discovery: add a devel.discovery.exchange-heads

Currently all discovery start with testing local and remote heads. For analysis
purpose we make it possible to disable that initial "handshake" and start
discovery with the whole repository as undecided.

Differential Revision: https://phab.mercurial-scm.org/D9801

mercurial/configitems.py

@@ -1,2576 +1,2583
 # configitems.py - centralized declaration of configuration option
 #
 #  Copyright 2017 Pierre-Yves David <[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.
 
 from __future__ import absolute_import
 
 import functools
 import re
 
 from . import (
     encoding,
     error,
 )
 
 
 def loadconfigtable(ui, extname, configtable):
     """update config item known to the ui with the extension ones"""
     for section, items in sorted(configtable.items()):
         knownitems = ui._knownconfig.setdefault(section, itemregister())
         knownkeys = set(knownitems)
         newkeys = set(items)
         for key in sorted(knownkeys & newkeys):
             msg = b"extension '%s' overwrite config item '%s.%s'"
             msg %= (extname, section, key)
             ui.develwarn(msg, config=b'warn-config')
 
         knownitems.update(items)
 
 
 class configitem(object):
     """represent a known config item
 
     :section: the official config section where to find this item,
        :name: the official name within the section,
     :default: default value for this item,
     :alias: optional list of tuples as alternatives,
     :generic: this is a generic definition, match name using regular expression.
     """
 
     def __init__(
         self,
         section,
         name,
         default=None,
         alias=(),
         generic=False,
         priority=0,
         experimental=False,
     ):
         self.section = section
         self.name = name
         self.default = default
         self.alias = list(alias)
         self.generic = generic
         self.priority = priority
         self.experimental = experimental
         self._re = None
         if generic:
             self._re = re.compile(self.name)
 
 
 class itemregister(dict):
     """A specialized dictionary that can handle wild-card selection"""
 
     def __init__(self):
         super(itemregister, self).__init__()
         self._generics = set()
 
     def update(self, other):
         super(itemregister, self).update(other)
         self._generics.update(other._generics)
 
     def __setitem__(self, key, item):
         super(itemregister, self).__setitem__(key, item)
         if item.generic:
             self._generics.add(item)
 
     def get(self, key):
         baseitem = super(itemregister, self).get(key)
         if baseitem is not None and not baseitem.generic:
             return baseitem
 
         # search for a matching generic item
         generics = sorted(self._generics, key=(lambda x: (x.priority, x.name)))
         for item in generics:
             # we use 'match' instead of 'search' to make the matching simpler
             # for people unfamiliar with regular expression. Having the match
             # rooted to the start of the string will produce less surprising
             # result for user writing simple regex for sub-attribute.
             #
             # For example using "color\..*" match produces an unsurprising
             # result, while using search could suddenly match apparently
             # unrelated configuration that happens to contains "color."
             # anywhere. This is a tradeoff where we favor requiring ".*" on
             # some match to avoid the need to prefix most pattern with "^".
             # The "^" seems more error prone.
             if item._re.match(key):
                 return item
 
         return None
 
 
 coreitems = {}
 
 
 def _register(configtable, *args, **kwargs):
     item = configitem(*args, **kwargs)
     section = configtable.setdefault(item.section, itemregister())
     if item.name in section:
         msg = b"duplicated config item registration for '%s.%s'"
         raise error.ProgrammingError(msg % (item.section, item.name))
     section[item.name] = item
 
 
 # special value for case where the default is derived from other values
 dynamicdefault = object()
 
 # Registering actual config items
 
 
 def getitemregister(configtable):
     f = functools.partial(_register, configtable)
     # export pseudo enum as configitem.*
     f.dynamicdefault = dynamicdefault
     return f
 
 
 coreconfigitem = getitemregister(coreitems)
 
 
 def _registerdiffopts(section, configprefix=b''):
     coreconfigitem(
         section,
         configprefix + b'nodates',
         default=False,
     )
     coreconfigitem(
         section,
         configprefix + b'showfunc',
         default=False,
     )
     coreconfigitem(
         section,
         configprefix + b'unified',
         default=None,
     )
     coreconfigitem(
         section,
         configprefix + b'git',
         default=False,
     )
     coreconfigitem(
         section,
         configprefix + b'ignorews',
         default=False,
     )
     coreconfigitem(
         section,
         configprefix + b'ignorewsamount',
         default=False,
     )
     coreconfigitem(
         section,
         configprefix + b'ignoreblanklines',
         default=False,
     )
     coreconfigitem(
         section,
         configprefix + b'ignorewseol',
         default=False,
     )
     coreconfigitem(
         section,
         configprefix + b'nobinary',
         default=False,
     )
     coreconfigitem(
         section,
         configprefix + b'noprefix',
         default=False,
     )
     coreconfigitem(
         section,
         configprefix + b'word-diff',
         default=False,
     )
 
