
                             (data['time'], b.hex(), p1.hex(), p2.hex())
                         )
             fm.startitem()
             fm.data(**data)
             # make node pretty for the human output
             out = data.copy()
             out['base'] = fm.hexfunc(b.node())
             out['p1.node'] = fm.hexfunc(p1.node())
             out['p2.node'] = fm.hexfunc(p2.node())
             fm.plain(output % out)
 
     fm.end()
     if dostats:
         # use a second formatter because the data are quite different, not sure
         # how it flies with the templater.
         entries = [
             ('nbrevs', 'number of revision covered'),
             ('nbmissingfiles', 'number of missing files at head'),
         ]
         if dotiming:
             entries.append(
                 ('parentnbrenames', 'rename from one parent to base')
             )
             entries.append(('totalnbrenames', 'total number of renames'))
             entries.append(('parenttime', 'time for one parent'))
             entries.append(('totaltime', 'time for both parents'))
         _displaystats(ui, opts, entries, alldata)
 
 
 @command(
     b'perf::helper-pathcopies|perfhelper-pathcopies',
     formatteropts
     + [
         (b'r', b'revs', [], b'restrict search to these revisions'),
         (b'', b'timing', False, b'provides extra data (costly)'),
         (b'', b'stats', False, b'provides statistic about the measured data'),
     ],
 )
 def perfhelperpathcopies(ui, repo, revs=[], **opts):
     """find statistic about potential parameters for the `perftracecopies`
 
     This command find source-destination pair relevant for copytracing testing.
     It report value for some of the parameters that impact copy tracing time.
 
     If `--timing` is set, rename detection is run and the associated timing
     will be reported. The extra details comes at the cost of a slower command
     execution.
 
     Since the rename detection is only run once, other factors might easily
     affect the precision of the timing. However it should give a good
     approximation of which revision pairs are very costly.
     """
     opts = _byteskwargs(opts)
     fm = ui.formatter(b'perf', opts)
     dotiming = opts[b'timing']
     dostats = opts[b'stats']
 
     if dotiming:
         header = '%12s %12s %12s %12s %12s %12s\n'
         output = (
             "%(source)12s %(destination)12s "
             "%(nbrevs)12d %(nbmissingfiles)12d "
             "%(nbrenamedfiles)12d %(time)18.5f\n"
         )
         header_names = (
             "source",
             "destination",
             "nb-revs",
             "nb-files",
             "nb-renames",
             "time",
         )
         fm.plain(header % header_names)
     else:
         header = '%12s %12s %12s %12s\n'
         output = (
             "%(source)12s %(destination)12s "
             "%(nbrevs)12d %(nbmissingfiles)12d\n"
         )
         fm.plain(header % ("source", "destination", "nb-revs", "nb-files"))
 
     if not revs:
         revs = ['all()']
     revs = scmutil.revrange(repo, revs)
 
     if dostats:
         alldata = {
             'nbrevs': [],
             'nbmissingfiles': [],
         }
         if dotiming:
             alldata['nbrenames'] = []
             alldata['time'] = []
 
     roi = repo.revs('merge() and %ld', revs)
     for r in roi:
         ctx = repo[r]
         p1 = ctx.p1().rev()
         p2 = ctx.p2().rev()
         bases = repo.changelog._commonancestorsheads(p1, p2)
         for p in (p1, p2):
             for b in bases:
                 base = repo[b]
                 parent = repo[p]
                 missing = copies._computeforwardmissing(base, parent)
                 if not missing:
                     continue
                 data = {
                     b'source': base.hex(),
                     b'destination': parent.hex(),
                     b'nbrevs': len(repo.revs('only(%d, %d)', p, b)),
                     b'nbmissingfiles': len(missing),
                 }
                 if dostats:
                     alldata['nbrevs'].append(
                         (
                             data['nbrevs'],
                             base.hex(),
                             parent.hex(),
                         )
                     )
                     alldata['nbmissingfiles'].append(
                         (
                             data['nbmissingfiles'],
                             base.hex(),
                             parent.hex(),
                         )
                     )
                 if dotiming:
                     begin = util.timer()
                     renames = copies.pathcopies(base, parent)
                     end = util.timer()
                     # not very stable timing since we did only one run
                     data['time'] = end - begin
                     data['nbrenamedfiles'] = len(renames)
                     if dostats:
                         alldata['time'].append(
                             (
                                 data['time'],
                                 base.hex(),
                                 parent.hex(),
                             )
                         )
                         alldata['nbrenames'].append(
                             (
                                 data['nbrenamedfiles'],
                                 base.hex(),
                                 parent.hex(),
                             )
                         )
                 fm.startitem()
                 fm.data(**data)
                 out = data.copy()
                 out['source'] = fm.hexfunc(base.node())
                 out['destination'] = fm.hexfunc(parent.node())
                 fm.plain(output % out)
 
     fm.end()
     if dostats:
         entries = [
             ('nbrevs', 'number of revision covered'),
             ('nbmissingfiles', 'number of missing files at head'),
         ]
         if dotiming:
             entries.append(('nbrenames', 'renamed files'))
             entries.append(('time', 'time'))
         _displaystats(ui, opts, entries, alldata)
 
 
 @command(b'perf::cca|perfcca', formatteropts)
 def perfcca(ui, repo, **opts):
     opts = _byteskwargs(opts)
     timer, fm = gettimer(ui, opts)
     timer(lambda: scmutil.casecollisionauditor(ui, False, repo.dirstate))
     fm.end()
 
 
 @command(b'perf::fncacheload|perffncacheload', formatteropts)
 def perffncacheload(ui, repo, **opts):
     opts = _byteskwargs(opts)
     timer, fm = gettimer(ui, opts)
     s = repo.store
 
     def d():
         s.fncache._load()
 
     timer(d)
     fm.end()
 
 
 @command(b'perf::fncachewrite|perffncachewrite', formatteropts)
 def perffncachewrite(ui, repo, **opts):
     opts = _byteskwargs(opts)
     timer, fm = gettimer(ui, opts)
     s = repo.store
     lock = repo.lock()
     s.fncache._load()
     tr = repo.transaction(b'perffncachewrite')
     tr.addbackup(b'fncache')
 
     def d():
         s.fncache._dirty = True
         s.fncache.write(tr)
 
     timer(d)
     tr.close()
     lock.release()
     fm.end()
 
 
 @command(b'perf::fncacheencode|perffncacheencode', formatteropts)
 def perffncacheencode(ui, repo, **opts):
     opts = _byteskwargs(opts)
     timer, fm = gettimer(ui, opts)
     s = repo.store
     s.fncache._load()
 
     def d():
         for p in s.fncache.entries:
             s.encode(p)
 
     timer(d)
     fm.end()
 
 
 def _bdiffworker(q, blocks, xdiff, ready, done):
     while not done.is_set():
         pair = q.get()
         while pair is not None:
             if xdiff:
                 mdiff.bdiff.xdiffblocks(*pair)
             elif blocks:
                 mdiff.bdiff.blocks(*pair)
             else:
                 mdiff.textdiff(*pair)
             q.task_done()
             pair = q.get()
         q.task_done()  # for the None one
         with ready:
             ready.wait()
 
 
 def _manifestrevision(repo, mnode):
     ml = repo.manifestlog
 
     if util.safehasattr(ml, b'getstorage'):
         store = ml.getstorage(b'')
     else:
         store = ml._revlog
 
     return store.revision(mnode)
 
 
 @command(
     b'perf::bdiff|perfbdiff',
     revlogopts
     + formatteropts
     + [
         (
             b'',
             b'count',
             1,
             b'number of revisions to test (when using --startrev)',
         ),
         (b'', b'alldata', False, b'test bdiffs for all associated revisions'),
         (b'', b'threads', 0, b'number of thread to use (disable with 0)'),
         (b'', b'blocks', False, b'test computing diffs into blocks'),
         (b'', b'xdiff', False, b'use xdiff algorithm'),
     ],
     b'-c|-m|FILE REV',
 )
 def perfbdiff(ui, repo, file_, rev=None, count=None, threads=0, **opts):
     """benchmark a bdiff between revisions
 
     By default, benchmark a bdiff between its delta parent and itself.
 
     With ``--count``, benchmark bdiffs between delta parents and self for N
     revisions starting at the specified revision.
 
     With ``--alldata``, assume the requested revision is a changeset and
     measure bdiffs for all changes related to that changeset (manifest
     and filelogs).
     """
     opts = _byteskwargs(opts)
 
     if opts[b'xdiff'] and not opts[b'blocks']:
         raise error.CommandError(b'perfbdiff', b'--xdiff requires --blocks')
 
     if opts[b'alldata']:
         opts[b'changelog'] = True
 
     if opts.get(b'changelog') or opts.get(b'manifest'):
         file_, rev = None, file_
     elif rev is None:
         raise error.CommandError(b'perfbdiff', b'invalid arguments')
 
     blocks = opts[b'blocks']
     xdiff = opts[b'xdiff']
     textpairs = []
 
     r = cmdutil.openrevlog(repo, b'perfbdiff', file_, opts)
 
     startrev = r.rev(r.lookup(rev))
     for rev in range(startrev, min(startrev + count, len(r) - 1)):
         if opts[b'alldata']:
             # Load revisions associated with changeset.
             ctx = repo[rev]
             mtext = _manifestrevision(repo, ctx.manifestnode())
             for pctx in ctx.parents():
                 pman = _manifestrevision(repo, pctx.manifestnode())
                 textpairs.append((pman, mtext))
 
             # Load filelog revisions by iterating manifest delta.
             man = ctx.manifest()
             pman = ctx.p1().manifest()
             for filename, change in pman.diff(man).items():
                 fctx = repo.file(filename)
                 f1 = fctx.revision(change[0][0] or -1)
                 f2 = fctx.revision(change[1][0] or -1)
                 textpairs.append((f1, f2))
         else:
             dp = r.deltaparent(rev)
             textpairs.append((r.revision(dp), r.revision(rev)))
 
     withthreads = threads > 0
     if not withthreads:
 
         def d():
             for pair in textpairs:
                 if xdiff:
                     mdiff.bdiff.xdiffblocks(*pair)
                 elif blocks:
                     mdiff.bdiff.blocks(*pair)
                 else:
                     mdiff.textdiff(*pair)
 
     else:
         q = queue()
         for i in _xrange(threads):
             q.put(None)
         ready = threading.Condition()
         done = threading.Event()
         for i in _xrange(threads):
             threading.Thread(
                 target=_bdiffworker, args=(q, blocks, xdiff, ready, done)
             ).start()
         q.join()
 
         def d():
             for pair in textpairs:
                 q.put(pair)
             for i in _xrange(threads):
                 q.put(None)
             with ready:
                 ready.notify_all()
             q.join()
 
     timer, fm = gettimer(ui, opts)
     timer(d)
     fm.end()
 
     if withthreads:
         done.set()
         for i in _xrange(threads):
             q.put(None)
         with ready:
             ready.notify_all()
 
 
 @command(
     b'perf::unbundle',
     [
         (b'', b'as-push', None, b'pretend the bundle comes from a push'),
     ]
     + formatteropts,
     b'BUNDLE_FILE',
 )
 def perf_unbundle(ui, repo, fname, **opts):
     """benchmark application of a bundle in a repository.
 