 
 coreconfigitem(
     b'alias',
     b'.*',
     default=dynamicdefault,
     generic=True,
 )
 coreconfigitem(
     b'auth',
     b'cookiefile',
     default=None,
 )
 _registerdiffopts(section=b'annotate')
 # bookmarks.pushing: internal hack for discovery
 coreconfigitem(
     b'bookmarks',
     b'pushing',
     default=list,
 )
 # bundle.mainreporoot: internal hack for bundlerepo
 coreconfigitem(
     b'bundle',
     b'mainreporoot',
     default=b'',
 )
 coreconfigitem(
     b'censor',
     b'policy',
     default=b'abort',
     experimental=True,
 )
 coreconfigitem(
     b'chgserver',
     b'idletimeout',
     default=3600,
 )
 coreconfigitem(
     b'chgserver',
     b'skiphash',
     default=False,
 )
 coreconfigitem(
     b'cmdserver',
     b'log',
     default=None,
 )
 coreconfigitem(
     b'cmdserver',
     b'max-log-files',
     default=7,
 )
 coreconfigitem(
     b'cmdserver',
     b'max-log-size',
     default=b'1 MB',
 )
 coreconfigitem(
     b'cmdserver',
     b'max-repo-cache',
     default=0,
     experimental=True,
 )
 coreconfigitem(
     b'cmdserver',
     b'message-encodings',
     default=list,
 )
 coreconfigitem(
     b'cmdserver',
     b'track-log',
     default=lambda: [b'chgserver', b'cmdserver', b'repocache'],
 )
 coreconfigitem(
     b'cmdserver',
     b'shutdown-on-interrupt',
     default=True,
 )
 coreconfigitem(
     b'color',
     b'.*',
     default=None,
     generic=True,
 )
 coreconfigitem(
     b'color',
     b'mode',
     default=b'auto',
 )
 coreconfigitem(
     b'color',
     b'pagermode',
     default=dynamicdefault,
 )
 coreconfigitem(
     b'command-templates',
     b'graphnode',
     default=None,
     alias=[(b'ui', b'graphnodetemplate')],
 )
 coreconfigitem(
     b'command-templates',
     b'log',
     default=None,
     alias=[(b'ui', b'logtemplate')],
 )
 coreconfigitem(
     b'command-templates',
     b'mergemarker',
     default=(
         b'{node|short} '
         b'{ifeq(tags, "tip", "", '
         b'ifeq(tags, "", "", "{tags} "))}'
         b'{if(bookmarks, "{bookmarks} ")}'
         b'{ifeq(branch, "default", "", "{branch} ")}'
         b'- {author|user}: {desc|firstline}'
     ),
     alias=[(b'ui', b'mergemarkertemplate')],
 )
 coreconfigitem(
     b'command-templates',
     b'pre-merge-tool-output',
     default=None,
     alias=[(b'ui', b'pre-merge-tool-output-template')],
 )
 coreconfigitem(
     b'command-templates',
     b'oneline-summary',
     default=None,
 )
 coreconfigitem(
     b'command-templates',
     b'oneline-summary.*',
     default=dynamicdefault,
     generic=True,
 )
 _registerdiffopts(section=b'commands', configprefix=b'commit.interactive.')
 coreconfigitem(
     b'commands',
     b'commit.post-status',
     default=False,
 )
 coreconfigitem(
     b'commands',
     b'grep.all-files',
     default=False,
     experimental=True,
 )
 coreconfigitem(
     b'commands',
     b'merge.require-rev',
     default=False,
 )
 coreconfigitem(
     b'commands',
     b'push.require-revs',
     default=False,
 )
 coreconfigitem(
     b'commands',
     b'resolve.confirm',
     default=False,
 )
 coreconfigitem(
     b'commands',
     b'resolve.explicit-re-merge',
     default=False,
 )
 coreconfigitem(
     b'commands',
     b'resolve.mark-check',
     default=b'none',
 )
 _registerdiffopts(section=b'commands', configprefix=b'revert.interactive.')
 coreconfigitem(
     b'commands',
     b'show.aliasprefix',
     default=list,
 )
 coreconfigitem(
     b'commands',
     b'status.relative',
     default=False,
 )
 coreconfigitem(
     b'commands',
     b'status.skipstates',
     default=[],
     experimental=True,
 )
 coreconfigitem(
     b'commands',
     b'status.terse',
     default=b'',
 )
 coreconfigitem(
     b'commands',
     b'status.verbose',
     default=False,
 )
 coreconfigitem(
     b'commands',
     b'update.check',
     default=None,
 )
 coreconfigitem(
     b'commands',
     b'update.requiredest',
     default=False,
 )
 coreconfigitem(
     b'committemplate',
     b'.*',
     default=None,
     generic=True,
 )
 coreconfigitem(
     b'convert',
     b'bzr.saverev',
     default=True,
 )
 coreconfigitem(
     b'convert',
     b'cvsps.cache',
     default=True,
 )
 coreconfigitem(
     b'convert',
     b'cvsps.fuzz',
     default=60,
 )
 coreconfigitem(
     b'convert',
     b'cvsps.logencoding',
     default=None,
 )
 coreconfigitem(
     b'convert',
     b'cvsps.mergefrom',
     default=None,
 )
 coreconfigitem(
     b'convert',
     b'cvsps.mergeto',
     default=None,
 )
 coreconfigitem(
     b'convert',
     b'git.committeractions',
     default=lambda: [b'messagedifferent'],
 )
 coreconfigitem(
     b'convert',
     b'git.extrakeys',
     default=list,
 )
 coreconfigitem(
     b'convert',
     b'git.findcopiesharder',
     default=False,
 )
 coreconfigitem(
     b'convert',
     b'git.remoteprefix',
     default=b'remote',
 )
 coreconfigitem(
     b'convert',
     b'git.renamelimit',
     default=400,
 )
 coreconfigitem(
     b'convert',
     b'git.saverev',
     default=True,
 )
 coreconfigitem(
     b'convert',
     b'git.similarity',
     default=50,
 )
 coreconfigitem(
     b'convert',
     b'git.skipsubmodules',
     default=False,
 )
 coreconfigitem(
     b'convert',
     b'hg.clonebranches',
     default=False,
 )
 coreconfigitem(
     b'convert',
     b'hg.ignoreerrors',
     default=False,
 )
 coreconfigitem(
     b'convert',
     b'hg.preserve-hash',
     default=False,
 )
 coreconfigitem(
     b'convert',
     b'hg.revs',
     default=None,
 )
 coreconfigitem(
     b'convert',
     b'hg.saverev',
     default=False,
 )
 coreconfigitem(
     b'convert',
     b'hg.sourcename',
     default=None,
 )
 coreconfigitem(
     b'convert',
     b'hg.startrev',
     default=None,
 )
 coreconfigitem(
     b'convert',
     b'hg.tagsbranch',
     default=b'default',
 )
 coreconfigitem(
     b'convert',
     b'hg.usebranchnames',
     default=True,
 )
 coreconfigitem(
     b'convert',
     b'ignoreancestorcheck',
     default=False,
     experimental=True,
 )
 coreconfigitem(
     b'convert',
     b'localtimezone',
     default=False,
 )
 coreconfigitem(
     b'convert',
     b'p4.encoding',
     default=dynamicdefault,
 )
 coreconfigitem(
     b'convert',
     b'p4.startrev',
     default=0,
 )
 coreconfigitem(
     b'convert',
     b'skiptags',
     default=False,
 )
 coreconfigitem(
     b'convert',
     b'svn.debugsvnlog',
     default=True,
 )
 coreconfigitem(
     b'convert',
     b'svn.trunk',
     default=None,
 )
 coreconfigitem(
     b'convert',
     b'svn.tags',
     default=None,
 )
 coreconfigitem(
     b'convert',
     b'svn.branches',
     default=None,
 )
 coreconfigitem(
     b'convert',
     b'svn.startrev',
     default=0,
 )
 coreconfigitem(
     b'debug',
     b'dirstate.delaywrite',
     default=0,
 )
 coreconfigitem(
     b'defaults',
     b'.*',
     default=None,
     generic=True,
 )
 coreconfigitem(
     b'devel',
     b'all-warnings',
     default=False,
 )
 coreconfigitem(
     b'devel',
     b'bundle2.debug',
     default=False,
 )
 coreconfigitem(
     b'devel',
     b'bundle.delta',
     default=b'',
 )
 coreconfigitem(
     b'devel',
     b'cache-vfs',
     default=None,
 )
 coreconfigitem(
     b'devel',
     b'check-locks',
     default=False,
 )
 coreconfigitem(
     b'devel',
     b'check-relroot',
     default=False,
 )
 coreconfigitem(
     b'devel',
     b'default-date',
     default=None,
 )
 coreconfigitem(
     b'devel',
     b'deprec-warn',
     default=False,
 )
 coreconfigitem(
     b'devel',
     b'disableloaddefaultcerts',
     default=False,
 )
 coreconfigitem(
     b'devel',
     b'warn-empty-changegroup',
     default=False,
 )
 coreconfigitem(
     b'devel',
     b'legacy.exchange',
     default=list,
 )
 # When True, revlogs use a special reference version of the nodemap, that is not
 # performant but is "known" to behave properly.
 coreconfigitem(
     b'devel',
     b'persistent-nodemap',
     default=False,
 )
 coreconfigitem(
     b'devel',
     b'servercafile',
     default=b'',
 )
 coreconfigitem(
     b'devel',
     b'serverexactprotocol',
     default=b'',
 )
 coreconfigitem(
     b'devel',
     b'serverrequirecert',
     default=False,
 )
 coreconfigitem(
     b'devel',
     b'strip-obsmarkers',
     default=True,
 )
 coreconfigitem(
     b'devel',
     b'warn-config',
     default=None,
 )
 coreconfigitem(
     b'devel',
     b'warn-config-default',
     default=None,
 )
 coreconfigitem(
     b'devel',
     b'user.obsmarker',
     default=None,
 )
 coreconfigitem(
     b'devel',
     b'warn-config-unknown',
     default=None,
 )
 coreconfigitem(
     b'devel',
     b'debug.copies',
     default=False,
 )
 coreconfigitem(
     b'devel',
     b'debug.extensions',
     default=False,
 )
 coreconfigitem(
     b'devel',
     b'debug.repo-filters',
     default=False,
 )
 coreconfigitem(
     b'devel',
     b'debug.peer-request',
     default=False,
 )
+# If discovery.exchange-heads is False, the discovery will not start with
+# remote head fetching and local head querying.
+coreconfigitem(
+    b'devel',
+    b'discovery.exchange-heads',
+    default=True,
+)
 # If discovery.grow-sample is False, the sample size used in set discovery will
 # not be increased through the process
 coreconfigitem(
     b'devel',
     b'discovery.grow-sample',
     default=True,
 )
 # discovery.grow-sample.rate control the rate at which the sample grow
 coreconfigitem(
     b'devel',
     b'discovery.grow-sample.rate',
     default=1.05,
 )
 # If discovery.randomize is False, random sampling during discovery are
 # deterministic. It is meant for integration tests.
 coreconfigitem(
     b'devel',
     b'discovery.randomize',
     default=True,
 )
 _registerdiffopts(section=b'diff')
 coreconfigitem(
     b'email',
     b'bcc',
     default=None,
 )
 coreconfigitem(
     b'email',
     b'cc',
     default=None,
 )
 coreconfigitem(
     b'email',
     b'charsets',
     default=list,
 )
 coreconfigitem(
     b'email',
     b'from',
     default=None,
 )
 coreconfigitem(
     b'email',
     b'method',
     default=b'smtp',
 )
 coreconfigitem(
     b'email',
     b'reply-to',
     default=None,
 )
 coreconfigitem(
     b'email',
     b'to',
     default=None,
 )
 coreconfigitem(
     b'experimental',
     b'archivemetatemplate',
     default=dynamicdefault,
 )
 coreconfigitem(
     b'experimental',
     b'auto-publish',
     default=b'publish',
 )
 coreconfigitem(
     b'experimental',
     b'bundle-phases',
     default=False,
 )
 coreconfigitem(
     b'experimental',
     b'bundle2-advertise',
     default=True,
 )
 coreconfigitem(
     b'experimental',
     b'bundle2-output-capture',
     default=False,
 )
 coreconfigitem(
     b'experimental',
     b'bundle2.pushback',
     default=False,
 )
 coreconfigitem(
     b'experimental',
     b'bundle2lazylocking',
     default=False,
 )
 coreconfigitem(
     b'experimental',
     b'bundlecomplevel',
     default=None,
 )
 coreconfigitem(
     b'experimental',
     b'bundlecomplevel.bzip2',
     default=None,
 )
 coreconfigitem(
     b'experimental',
     b'bundlecomplevel.gzip',
     default=None,
 )
 coreconfigitem(
     b'experimental',
     b'bundlecomplevel.none',
     default=None,
 )
 coreconfigitem(
     b'experimental',
     b'bundlecomplevel.zstd',
     default=None,
 )
 coreconfigitem(
     b'experimental',
     b'changegroup3',
     default=False,
 )
 coreconfigitem(
     b'experimental',
     b'cleanup-as-archived',
     default=False,
 )
 coreconfigitem(
     b'experimental',
     b'clientcompressionengines',
     default=list,
 )
 coreconfigitem(
     b'experimental',
     b'copytrace',
     default=b'on',
 )
 coreconfigitem(
     b'experimental',
     b'copytrace.movecandidateslimit',
     default=100,
 )
 coreconfigitem(
     b'experimental',
     b'copytrace.sourcecommitlimit',
     default=100,
 )
 coreconfigitem(
     b'experimental',
     b'copies.read-from',
     default=b"filelog-only",
 )
 coreconfigitem(
     b'experimental',
     b'copies.write-to',
     default=b'filelog-only',
 )
 coreconfigitem(
     b'experimental',
     b'crecordtest',
     default=None,
 )
 coreconfigitem(
     b'experimental',
     b'directaccess',
     default=False,
 )
 coreconfigitem(
     b'experimental',
     b'directaccess.revnums',
     default=False,
 )
 coreconfigitem(
     b'experimental',
     b'editortmpinhg',
     default=False,
 )
 coreconfigitem(
     b'experimental',
     b'evolution',
     default=list,
 )
 coreconfigitem(
     b'experimental',
     b'evolution.allowdivergence',
     default=False,
     alias=[(b'experimental', b'allowdivergence')],
 )
 coreconfigitem(
     b'experimental',
     b'evolution.allowunstable',
     default=None,
 )
 coreconfigitem(
     b'experimental',
     b'evolution.createmarkers',
     default=None,
 )
 coreconfigitem(
     b'experimental',
     b'evolution.effect-flags',
     default=True,
     alias=[(b'experimental', b'effect-flags')],
 )
 coreconfigitem(
     b'experimental',
     b'evolution.exchange',
     default=None,
 )
 coreconfigitem(
     b'experimental',
     b'evolution.bundle-obsmarker',
     default=False,
 )
 coreconfigitem(
     b'experimental',
     b'evolution.bundle-obsmarker:mandatory',
     default=True,
 )
 coreconfigitem(
     b'experimental',
     b'log.topo',
     default=False,
 )
 coreconfigitem(
     b'experimental',
     b'evolution.report-instabilities',
     default=True,
 )
 coreconfigitem(
     b'experimental',
     b'evolution.track-operation',
     default=True,
 )
 # repo-level config to exclude a revset visibility
 #
 # The target use case is to use `share` to expose different subset of the same
 # repository, especially server side. See also `server.view`.
 coreconfigitem(
     b'experimental',
     b'extra-filter-revs',
     default=None,
 )
 coreconfigitem(
     b'experimental',
     b'maxdeltachainspan',
     default=-1,
 )
 # tracks files which were undeleted (merge might delete them but we explicitly
 # kept/undeleted them) and creates new filenodes for them
 coreconfigitem(
     b'experimental',
     b'merge-track-salvaged',
     default=False,
 )
 coreconfigitem(
     b'experimental',
     b'mergetempdirprefix',
     default=None,
 )
 coreconfigitem(
     b'experimental',
     b'mmapindexthreshold',
     default=None,
 )
 coreconfigitem(
     b'experimental',
     b'narrow',
     default=False,
 )
 coreconfigitem(
     b'experimental',
     b'nonnormalparanoidcheck',
     default=False,
 )
 coreconfigitem(
     b'experimental',
     b'exportableenviron',
     default=list,
 )
 coreconfigitem(
     b'experimental',
     b'extendedheader.index',
     default=None,
 )
 coreconfigitem(
     b'experimental',
     b'extendedheader.similarity',
     default=False,
 )
 coreconfigitem(
     b'experimental',
     b'graphshorten',
     default=False,
 )
 coreconfigitem(
     b'experimental',
     b'graphstyle.parent',
     default=dynamicdefault,
 )
 coreconfigitem(
     b'experimental',
     b'graphstyle.missing',
     default=dynamicdefault,
 )
 coreconfigitem(
     b'experimental',
     b'graphstyle.grandparent',
     default=dynamicdefault,
 )
 coreconfigitem(
     b'experimental',
     b'hook-track-tags',
     default=False,
 )
 coreconfigitem(
     b'experimental',
     b'httppeer.advertise-v2',
     default=False,
 )
 coreconfigitem(
     b'experimental',
     b'httppeer.v2-encoder-order',
     default=None,
 )
 coreconfigitem(
     b'experimental',
     b'httppostargs',
     default=False,
 )
 coreconfigitem(b'experimental', b'nointerrupt', default=False)
 coreconfigitem(b'experimental', b'nointerrupt-interactiveonly', default=True)
 
 coreconfigitem(
     b'experimental',
     b'obsmarkers-exchange-debug',
     default=False,
 )
 coreconfigitem(
     b'experimental',
     b'remotenames',
     default=False,
 )
 coreconfigitem(
     b'experimental',
     b'removeemptydirs',
     default=True,
 )
 coreconfigitem(
     b'experimental',
     b'revert.interactive.select-to-keep',
     default=False,
 )
 coreconfigitem(
     b'experimental',
     b'revisions.prefixhexnode',
     default=False,
 )
 coreconfigitem(
     b'experimental',
     b'revlogv2',
     default=None,
 )
 coreconfigitem(
     b'experimental',
     b'revisions.disambiguatewithin',
     default=None,
 )
 coreconfigitem(
     b'experimental',
     b'rust.index',
     default=False,
 )
 coreconfigitem(
     b'experimental',
     b'server.filesdata.recommended-batch-size',
     default=50000,
 )
 coreconfigitem(
     b'experimental',
     b'server.manifestdata.recommended-batch-size',
     default=100000,
 )
 coreconfigitem(
     b'experimental',
     b'server.stream-narrow-clones',
     default=False,
 )
 coreconfigitem(
     b'experimental',
     b'sharesafe-auto-downgrade-shares',
     default=False,
 )
 coreconfigitem(
     b'experimental',
     b'sharesafe-auto-upgrade-shares',
     default=False,
 )
 coreconfigitem(
     b'experimental',
     b'sharesafe-auto-upgrade-fail-error',
     default=False,
 )
 coreconfigitem(
     b'experimental',
     b'sharesafe-warn-outdated-shares',
     default=True,
 )
 coreconfigitem(
     b'experimental',
     b'single-head-per-branch',
     default=False,
 )
 coreconfigitem(
     b'experimental',
     b'single-head-per-branch:account-closed-heads',
     default=False,
 )
 coreconfigitem(
     b'experimental',
     b'single-head-per-branch:public-changes-only',
     default=False,
 )
 coreconfigitem(
     b'experimental',
     b'sshserver.support-v2',
     default=False,
 )
 coreconfigitem(
     b'experimental',
     b'sparse-read',
     default=False,
 )
 coreconfigitem(
     b'experimental',
     b'sparse-read.density-threshold',
     default=0.50,
 )
 coreconfigitem(
     b'experimental',
     b'sparse-read.min-gap-size',
     default=b'65K',
 )
 coreconfigitem(
     b'experimental',
     b'treemanifest',
     default=False,
 )
 coreconfigitem(
     b'experimental',
     b'update.atomic-file',
     default=False,
 )
 coreconfigitem(
     b'experimental',
     b'sshpeer.advertise-v2',
     default=False,
 )
 coreconfigitem(
     b'experimental',
     b'web.apiserver',
     default=False,
 )
 coreconfigitem(
     b'experimental',
     b'web.api.http-v2',
     default=False,
 )
 coreconfigitem(
     b'experimental',
     b'web.api.debugreflect',
     default=False,
 )
 coreconfigitem(
     b'experimental',
     b'worker.wdir-get-thread-safe',
     default=False,
 )
 coreconfigitem(
     b'experimental',
     b'worker.repository-upgrade',
     default=False,
 )
 coreconfigitem(
     b'experimental',
     b'xdiff',
     default=False,
 )
 coreconfigitem(
     b'extensions',
     b'.*',
     default=None,
     generic=True,
 )
 coreconfigitem(
     b'extdata',
     b'.*',
     default=None,
     generic=True,
 )
 coreconfigitem(
     b'format',
     b'bookmarks-in-store',
     default=False,
 )
 coreconfigitem(
     b'format',
     b'chunkcachesize',
     default=None,
     experimental=True,
 )
 coreconfigitem(
     b'format',
     b'dotencode',
     default=True,
 )
 coreconfigitem(
     b'format',
     b'generaldelta',
     default=False,
     experimental=True,
 )
 coreconfigitem(
     b'format',
     b'manifestcachesize',
     default=None,
     experimental=True,
 )
 coreconfigitem(
     b'format',
     b'maxchainlen',
     default=dynamicdefault,
     experimental=True,
 )
 coreconfigitem(
     b'format',
     b'obsstore-version',
     default=None,
 )
 coreconfigitem(
     b'format',
     b'sparse-revlog',
     default=True,
 )
 coreconfigitem(
     b'format',
     b'revlog-compression',
     default=lambda: [b'zlib'],
     alias=[(b'experimental', b'format.compression')],
 )
 coreconfigitem(
     b'format',
     b'usefncache',
     default=True,
 )
 coreconfigitem(
     b'format',
     b'usegeneraldelta',
     default=True,
 )
 coreconfigitem(
     b'format',
     b'usestore',
     default=True,
 )
 coreconfigitem(
     b'format',
     b'use-persistent-nodemap',
     default=False,
 )
 coreconfigitem(
     b'format',
     b'exp-use-copies-side-data-changeset',
     default=False,
     experimental=True,
 )
 coreconfigitem(
     b'format',
     b'exp-use-side-data',
     default=False,
     experimental=True,
 )
 coreconfigitem(
     b'format',
     b'exp-share-safe',
     default=False,
     experimental=True,
 )
 coreconfigitem(
     b'format',
     b'internal-phase',
     default=False,
     experimental=True,
 )
 coreconfigitem(
     b'fsmonitor',
     b'warn_when_unused',
     default=True,
 )
 coreconfigitem(
     b'fsmonitor',
     b'warn_update_file_count',
     default=50000,
 )
 coreconfigitem(
     b'fsmonitor',
     b'warn_update_file_count_rust',
     default=400000,
 )
 coreconfigitem(
     b'help',
     br'hidden-command\..*',
     default=False,
     generic=True,
 )
 coreconfigitem(
     b'help',
     br'hidden-topic\..*',
     default=False,
     generic=True,
 )
 coreconfigitem(
     b'hooks',
     b'.*',
     default=dynamicdefault,
     generic=True,
 )
 coreconfigitem(
     b'hgweb-paths',
     b'.*',
     default=list,
     generic=True,
 )
 coreconfigitem(
     b'hostfingerprints',
     b'.*',
     default=list,
     generic=True,
 )
 coreconfigitem(
     b'hostsecurity',
     b'ciphers',
     default=None,
 )
 coreconfigitem(
     b'hostsecurity',
     b'minimumprotocol',
     default=dynamicdefault,
 )
 coreconfigitem(
     b'hostsecurity',
     b'.*:minimumprotocol$',
     default=dynamicdefault,
     generic=True,
 )
 coreconfigitem(
     b'hostsecurity',
     b'.*:ciphers$',
     default=dynamicdefault,
     generic=True,
 )
 coreconfigitem(
     b'hostsecurity',
     b'.*:fingerprints$',
     default=list,
     generic=True,
 )
 coreconfigitem(
     b'hostsecurity',
     b'.*:verifycertsfile$',
     default=None,
     generic=True,
 )
 
 coreconfigitem(
     b'http_proxy',
     b'always',
     default=False,
 )
 coreconfigitem(
     b'http_proxy',
     b'host',
     default=None,
 )
 coreconfigitem(
     b'http_proxy',
     b'no',
     default=list,
 )
 coreconfigitem(
     b'http_proxy',
     b'passwd',
     default=None,
 )
 coreconfigitem(
     b'http_proxy',
     b'user',
     default=None,
 )
 
 coreconfigitem(
     b'http',
     b'timeout',
     default=None,
 )
 