     This does not include the final transaction processing
 
     The --as-push option make the unbundle operation appears like it comes from
     a client push. It change some aspect of the processing and associated
     performance profile.
     """
 
     from mercurial import exchange
     from mercurial import bundle2
     from mercurial import transaction
 
     opts = _byteskwargs(opts)
 
     ###  some compatibility hotfix
     #
     # the data attribute is dropped in 63edc384d3b7 a changeset introducing a
     # critical regression that break transaction rollback for files that are
     # de-inlined.
     method = transaction.transaction._addentry
     pre_63edc384d3b7 = "data" in getargspec(method).args
     # the `detailed_exit_code` attribute is introduced in 33c0c25d0b0f
     # a changeset that is a close descendant of 18415fc918a1, the changeset
     # that conclude the fix run for the bug introduced in 63edc384d3b7.
     args = getargspec(error.Abort.__init__).args
     post_18415fc918a1 = "detailed_exit_code" in args
 
     unbundle_source = b'perf::unbundle'
     if opts[b'as_push']:
         unbundle_source = b'push'
 
     old_max_inline = None
     try:
         if not (pre_63edc384d3b7 or post_18415fc918a1):
             # disable inlining
             old_max_inline = mercurial.revlog._maxinline
             # large enough to never happen
             mercurial.revlog._maxinline = 2 ** 50
 
         with repo.lock():
             bundle = [None, None]
             orig_quiet = repo.ui.quiet
             try:
                 repo.ui.quiet = True
                 with open(fname, mode="rb") as f:
 
                     def noop_report(*args, **kwargs):
                         pass
 
                     def setup():
                         gen, tr = bundle
                         if tr is not None:
                             tr.abort()
                         bundle[:] = [None, None]
                         f.seek(0)
                         bundle[0] = exchange.readbundle(ui, f, fname)
                         bundle[1] = repo.transaction(b'perf::unbundle')
                         # silence the transaction
                         bundle[1]._report = noop_report
 
                     def apply():
                         gen, tr = bundle
                         bundle2.applybundle(
                             repo,
                             gen,
                             tr,
                             source=unbundle_source,
                             url=fname,
                         )
 
                     timer, fm = gettimer(ui, opts)
                     timer(apply, setup=setup)
                     fm.end()
             finally:
                 repo.ui.quiet == orig_quiet
                 gen, tr = bundle
                 if tr is not None:
                     tr.abort()
     finally:
         if old_max_inline is not None:
             mercurial.revlog._maxinline = old_max_inline
 
 
 @command(
     b'perf::unidiff|perfunidiff',
     revlogopts
     + formatteropts
     + [
         (
             b'',
             b'count',
             1,
             b'number of revisions to test (when using --startrev)',
         ),
         (b'', b'alldata', False, b'test unidiffs for all associated revisions'),
     ],
     b'-c|-m|FILE REV',
 )
 def perfunidiff(ui, repo, file_, rev=None, count=None, **opts):
     """benchmark a unified diff between revisions
 
     This doesn't include any copy tracing - it's just a unified diff
     of the texts.
 
     By default, benchmark a diff between its delta parent and itself.
 
     With ``--count``, benchmark diffs between delta parents and self for N
     revisions starting at the specified revision.
 
     With ``--alldata``, assume the requested revision is a changeset and
     measure diffs for all changes related to that changeset (manifest
     and filelogs).
     """
     opts = _byteskwargs(opts)
     if opts[b'alldata']:
         opts[b'changelog'] = True
 
     if opts.get(b'changelog') or opts.get(b'manifest'):
         file_, rev = None, file_
     elif rev is None:
         raise error.CommandError(b'perfunidiff', b'invalid arguments')
 
     textpairs = []
 
     r = cmdutil.openrevlog(repo, b'perfunidiff', file_, opts)
 
     startrev = r.rev(r.lookup(rev))
     for rev in range(startrev, min(startrev + count, len(r) - 1)):
         if opts[b'alldata']:
             # Load revisions associated with changeset.
             ctx = repo[rev]
             mtext = _manifestrevision(repo, ctx.manifestnode())
             for pctx in ctx.parents():
                 pman = _manifestrevision(repo, pctx.manifestnode())
                 textpairs.append((pman, mtext))
 
             # Load filelog revisions by iterating manifest delta.
             man = ctx.manifest()
             pman = ctx.p1().manifest()
             for filename, change in pman.diff(man).items():
                 fctx = repo.file(filename)
                 f1 = fctx.revision(change[0][0] or -1)
                 f2 = fctx.revision(change[1][0] or -1)
                 textpairs.append((f1, f2))
         else:
             dp = r.deltaparent(rev)
             textpairs.append((r.revision(dp), r.revision(rev)))
 
     def d():
         for left, right in textpairs:
             # The date strings don't matter, so we pass empty strings.
             headerlines, hunks = mdiff.unidiff(
                 left, b'', right, b'', b'left', b'right', binary=False
             )
             # consume iterators in roughly the way patch.py does
             b'\n'.join(headerlines)
             b''.join(sum((list(hlines) for hrange, hlines in hunks), []))
 
     timer, fm = gettimer(ui, opts)
     timer(d)
     fm.end()
 
 
 @command(b'perf::diffwd|perfdiffwd', formatteropts)
 def perfdiffwd(ui, repo, **opts):
     """Profile diff of working directory changes"""
     opts = _byteskwargs(opts)
     timer, fm = gettimer(ui, opts)
     options = {
         'w': 'ignore_all_space',
         'b': 'ignore_space_change',
         'B': 'ignore_blank_lines',
     }
 
     for diffopt in ('', 'w', 'b', 'B', 'wB'):
         opts = {options[c]: b'1' for c in diffopt}
 
         def d():
             ui.pushbuffer()
             commands.diff(ui, repo, **opts)
             ui.popbuffer()
 
         diffopt = diffopt.encode('ascii')
         title = b'diffopts: %s' % (diffopt and (b'-' + diffopt) or b'none')
         timer(d, title=title)
     fm.end()
 
 
 @command(
     b'perf::revlogindex|perfrevlogindex',
     revlogopts + formatteropts,
     b'-c|-m|FILE',
 )
 def perfrevlogindex(ui, repo, file_=None, **opts):
     """Benchmark operations against a revlog index.
 
     This tests constructing a revlog instance, reading index data,
     parsing index data, and performing various operations related to
     index data.
     """
 
     opts = _byteskwargs(opts)
 
     rl = cmdutil.openrevlog(repo, b'perfrevlogindex', file_, opts)
 
     opener = getattr(rl, 'opener')  # trick linter
     # compat with hg <= 5.8
     radix = getattr(rl, 'radix', None)
     indexfile = getattr(rl, '_indexfile', None)
     if indexfile is None:
         # compatibility with <= hg-5.8
         indexfile = getattr(rl, 'indexfile')
     data = opener.read(indexfile)
 
     header = struct.unpack(b'>I', data[0:4])[0]
     version = header & 0xFFFF
     if version == 1:
         inline = header & (1 << 16)
     else:
         raise error.Abort(b'unsupported revlog version: %d' % version)
 
     parse_index_v1 = getattr(mercurial.revlog, 'parse_index_v1', None)
     if parse_index_v1 is None:
         parse_index_v1 = mercurial.revlog.revlogio().parseindex
 
     rllen = len(rl)
 
     node0 = rl.node(0)
     node25 = rl.node(rllen // 4)
     node50 = rl.node(rllen // 2)
     node75 = rl.node(rllen // 4 * 3)
     node100 = rl.node(rllen - 1)
 
     allrevs = range(rllen)
     allrevsrev = list(reversed(allrevs))
     allnodes = [rl.node(rev) for rev in range(rllen)]
     allnodesrev = list(reversed(allnodes))
 
     def constructor():
         if radix is not None:
             revlog(opener, radix=radix)
         else:
             # hg <= 5.8
             revlog(opener, indexfile=indexfile)
 
     def read():
         with opener(indexfile) as fh:
             fh.read()
 
     def parseindex():
         parse_index_v1(data, inline)
 
     def getentry(revornode):
         index = parse_index_v1(data, inline)[0]
         index[revornode]
 
     def getentries(revs, count=1):
         index = parse_index_v1(data, inline)[0]
 
         for i in range(count):
             for rev in revs:
                 index[rev]
 
     def resolvenode(node):
         index = parse_index_v1(data, inline)[0]
         rev = getattr(index, 'rev', None)
         if rev is None:
             nodemap = getattr(parse_index_v1(data, inline)[0], 'nodemap', None)
             # This only works for the C code.
             if nodemap is None:
                 return
             rev = nodemap.__getitem__
 
         try:
             rev(node)
         except error.RevlogError:
             pass
 
     def resolvenodes(nodes, count=1):
         index = parse_index_v1(data, inline)[0]
         rev = getattr(index, 'rev', None)
         if rev is None:
             nodemap = getattr(parse_index_v1(data, inline)[0], 'nodemap', None)
             # This only works for the C code.
             if nodemap is None:
                 return
             rev = nodemap.__getitem__
 
         for i in range(count):
             for node in nodes:
                 try:
                     rev(node)
                 except error.RevlogError:
                     pass
 
     benches = [
         (constructor, b'revlog constructor'),
         (read, b'read'),
         (parseindex, b'create index object'),
         (lambda: getentry(0), b'retrieve index entry for rev 0'),
         (lambda: resolvenode(b'a' * 20), b'look up missing node'),
         (lambda: resolvenode(node0), b'look up node at rev 0'),
         (lambda: resolvenode(node25), b'look up node at 1/4 len'),
         (lambda: resolvenode(node50), b'look up node at 1/2 len'),
         (lambda: resolvenode(node75), b'look up node at 3/4 len'),
         (lambda: resolvenode(node100), b'look up node at tip'),
         # 2x variation is to measure caching impact.
         (lambda: resolvenodes(allnodes), b'look up all nodes (forward)'),
         (lambda: resolvenodes(allnodes, 2), b'look up all nodes 2x (forward)'),
         (lambda: resolvenodes(allnodesrev), b'look up all nodes (reverse)'),
         (
             lambda: resolvenodes(allnodesrev, 2),
             b'look up all nodes 2x (reverse)',
         ),
         (lambda: getentries(allrevs), b'retrieve all index entries (forward)'),
         (
             lambda: getentries(allrevs, 2),
             b'retrieve all index entries 2x (forward)',
         ),
         (
             lambda: getentries(allrevsrev),
             b'retrieve all index entries (reverse)',
         ),
         (
             lambda: getentries(allrevsrev, 2),
             b'retrieve all index entries 2x (reverse)',
         ),
     ]
 
     for fn, title in benches:
         timer, fm = gettimer(ui, opts)
         timer(fn, title=title)
         fm.end()
 
 
 @command(
     b'perf::revlogrevisions|perfrevlogrevisions',
     revlogopts
     + formatteropts
     + [
         (b'd', b'dist', 100, b'distance between the revisions'),
         (b's', b'startrev', 0, b'revision to start reading at'),
         (b'', b'reverse', False, b'read in reverse'),
     ],
     b'-c|-m|FILE',
 )
 def perfrevlogrevisions(
     ui, repo, file_=None, startrev=0, reverse=False, **opts
 ):
     """Benchmark reading a series of revisions from a revlog.
 
     By default, we read every ``-d/--dist`` revision from 0 to tip of
     the specified revlog.
 
     The start revision can be defined via ``-s/--startrev``.
     """
     opts = _byteskwargs(opts)
 
     rl = cmdutil.openrevlog(repo, b'perfrevlogrevisions', file_, opts)
     rllen = getlen(ui)(rl)
 
     if startrev < 0:
         startrev = rllen + startrev
 
     def d():
         rl.clearcaches()
 
         beginrev = startrev
         endrev = rllen
         dist = opts[b'dist']
 
         if reverse:
             beginrev, endrev = endrev - 1, beginrev - 1
             dist = -1 * dist
 
         for x in _xrange(beginrev, endrev, dist):
             # Old revisions don't support passing int.
             n = rl.node(x)
             rl.revision(n)
 
     timer, fm = gettimer(ui, opts)
     timer(d)
     fm.end()
 
 
 @command(
     b'perf::revlogwrite|perfrevlogwrite',
     revlogopts
     + formatteropts
     + [
         (b's', b'startrev', 1000, b'revision to start writing at'),
         (b'', b'stoprev', -1, b'last revision to write'),
         (b'', b'count', 3, b'number of passes to perform'),
         (b'', b'details', False, b'print timing for every revisions tested'),
         (b'', b'source', b'full', b'the kind of data feed in the revlog'),
         (b'', b'lazydeltabase', True, b'try the provided delta first'),
         (b'', b'clear-caches', True, b'clear revlog cache between calls'),
     ],
     b'-c|-m|FILE',
 )
 def perfrevlogwrite(ui, repo, file_=None, startrev=1000, stoprev=-1, **opts):
     """Benchmark writing a series of revisions to a revlog.
 