 coreconfigitem(
     b'logtoprocess',
     b'commandexception',
     default=None,
 )
 coreconfigitem(
     b'logtoprocess',
     b'commandfinish',
     default=None,
 )
 coreconfigitem(
     b'logtoprocess',
     b'command',
     default=None,
 )
 coreconfigitem(
     b'logtoprocess',
     b'develwarn',
     default=None,
 )
 coreconfigitem(
     b'logtoprocess',
     b'uiblocked',
     default=None,
 )
 coreconfigitem(
     b'merge',
     b'checkunknown',
     default=b'abort',
 )
 coreconfigitem(
     b'merge',
     b'checkignored',
     default=b'abort',
 )
 coreconfigitem(
     b'experimental',
     b'merge.checkpathconflicts',
     default=False,
 )
 coreconfigitem(
     b'merge',
     b'followcopies',
     default=True,
 )
 coreconfigitem(
     b'merge',
     b'on-failure',
     default=b'continue',
 )
 coreconfigitem(
     b'merge',
     b'preferancestor',
     default=lambda: [b'*'],
     experimental=True,
 )
 coreconfigitem(
     b'merge',
     b'strict-capability-check',
     default=False,
 )
 coreconfigitem(
     b'merge-tools',
     b'.*',
     default=None,
     generic=True,
 )
 coreconfigitem(
     b'merge-tools',
     br'.*\.args$',
     default=b"$local $base $other",
     generic=True,
     priority=-1,
 )
 coreconfigitem(
     b'merge-tools',
     br'.*\.binary$',
     default=False,
     generic=True,
     priority=-1,
 )
 coreconfigitem(
     b'merge-tools',
     br'.*\.check$',
     default=list,
     generic=True,
     priority=-1,
 )
 coreconfigitem(
     b'merge-tools',
     br'.*\.checkchanged$',
     default=False,
     generic=True,
     priority=-1,
 )
 coreconfigitem(
     b'merge-tools',
     br'.*\.executable$',
     default=dynamicdefault,
     generic=True,
     priority=-1,
 )
 coreconfigitem(
     b'merge-tools',
     br'.*\.fixeol$',
     default=False,
     generic=True,
     priority=-1,
 )
 coreconfigitem(
     b'merge-tools',
     br'.*\.gui$',
     default=False,
     generic=True,
     priority=-1,
 )
 coreconfigitem(
     b'merge-tools',
     br'.*\.mergemarkers$',
     default=b'basic',
     generic=True,
     priority=-1,
 )
 coreconfigitem(
     b'merge-tools',
     br'.*\.mergemarkertemplate$',
     default=dynamicdefault,  # take from command-templates.mergemarker
     generic=True,
     priority=-1,
 )
 coreconfigitem(
     b'merge-tools',
     br'.*\.priority$',
     default=0,
     generic=True,
     priority=-1,
 )
 coreconfigitem(
     b'merge-tools',
     br'.*\.premerge$',
     default=dynamicdefault,
     generic=True,
     priority=-1,
 )
 coreconfigitem(
     b'merge-tools',
     br'.*\.symlink$',
     default=False,
     generic=True,
     priority=-1,
 )
 coreconfigitem(
     b'pager',
     b'attend-.*',
     default=dynamicdefault,
     generic=True,
 )
 coreconfigitem(
     b'pager',
     b'ignore',
     default=list,
 )
 coreconfigitem(
     b'pager',
     b'pager',
     default=dynamicdefault,
 )
 coreconfigitem(
     b'patch',
     b'eol',
     default=b'strict',
 )
 coreconfigitem(
     b'patch',
     b'fuzz',
     default=2,
 )
 coreconfigitem(
     b'paths',
     b'default',
     default=None,
 )
 coreconfigitem(
     b'paths',
     b'default-push',
     default=None,
 )
 coreconfigitem(
     b'paths',
     b'.*',
     default=None,
     generic=True,
 )
 coreconfigitem(
     b'phases',
     b'checksubrepos',
     default=b'follow',
 )
 coreconfigitem(
     b'phases',
     b'new-commit',
     default=b'draft',
 )
 coreconfigitem(
     b'phases',
     b'publish',
     default=True,
 )
 coreconfigitem(
     b'profiling',
     b'enabled',
     default=False,
 )
 coreconfigitem(
     b'profiling',
     b'format',
     default=b'text',
 )
 coreconfigitem(
     b'profiling',
     b'freq',
     default=1000,
 )
 coreconfigitem(
     b'profiling',
     b'limit',
     default=30,
 )
 coreconfigitem(
     b'profiling',
     b'nested',
     default=0,
 )
 coreconfigitem(
     b'profiling',
     b'output',
     default=None,
 )
 coreconfigitem(
     b'profiling',
     b'showmax',
     default=0.999,
 )
 coreconfigitem(
     b'profiling',
     b'showmin',
     default=dynamicdefault,
 )
 coreconfigitem(
     b'profiling',
     b'showtime',
     default=True,
 )
 coreconfigitem(
     b'profiling',
     b'sort',
     default=b'inlinetime',
 )
 coreconfigitem(
     b'profiling',
     b'statformat',
     default=b'hotpath',
 )
 coreconfigitem(
     b'profiling',
     b'time-track',
     default=dynamicdefault,
 )
 coreconfigitem(
     b'profiling',
     b'type',
     default=b'stat',
 )
 coreconfigitem(
     b'progress',
     b'assume-tty',
     default=False,
 )
 coreconfigitem(
     b'progress',
     b'changedelay',
     default=1,
 )
 coreconfigitem(
     b'progress',
     b'clear-complete',
     default=True,
 )
 coreconfigitem(
     b'progress',
     b'debug',
     default=False,
 )
 coreconfigitem(
     b'progress',
     b'delay',
     default=3,
 )
 coreconfigitem(
     b'progress',
     b'disable',
     default=False,
 )
 coreconfigitem(
     b'progress',
     b'estimateinterval',
     default=60.0,
 )
 coreconfigitem(
     b'progress',
     b'format',
     default=lambda: [b'topic', b'bar', b'number', b'estimate'],
 )
 coreconfigitem(
     b'progress',
     b'refresh',
     default=0.1,
 )
 coreconfigitem(
     b'progress',
     b'width',
     default=dynamicdefault,
 )
 coreconfigitem(
     b'pull',
     b'confirm',
     default=False,
 )
 coreconfigitem(
     b'push',
     b'pushvars.server',
     default=False,
 )
 coreconfigitem(
     b'rewrite',
     b'backup-bundle',
     default=True,
     alias=[(b'ui', b'history-editing-backup')],
 )
 coreconfigitem(
     b'rewrite',
     b'update-timestamp',
     default=False,
 )
 coreconfigitem(
     b'rewrite',
     b'empty-successor',
     default=b'skip',
     experimental=True,
 )
 coreconfigitem(
     b'storage',
     b'new-repo-backend',
     default=b'revlogv1',
     experimental=True,
 )
 coreconfigitem(
     b'storage',
     b'revlog.optimize-delta-parent-choice',
     default=True,
     alias=[(b'format', b'aggressivemergedeltas')],
 )
 # experimental as long as rust is experimental (or a C version is implemented)
 coreconfigitem(
     b'storage',
     b'revlog.persistent-nodemap.mmap',
     default=True,
 )
 # experimental as long as format.use-persistent-nodemap is.
 coreconfigitem(
     b'storage',
     b'revlog.persistent-nodemap.slow-path',
     default=b"abort",
 )
 
 coreconfigitem(
     b'storage',
     b'revlog.reuse-external-delta',
     default=True,
 )
 coreconfigitem(
     b'storage',
     b'revlog.reuse-external-delta-parent',
     default=None,
 )
 coreconfigitem(
     b'storage',
     b'revlog.zlib.level',
     default=None,
 )
 coreconfigitem(
     b'storage',
     b'revlog.zstd.level',
     default=None,
 )
 coreconfigitem(
     b'server',
     b'bookmarks-pushkey-compat',
     default=True,
 )
 coreconfigitem(
     b'server',
     b'bundle1',
     default=True,
 )
 coreconfigitem(
     b'server',
     b'bundle1gd',
     default=None,
 )
 coreconfigitem(
     b'server',
     b'bundle1.pull',
     default=None,
 )
 coreconfigitem(
     b'server',
     b'bundle1gd.pull',
     default=None,
 )
 coreconfigitem(
     b'server',
     b'bundle1.push',
     default=None,
 )
 coreconfigitem(
     b'server',
     b'bundle1gd.push',
     default=None,
 )
 coreconfigitem(
     b'server',
     b'bundle2.stream',
     default=True,
     alias=[(b'experimental', b'bundle2.stream')],
 )
 coreconfigitem(
     b'server',
     b'compressionengines',
     default=list,
 )
 coreconfigitem(
     b'server',
     b'concurrent-push-mode',
     default=b'check-related',
 )
 coreconfigitem(
     b'server',
     b'disablefullbundle',
     default=False,
 )
 coreconfigitem(
     b'server',
     b'maxhttpheaderlen',
     default=1024,
 )
 coreconfigitem(
     b'server',
     b'pullbundle',
     default=False,
 )
 coreconfigitem(
     b'server',
     b'preferuncompressed',
     default=False,
 )
 coreconfigitem(
     b'server',
     b'streamunbundle',
     default=False,
 )
 coreconfigitem(
     b'server',
     b'uncompressed',
     default=True,
 )
 coreconfigitem(
     b'server',
     b'uncompressedallowsecret',
     default=False,
 )
 coreconfigitem(
     b'server',
     b'view',
     default=b'served',
 )
 coreconfigitem(
     b'server',
     b'validate',
     default=False,
 )
 coreconfigitem(
     b'server',
     b'zliblevel',
     default=-1,
 )
 coreconfigitem(
     b'server',
     b'zstdlevel',
     default=3,
 )
 coreconfigitem(
     b'share',
     b'pool',
     default=None,
 )
 coreconfigitem(
     b'share',
     b'poolnaming',
     default=b'identity',
 )
 coreconfigitem(
     b'shelve',
     b'maxbackups',
     default=10,
 )
 coreconfigitem(
     b'smtp',
     b'host',
     default=None,
 )
 coreconfigitem(
     b'smtp',
     b'local_hostname',
     default=None,
 )
 coreconfigitem(
     b'smtp',
     b'password',
     default=None,
 )
 coreconfigitem(
     b'smtp',
     b'port',
     default=dynamicdefault,
 )
 coreconfigitem(
     b'smtp',
     b'tls',
     default=b'none',
 )
 coreconfigitem(
     b'smtp',
     b'username',
     default=None,
 )
 coreconfigitem(
     b'sparse',
     b'missingwarning',
     default=True,
     experimental=True,
 )
 coreconfigitem(
     b'subrepos',
     b'allowed',
     default=dynamicdefault,  # to make backporting simpler
 )
 coreconfigitem(
     b'subrepos',
     b'hg:allowed',
     default=dynamicdefault,
 )
 coreconfigitem(
     b'subrepos',
     b'git:allowed',
     default=dynamicdefault,
 )
 coreconfigitem(
     b'subrepos',
     b'svn:allowed',
     default=dynamicdefault,
 )
 coreconfigitem(
     b'templates',
     b'.*',
     default=None,
     generic=True,
 )
 coreconfigitem(
     b'templateconfig',
     b'.*',
     default=dynamicdefault,
     generic=True,
 )
 coreconfigitem(
     b'trusted',
     b'groups',
     default=list,
 )
 coreconfigitem(
     b'trusted',
     b'users',
     default=list,
 )
 coreconfigitem(
     b'ui',
     b'_usedassubrepo',
     default=False,
 )
 coreconfigitem(
     b'ui',
     b'allowemptycommit',
     default=False,
 )
 coreconfigitem(
     b'ui',
     b'archivemeta',
     default=True,
 )
 coreconfigitem(
     b'ui',
     b'askusername',
     default=False,
 )
 coreconfigitem(
     b'ui',
     b'available-memory',
     default=None,
 )
 
 coreconfigitem(
     b'ui',
     b'clonebundlefallback',
     default=False,
 )
 coreconfigitem(
     b'ui',
     b'clonebundleprefers',
     default=list,
 )
 coreconfigitem(
     b'ui',
     b'clonebundles',
     default=True,
 )
 coreconfigitem(
     b'ui',
     b'color',
     default=b'auto',
 )
 coreconfigitem(
     b'ui',
     b'commitsubrepos',
     default=False,
 )
 coreconfigitem(
     b'ui',
     b'debug',
     default=False,
 )
 coreconfigitem(
     b'ui',
     b'debugger',
     default=None,
 )
 coreconfigitem(
     b'ui',
     b'editor',
     default=dynamicdefault,
 )
 coreconfigitem(
     b'ui',
     b'detailed-exit-code',
     default=False,
     experimental=True,
 )
 coreconfigitem(
     b'ui',
     b'fallbackencoding',
     default=None,
 )
 coreconfigitem(
     b'ui',
     b'forcecwd',
     default=None,
 )
 coreconfigitem(
     b'ui',
     b'forcemerge',
     default=None,
 )
 coreconfigitem(
     b'ui',
     b'formatdebug',
     default=False,
 )
 coreconfigitem(
     b'ui',
     b'formatjson',
     default=False,
 )
 coreconfigitem(
     b'ui',
     b'formatted',
     default=None,
 )
 coreconfigitem(
     b'ui',
     b'interactive',
     default=None,
 )
 coreconfigitem(
     b'ui',
     b'interface',
     default=None,
 )
 coreconfigitem(
     b'ui',
     b'interface.chunkselector',
     default=None,
 )
 coreconfigitem(
     b'ui',
     b'large-file-limit',
     default=10000000,
 )
 coreconfigitem(
     b'ui',
     b'logblockedtimes',
     default=False,
 )
 coreconfigitem(
     b'ui',
     b'merge',
     default=None,
 )
 coreconfigitem(
     b'ui',
     b'mergemarkers',
     default=b'basic',
 )
 coreconfigitem(
     b'ui',
     b'message-output',
     default=b'stdio',
 )
 coreconfigitem(
     b'ui',
     b'nontty',
     default=False,
 )
 coreconfigitem(
     b'ui',
     b'origbackuppath',
     default=None,
 )
 coreconfigitem(
     b'ui',
     b'paginate',
     default=True,
 )
 coreconfigitem(
     b'ui',
     b'patch',
     default=None,
 )
 coreconfigitem(
     b'ui',
     b'portablefilenames',
     default=b'warn',
 )
 coreconfigitem(
     b'ui',
     b'promptecho',
     default=False,
 )
 coreconfigitem(
     b'ui',
     b'quiet',
     default=False,
 )
 coreconfigitem(
     b'ui',
     b'quietbookmarkmove',
     default=False,
 )
 coreconfigitem(
     b'ui',
     b'relative-paths',
     default=b'legacy',
 )
 coreconfigitem(
     b'ui',
     b'remotecmd',
     default=b'hg',
 )
 coreconfigitem(
     b'ui',
     b'report_untrusted',
     default=True,
 )
 coreconfigitem(
     b'ui',
     b'rollback',
     default=True,
 )
 coreconfigitem(
     b'ui',
     b'signal-safe-lock',
     default=True,
 )
 coreconfigitem(
     b'ui',
     b'slash',
     default=False,
 )
 coreconfigitem(
     b'ui',
     b'ssh',
     default=b'ssh',
 )
 coreconfigitem(
     b'ui',
     b'ssherrorhint',
     default=None,
 )
 coreconfigitem(
     b'ui',
     b'statuscopies',
     default=False,
 )
 coreconfigitem(
     b'ui',
     b'strict',
     default=False,
 )
 coreconfigitem(
     b'ui',
     b'style',
     default=b'',
 )
 coreconfigitem(
     b'ui',
     b'supportcontact',
     default=None,
 )
 coreconfigitem(
     b'ui',
     b'textwidth',
     default=78,
 )
 coreconfigitem(
     b'ui',
     b'timeout',
     default=b'600',
 )
 coreconfigitem(
     b'ui',
     b'timeout.warn',
     default=0,
 )
 coreconfigitem(
     b'ui',
     b'timestamp-output',
     default=False,
 )
 coreconfigitem(
     b'ui',
     b'traceback',
     default=False,
 )
 coreconfigitem(
     b'ui',
     b'tweakdefaults',
     default=False,
 )
 coreconfigitem(b'ui', b'username', alias=[(b'ui', b'user')])
 coreconfigitem(
     b'ui',
     b'verbose',
     default=False,
 )
 coreconfigitem(
     b'verify',
     b'skipflags',
     default=None,
 )
 coreconfigitem(
     b'web',
     b'allowbz2',
     default=False,
 )
 coreconfigitem(
     b'web',
     b'allowgz',
     default=False,
 )
 coreconfigitem(
     b'web',
     b'allow-pull',
     alias=[(b'web', b'allowpull')],
     default=True,
 )
 coreconfigitem(
     b'web',
     b'allow-push',
     alias=[(b'web', b'allow_push')],
     default=list,
 )
 coreconfigitem(
     b'web',
     b'allowzip',
     default=False,
 )
 coreconfigitem(
     b'web',
     b'archivesubrepos',
     default=False,
 )
 coreconfigitem(
     b'web',
     b'cache',
     default=True,
 )
 coreconfigitem(
     b'web',
     b'comparisoncontext',
     default=5,
 )
 coreconfigitem(
     b'web',
     b'contact',
     default=None,
 )
 coreconfigitem(
     b'web',
     b'deny_push',
     default=list,
 )
 coreconfigitem(
     b'web',
     b'guessmime',
     default=False,
 )
 coreconfigitem(
     b'web',
     b'hidden',
     default=False,
 )
 coreconfigitem(
     b'web',
     b'labels',
     default=list,
 )
 coreconfigitem(
     b'web',
     b'logoimg',
     default=b'hglogo.png',
 )
 coreconfigitem(
     b'web',
     b'logourl',
     default=b'https://mercurial-scm.org/',
 )
 coreconfigitem(
     b'web',
     b'accesslog',
     default=b'-',
 )
 coreconfigitem(
     b'web',
     b'address',
     default=b'',
 )
 coreconfigitem(
     b'web',
     b'allow-archive',
     alias=[(b'web', b'allow_archive')],
     default=list,
 )
 coreconfigitem(
     b'web',
     b'allow_read',
     default=list,
 )
 coreconfigitem(
     b'web',
     b'baseurl',
     default=None,
 )
 coreconfigitem(
     b'web',
     b'cacerts',
     default=None,
 )
 coreconfigitem(
     b'web',
     b'certificate',
     default=None,
 )
 coreconfigitem(
     b'web',
     b'collapse',
     default=False,
 )
 coreconfigitem(
     b'web',
     b'csp',
     default=None,
 )
 coreconfigitem(
     b'web',
     b'deny_read',
     default=list,
 )
 coreconfigitem(
     b'web',
     b'descend',
     default=True,
 )
 coreconfigitem(
     b'web',
     b'description',
     default=b"",
 )
 coreconfigitem(
     b'web',
     b'encoding',
     default=lambda: encoding.encoding,
 )
 coreconfigitem(
     b'web',
     b'errorlog',
     default=b'-',
 )
 coreconfigitem(
     b'web',
     b'ipv6',
     default=False,
 )
 coreconfigitem(
     b'web',
     b'maxchanges',
     default=10,
 )
 coreconfigitem(
     b'web',
     b'maxfiles',
     default=10,
 )
 coreconfigitem(
     b'web',
     b'maxshortchanges',
     default=60,
 )
 coreconfigitem(
     b'web',
     b'motd',
     default=b'',
 )
 coreconfigitem(
     b'web',
     b'name',
     default=dynamicdefault,
 )
 coreconfigitem(
     b'web',
     b'port',
     default=8000,
 )
 coreconfigitem(
     b'web',
     b'prefix',
     default=b'',
 )
 coreconfigitem(
     b'web',
     b'push_ssl',
     default=True,
 )
 coreconfigitem(
     b'web',
     b'refreshinterval',
     default=20,
 )
 coreconfigitem(
     b'web',
     b'server-header',
     default=None,
 )
 coreconfigitem(
     b'web',
     b'static',
     default=None,
 )
 coreconfigitem(
     b'web',
     b'staticurl',
     default=None,
 )
 coreconfigitem(
     b'web',
     b'stripes',
     default=1,
 )
 coreconfigitem(
     b'web',
     b'style',
     default=b'paper',
 )
 coreconfigitem(
     b'web',
     b'templates',
     default=None,
 )
 coreconfigitem(
     b'web',
     b'view',
     default=b'served',
     experimental=True,
 )
 coreconfigitem(
     b'worker',
     b'backgroundclose',
     default=dynamicdefault,
 )
 # Windows defaults to a limit of 512 open files. A buffer of 128
 # should give us enough headway.
 coreconfigitem(
     b'worker',
     b'backgroundclosemaxqueue',
     default=384,
 )
 coreconfigitem(
     b'worker',
     b'backgroundcloseminfilecount',
     default=2048,
 )
 coreconfigitem(
     b'worker',
     b'backgroundclosethreadcount',
     default=4,
 )
 coreconfigitem(
     b'worker',
     b'enabled',
     default=True,
 )
 coreconfigitem(
     b'worker',
     b'numcpus',
     default=None,
 )
 
 # Rebase related configuration moved to core because other extension are doing
 # strange things. For example, shelve import the extensions to reuse some bit
 # without formally loading it.
 coreconfigitem(
     b'commands',
     b'rebase.requiredest',
     default=False,
 )
 coreconfigitem(
     b'experimental',
     b'rebaseskipobsolete',
     default=True,
 )
 coreconfigitem(
     b'rebase',
     b'singletransaction',
     default=False,
 )
 coreconfigitem(
     b'rebase',
     b'experimental.inmemory',
     default=False,
 )

mercurial/setdiscovery.py

@@ -1,507 +1,517
 # setdiscovery.py - improved discovery of common nodeset for mercurial
 #
 # Copyright 2010 Benoit Boissinot <[e-mail]>
 # and Peter Arrenbrecht <[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.
 """
 Algorithm works in the following way. You have two repository: local and
 remote. They both contains a DAG of changelists.
 
 The goal of the discovery protocol is to find one set of node *common*,
 the set of nodes shared by local and remote.
 
 One of the issue with the original protocol was latency, it could
 potentially require lots of roundtrips to discover that the local repo was a
 subset of remote (which is a very common case, you usually have few changes
 compared to upstream, while upstream probably had lots of development).
 