     Possible source values are:
     * `full`: add from a full text (default).
     * `parent-1`: add from a delta to the first parent
     * `parent-2`: add from a delta to the second parent if it exists
                   (use a delta from the first parent otherwise)
     * `parent-smallest`: add from the smallest delta (either p1 or p2)
     * `storage`: add from the existing precomputed deltas
 
     Note: This performance command measures performance in a custom way. As a
     result some of the global configuration of the 'perf' command does not
     apply to it:
 
     * ``pre-run``: disabled
 
     * ``profile-benchmark``: disabled
 
     * ``run-limits``: disabled use --count instead
     """
     opts = _byteskwargs(opts)
 
     rl = cmdutil.openrevlog(repo, b'perfrevlogwrite', file_, opts)
     rllen = getlen(ui)(rl)
     if startrev < 0:
         startrev = rllen + startrev
     if stoprev < 0:
         stoprev = rllen + stoprev
 
     lazydeltabase = opts['lazydeltabase']
     source = opts['source']
     clearcaches = opts['clear_caches']
     validsource = (
         b'full',
         b'parent-1',
         b'parent-2',
         b'parent-smallest',
         b'storage',
     )
     if source not in validsource:
         raise error.Abort('invalid source type: %s' % source)
 
     ### actually gather results
     count = opts['count']
     if count <= 0:
         raise error.Abort('invalide run count: %d' % count)
     allresults = []
     for c in range(count):
         timing = _timeonewrite(
             ui,
             rl,
             source,
             startrev,
             stoprev,
             c + 1,
             lazydeltabase=lazydeltabase,
             clearcaches=clearcaches,
         )
         allresults.append(timing)
 
     ### consolidate the results in a single list
     results = []
     for idx, (rev, t) in enumerate(allresults[0]):
         ts = [t]
         for other in allresults[1:]:
             orev, ot = other[idx]
             assert orev == rev
             ts.append(ot)
         results.append((rev, ts))
     resultcount = len(results)
 
     ### Compute and display relevant statistics
 
     # get a formatter
     fm = ui.formatter(b'perf', opts)
     displayall = ui.configbool(b"perf", b"all-timing", True)
 
     # print individual details if requested
     if opts['details']:
         for idx, item in enumerate(results, 1):
             rev, data = item
             title = 'revisions #%d of %d, rev %d' % (idx, resultcount, rev)
             formatone(fm, data, title=title, displayall=displayall)
 
     # sorts results by median time
     results.sort(key=lambda x: sorted(x[1])[len(x[1]) // 2])
     # list of (name, index) to display)
     relevants = [
         ("min", 0),
         ("10%", resultcount * 10 // 100),
         ("25%", resultcount * 25 // 100),
         ("50%", resultcount * 70 // 100),
         ("75%", resultcount * 75 // 100),
         ("90%", resultcount * 90 // 100),
         ("95%", resultcount * 95 // 100),
         ("99%", resultcount * 99 // 100),
         ("99.9%", resultcount * 999 // 1000),
         ("99.99%", resultcount * 9999 // 10000),
         ("99.999%", resultcount * 99999 // 100000),
         ("max", -1),
     ]
     if not ui.quiet:
         for name, idx in relevants:
             data = results[idx]
             title = '%s of %d, rev %d' % (name, resultcount, data[0])
             formatone(fm, data[1], title=title, displayall=displayall)
 
     # XXX summing that many float will not be very precise, we ignore this fact
     # for now
     totaltime = []
     for item in allresults:
         totaltime.append(
             (
                 sum(x[1][0] for x in item),
                 sum(x[1][1] for x in item),
                 sum(x[1][2] for x in item),
             )
         )
     formatone(
         fm,
         totaltime,
         title="total time (%d revs)" % resultcount,
         displayall=displayall,
     )
     fm.end()
 
 
 class _faketr:
     def add(s, x, y, z=None):
         return None
 
 
 def _timeonewrite(
     ui,
     orig,
     source,
     startrev,
     stoprev,
     runidx=None,
     lazydeltabase=True,
     clearcaches=True,
 ):
     timings = []
     tr = _faketr()
     with _temprevlog(ui, orig, startrev) as dest:
         if hasattr(dest, "delta_config"):
             dest.delta_config.lazy_delta_base = lazydeltabase
         else:
             dest._lazydeltabase = lazydeltabase
         revs = list(orig.revs(startrev, stoprev))
         total = len(revs)
         topic = 'adding'
         if runidx is not None:
             topic += ' (run #%d)' % runidx
         # Support both old and new progress API
         if util.safehasattr(ui, 'makeprogress'):
             progress = ui.makeprogress(topic, unit='revs', total=total)
 
             def updateprogress(pos):
                 progress.update(pos)
 
             def completeprogress():
                 progress.complete()
 
         else:
 
             def updateprogress(pos):
                 ui.progress(topic, pos, unit='revs', total=total)
 
             def completeprogress():
                 ui.progress(topic, None, unit='revs', total=total)
 
         for idx, rev in enumerate(revs):
             updateprogress(idx)
             addargs, addkwargs = _getrevisionseed(orig, rev, tr, source)
             if clearcaches:
                 dest.index.clearcaches()
                 dest.clearcaches()
             with timeone() as r:
                 dest.addrawrevision(*addargs, **addkwargs)
             timings.append((rev, r[0]))
         updateprogress(total)
         completeprogress()
     return timings
 
 
 def _getrevisionseed(orig, rev, tr, source):
     from mercurial.node import nullid
 
     linkrev = orig.linkrev(rev)
     node = orig.node(rev)
     p1, p2 = orig.parents(node)
     flags = orig.flags(rev)
     cachedelta = None
     text = None
 
     if source == b'full':
         text = orig.revision(rev)
     elif source == b'parent-1':
         baserev = orig.rev(p1)
         cachedelta = (baserev, orig.revdiff(p1, rev))
     elif source == b'parent-2':
         parent = p2
         if p2 == nullid:
             parent = p1
         baserev = orig.rev(parent)
         cachedelta = (baserev, orig.revdiff(parent, rev))
     elif source == b'parent-smallest':
         p1diff = orig.revdiff(p1, rev)
         parent = p1
         diff = p1diff
         if p2 != nullid:
             p2diff = orig.revdiff(p2, rev)
             if len(p1diff) > len(p2diff):
                 parent = p2
                 diff = p2diff
         baserev = orig.rev(parent)
         cachedelta = (baserev, diff)
     elif source == b'storage':
         baserev = orig.deltaparent(rev)
         cachedelta = (baserev, orig.revdiff(orig.node(baserev), rev))
 
     return (
         (text, tr, linkrev, p1, p2),
         {'node': node, 'flags': flags, 'cachedelta': cachedelta},
     )
 
 
 @contextlib.contextmanager
 def _temprevlog(ui, orig, truncaterev):
     from mercurial import vfs as vfsmod
 
     if orig._inline:
         raise error.Abort('not supporting inline revlog (yet)')
     revlogkwargs = {}
     k = 'upperboundcomp'
     if util.safehasattr(orig, k):
         revlogkwargs[k] = getattr(orig, k)
 
     indexfile = getattr(orig, '_indexfile', None)
     if indexfile is None:
         # compatibility with <= hg-5.8
         indexfile = getattr(orig, 'indexfile')
     origindexpath = orig.opener.join(indexfile)
 
     datafile = getattr(orig, '_datafile', getattr(orig, 'datafile'))
     origdatapath = orig.opener.join(datafile)
     radix = b'revlog'
     indexname = b'revlog.i'
     dataname = b'revlog.d'
 
     tmpdir = tempfile.mkdtemp(prefix='tmp-hgperf-')
     try:
         # copy the data file in a temporary directory
         ui.debug('copying data in %s\n' % tmpdir)
         destindexpath = os.path.join(tmpdir, 'revlog.i')
         destdatapath = os.path.join(tmpdir, 'revlog.d')
         shutil.copyfile(origindexpath, destindexpath)
         shutil.copyfile(origdatapath, destdatapath)
 
         # remove the data we want to add again
         ui.debug('truncating data to be rewritten\n')
         with open(destindexpath, 'ab') as index:
             index.seek(0)
             index.truncate(truncaterev * orig._io.size)
         with open(destdatapath, 'ab') as data:
             data.seek(0)
             data.truncate(orig.start(truncaterev))
 
         # instantiate a new revlog from the temporary copy
         ui.debug('truncating adding to be rewritten\n')
         vfs = vfsmod.vfs(tmpdir)
         vfs.options = getattr(orig.opener, 'options', None)
 
         try:
             dest = revlog(vfs, radix=radix, **revlogkwargs)
         except TypeError:
             dest = revlog(
                 vfs, indexfile=indexname, datafile=dataname, **revlogkwargs
             )
         if dest._inline:
             raise error.Abort('not supporting inline revlog (yet)')
         # make sure internals are initialized
         dest.revision(len(dest) - 1)
         yield dest
         del dest, vfs
     finally:
         shutil.rmtree(tmpdir, True)
 
 
 @command(
     b'perf::revlogchunks|perfrevlogchunks',
     revlogopts
     + formatteropts
     + [
         (b'e', b'engines', b'', b'compression engines to use'),
         (b's', b'startrev', 0, b'revision to start at'),
     ],
     b'-c|-m|FILE',
 )
 def perfrevlogchunks(ui, repo, file_=None, engines=None, startrev=0, **opts):
     """Benchmark operations on revlog chunks.
 
     Logically, each revlog is a collection of fulltext revisions. However,
     stored within each revlog are "chunks" of possibly compressed data. This
     data needs to be read and decompressed or compressed and written.
 
     This command measures the time it takes to read+decompress and recompress
     chunks in a revlog. It effectively isolates I/O and compression performance.
     For measurements of higher-level operations like resolving revisions,
     see ``perfrevlogrevisions`` and ``perfrevlogrevision``.
     """
     opts = _byteskwargs(opts)
 
     rl = cmdutil.openrevlog(repo, b'perfrevlogchunks', file_, opts)
 
     # - _chunkraw was renamed to _getsegmentforrevs
     # - _getsegmentforrevs was moved on the inner object
     try:
         segmentforrevs = rl._inner.get_segment_for_revs
     except AttributeError:
         try:
             segmentforrevs = rl._getsegmentforrevs
         except AttributeError:
             segmentforrevs = rl._chunkraw
 
     # Verify engines argument.
     if engines:
         engines = {e.strip() for e in engines.split(b',')}
         for engine in engines:
             try:
                 util.compressionengines[engine]
             except KeyError:
                 raise error.Abort(b'unknown compression engine: %s' % engine)
     else:
         engines = []
         for e in util.compengines:
             engine = util.compengines[e]
             try:
                 if engine.available():
                     engine.revlogcompressor().compress(b'dummy')
                     engines.append(e)
             except NotImplementedError:
                 pass
 
     revs = list(rl.revs(startrev, len(rl) - 1))
 
     @contextlib.contextmanager
     def reading(rl):
         if getattr(rl, 'reading', None) is not None:
             with rl.reading():
                 yield None
         elif rl._inline:
             indexfile = getattr(rl, '_indexfile', None)
             if indexfile is None:
                 # compatibility with <= hg-5.8
                 indexfile = getattr(rl, 'indexfile')
             yield getsvfs(repo)(indexfile)
         else:
             datafile = getattr(rl, 'datafile', getattr(rl, 'datafile'))
             yield getsvfs(repo)(datafile)
 
     if getattr(rl, 'reading', None) is not None:
 
         @contextlib.contextmanager
         def lazy_reading(rl):
             with rl.reading():
                 yield
 
     else:
 
         @contextlib.contextmanager
         def lazy_reading(rl):
             yield
 
     def doread():
         rl.clearcaches()
         for rev in revs:
             with lazy_reading(rl):
                 segmentforrevs(rev, rev)
 
     def doreadcachedfh():
         rl.clearcaches()
         with reading(rl) as fh:
             if fh is not None:
                 for rev in revs:
                     segmentforrevs(rev, rev, df=fh)
             else:
                 for rev in revs:
                     segmentforrevs(rev, rev)
 
     def doreadbatch():
         rl.clearcaches()
         with lazy_reading(rl):
             segmentforrevs(revs[0], revs[-1])
 
     def doreadbatchcachedfh():
         rl.clearcaches()
         with reading(rl) as fh:
             if fh is not None:
                 segmentforrevs(revs[0], revs[-1], df=fh)
             else:
                 segmentforrevs(revs[0], revs[-1])
 
     def dochunk():
         rl.clearcaches()
         # chunk used to be available directly on the revlog
         _chunk = getattr(rl, '_inner', rl)._chunk
         with reading(rl) as fh:
             if fh is not None:
                 for rev in revs:
                     _chunk(rev, df=fh)
             else:
                 for rev in revs:
                     _chunk(rev)
 
     chunks = [None]
 
     def dochunkbatch():
         rl.clearcaches()
         _chunks = getattr(rl, '_inner', rl)._chunks
         with reading(rl) as fh:
             if fh is not None:
                 # Save chunks as a side-effect.
                 chunks[0] = _chunks(revs, df=fh)
             else:
                 # Save chunks as a side-effect.
                 chunks[0] = _chunks(revs)
 
     def docompress(compressor):
         rl.clearcaches()
 
         compressor_holder = getattr(rl, '_inner', rl)
 
         try:
             # Swap in the requested compression engine.
             oldcompressor = compressor_holder._compressor
             compressor_holder._compressor = compressor
             for chunk in chunks[0]:
                 rl.compress(chunk)
         finally:
             compressor_holder._compressor = oldcompressor
 
     benches = [
         (lambda: doread(), b'read'),
         (lambda: doreadcachedfh(), b'read w/ reused fd'),
         (lambda: doreadbatch(), b'read batch'),
         (lambda: doreadbatchcachedfh(), b'read batch w/ reused fd'),
         (lambda: dochunk(), b'chunk'),
         (lambda: dochunkbatch(), b'chunk batch'),
     ]
 
     for engine in sorted(engines):
         compressor = util.compengines[engine].revlogcompressor()
         benches.append(
             (
                 functools.partial(docompress, compressor),
                 b'compress w/ %s' % engine,
             )
         )
 
     for fn, title in benches:
         timer, fm = gettimer(ui, opts)
         timer(fn, title=title)
         fm.end()
 
 
 @command(
     b'perf::revlogrevision|perfrevlogrevision',
     revlogopts
     + formatteropts
     + [(b'', b'cache', False, b'use caches instead of clearing')],
     b'-c|-m|FILE REV',
 )
 def perfrevlogrevision(ui, repo, file_, rev=None, cache=None, **opts):
     """Benchmark obtaining a revlog revision.
 
     Obtaining a revlog revision consists of roughly the following steps:
 
     1. Compute the delta chain
     2. Slice the delta chain if applicable
     3. Obtain the raw chunks for that delta chain
     4. Decompress each raw chunk
     5. Apply binary patches to obtain fulltext
     6. Verify hash of fulltext
 
     This command measures the time spent in each of these phases.
     """
     opts = _byteskwargs(opts)
 
     if opts.get(b'changelog') or opts.get(b'manifest'):
         file_, rev = None, file_
     elif rev is None:
         raise error.CommandError(b'perfrevlogrevision', b'invalid arguments')
 
     r = cmdutil.openrevlog(repo, b'perfrevlogrevision', file_, opts)
 
     # _chunkraw was renamed to _getsegmentforrevs.
     try:
         segmentforrevs = r._inner.get_segment_for_revs
     except AttributeError:
         try:
             segmentforrevs = r._getsegmentforrevs
         except AttributeError:
             segmentforrevs = r._chunkraw
 
     node = r.lookup(rev)
     rev = r.rev(node)
 
     if getattr(r, 'reading', None) is not None:
 
         @contextlib.contextmanager
         def lazy_reading(r):
             with r.reading():
                 yield
 
     else:
 
         @contextlib.contextmanager
         def lazy_reading(r):
             yield
 
     def getrawchunks(data, chain):
         start = r.start
         length = r.length
         inline = r._inline
         try:
             iosize = r.index.entry_size
         except AttributeError:
             iosize = r._io.size
         buffer = util.buffer
 
         chunks = []
         ladd = chunks.append
         for idx, item in enumerate(chain):
             offset = start(item[0])
             bits = data[idx]
             for rev in item:
                 chunkstart = start(rev)
                 if inline:
                     chunkstart += (rev + 1) * iosize
                 chunklength = length(rev)
                 ladd(buffer(bits, chunkstart - offset, chunklength))
 
         return chunks
 
     def dodeltachain(rev):
         if not cache:
             r.clearcaches()
         r._deltachain(rev)
 
     def doread(chain):
         if not cache:
             r.clearcaches()
         for item in slicedchain:
             with lazy_reading(r):
                 segmentforrevs(item[0], item[-1])
 
     def doslice(r, chain, size):
         for s in slicechunk(r, chain, targetsize=size):
             pass
 
     def dorawchunks(data, chain):
         if not cache:
             r.clearcaches()
         getrawchunks(data, chain)
 
     def dodecompress(chunks):
         decomp = r.decompress
         for chunk in chunks:
             decomp(chunk)
 
     def dopatch(text, bins):
         if not cache:
             r.clearcaches()
         mdiff.patches(text, bins)
 
     def dohash(text):
         if not cache:
             r.clearcaches()
         r.checkhash(text, node, rev=rev)
 
     def dorevision():
         if not cache:
             r.clearcaches()
         r.revision(node)
 
     try:
         from mercurial.revlogutils.deltas import slicechunk
     except ImportError:
         slicechunk = getattr(revlog, '_slicechunk', None)
 
     size = r.length(rev)
     chain = r._deltachain(rev)[0]
 
     with_sparse_read = False
     if hasattr(r, 'data_config'):
         with_sparse_read = r.data_config.with_sparse_read
     elif hasattr(r, '_withsparseread'):
         with_sparse_read = r._withsparseread
     if with_sparse_read:
         slicedchain = (chain,)
     else:
         slicedchain = tuple(slicechunk(r, chain, targetsize=size))
     data = [segmentforrevs(seg[0], seg[-1])[1] for seg in slicedchain]
     rawchunks = getrawchunks(data, slicedchain)
     bins = r._inner._chunks(chain)
     text = bytes(bins[0])
     bins = bins[1:]
     text = mdiff.patches(text, bins)
 
     benches = [
         (lambda: dorevision(), b'full'),
         (lambda: dodeltachain(rev), b'deltachain'),
         (lambda: doread(chain), b'read'),
     ]
 
     if with_sparse_read:
         slicing = (lambda: doslice(r, chain, size), b'slice-sparse-chain')
         benches.append(slicing)
 
     benches.extend(
         [
             (lambda: dorawchunks(data, slicedchain), b'rawchunks'),
             (lambda: dodecompress(rawchunks), b'decompress'),
             (lambda: dopatch(text, bins), b'patch'),
             (lambda: dohash(text), b'hash'),
         ]
     )
 
     timer, fm = gettimer(ui, opts)
     for fn, title in benches:
         timer(fn, title=title)
     fm.end()
 
 
 @command(
     b'perf::revset|perfrevset',
     [
         (b'C', b'clear', False, b'clear volatile cache between each call.'),
         (b'', b'contexts', False, b'obtain changectx for each revision'),
     ]
     + formatteropts,
     b"REVSET",
 )
 def perfrevset(ui, repo, expr, clear=False, contexts=False, **opts):
     """benchmark the execution time of a revset
 
     Use the --clean option if need to evaluate the impact of build volatile
     revisions set cache on the revset execution. Volatile cache hold filtered
     and obsolete related cache."""
     opts = _byteskwargs(opts)
 
     timer, fm = gettimer(ui, opts)
 
     def d():
         if clear:
             repo.invalidatevolatilesets()
         if contexts:
             for ctx in repo.set(expr):
                 pass
         else:
             for r in repo.revs(expr):
                 pass
 
     timer(d)
     fm.end()
 
 
 @command(
     b'perf::volatilesets|perfvolatilesets',
     [
         (b'', b'clear-obsstore', False, b'drop obsstore between each call.'),
     ]
     + formatteropts,
 )
 def perfvolatilesets(ui, repo, *names, **opts):
     """benchmark the computation of various volatile set
 
     Volatile set computes element related to filtering and obsolescence."""
     opts = _byteskwargs(opts)
     timer, fm = gettimer(ui, opts)
     repo = repo.unfiltered()
 
     def getobs(name):
         def d():
             repo.invalidatevolatilesets()
             if opts[b'clear_obsstore']:
                 clearfilecache(repo, b'obsstore')
             obsolete.getrevs(repo, name)
 
         return d
 
     allobs = sorted(obsolete.cachefuncs)
     if names:
         allobs = [n for n in allobs if n in names]
 
     for name in allobs:
         timer(getobs(name), title=name)
 
     def getfiltered(name):
         def d():
             repo.invalidatevolatilesets()
             if opts[b'clear_obsstore']:
                 clearfilecache(repo, b'obsstore')
             repoview.filterrevs(repo, name)
 
         return d
 
     allfilter = sorted(repoview.filtertable)
     if names:
         allfilter = [n for n in allfilter if n in names]
 
     for name in allfilter:
         timer(getfiltered(name), title=name)
     fm.end()
 
 
 @command(
     b'perf::branchmap|perfbranchmap',
     [
         (b'f', b'full', False, b'Includes build time of subset'),
         (
             b'',
             b'clear-revbranch',
             False,
             b'purge the revbranch cache between computation',
         ),
     ]
     + formatteropts,
 )
 def perfbranchmap(ui, repo, *filternames, **opts):
     """benchmark the update of a branchmap
 
     This benchmarks the full repo.branchmap() call with read and write disabled
     """
     opts = _byteskwargs(opts)
     full = opts.get(b"full", False)
     clear_revbranch = opts.get(b"clear_revbranch", False)
     timer, fm = gettimer(ui, opts)
 
     def getbranchmap(filtername):
         """generate a benchmark function for the filtername"""
         if filtername is None:
             view = repo
         else:
             view = repo.filtered(filtername)
         if util.safehasattr(view._branchcaches, '_per_filter'):
             filtered = view._branchcaches._per_filter
         else:
             # older versions
             filtered = view._branchcaches
 
         def d():
             if clear_revbranch:
                 repo.revbranchcache()._clear()
             if full:
                 view._branchcaches.clear()
             else:
                 filtered.pop(filtername, None)
             view.branchmap()
 
         return d
 
     # add filter in smaller subset to bigger subset
     possiblefilters = set(repoview.filtertable)
     if filternames:
         possiblefilters &= set(filternames)
     subsettable = getbranchmapsubsettable()
     allfilters = []
     while possiblefilters:
         for name in possiblefilters:
             subset = subsettable.get(name)
             if subset not in possiblefilters:
                 break
         else:
             assert False, b'subset cycle %s!' % possiblefilters
         allfilters.append(name)
         possiblefilters.remove(name)
 
     # warm the cache
     if not full:
         for name in allfilters:
             repo.filtered(name).branchmap()
     if not filternames or b'unfiltered' in filternames:
         # add unfiltered
         allfilters.append(None)
 
-    if util.safehasattr(branchmap.branchcache, 'fromfile'):
+    old_branch_cache_from_file = None
+    branchcacheread = None
+    if util.safehasattr(branchmap, 'branch_cache_from_file'):
+        old_branch_cache_from_file = branchmap.branch_cache_from_file
+        branchmap.branch_cache_from_file = lambda *args: None
+    elif util.safehasattr(branchmap.branchcache, 'fromfile'):
         branchcacheread = safeattrsetter(branchmap.branchcache, b'fromfile')
         branchcacheread.set(classmethod(lambda *args: None))
     else:
         # older versions
         branchcacheread = safeattrsetter(branchmap, b'read')
         branchcacheread.set(lambda *args: None)
-    branchcachewrite = safeattrsetter(branchmap.branchcache, b'write')
-    branchcachewrite.set(lambda *args: None)
+    if util.safehasattr(branchmap, '_LocalBranchCache'):
+        branchcachewrite = safeattrsetter(branchmap._LocalBranchCache, b'write')
+        branchcachewrite.set(lambda *args: None)
+    else:
+        branchcachewrite = safeattrsetter(branchmap.branchcache, b'write')
+        branchcachewrite.set(lambda *args: None)
     try:
         for name in allfilters:
             printname = name
             if name is None:
                 printname = b'unfiltered'
             timer(getbranchmap(name), title=printname)
     finally:
-        branchcacheread.restore()
+        if old_branch_cache_from_file is not None:
+            branchmap.branch_cache_from_file = old_branch_cache_from_file
+        if branchcacheread is not None:
+            branchcacheread.restore()
         branchcachewrite.restore()
     fm.end()
 
 
 @command(
     b'perf::branchmapupdate|perfbranchmapupdate',
     [
         (b'', b'base', [], b'subset of revision to start from'),
         (b'', b'target', [], b'subset of revision to end with'),
         (b'', b'clear-caches', False, b'clear cache between each runs'),
     ]
     + formatteropts,
 )
 def perfbranchmapupdate(ui, repo, base=(), target=(), **opts):
     """benchmark branchmap update from for <base> revs to <target> revs
 