 The new protocol only requires one interface for the remote repo: `known()`,
 which given a set of changelists tells you if they are present in the DAG.
 
 The algorithm then works as follow:
 
  - We will be using three sets, `common`, `missing`, `unknown`. Originally
  all nodes are in `unknown`.
  - Take a sample from `unknown`, call `remote.known(sample)`
    - For each node that remote knows, move it and all its ancestors to `common`
    - For each node that remote doesn't know, move it and all its descendants
    to `missing`
  - Iterate until `unknown` is empty
 
 There are a couple optimizations, first is instead of starting with a random
 sample of missing, start by sending all heads, in the case where the local
 repo is a subset, you computed the answer in one round trip.
 
 Then you can do something similar to the bisecting strategy used when
 finding faulty changesets. Instead of random samples, you can try picking
 nodes that will maximize the number of nodes that will be
 classified with it (since all ancestors or descendants will be marked as well).
 """
 
 from __future__ import absolute_import
 
 import collections
 import random
 
 from .i18n import _
 from .node import (
     nullid,
     nullrev,
 )
 from . import (
     error,
     policy,
     util,
 )
 
 
 def _updatesample(revs, heads, sample, parentfn, quicksamplesize=0):
     """update an existing sample to match the expected size
 
     The sample is updated with revs exponentially distant from each head of the
     <revs> set. (H~1, H~2, H~4, H~8, etc).
 
     If a target size is specified, the sampling will stop once this size is
     reached. Otherwise sampling will happen until roots of the <revs> set are
     reached.
 
     :revs:  set of revs we want to discover (if None, assume the whole dag)
     :heads: set of DAG head revs
     :sample: a sample to update
     :parentfn: a callable to resolve parents for a revision
     :quicksamplesize: optional target size of the sample"""
     dist = {}
     visit = collections.deque(heads)
     seen = set()
     factor = 1
     while visit:
         curr = visit.popleft()
         if curr in seen:
             continue
         d = dist.setdefault(curr, 1)
         if d > factor:
             factor *= 2
         if d == factor:
             sample.add(curr)
             if quicksamplesize and (len(sample) >= quicksamplesize):
                 return
         seen.add(curr)
 
         for p in parentfn(curr):
             if p != nullrev and (not revs or p in revs):
                 dist.setdefault(p, d + 1)
                 visit.append(p)
 
 
 def _limitsample(sample, desiredlen, randomize=True):
     """return a random subset of sample of at most desiredlen item.
 
     If randomize is False, though, a deterministic subset is returned.
     This is meant for integration tests.
     """
     if len(sample) <= desiredlen:
         return sample
     if randomize:
         return set(random.sample(sample, desiredlen))
     sample = list(sample)
     sample.sort()
     return set(sample[:desiredlen])
 
 
 class partialdiscovery(object):
     """an object representing ongoing discovery
 
     Feed with data from the remote repository, this object keep track of the
     current set of changeset in various states:
 
     - common:    revs also known remotely
     - undecided: revs we don't have information on yet
     - missing:   revs missing remotely
     (all tracked revisions are known locally)
     """
 
     def __init__(self, repo, targetheads, respectsize, randomize=True):
         self._repo = repo
         self._targetheads = targetheads
         self._common = repo.changelog.incrementalmissingrevs()
         self._undecided = None
         self.missing = set()
         self._childrenmap = None
         self._respectsize = respectsize
         self.randomize = randomize
 
     def addcommons(self, commons):
         """register nodes known as common"""
         self._common.addbases(commons)
         if self._undecided is not None:
             self._common.removeancestorsfrom(self._undecided)
 
     def addmissings(self, missings):
         """register some nodes as missing"""
         newmissing = self._repo.revs(b'%ld::%ld', missings, self.undecided)
         if newmissing:
             self.missing.update(newmissing)
             self.undecided.difference_update(newmissing)
 
     def addinfo(self, sample):
         """consume an iterable of (rev, known) tuples"""
         common = set()
         missing = set()
         for rev, known in sample:
             if known:
                 common.add(rev)
             else:
                 missing.add(rev)
         if common:
             self.addcommons(common)
         if missing:
             self.addmissings(missing)
 
     def hasinfo(self):
         """return True is we have any clue about the remote state"""
         return self._common.hasbases()
 
     def iscomplete(self):
         """True if all the necessary data have been gathered"""
         return self._undecided is not None and not self._undecided
 
     @property
     def undecided(self):
         if self._undecided is not None:
             return self._undecided
         self._undecided = set(self._common.missingancestors(self._targetheads))
         return self._undecided
 
     def stats(self):
         return {
             'undecided': len(self.undecided),
         }
 
     def commonheads(self):
         """the heads of the known common set"""
         # heads(common) == heads(common.bases) since common represents
         # common.bases and all its ancestors
         return self._common.basesheads()
 
     def _parentsgetter(self):
         getrev = self._repo.changelog.index.__getitem__
 
         def getparents(r):
             return getrev(r)[5:7]
 
         return getparents
 
     def _childrengetter(self):
 
         if self._childrenmap is not None:
             # During discovery, the `undecided` set keep shrinking.
             # Therefore, the map computed for an iteration N will be
             # valid for iteration N+1. Instead of computing the same
             # data over and over we cached it the first time.
             return self._childrenmap.__getitem__
 
         # _updatesample() essentially does interaction over revisions to look
         # up their children. This lookup is expensive and doing it in a loop is
         # quadratic. We precompute the children for all relevant revisions and
         # make the lookup in _updatesample() a simple dict lookup.
         self._childrenmap = children = {}
 
         parentrevs = self._parentsgetter()
         revs = self.undecided
 
         for rev in sorted(revs):
             # Always ensure revision has an entry so we don't need to worry
             # about missing keys.
             children[rev] = []
             for prev in parentrevs(rev):
                 if prev == nullrev:
                     continue
                 c = children.get(prev)
                 if c is not None:
                     c.append(rev)
         return children.__getitem__
 
     def takequicksample(self, headrevs, size):
         """takes a quick sample of size <size>
 
         It is meant for initial sampling and focuses on querying heads and close
         ancestors of heads.
 
         :headrevs: set of head revisions in local DAG to consider
         :size: the maximum size of the sample"""
         revs = self.undecided
         if len(revs) <= size:
             return list(revs)
         sample = set(self._repo.revs(b'heads(%ld)', revs))
 
         if len(sample) >= size:
             return _limitsample(sample, size, randomize=self.randomize)
 
         _updatesample(
             None, headrevs, sample, self._parentsgetter(), quicksamplesize=size
         )
         return sample
 
     def takefullsample(self, headrevs, size):
         revs = self.undecided
         if len(revs) <= size:
             return list(revs)
         repo = self._repo
         sample = set(repo.revs(b'heads(%ld)', revs))
         parentrevs = self._parentsgetter()
 
         # update from heads
         revsheads = sample.copy()
         _updatesample(revs, revsheads, sample, parentrevs)
 
         # update from roots
         revsroots = set(repo.revs(b'roots(%ld)', revs))
         childrenrevs = self._childrengetter()
         _updatesample(revs, revsroots, sample, childrenrevs)
         assert sample
 
         if not self._respectsize:
             size = max(size, min(len(revsroots), len(revsheads)))
 
         sample = _limitsample(sample, size, randomize=self.randomize)
         if len(sample) < size:
             more = size - len(sample)
             takefrom = list(revs - sample)
             if self.randomize:
                 sample.update(random.sample(takefrom, more))
             else:
                 takefrom.sort()
                 sample.update(takefrom[:more])
         return sample
 
 
 partialdiscovery = policy.importrust(
     'discovery', member='PartialDiscovery', default=partialdiscovery
 )
 
 
 def findcommonheads(
     ui,
     local,
     remote,
     initialsamplesize=100,
     fullsamplesize=200,
     abortwhenunrelated=True,
     ancestorsof=None,
     audit=None,
 ):
     """Return a tuple (common, anyincoming, remoteheads) used to identify
     missing nodes from or in remote.
 
     The audit argument is an optional dictionnary that a caller can pass. it
     will be updated with extra data about the discovery, this is useful for
     debug.
     """
 
     samplegrowth = float(ui.config(b'devel', b'discovery.grow-sample.rate'))
 
     start = util.timer()
 
     roundtrips = 0
     cl = local.changelog
     clnode = cl.node
     clrev = cl.rev
 
     if ancestorsof is not None:
         ownheads = [clrev(n) for n in ancestorsof]
     else:
         ownheads = [rev for rev in cl.headrevs() if rev != nullrev]
 
+    initial_head_exchange = ui.configbool(b'devel', b'discovery.exchange-heads')
+
     # We also ask remote about all the local heads. That set can be arbitrarily
     # large, so we used to limit it size to `initialsamplesize`. We no longer
     # do as it proved counter productive. The skipped heads could lead to a
     # large "undecided" set, slower to be clarified than if we asked the
     # question for all heads right away.
     #
     # We are already fetching all server heads using the `heads` commands,
     # sending a equivalent number of heads the other way should not have a
     # significant impact.  In addition, it is very likely that we are going to
     # have to issue "known" request for an equivalent amount of revisions in
     # order to decide if theses heads are common or missing.
     #
     # find a detailled analysis below.
     #
     # Case A: local and server both has few heads
     #
     #     Ownheads is below initialsamplesize, limit would not have any effect.
     #
     # Case B: local has few heads and server has many
     #
     #     Ownheads is below initialsamplesize, limit would not have any effect.
     #
     # Case C: local and server both has many heads
     #
     #     We now transfert some more data, but not significantly more than is
     #     already transfered to carry the server heads.
     #
     # Case D: local has many heads, server has few
     #
     #   D.1 local heads are mostly known remotely
     #
     #     All the known head will have be part of a `known` request at some
     #     point for the discovery to finish. Sending them all earlier is
     #     actually helping.
     #
     #     (This case is fairly unlikely, it requires the numerous heads to all
     #     be merged server side in only a few heads)
     #
     #   D.2 local heads are mostly missing remotely
     #
     #     To determine that the heads are missing, we'll have to issue `known`
     #     request for them or one of their ancestors. This amount of `known`
     #     request will likely be in the same order of magnitude than the amount
     #     of local heads.
     #
     #     The only case where we can be more efficient using `known` request on
     #     ancestors are case were all the "missing" local heads are based on a
     #     few changeset, also "missing".  This means we would have a "complex"
     #     graph (with many heads) attached to, but very independant to a the
     #     "simple" graph on the server. This is a fairly usual case and have
     #     not been met in the wild so far.
+    if initial_head_exchange:
     if remote.limitedarguments:
         sample = _limitsample(ownheads, initialsamplesize)
         # indices between sample and externalized version must match
         sample = list(sample)
     else:
         sample = ownheads
 
     ui.debug(b"query 1; heads\n")
     roundtrips += 1
     with remote.commandexecutor() as e:
         fheads = e.callcommand(b'heads', {})
         fknown = e.callcommand(
             b'known',
             {
                 b'nodes': [clnode(r) for r in sample],
             },
         )
 
     srvheadhashes, yesno = fheads.result(), fknown.result()
 
     if audit is not None:
         audit[b'total-roundtrips'] = 1
 
     if cl.tip() == nullid:
         if srvheadhashes != [nullid]:
             return [nullid], True, srvheadhashes
         return [nullid], False, []
+    else:
+        # we still need the remote head for the function return
+        with remote.commandexecutor() as e:
+            fheads = e.callcommand(b'heads', {})
+        srvheadhashes = fheads.result()
 