     If `--clear-caches` is passed, the following items will be reset before
     each update:
         * the changelog instance and associated indexes
         * the rev-branch-cache instance
 
     Examples:
 
        # update for the one last revision
        $ hg perfbranchmapupdate --base 'not tip' --target 'tip'
 
        $ update for change coming with a new branch
        $ hg perfbranchmapupdate --base 'stable' --target 'default'
     """
     from mercurial import branchmap
     from mercurial import repoview
 
     opts = _byteskwargs(opts)
     timer, fm = gettimer(ui, opts)
     clearcaches = opts[b'clear_caches']
     unfi = repo.unfiltered()
     x = [None]  # used to pass data between closure
 
     # we use a `list` here to avoid possible side effect from smartset
     baserevs = list(scmutil.revrange(repo, base))
     targetrevs = list(scmutil.revrange(repo, target))
     if not baserevs:
         raise error.Abort(b'no revisions selected for --base')
     if not targetrevs:
         raise error.Abort(b'no revisions selected for --target')
 
     # make sure the target branchmap also contains the one in the base
     targetrevs = list(set(baserevs) | set(targetrevs))
     targetrevs.sort()
 
     cl = repo.changelog
     allbaserevs = list(cl.ancestors(baserevs, inclusive=True))
     allbaserevs.sort()
     alltargetrevs = frozenset(cl.ancestors(targetrevs, inclusive=True))
 
     newrevs = list(alltargetrevs.difference(allbaserevs))
     newrevs.sort()
 
     allrevs = frozenset(unfi.changelog.revs())
     basefilterrevs = frozenset(allrevs.difference(allbaserevs))
     targetfilterrevs = frozenset(allrevs.difference(alltargetrevs))
 
     def basefilter(repo, visibilityexceptions=None):
         return basefilterrevs
 
     def targetfilter(repo, visibilityexceptions=None):
         return targetfilterrevs
 
     msg = b'benchmark of branchmap with %d revisions with %d new ones\n'
     ui.status(msg % (len(allbaserevs), len(newrevs)))
     if targetfilterrevs:
         msg = b'(%d revisions still filtered)\n'
         ui.status(msg % len(targetfilterrevs))
 
     try:
         repoview.filtertable[b'__perf_branchmap_update_base'] = basefilter
         repoview.filtertable[b'__perf_branchmap_update_target'] = targetfilter
 
         baserepo = repo.filtered(b'__perf_branchmap_update_base')
         targetrepo = repo.filtered(b'__perf_branchmap_update_target')
 
         bcache = repo.branchmap()
         copy_method = 'copy'
 
         copy_base_kwargs = copy_base_kwargs = {}
         if hasattr(bcache, 'copy'):
             if 'repo' in getargspec(bcache.copy).args:
                 copy_base_kwargs = {"repo": baserepo}
                 copy_target_kwargs = {"repo": targetrepo}
         else:
             copy_method = 'inherit_for'
             copy_base_kwargs = {"repo": baserepo}
             copy_target_kwargs = {"repo": targetrepo}
 
         # try to find an existing branchmap to reuse
         subsettable = getbranchmapsubsettable()
         candidatefilter = subsettable.get(None)
         while candidatefilter is not None:
             candidatebm = repo.filtered(candidatefilter).branchmap()
             if candidatebm.validfor(baserepo):
                 filtered = repoview.filterrevs(repo, candidatefilter)
                 missing = [r for r in allbaserevs if r in filtered]
                 base = getattr(candidatebm, copy_method)(**copy_base_kwargs)
                 base.update(baserepo, missing)
                 break
             candidatefilter = subsettable.get(candidatefilter)
         else:
             # no suitable subset where found
             base = branchmap.branchcache()
             base.update(baserepo, allbaserevs)
 
         def setup():
             x[0] = getattr(base, copy_method)(**copy_target_kwargs)
             if clearcaches:
                 unfi._revbranchcache = None
                 clearchangelog(repo)
 
         def bench():
             x[0].update(targetrepo, newrevs)
 
         timer(bench, setup=setup)
         fm.end()
     finally:
         repoview.filtertable.pop(b'__perf_branchmap_update_base', None)
         repoview.filtertable.pop(b'__perf_branchmap_update_target', None)
 
 
 @command(
     b'perf::branchmapload|perfbranchmapload',
     [
         (b'f', b'filter', b'', b'Specify repoview filter'),
         (b'', b'list', False, b'List brachmap filter caches'),
         (b'', b'clear-revlogs', False, b'refresh changelog and manifest'),
     ]
     + formatteropts,
 )
 def perfbranchmapload(ui, repo, filter=b'', list=False, **opts):
     """benchmark reading the branchmap"""
     opts = _byteskwargs(opts)
     clearrevlogs = opts[b'clear_revlogs']
 
     if list:
         for name, kind, st in repo.cachevfs.readdir(stat=True):
             if name.startswith(b'branch2'):
                 filtername = name.partition(b'-')[2] or b'unfiltered'
                 ui.status(
                     b'%s - %s\n' % (filtername, util.bytecount(st.st_size))
                 )
         return
     if not filter:
         filter = None
     subsettable = getbranchmapsubsettable()
     if filter is None:
         repo = repo.unfiltered()
     else:
         repo = repoview.repoview(repo, filter)
 
     repo.branchmap()  # make sure we have a relevant, up to date branchmap
 
-    try:
-        fromfile = branchmap.branchcache.fromfile
-    except AttributeError:
-        # older versions
+    fromfile = getattr(branchmap, 'branch_cache_from_file', None)
+    if fromfile is None:
+        fromfile = getattr(branchmap.branchcache, 'fromfile', None)
+    if fromfile is None:
         fromfile = branchmap.read
 
     currentfilter = filter
     # try once without timer, the filter may not be cached
     while fromfile(repo) is None:
         currentfilter = subsettable.get(currentfilter)
         if currentfilter is None:
             raise error.Abort(
                 b'No branchmap cached for %s repo' % (filter or b'unfiltered')
             )
         repo = repo.filtered(currentfilter)
     timer, fm = gettimer(ui, opts)
 
     def setup():
         if clearrevlogs:
             clearchangelog(repo)
 
     def bench():
         fromfile(repo)
 
     timer(bench, setup=setup)
     fm.end()
 
 
 @command(b'perf::loadmarkers|perfloadmarkers')
 def perfloadmarkers(ui, repo):
     """benchmark the time to parse the on-disk markers for a repo
 
     Result is the number of markers in the repo."""
     timer, fm = gettimer(ui)
     svfs = getsvfs(repo)
     timer(lambda: len(obsolete.obsstore(repo, svfs)))
     fm.end()
 
 
 @command(
     b'perf::lrucachedict|perflrucachedict',
     formatteropts
     + [
         (b'', b'costlimit', 0, b'maximum total cost of items in cache'),
         (b'', b'mincost', 0, b'smallest cost of items in cache'),
         (b'', b'maxcost', 100, b'maximum cost of items in cache'),
         (b'', b'size', 4, b'size of cache'),
         (b'', b'gets', 10000, b'number of key lookups'),
         (b'', b'sets', 10000, b'number of key sets'),
         (b'', b'mixed', 10000, b'number of mixed mode operations'),
         (
             b'',
             b'mixedgetfreq',
             50,
             b'frequency of get vs set ops in mixed mode',
         ),
     ],
     norepo=True,
 )
 def perflrucache(
     ui,
     mincost=0,
     maxcost=100,
     costlimit=0,
     size=4,
     gets=10000,
     sets=10000,
     mixed=10000,
     mixedgetfreq=50,
     **opts
 ):
     opts = _byteskwargs(opts)
 
     def doinit():
         for i in _xrange(10000):
             util.lrucachedict(size)
 
     costrange = list(range(mincost, maxcost + 1))
 
     values = []
     for i in _xrange(size):
         values.append(random.randint(0, _maxint))
 
     # Get mode fills the cache and tests raw lookup performance with no
     # eviction.
     getseq = []
     for i in _xrange(gets):
         getseq.append(random.choice(values))
 
     def dogets():
         d = util.lrucachedict(size)
         for v in values:
             d[v] = v
         for key in getseq:
             value = d[key]
             value  # silence pyflakes warning
 
     def dogetscost():
         d = util.lrucachedict(size, maxcost=costlimit)
         for i, v in enumerate(values):
             d.insert(v, v, cost=costs[i])
         for key in getseq:
             try:
                 value = d[key]
                 value  # silence pyflakes warning
             except KeyError:
                 pass
 
     # Set mode tests insertion speed with cache eviction.
     setseq = []
     costs = []
     for i in _xrange(sets):
         setseq.append(random.randint(0, _maxint))
         costs.append(random.choice(costrange))
 
     def doinserts():
         d = util.lrucachedict(size)
         for v in setseq:
             d.insert(v, v)
 
     def doinsertscost():
         d = util.lrucachedict(size, maxcost=costlimit)
         for i, v in enumerate(setseq):
             d.insert(v, v, cost=costs[i])
 
     def dosets():
         d = util.lrucachedict(size)
         for v in setseq:
             d[v] = v
 
     # Mixed mode randomly performs gets and sets with eviction.
     mixedops = []
     for i in _xrange(mixed):
         r = random.randint(0, 100)
         if r < mixedgetfreq:
             op = 0
         else:
             op = 1
 
         mixedops.append(
             (op, random.randint(0, size * 2), random.choice(costrange))
         )
 
     def domixed():
         d = util.lrucachedict(size)
 
         for op, v, cost in mixedops:
             if op == 0:
                 try:
                     d[v]
                 except KeyError:
                     pass
             else:
                 d[v] = v
 
     def domixedcost():
         d = util.lrucachedict(size, maxcost=costlimit)
 
         for op, v, cost in mixedops:
             if op == 0:
                 try:
                     d[v]
                 except KeyError:
                     pass
             else:
                 d.insert(v, v, cost=cost)
 
     benches = [
         (doinit, b'init'),
     ]
 
     if costlimit:
         benches.extend(
             [
                 (dogetscost, b'gets w/ cost limit'),
                 (doinsertscost, b'inserts w/ cost limit'),
                 (domixedcost, b'mixed w/ cost limit'),
             ]
         )
     else:
         benches.extend(
             [
                 (dogets, b'gets'),
                 (doinserts, b'inserts'),
                 (dosets, b'sets'),
                 (domixed, b'mixed'),
             ]
         )
 
     for fn, title in benches:
         timer, fm = gettimer(ui, opts)
         timer(fn, title=title)
         fm.end()
 
 
 @command(
     b'perf::write|perfwrite',
     formatteropts
     + [
         (b'', b'write-method', b'write', b'ui write method'),
         (b'', b'nlines', 100, b'number of lines'),
         (b'', b'nitems', 100, b'number of items (per line)'),
         (b'', b'item', b'x', b'item that is written'),
         (b'', b'batch-line', None, b'pass whole line to write method at once'),
         (b'', b'flush-line', None, b'flush after each line'),
     ],
 )
 def perfwrite(ui, repo, **opts):
     """microbenchmark ui.write (and others)"""
     opts = _byteskwargs(opts)
 
     write = getattr(ui, _sysstr(opts[b'write_method']))
     nlines = int(opts[b'nlines'])
     nitems = int(opts[b'nitems'])
     item = opts[b'item']
     batch_line = opts.get(b'batch_line')
     flush_line = opts.get(b'flush_line')
 
     if batch_line:
         line = item * nitems + b'\n'
 
     def benchmark():
         for i in pycompat.xrange(nlines):
             if batch_line:
                 write(line)
             else:
                 for i in pycompat.xrange(nitems):
                     write(item)
                 write(b'\n')
             if flush_line:
                 ui.flush()
         ui.flush()
 
     timer, fm = gettimer(ui, opts)
     timer(benchmark)
     fm.end()
 
 
 def uisetup(ui):
     if util.safehasattr(cmdutil, b'openrevlog') and not util.safehasattr(
         commands, b'debugrevlogopts'
     ):
         # for "historical portability":
         # In this case, Mercurial should be 1.9 (or a79fea6b3e77) -
         # 3.7 (or 5606f7d0d063). Therefore, '--dir' option for
         # openrevlog() should cause failure, because it has been
         # available since 3.5 (or 49c583ca48c4).
         def openrevlog(orig, repo, cmd, file_, opts):
             if opts.get(b'dir') and not util.safehasattr(repo, b'dirlog'):
                 raise error.Abort(
                     b"This version doesn't support --dir option",
                     hint=b"use 3.5 or later",
                 )
             return orig(repo, cmd, file_, opts)
 
         name = _sysstr(b'openrevlog')
         extensions.wrapfunction(cmdutil, name, openrevlog)
 
 
 @command(
     b'perf::progress|perfprogress',
     formatteropts
     + [
         (b'', b'topic', b'topic', b'topic for progress messages'),
         (b'c', b'total', 1000000, b'total value we are progressing to'),
     ],
     norepo=True,
 )
 def perfprogress(ui, topic=None, total=None, **opts):
     """printing of progress bars"""
     opts = _byteskwargs(opts)
 
     timer, fm = gettimer(ui, opts)
 
     def doprogress():
         with ui.makeprogress(topic, total=total) as progress:
             for i in _xrange(total):
                 progress.increment()
 
     timer(doprogress)
     fm.end()

mercurial/branchmap.py

@@ -1,1079 +1,1097 b''
 # branchmap.py - logic to computes, maintain and stores branchmap for local repo
 #
 # Copyright 2005-2007 Olivia Mackall <[e-mail]>
 #
 # This software may be used and distributed according to the terms of the
 # GNU General Public License version 2 or any later version.
 
 
 import struct
 
 from .node import (
     bin,
     hex,
     nullrev,
 )
 
 from typing import (
     Any,
     Callable,
     Dict,
     Iterable,
     List,
     Optional,
     Set,
     TYPE_CHECKING,
     Tuple,
     Union,
 )
 
 from . import (
     encoding,
     error,
     obsolete,
     scmutil,
     util,
 )
 
 from .utils import (
     repoviewutil,
     stringutil,
 )
 
 if TYPE_CHECKING:
     from . import localrepo
 
     assert [localrepo]
 
 subsettable = repoviewutil.subsettable
 
 calcsize = struct.calcsize
 pack_into = struct.pack_into
 unpack_from = struct.unpack_from
 
 
 class BranchMapCache:
     """mapping of filtered views of repo with their branchcache"""
 
     def __init__(self):
         self._per_filter = {}
 
     def __getitem__(self, repo):
         self.updatecache(repo)
         bcache = self._per_filter[repo.filtername]
         assert bcache._filtername == repo.filtername, (
             bcache._filtername,
             repo.filtername,
         )
         return bcache
 
     def update_disk(self, repo):
         """ensure and up-to-date cache is (or will be) written on disk
 
         The cache for this repository view is updated  if needed and written on
         disk.
 
         If a transaction is in progress, the writing is schedule to transaction
         close. See the `BranchMapCache.write_dirty` method.
 
         This method exist independently of __getitem__ as it is sometime useful
         to signal that we have no intend to use the data in memory yet.
         """
         self.updatecache(repo)
         bcache = self._per_filter[repo.filtername]
         assert bcache._filtername == repo.filtername, (
             bcache._filtername,
             repo.filtername,
         )
         tr = repo.currenttransaction()
         if getattr(tr, 'finalized', True):
             bcache.sync_disk(repo)
 
     def updatecache(self, repo):
         """Update the cache for the given filtered view on a repository"""
         # This can trigger updates for the caches for subsets of the filtered
         # view, e.g. when there is no cache for this filtered view or the cache
         # is stale.
 
         cl = repo.changelog
         filtername = repo.filtername
         bcache = self._per_filter.get(filtername)
         if bcache is None or not bcache.validfor(repo):
             # cache object missing or cache object stale? Read from disk
-            bcache = branchcache.fromfile(repo)
+            bcache = branch_cache_from_file(repo)
 
         revs = []
         if bcache is None:
             # no (fresh) cache available anymore, perhaps we can re-use
             # the cache for a subset, then extend that to add info on missing
             # revisions.
             subsetname = subsettable.get(filtername)
             if subsetname is not None:
                 subset = repo.filtered(subsetname)
                 self.updatecache(subset)
                 bcache = self._per_filter[subset.filtername].inherit_for(repo)
                 extrarevs = subset.changelog.filteredrevs - cl.filteredrevs
                 revs.extend(r for r in extrarevs if r <= bcache.tiprev)
             else:
                 # nothing to fall back on, start empty.
-                bcache = branchcache(repo)
+                bcache = new_branch_cache(repo)
 
         revs.extend(cl.revs(start=bcache.tiprev + 1))
         if revs:
             bcache.update(repo, revs)
 
         assert bcache.validfor(repo), filtername
         self._per_filter[repo.filtername] = bcache
 
     def replace(self, repo, remotebranchmap):
         """Replace the branchmap cache for a repo with a branch mapping.
 
         This is likely only called during clone with a branch map from a
         remote.
 
         """
         cl = repo.changelog
         clrev = cl.rev
         clbranchinfo = cl.branchinfo
         rbheads = []
         closed = set()
         for bheads in remotebranchmap.values():
             rbheads += bheads
             for h in bheads:
                 r = clrev(h)
                 b, c = clbranchinfo(r)
                 if c:
                     closed.add(h)
 
         if rbheads:
             rtiprev = max((int(clrev(node)) for node in rbheads))
-            cache = branchcache(
+            cache = new_branch_cache(
                 repo,
                 remotebranchmap,
                 repo[rtiprev].node(),
                 rtiprev,
                 closednodes=closed,
             )
 
             # Try to stick it as low as possible
             # filter above served are unlikely to be fetch from a clone
             for candidate in (b'base', b'immutable', b'served'):
                 rview = repo.filtered(candidate)
                 if cache.validfor(rview):
                     cache._filtername = candidate
                     self._per_filter[candidate] = cache
                     cache._state = STATE_DIRTY
                     cache.write(rview)
                     return
 
     def clear(self):
         self._per_filter.clear()
 
     def write_dirty(self, repo):
         unfi = repo.unfiltered()
         for filtername in repoviewutil.get_ordered_subset():
             cache = self._per_filter.get(filtername)
             if cache is None:
                 continue
             if filtername is None:
                 repo = unfi
             else:
                 repo = unfi.filtered(filtername)
             cache.sync_disk(repo)
 
 
 def _unknownnode(node):
     """raises ValueError when branchcache found a node which does not exists"""
     raise ValueError('node %s does not exist' % node.hex())
 
 
 def _branchcachedesc(repo):
     if repo.filtername is not None:
         return b'branch cache (%s)' % repo.filtername
     else:
         return b'branch cache'
 
 
 class _BaseBranchCache:
     """A dict like object that hold branches heads cache.
 
     This cache is used to avoid costly computations to determine all the
     branch heads of a repo.
-
-    The cache is serialized on disk in the following format:
-
-    <tip hex node> <tip rev number> [optional filtered repo hex hash]
-    <branch head hex node> <open/closed state> <branch name>
-    <branch head hex node> <open/closed state> <branch name>
-    ...
-
-    The first line is used to check if the cache is still valid. If the
-    branch cache is for a filtered repo view, an optional third hash is
-    included that hashes the hashes of all filtered and obsolete revisions.
-
-    The open/closed state is represented by a single letter 'o' or 'c'.
-    This field can be used to avoid changelog reads when determining if a
-    branch head closes a branch or not.
     """
 
     def __init__(
         self,
         repo: "localrepo.localrepository",
         entries: Union[
             Dict[bytes, List[bytes]], Iterable[Tuple[bytes, List[bytes]]]
         ] = (),
         closed_nodes: Optional[Set[bytes]] = None,
     ) -> None:
         """hasnode is a function which can be used to verify whether changelog
         has a given node or not. If it's not provided, we assume that every node
         we have exists in changelog"""
         # closednodes is a set of nodes that close their branch. If the branch
         # cache has been updated, it may contain nodes that are no longer
         # heads.
         if closed_nodes is None:
             closed_nodes = set()
         self._closednodes = set(closed_nodes)
         self._entries = dict(entries)
 
     def __iter__(self):
         return iter(self._entries)
 
     def __setitem__(self, key, value):
         self._entries[key] = value
 
     def __getitem__(self, key):
         return self._entries[key]
 
     def __contains__(self, key):
         return key in self._entries
 
     def iteritems(self):
         return self._entries.items()
 
     items = iteritems
 
     def hasbranch(self, label):
         """checks whether a branch of this name exists or not"""
         return label in self._entries
 
     def _branchtip(self, heads):
         """Return tuple with last open head in heads and false,
         otherwise return last closed head and true."""
         tip = heads[-1]
         closed = True
         for h in reversed(heads):
             if h not in self._closednodes:
                 tip = h
                 closed = False
                 break
         return tip, closed
 
     def branchtip(self, branch):
         """Return the tipmost open head on branch head, otherwise return the
         tipmost closed head on branch.
         Raise KeyError for unknown branch."""
         return self._branchtip(self[branch])[0]
 
     def iteropen(self, nodes):
         return (n for n in nodes if n not in self._closednodes)
 
     def branchheads(self, branch, closed=False):
         heads = self._entries[branch]
         if not closed:
             heads = list(self.iteropen(heads))
         return heads
 
     def iterbranches(self):
         for bn, heads in self.items():
             yield (bn, heads) + self._branchtip(heads)
 
     def iterheads(self):
         """returns all the heads"""
         return self._entries.values()
 
     def update(self, repo, revgen):
         """Given a branchhead cache, self, that may have extra nodes or be
         missing heads, and a generator of nodes that are strictly a superset of
         heads missing, this function updates self to be correct.
         """
         starttime = util.timer()
         cl = repo.changelog
         # collect new branch entries
         newbranches = {}
         getbranchinfo = repo.revbranchcache().branchinfo
         max_rev = -1
         for r in revgen:
             branch, closesbranch = getbranchinfo(r)
             newbranches.setdefault(branch, []).append(r)
             if closesbranch:
                 self._closednodes.add(cl.node(r))
             max_rev = max(max_rev, r)
         if max_rev < 0:
             msg = "running branchcache.update without revision to update"
             raise error.ProgrammingError(msg)
 
         # Delay fetching the topological heads until they are needed.
         # A repository without non-continous branches can skip this part.
         topoheads = None
 
         # If a changeset is visible, its parents must be visible too, so
         # use the faster unfiltered parent accessor.
         parentrevs = repo.unfiltered().changelog.parentrevs
 
         # Faster than using ctx.obsolete()
         obsrevs = obsolete.getrevs(repo, b'obsolete')
 
         for branch, newheadrevs in newbranches.items():
             # For every branch, compute the new branchheads.
             # A branchhead is a revision such that no descendant is on
             # the same branch.
             #
             # The branchheads are computed iteratively in revision order.
             # This ensures topological order, i.e. parents are processed
             # before their children. Ancestors are inclusive here, i.e.
             # any revision is an ancestor of itself.
             #
             # Core observations:
             # - The current revision is always a branchhead for the
             #   repository up to that point.
             # - It is the first revision of the branch if and only if
             #   there was no branchhead before. In that case, it is the
             #   only branchhead as there are no possible ancestors on
             #   the same branch.
             # - If a parent is on the same branch, a branchhead can
             #   only be an ancestor of that parent, if it is parent
             #   itself. Otherwise it would have been removed as ancestor
             #   of that parent before.
             # - Therefore, if all parents are on the same branch, they
             #   can just be removed from the branchhead set.
             # - If one parent is on the same branch and the other is not
             #   and there was exactly one branchhead known, the existing
             #   branchhead can only be an ancestor if it is the parent.
             #   Otherwise it would have been removed as ancestor of
             #   the parent before. The other parent therefore can't have
             #   a branchhead as ancestor.
             # - In all other cases, the parents on different branches
             #   could have a branchhead as ancestor. Those parents are
             #   kept in the "uncertain" set. If all branchheads are also
             #   topological heads, they can't have descendants and further
             #   checks can be skipped. Otherwise, the ancestors of the
             #   "uncertain" set are removed from branchheads.
             #   This computation is heavy and avoided if at all possible.
             bheads = self._entries.get(branch, [])
             bheadset = {cl.rev(node) for node in bheads}
             uncertain = set()
             for newrev in sorted(newheadrevs):
                 if newrev in obsrevs:
                     # We ignore obsolete changesets as they shouldn't be
                     # considered heads.
                     continue
 
                 if not bheadset:
                     bheadset.add(newrev)
                     continue
 
                 parents = [p for p in parentrevs(newrev) if p != nullrev]
                 samebranch = set()
                 otherbranch = set()
                 obsparents = set()
                 for p in parents:
                     if p in obsrevs:
                         # We ignored this obsolete changeset earlier, but now
                         # that it has non-ignored children, we need to make
                         # sure their ancestors are not considered heads. To
                         # achieve that, we will simply treat this obsolete
                         # changeset as a parent from other branch.
                         obsparents.add(p)
                     elif p in bheadset or getbranchinfo(p)[0] == branch:
                         samebranch.add(p)
                     else:
                         otherbranch.add(p)
                 if not (len(bheadset) == len(samebranch) == 1):
                     uncertain.update(otherbranch)
                     uncertain.update(obsparents)
                 bheadset.difference_update(samebranch)
                 bheadset.add(newrev)
 
             if uncertain:
                 if topoheads is None:
                     topoheads = set(cl.headrevs())
                 if bheadset - topoheads:
                     floorrev = min(bheadset)
                     if floorrev <= max(uncertain):
                         ancestors = set(cl.ancestors(uncertain, floorrev))
                         bheadset -= ancestors
             if bheadset:
                 self[branch] = [cl.node(rev) for rev in sorted(bheadset)]
 
         duration = util.timer() - starttime
         repo.ui.log(
             b'branchcache',
             b'updated %s in %.4f seconds\n',
             _branchcachedesc(repo),
             duration,
         )
         return max_rev
 