     # start actual discovery (we note this before the next "if" for
     # compatibility reasons)
     ui.status(_(b"searching for changes\n"))
 
     knownsrvheads = []  # revnos of remote heads that are known locally
     for node in srvheadhashes:
         if node == nullid:
             continue
 
         try:
             knownsrvheads.append(clrev(node))
         # Catches unknown and filtered nodes.
         except error.LookupError:
             continue
 
+    if initial_head_exchange:
     # early exit if we know all the specified remote heads already
     if len(knownsrvheads) == len(srvheadhashes):
         ui.debug(b"all remote heads known locally\n")
         return srvheadhashes, False, srvheadhashes
 
     if len(sample) == len(ownheads) and all(yesno):
         ui.note(_(b"all local changesets known remotely\n"))
         ownheadhashes = [clnode(r) for r in ownheads]
         return ownheadhashes, True, srvheadhashes
 
     # full blown discovery
 
     # if the server has a limit to its arguments size, we can't grow the sample.
     hard_limit_sample = remote.limitedarguments
     grow_sample = local.ui.configbool(b'devel', b'discovery.grow-sample')
     hard_limit_sample = hard_limit_sample and grow_sample
 
     randomize = ui.configbool(b'devel', b'discovery.randomize')
     disco = partialdiscovery(
         local, ownheads, hard_limit_sample, randomize=randomize
     )
+    if initial_head_exchange:
     # treat remote heads (and maybe own heads) as a first implicit sample
     # response
     disco.addcommons(knownsrvheads)
     disco.addinfo(zip(sample, yesno))
 
-    full = False
+    full = not initial_head_exchange
     progress = ui.makeprogress(_(b'searching'), unit=_(b'queries'))
     while not disco.iscomplete():
 
         if full or disco.hasinfo():
             if full:
                 ui.note(_(b"sampling from both directions\n"))
             else:
                 ui.debug(b"taking initial sample\n")
             samplefunc = disco.takefullsample
             targetsize = fullsamplesize
             if not hard_limit_sample:
                 fullsamplesize = int(fullsamplesize * samplegrowth)
         else:
             # use even cheaper initial sample
             ui.debug(b"taking quick initial sample\n")
             samplefunc = disco.takequicksample
             targetsize = initialsamplesize
         sample = samplefunc(ownheads, targetsize)
 
         roundtrips += 1
         progress.update(roundtrips)
         stats = disco.stats()
         ui.debug(
             b"query %i; still undecided: %i, sample size is: %i\n"
             % (roundtrips, stats['undecided'], len(sample))
         )
 
         # indices between sample and externalized version must match
         sample = list(sample)
 
         with remote.commandexecutor() as e:
             yesno = e.callcommand(
                 b'known',
                 {
                     b'nodes': [clnode(r) for r in sample],
                 },
             ).result()
 
         full = True
 
         disco.addinfo(zip(sample, yesno))
 
     result = disco.commonheads()
     elapsed = util.timer() - start
     progress.complete()
     ui.debug(b"%d total queries in %.4fs\n" % (roundtrips, elapsed))
     msg = (
         b'found %d common and %d unknown server heads,'
         b' %d roundtrips in %.4fs\n'
     )
     missing = set(result) - set(knownsrvheads)
     ui.log(b'discovery', msg, len(result), len(missing), roundtrips, elapsed)
 
     if audit is not None:
         audit[b'total-roundtrips'] = roundtrips
 
     if not result and srvheadhashes != [nullid]:
         if abortwhenunrelated:
             raise error.Abort(_(b"repository is unrelated"))
         else:
             ui.warn(_(b"warning: repository is unrelated\n"))
         return (
             {nullid},
             True,
             srvheadhashes,
         )
 
     anyincoming = srvheadhashes != [nullid]
     result = {clnode(r) for r in result}
     return result, anyincoming, srvheadhashes

tests/test-setdiscovery.t

@@ -1,1583 +1,1582
 
 Function to test discovery between two repos in both directions, using both the local shortcut
 (which is currently not activated by default) and the full remotable protocol:
 
   $ testdesc() { # revs_a, revs_b, dagdesc
   >     if [ -d foo ]; then rm -rf foo; fi
   >     hg init foo
   >     cd foo
   >     hg debugbuilddag "$3"
   >     hg clone . a $1 --quiet
   >     hg clone . b $2 --quiet
   >     echo
   >     echo "% -- a -> b tree"
   >     hg -R a debugdiscovery b --verbose --old
   >     echo
   >     echo "% -- a -> b set"
   >     hg -R a debugdiscovery b --verbose --debug --config progress.debug=true
   >     echo
   >     echo "% -- a -> b set (tip only)"
   >     hg -R a debugdiscovery b --verbose --debug --config progress.debug=true --rev tip
   >     echo
   >     echo "% -- b -> a tree"
   >     hg -R b debugdiscovery a --verbose --old
   >     echo
   >     echo "% -- b -> a set"
   >     hg -R b debugdiscovery a --verbose --debug --config progress.debug=true
   >     echo
   >     echo "% -- b -> a set (tip only)"
   >     hg -R b debugdiscovery a --verbose --debug --config progress.debug=true --rev tip
   >     cd ..
   > }
 
 
 Small superset:
 
   $ testdesc '-ra1 -ra2' '-rb1 -rb2 -rb3' '
   > +2:f +1:a1:b1
   > <f +4 :a2
   > +5 :b2
   > <f +3 :b3'
   
   % -- a -> b tree
   comparing with b
   searching for changes
   unpruned common: 01241442b3c2 66f7d451a68b b5714e113bc0
   elapsed time:  * seconds (glob)
   round-trips:                   2
   heads summary:
     total common heads:          2
       also local heads:          2
       also remote heads:         1
       both:                      1
     local heads:                 2
       common:                    2
       missing:                   0
     remote heads:                3
       common:                    1
       unknown:                   2
   local changesets:              7
     common:                      7
       heads:                     2
       roots:                     1
     missing:                     0
       heads:                     0
       roots:                     0
     first undecided set:         3
       heads:                     1
       roots:                     1
       common:                    3
       missing:                   0
   common heads: 01241442b3c2 b5714e113bc0
   
   % -- a -> b set
   comparing with b
   query 1; heads
   searching for changes
   all local changesets known remotely
   elapsed time:  * seconds (glob)
   round-trips:                   1
   heads summary:
     total common heads:          2
       also local heads:          2
       also remote heads:         1
       both:                      1
     local heads:                 2
       common:                    2
       missing:                   0
     remote heads:                3
       common:                    1
       unknown:                   2
   local changesets:              7
     common:                      7
       heads:                     2
       roots:                     1
     missing:                     0
       heads:                     0
       roots:                     0
     first undecided set:         3
       heads:                     1
       roots:                     1
       common:                    3
       missing:                   0
   common heads: 01241442b3c2 b5714e113bc0
   
   % -- a -> b set (tip only)
   comparing with b
   query 1; heads
   searching for changes
   all local changesets known remotely
   elapsed time:  * seconds (glob)
   round-trips:                   1
   heads summary:
     total common heads:          1
       also local heads:          1
       also remote heads:         0
       both:                      0
     local heads:                 2
       common:                    1
       missing:                   1
     remote heads:                3
       common:                    0
       unknown:                   3
   local changesets:              7
     common:                      6
       heads:                     1
       roots:                     1
     missing:                     1
       heads:                     1
       roots:                     1
     first undecided set:         6
       heads:                     2
       roots:                     1
       common:                    5
       missing:                   1
   common heads: b5714e113bc0
   
   % -- b -> a tree
   comparing with a
   searching for changes
   unpruned common: 01241442b3c2 b5714e113bc0
   elapsed time:  * seconds (glob)
   round-trips:                   1
   heads summary:
     total common heads:          2
       also local heads:          1
       also remote heads:         2
       both:                      1
     local heads:                 3
       common:                    1
       missing:                   2
     remote heads:                2
       common:                    2
       unknown:                   0
   local changesets:             15
     common:                      7
       heads:                     2
       roots:                     1
     missing:                     8
       heads:                     2
       roots:                     2
     first undecided set:         8
       heads:                     2
       roots:                     2
       common:                    0
       missing:                   8
   common heads: 01241442b3c2 b5714e113bc0
   
   % -- b -> a set
   comparing with a
   query 1; heads
   searching for changes
   all remote heads known locally
   elapsed time:  * seconds (glob)
   round-trips:                   1
   heads summary:
     total common heads:          2
       also local heads:          1
       also remote heads:         2
       both:                      1
     local heads:                 3
       common:                    1
       missing:                   2
     remote heads:                2
       common:                    2
       unknown:                   0
   local changesets:             15
     common:                      7
       heads:                     2
       roots:                     1
     missing:                     8
       heads:                     2
       roots:                     2
     first undecided set:         8
       heads:                     2
       roots:                     2
       common:                    0
       missing:                   8
   common heads: 01241442b3c2 b5714e113bc0
   
   % -- b -> a set (tip only)
   comparing with a
   query 1; heads
   searching for changes
   all remote heads known locally
   elapsed time:  * seconds (glob)
   round-trips:                   1
   heads summary:
     total common heads:          2
       also local heads:          1
       also remote heads:         2
       both:                      1
     local heads:                 3
       common:                    1
       missing:                   2
     remote heads:                2
       common:                    2
       unknown:                   0
   local changesets:             15
     common:                      7
       heads:                     2
       roots:                     1
     missing:                     8
       heads:                     2
       roots:                     2
     first undecided set:         8
       heads:                     2
       roots:                     2
       common:                    0
       missing:                   8
   common heads: 01241442b3c2 b5714e113bc0
 
 
 Many new:
 