 
 STATE_CLEAN = 1
 STATE_INHERITED = 2
 STATE_DIRTY = 3
 
 
-class branchcache(_BaseBranchCache):
-    """Branchmap info for a local repo or repoview"""
+class _LocalBranchCache(_BaseBranchCache):
+    """base class of branch-map info for a local repo or repoview"""
 
-    _base_filename = b"branch2"
+    _base_filename = None
 
     def __init__(
         self,
         repo: "localrepo.localrepository",
         entries: Union[
             Dict[bytes, List[bytes]], Iterable[Tuple[bytes, List[bytes]]]
         ] = (),
         tipnode: Optional[bytes] = None,
         tiprev: Optional[int] = nullrev,
         filteredhash: Optional[bytes] = None,
         closednodes: Optional[Set[bytes]] = None,
         hasnode: Optional[Callable[[bytes], bool]] = None,
         verify_node: bool = False,
         inherited: bool = False,
     ) -> None:
         """hasnode is a function which can be used to verify whether changelog
         has a given node or not. If it's not provided, we assume that every node
         we have exists in changelog"""
         self._filtername = repo.filtername
         if tipnode is None:
             self.tipnode = repo.nullid
         else:
             self.tipnode = tipnode
         self.tiprev = tiprev
         self.filteredhash = filteredhash
         self._state = STATE_CLEAN
         if inherited:
             self._state = STATE_INHERITED
 
         super().__init__(repo=repo, entries=entries, closed_nodes=closednodes)
         # closednodes is a set of nodes that close their branch. If the branch
         # cache has been updated, it may contain nodes that are no longer
         # heads.
 
         # Do we need to verify branch at all ?
         self._verify_node = verify_node
         # branches for which nodes are verified
         self._verifiedbranches = set()
         self._hasnode = None
         if self._verify_node:
             self._hasnode = repo.changelog.hasnode
 
     def validfor(self, repo):
         """check that cache contents are valid for (a subset of) this repo
 
         - False when the order of changesets changed or if we detect a strip.
         - True when cache is up-to-date for the current repo or its subset."""
         try:
             node = repo.changelog.node(self.tiprev)
         except IndexError:
             # changesets were stripped and now we don't even have enough to
             # find tiprev
             return False
         if self.tipnode != node:
             # tiprev doesn't correspond to tipnode: repo was stripped, or this
             # repo has a different order of changesets
             return False
         tiphash = scmutil.filteredhash(repo, self.tiprev, needobsolete=True)
         # hashes don't match if this repo view has a different set of filtered
         # revisions (e.g. due to phase changes) or obsolete revisions (e.g.
         # history was rewritten)
         return self.filteredhash == tiphash
 
     @classmethod
     def fromfile(cls, repo):
         f = None
         try:
             f = repo.cachevfs(cls._filename(repo))
             lineiter = iter(f)
             init_kwargs = cls._load_header(repo, lineiter)
             bcache = cls(
                 repo,
                 verify_node=True,
                 **init_kwargs,
             )
             if not bcache.validfor(repo):
                 # invalidate the cache
                 raise ValueError('tip differs')
             bcache._load_heads(repo, lineiter)
         except (IOError, OSError):
             return None
 
         except Exception as inst:
             if repo.ui.debugflag:
                 msg = b'invalid %s: %s\n'
                 msg %= (
                     _branchcachedesc(repo),
                     stringutil.forcebytestr(inst),
                 )
                 repo.ui.debug(msg)
             bcache = None
 
         finally:
             if f:
                 f.close()
 
         return bcache
 
     @classmethod
     def _load_header(cls, repo, lineiter) -> "dict[str, Any]":
         """parse the head of a branchmap file
 
         return parameters to pass to a newly created class instance.
         """
         cachekey = next(lineiter).rstrip(b'\n').split(b" ", 2)
         last, lrev = cachekey[:2]
         last, lrev = bin(last), int(lrev)
         filteredhash = None
         if len(cachekey) > 2:
             filteredhash = bin(cachekey[2])
         return {
             "tipnode": last,
             "tiprev": lrev,
             "filteredhash": filteredhash,
         }
 
     def _load_heads(self, repo, lineiter):
         """fully loads the branchcache by reading from the file using the line
         iterator passed"""
         for line in lineiter:
             line = line.rstrip(b'\n')
             if not line:
                 continue
             node, state, label = line.split(b" ", 2)
             if state not in b'oc':
                 raise ValueError('invalid branch state')
             label = encoding.tolocal(label.strip())
             node = bin(node)
             self._entries.setdefault(label, []).append(node)
             if state == b'c':
                 self._closednodes.add(node)
 
     @classmethod
     def _filename(cls, repo):
         """name of a branchcache file for a given repo or repoview"""
         filename = cls._base_filename
+        assert filename is not None
         if repo.filtername:
             filename = b'%s-%s' % (filename, repo.filtername)
         return filename
 
     def inherit_for(self, repo):
         """return a deep copy of the branchcache object"""
         assert repo.filtername != self._filtername
         other = type(self)(
             repo=repo,
             # we always do a shally copy of self._entries, and the values is
             # always replaced, so no need to deepcopy until the above remains
             # true.
             entries=self._entries,
             tipnode=self.tipnode,
             tiprev=self.tiprev,
             filteredhash=self.filteredhash,
             closednodes=set(self._closednodes),
             verify_node=self._verify_node,
             inherited=True,
         )
         # also copy information about the current verification state
         other._verifiedbranches = set(self._verifiedbranches)
         return other
 
     def sync_disk(self, repo):
         """synchronise the on disk file with the cache state
 
         If new value specific to this filter level need to be written, the file
         will be updated, if the state of the branchcache is inherited from a
         subset, any stalled on disk file will be deleted.
 
         That method does nothing if there is nothing to do.
         """
         if self._state == STATE_DIRTY:
             self.write(repo)
         elif self._state == STATE_INHERITED:
             filename = self._filename(repo)
             repo.cachevfs.tryunlink(filename)
 
     def write(self, repo):
         assert self._filtername == repo.filtername, (
             self._filtername,
             repo.filtername,
         )
         assert self._state == STATE_DIRTY, self._state
         # This method should not be called during an open transaction
         tr = repo.currenttransaction()
         if not getattr(tr, 'finalized', True):
             msg = "writing branchcache in the middle of a transaction"
             raise error.ProgrammingError(msg)
         try:
             filename = self._filename(repo)
             with repo.cachevfs(filename, b"w", atomictemp=True) as f:
                 self._write_header(f)
                 nodecount = self._write_heads(f)
             repo.ui.log(
                 b'branchcache',
                 b'wrote %s with %d labels and %d nodes\n',
                 _branchcachedesc(repo),
                 len(self._entries),
                 nodecount,
             )
             self._state = STATE_CLEAN
         except (IOError, OSError, error.Abort) as inst:
             # Abort may be raised by read only opener, so log and continue
             repo.ui.debug(
                 b"couldn't write branch cache: %s\n"
                 % stringutil.forcebytestr(inst)
             )
 
     def _write_header(self, fp) -> None:
         """write the branch cache header to a file"""
         cachekey = [hex(self.tipnode), b'%d' % self.tiprev]
         if self.filteredhash is not None:
             cachekey.append(hex(self.filteredhash))
         fp.write(b" ".join(cachekey) + b'\n')
 
     def _write_heads(self, fp) -> int:
         """write list of heads to a file
 
         Return the number of heads written."""
         nodecount = 0
         for label, nodes in sorted(self._entries.items()):
             label = encoding.fromlocal(label)
             for node in nodes:
                 nodecount += 1
                 if node in self._closednodes:
                     state = b'c'
                 else:
                     state = b'o'
                 fp.write(b"%s %s %s\n" % (hex(node), state, label))
         return nodecount
 
     def _verifybranch(self, branch):
         """verify head nodes for the given branch."""
         if not self._verify_node:
             return
         if branch not in self._entries or branch in self._verifiedbranches:
             return
         assert self._hasnode is not None
         for n in self._entries[branch]:
             if not self._hasnode(n):
                 _unknownnode(n)
 
         self._verifiedbranches.add(branch)
 
     def _verifyall(self):
         """verifies nodes of all the branches"""
         for b in self._entries.keys():
             if b not in self._verifiedbranches:
                 self._verifybranch(b)
 
     def __getitem__(self, key):
         self._verifybranch(key)
         return super().__getitem__(key)
 
     def __contains__(self, key):
         self._verifybranch(key)
         return super().__contains__(key)
 
     def iteritems(self):
         self._verifyall()
         return super().iteritems()
 
     items = iteritems
 
     def iterheads(self):
         """returns all the heads"""
         self._verifyall()
         return super().iterheads()
 
     def hasbranch(self, label):
         """checks whether a branch of this name exists or not"""
         self._verifybranch(label)
         return super().hasbranch(label)
 
     def branchheads(self, branch, closed=False):
         self._verifybranch(branch)
         return super().branchheads(branch, closed=closed)
 
     def update(self, repo, revgen):
         assert self._filtername == repo.filtername, (
             self._filtername,
             repo.filtername,
         )
         cl = repo.changelog
         max_rev = super().update(repo, revgen)
         # new tip revision which we found after iterating items from new
         # branches
         if max_rev is not None and max_rev > self.tiprev:
             self.tiprev = max_rev
             self.tipnode = cl.node(max_rev)
 
         if not self.validfor(repo):
             # old cache key is now invalid for the repo, but we've just updated
             # the cache and we assume it's valid, so let's make the cache key
             # valid as well by recomputing it from the cached data
             self.tipnode = repo.nullid
             self.tiprev = nullrev
             for heads in self.iterheads():
                 if not heads:
                     # all revisions on a branch are obsolete
                     continue
                 # note: tiprev is not necessarily the tip revision of repo,
                 # because the tip could be obsolete (i.e. not a head)
                 tiprev = max(cl.rev(node) for node in heads)
                 if tiprev > self.tiprev:
                     self.tipnode = cl.node(tiprev)
                     self.tiprev = tiprev
         self.filteredhash = scmutil.filteredhash(
             repo, self.tiprev, needobsolete=True
         )
         self._state = STATE_DIRTY
         tr = repo.currenttransaction()
         if getattr(tr, 'finalized', True):
             # Avoid premature writing.
             #
             # (The cache warming setup by localrepo will update the file later.)
             self.write(repo)
 
 
+def branch_cache_from_file(repo) -> Optional[_LocalBranchCache]:
+    """Build a branch cache from on-disk data if possible"""
+    return BranchCacheV2.fromfile(repo)
+
+
+def new_branch_cache(repo, *args, **kwargs):
+    """Build a new branch cache from argument"""
+    return BranchCacheV2(repo, *args, **kwargs)
+
+
+class BranchCacheV2(_LocalBranchCache):
+    """a branch cache using version 2 of the format on disk
+
+    The cache is serialized on disk in the following format:
+
+    <tip hex node> <tip rev number> [optional filtered repo hex hash]
+    <branch head hex node> <open/closed state> <branch name>
+    <branch head hex node> <open/closed state> <branch name>
+    ...
+
+    The first line is used to check if the cache is still valid. If the
+    branch cache is for a filtered repo view, an optional third hash is
+    included that hashes the hashes of all filtered and obsolete revisions.
+
+    The open/closed state is represented by a single letter 'o' or 'c'.
+    This field can be used to avoid changelog reads when determining if a
+    branch head closes a branch or not.
+    """
+
+    _base_filename = b"branch2"
+
+
 class remotebranchcache(_BaseBranchCache):
     """Branchmap info for a remote connection, should not write locally"""
 
     def __init__(
         self,
         repo: "localrepo.localrepository",
         entries: Union[
             Dict[bytes, List[bytes]], Iterable[Tuple[bytes, List[bytes]]]
         ] = (),
         closednodes: Optional[Set[bytes]] = None,
     ) -> None:
         super().__init__(repo=repo, entries=entries, closed_nodes=closednodes)
 
 
 # Revision branch info cache
 
 _rbcversion = b'-v1'
 _rbcnames = b'rbc-names' + _rbcversion
 _rbcrevs = b'rbc-revs' + _rbcversion
 # [4 byte hash prefix][4 byte branch name number with sign bit indicating open]
 _rbcrecfmt = b'>4sI'
 _rbcrecsize = calcsize(_rbcrecfmt)
 _rbcmininc = 64 * _rbcrecsize
 _rbcnodelen = 4
 _rbcbranchidxmask = 0x7FFFFFFF
 _rbccloseflag = 0x80000000
 
 
 class rbcrevs:
     """a byte string consisting of an immutable prefix followed by a mutable suffix"""
 
     def __init__(self, revs):
         self._prefix = revs
         self._rest = bytearray()
 
     def __len__(self):
         return len(self._prefix) + len(self._rest)
 
     def unpack_record(self, rbcrevidx):
         if rbcrevidx < len(self._prefix):
             return unpack_from(_rbcrecfmt, util.buffer(self._prefix), rbcrevidx)
         else:
             return unpack_from(
                 _rbcrecfmt,
                 util.buffer(self._rest),
                 rbcrevidx - len(self._prefix),
             )
 
     def make_mutable(self):
         if len(self._prefix) > 0:
             entirety = bytearray()
             entirety[:] = self._prefix
             entirety.extend(self._rest)
             self._rest = entirety
             self._prefix = bytearray()
 
     def truncate(self, pos):
         self.make_mutable()
         del self._rest[pos:]
 
     def pack_into(self, rbcrevidx, node, branchidx):
         if rbcrevidx < len(self._prefix):
             self.make_mutable()
         buf = self._rest
         start_offset = rbcrevidx - len(self._prefix)
         end_offset = start_offset + _rbcrecsize
 
         if len(self._rest) < end_offset:
             # bytearray doesn't allocate extra space at least in Python 3.7.
             # When multiple changesets are added in a row, precise resize would
             # result in quadratic complexity. Overallocate to compensate by
             # using the classic doubling technique for dynamic arrays instead.
             # If there was a gap in the map before, less space will be reserved.
             self._rest.extend(b'\0' * end_offset)
         return pack_into(
             _rbcrecfmt,
             buf,
             start_offset,
             node,
             branchidx,
         )
 
     def extend(self, extension):
         return self._rest.extend(extension)
 
     def slice(self, begin, end):
         if begin < len(self._prefix):
             acc = bytearray()
             acc[:] = self._prefix[begin:end]
             acc.extend(
                 self._rest[begin - len(self._prefix) : end - len(self._prefix)]
             )
             return acc
         return self._rest[begin - len(self._prefix) : end - len(self._prefix)]
 
 
 class revbranchcache:
     """Persistent cache, mapping from revision number to branch name and close.
     This is a low level cache, independent of filtering.
 
     Branch names are stored in rbc-names in internal encoding separated by 0.
     rbc-names is append-only, and each branch name is only stored once and will
     thus have a unique index.
 
     The branch info for each revision is stored in rbc-revs as constant size
     records. The whole file is read into memory, but it is only 'parsed' on
     demand. The file is usually append-only but will be truncated if repo
     modification is detected.
     The record for each revision contains the first 4 bytes of the
     corresponding node hash, and the record is only used if it still matches.
     Even a completely trashed rbc-revs fill thus still give the right result
     while converging towards full recovery ... assuming no incorrectly matching
     node hashes.
     The record also contains 4 bytes where 31 bits contains the index of the
     branch and the last bit indicate that it is a branch close commit.
     The usage pattern for rbc-revs is thus somewhat similar to 00changelog.i
     and will grow with it but be 1/8th of its size.
     """
 
     def __init__(self, repo, readonly=True):
         assert repo.filtername is None
         self._repo = repo
         self._names = []  # branch names in local encoding with static index
         self._rbcrevs = rbcrevs(bytearray())
         self._rbcsnameslen = 0  # length of names read at _rbcsnameslen
         try:
             bndata = repo.cachevfs.read(_rbcnames)
             self._rbcsnameslen = len(bndata)  # for verification before writing
             if bndata:
                 self._names = [
                     encoding.tolocal(bn) for bn in bndata.split(b'\0')
                 ]
         except (IOError, OSError):
             if readonly:
                 # don't try to use cache - fall back to the slow path
                 self.branchinfo = self._branchinfo
 
         if self._names:
             try:
                 if repo.ui.configbool(b'storage', b'revbranchcache.mmap'):
                     with repo.cachevfs(_rbcrevs) as fp:
                         data = util.buffer(util.mmapread(fp))
                 else:
                     data = repo.cachevfs.read(_rbcrevs)
                 self._rbcrevs = rbcrevs(data)
             except (IOError, OSError) as inst:
                 repo.ui.debug(
                     b"couldn't read revision branch cache: %s\n"
                     % stringutil.forcebytestr(inst)
                 )
         # remember number of good records on disk
         self._rbcrevslen = min(
             len(self._rbcrevs) // _rbcrecsize, len(repo.changelog)
         )
         if self._rbcrevslen == 0:
             self._names = []
         self._rbcnamescount = len(self._names)  # number of names read at
         # _rbcsnameslen
 
     def _clear(self):
         self._rbcsnameslen = 0
         del self._names[:]
         self._rbcnamescount = 0
         self._rbcrevslen = len(self._repo.changelog)
         self._rbcrevs = rbcrevs(bytearray(self._rbcrevslen * _rbcrecsize))
         util.clearcachedproperty(self, b'_namesreverse')
 
     @util.propertycache
     def _namesreverse(self):
         return {b: r for r, b in enumerate(self._names)}
 
     def branchinfo(self, rev):
         """Return branch name and close flag for rev, using and updating
         persistent cache."""
         changelog = self._repo.changelog
         rbcrevidx = rev * _rbcrecsize
 
         # avoid negative index, changelog.read(nullrev) is fast without cache
         if rev == nullrev:
             return changelog.branchinfo(rev)
 
         # if requested rev isn't allocated, grow and cache the rev info
         if len(self._rbcrevs) < rbcrevidx + _rbcrecsize:
             return self._branchinfo(rev)
 
         # fast path: extract data from cache, use it if node is matching
         reponode = changelog.node(rev)[:_rbcnodelen]
         cachenode, branchidx = self._rbcrevs.unpack_record(rbcrevidx)
         close = bool(branchidx & _rbccloseflag)
         if close:
             branchidx &= _rbcbranchidxmask
         if cachenode == b'\0\0\0\0':
             pass
         elif cachenode == reponode:
             try:
                 return self._names[branchidx], close
             except IndexError:
                 # recover from invalid reference to unknown branch
                 self._repo.ui.debug(
                     b"referenced branch names not found"
                     b" - rebuilding revision branch cache from scratch\n"
                 )
                 self._clear()
         else:
             # rev/node map has changed, invalidate the cache from here up
             self._repo.ui.debug(
                 b"history modification detected - truncating "
                 b"revision branch cache to revision %d\n" % rev
             )
             truncate = rbcrevidx + _rbcrecsize
             self._rbcrevs.truncate(truncate)
             self._rbcrevslen = min(self._rbcrevslen, truncate)
 
         # fall back to slow path and make sure it will be written to disk
         return self._branchinfo(rev)
 
     def _branchinfo(self, rev):
         """Retrieve branch info from changelog and update _rbcrevs"""
         changelog = self._repo.changelog
         b, close = changelog.branchinfo(rev)
         if b in self._namesreverse:
             branchidx = self._namesreverse[b]
         else:
             branchidx = len(self._names)
             self._names.append(b)
             self._namesreverse[b] = branchidx
         reponode = changelog.node(rev)
         if close:
             branchidx |= _rbccloseflag
         self._setcachedata(rev, reponode, branchidx)
         return b, close
 
     def setdata(self, rev, changelogrevision):
         """add new data information to the cache"""
         branch, close = changelogrevision.branchinfo
 
         if branch in self._namesreverse:
             branchidx = self._namesreverse[branch]
         else:
             branchidx = len(self._names)
             self._names.append(branch)
             self._namesreverse[branch] = branchidx
         if close:
             branchidx |= _rbccloseflag
         self._setcachedata(rev, self._repo.changelog.node(rev), branchidx)
         # If no cache data were readable (non exists, bad permission, etc)
         # the cache was bypassing itself by setting:
         #
         #   self.branchinfo = self._branchinfo
         #
         # Since we now have data in the cache, we need to drop this bypassing.
         if 'branchinfo' in vars(self):
             del self.branchinfo
 
     def _setcachedata(self, rev, node, branchidx):
         """Writes the node's branch data to the in-memory cache data."""
         if rev == nullrev:
             return
         rbcrevidx = rev * _rbcrecsize
         self._rbcrevs.pack_into(rbcrevidx, node, branchidx)
         self._rbcrevslen = min(self._rbcrevslen, rev)
 
         tr = self._repo.currenttransaction()
         if tr:
             tr.addfinalize(b'write-revbranchcache', self.write)
 
     def write(self, tr=None):
         """Save branch cache if it is dirty."""
         repo = self._repo
         wlock = None
         step = b''
         try:
             # write the new names
             if self._rbcnamescount < len(self._names):
                 wlock = repo.wlock(wait=False)
                 step = b' names'
                 self._writenames(repo)
 
             # write the new revs
             start = self._rbcrevslen * _rbcrecsize
             if start != len(self._rbcrevs):
                 step = b''
                 if wlock is None:
                     wlock = repo.wlock(wait=False)
                 self._writerevs(repo, start)
 
         except (IOError, OSError, error.Abort, error.LockError) as inst:
             repo.ui.debug(
                 b"couldn't write revision branch cache%s: %s\n"
                 % (step, stringutil.forcebytestr(inst))
             )
         finally:
             if wlock is not None:
                 wlock.release()
 
     def _writenames(self, repo):
         """write the new branch names to revbranchcache"""
         if self._rbcnamescount != 0:
             f = repo.cachevfs.open(_rbcnames, b'ab')
             if f.tell() == self._rbcsnameslen:
                 f.write(b'\0')
             else:
                 f.close()
                 repo.ui.debug(b"%s changed - rewriting it\n" % _rbcnames)
                 self._rbcnamescount = 0
                 self._rbcrevslen = 0
         if self._rbcnamescount == 0:
             # before rewriting names, make sure references are removed
             repo.cachevfs.unlinkpath(_rbcrevs, ignoremissing=True)
             f = repo.cachevfs.open(_rbcnames, b'wb')
         f.write(
             b'\0'.join(
                 encoding.fromlocal(b)
                 for b in self._names[self._rbcnamescount :]
             )
         )
         self._rbcsnameslen = f.tell()
         f.close()
         self._rbcnamescount = len(self._names)
 
     def _writerevs(self, repo, start):
         """write the new revs to revbranchcache"""
         revs = min(len(repo.changelog), len(self._rbcrevs) // _rbcrecsize)
         with repo.cachevfs.open(_rbcrevs, b'ab') as f:
             if f.tell() != start:
                 repo.ui.debug(
                     b"truncating cache/%s to %d\n" % (_rbcrevs, start)
                 )
                 f.seek(start)
                 if f.tell() != start:
                     start = 0
                     f.seek(start)
                 f.truncate()
             end = revs * _rbcrecsize
             f.write(self._rbcrevs.slice(start, end))
         self._rbcrevslen = revs