   $ testdesc '-ra1 -ra2' '-rb' '
   > +2:f +3:a1 +3:b
   > <f +30 :a2'
   
   % -- a -> b tree
   comparing with b
   searching for changes
   unpruned common: bebd167eb94d
   elapsed time:  * seconds (glob)
   round-trips:                   2
   heads summary:
     total common heads:          1
       also local heads:          1
       also remote heads:         0
       both:                      0
     local heads:                 2
       common:                    1
       missing:                   1
     remote heads:                1
       common:                    0
       unknown:                   1
   local changesets:             35
     common:                      5
       heads:                     1
       roots:                     1
     missing:                    30
       heads:                     1
       roots:                     1
     first undecided set:        34
       heads:                     2
       roots:                     1
       common:                    4
       missing:                  30
   common heads: bebd167eb94d
   
   % -- a -> b set
   comparing with b
   query 1; heads
   searching for changes
   taking initial sample
   searching: 2 queries
   query 2; still undecided: 29, sample size is: 29
   2 total queries in *.????s (glob)
   elapsed time:  * seconds (glob)
   round-trips:                   2
   heads summary:
     total common heads:          1
       also local heads:          1
       also remote heads:         0
       both:                      0
     local heads:                 2
       common:                    1
       missing:                   1
     remote heads:                1
       common:                    0
       unknown:                   1
   local changesets:             35
     common:                      5
       heads:                     1
       roots:                     1
     missing:                    30
       heads:                     1
       roots:                     1
     first undecided set:        34
       heads:                     2
       roots:                     1
       common:                    4
       missing:                  30
   common heads: bebd167eb94d
   
   % -- a -> b set (tip only)
   comparing with b
   query 1; heads
   searching for changes
   taking quick initial sample
   searching: 2 queries
   query 2; still undecided: 31, sample size is: 31
   2 total queries in *.????s (glob)
   elapsed time:  * seconds (glob)
   round-trips:                   2
   heads summary:
     total common heads:          1
       also local heads:          0
       also remote heads:         0
       both:                      0
     local heads:                 2
       common:                    0
       missing:                   2
     remote heads:                1
       common:                    0
       unknown:                   1
   local changesets:             35
     common:                      2
       heads:                     1
       roots:                     1
     missing:                    33
       heads:                     2
       roots:                     2
     first undecided set:        35
       heads:                     2
       roots:                     1
       common:                    2
       missing:                  33
   common heads: 66f7d451a68b
   
   % -- b -> a tree
   comparing with a
   searching for changes
   unpruned common: 66f7d451a68b bebd167eb94d
   elapsed time:  * seconds (glob)
   round-trips:                   4
   heads summary:
     total common heads:          1
       also local heads:          0
       also remote heads:         1
       both:                      0
     local heads:                 1
       common:                    0
       missing:                   1
     remote heads:                2
       common:                    1
       unknown:                   1
   local changesets:              8
     common:                      5
       heads:                     1
       roots:                     1
     missing:                     3
       heads:                     1
       roots:                     1
     first undecided set:         3
       heads:                     1
       roots:                     1
       common:                    0
       missing:                   3
   common heads: bebd167eb94d
   
   % -- b -> a set
   comparing with a
   query 1; heads
   searching for changes
   taking initial sample
   searching: 2 queries
   query 2; still undecided: 2, sample size is: 2
   2 total queries in *.????s (glob)
   elapsed time:  * seconds (glob)
   round-trips:                   2
   heads summary:
     total common heads:          1
       also local heads:          0
       also remote heads:         1
       both:                      0
     local heads:                 1
       common:                    0
       missing:                   1
     remote heads:                2
       common:                    1
       unknown:                   1
   local changesets:              8
     common:                      5
       heads:                     1
       roots:                     1
     missing:                     3
       heads:                     1
       roots:                     1
     first undecided set:         3
       heads:                     1
       roots:                     1
       common:                    0
       missing:                   3
   common heads: bebd167eb94d
   
   % -- b -> a set (tip only)
   comparing with a
   query 1; heads
   searching for changes
   taking initial sample
   searching: 2 queries
   query 2; still undecided: 2, sample size is: 2
   2 total queries in *.????s (glob)
   elapsed time:  * seconds (glob)
   round-trips:                   2
   heads summary:
     total common heads:          1
       also local heads:          0
       also remote heads:         1
       both:                      0
     local heads:                 1
       common:                    0
       missing:                   1
     remote heads:                2
       common:                    1
       unknown:                   1
   local changesets:              8
     common:                      5
       heads:                     1
       roots:                     1
     missing:                     3
       heads:                     1
       roots:                     1
     first undecided set:         3
       heads:                     1
       roots:                     1
       common:                    0
       missing:                   3
   common heads: bebd167eb94d
 
 Both sides many new with stub:
 
   $ testdesc '-ra1 -ra2' '-rb' '
   > +2:f +2:a1 +30 :b
   > <f +30 :a2'
   
   % -- a -> b tree
   comparing with b
   searching for changes
   unpruned common: 2dc09a01254d
   elapsed time:  * seconds (glob)
   round-trips:                   4
   heads summary:
     total common heads:          1
       also local heads:          1
       also remote heads:         0
       both:                      0
     local heads:                 2
       common:                    1
       missing:                   1
     remote heads:                1
       common:                    0
       unknown:                   1
   local changesets:             34
     common:                      4
       heads:                     1
       roots:                     1
     missing:                    30
       heads:                     1
       roots:                     1
     first undecided set:        33
       heads:                     2
       roots:                     1
       common:                    3
       missing:                  30
   common heads: 2dc09a01254d
   
   % -- a -> b set
   comparing with b
   query 1; heads
   searching for changes
   taking initial sample
   searching: 2 queries
   query 2; still undecided: 29, sample size is: 29
   2 total queries in *.????s (glob)
   elapsed time:  * seconds (glob)
   round-trips:                   2
   heads summary:
     total common heads:          1
       also local heads:          1
       also remote heads:         0
       both:                      0
     local heads:                 2
       common:                    1
       missing:                   1
     remote heads:                1
       common:                    0
       unknown:                   1
   local changesets:             34
     common:                      4
       heads:                     1
       roots:                     1
     missing:                    30
       heads:                     1
       roots:                     1
     first undecided set:        33
       heads:                     2
       roots:                     1
       common:                    3
       missing:                  30
   common heads: 2dc09a01254d
   
   % -- a -> b set (tip only)
   comparing with b
   query 1; heads
   searching for changes
   taking quick initial sample
   searching: 2 queries
   query 2; still undecided: 31, sample size is: 31
   2 total queries in *.????s (glob)
   elapsed time:  * seconds (glob)
   round-trips:                   2
   heads summary:
     total common heads:          1
       also local heads:          0
       also remote heads:         0
       both:                      0
     local heads:                 2
       common:                    0
       missing:                   2
     remote heads:                1
       common:                    0
       unknown:                   1
   local changesets:             34
     common:                      2
       heads:                     1
       roots:                     1
     missing:                    32
       heads:                     2
       roots:                     2
     first undecided set:        34
       heads:                     2
       roots:                     1
       common:                    2
       missing:                  32
   common heads: 66f7d451a68b
   
   % -- b -> a tree
   comparing with a
   searching for changes
   unpruned common: 2dc09a01254d 66f7d451a68b
   elapsed time:  * seconds (glob)
   round-trips:                   4
   heads summary:
     total common heads:          1
       also local heads:          0
       also remote heads:         1
       both:                      0
     local heads:                 1
       common:                    0
       missing:                   1
     remote heads:                2
       common:                    1
       unknown:                   1
   local changesets:             34
     common:                      4
       heads:                     1
       roots:                     1
     missing:                    30
       heads:                     1
       roots:                     1
     first undecided set:        30
       heads:                     1
       roots:                     1
       common:                    0
       missing:                  30
   common heads: 2dc09a01254d
   
   % -- b -> a set
   comparing with a
   query 1; heads
   searching for changes
   taking initial sample
   searching: 2 queries
   query 2; still undecided: 29, sample size is: 29
   2 total queries in *.????s (glob)
   elapsed time:  * seconds (glob)
   round-trips:                   2
   heads summary:
     total common heads:          1
       also local heads:          0
       also remote heads:         1
       both:                      0
     local heads:                 1
       common:                    0
       missing:                   1
     remote heads:                2
       common:                    1
       unknown:                   1
   local changesets:             34
     common:                      4
       heads:                     1
       roots:                     1
     missing:                    30
       heads:                     1
       roots:                     1
     first undecided set:        30
       heads:                     1
       roots:                     1
       common:                    0
       missing:                  30
   common heads: 2dc09a01254d
   
   % -- b -> a set (tip only)
   comparing with a
   query 1; heads
   searching for changes
   taking initial sample
   searching: 2 queries
   query 2; still undecided: 29, sample size is: 29
   2 total queries in *.????s (glob)
   elapsed time:  * seconds (glob)
   round-trips:                   2
   heads summary:
     total common heads:          1
       also local heads:          0
       also remote heads:         1
       both:                      0
     local heads:                 1
       common:                    0
       missing:                   1
     remote heads:                2
       common:                    1
       unknown:                   1
   local changesets:             34
     common:                      4
       heads:                     1
       roots:                     1
     missing:                    30
       heads:                     1
       roots:                     1
     first undecided set:        30
       heads:                     1
       roots:                     1
       common:                    0
       missing:                  30
   common heads: 2dc09a01254d
 
 
 Both many new:
 
   $ testdesc '-ra' '-rb' '
   > +2:f +30 :b
   > <f +30 :a'
   
   % -- a -> b tree
   comparing with b
   searching for changes
   unpruned common: 66f7d451a68b
   elapsed time:  * seconds (glob)
   round-trips:                   4
   heads summary:
     total common heads:          1
       also local heads:          0
       also remote heads:         0
       both:                      0
     local heads:                 1
       common:                    0
       missing:                   1
     remote heads:                1
       common:                    0
       unknown:                   1
   local changesets:             32
     common:                      2
       heads:                     1
       roots:                     1
     missing:                    30
       heads:                     1
       roots:                     1
     first undecided set:        32
       heads:                     1
       roots:                     1
       common:                    2
       missing:                  30
   common heads: 66f7d451a68b
   
   % -- a -> b set
   comparing with b
   query 1; heads
   searching for changes
   taking quick initial sample
   searching: 2 queries
   query 2; still undecided: 31, sample size is: 31
   2 total queries in *.????s (glob)
   elapsed time:  * seconds (glob)
   round-trips:                   2
   heads summary:
     total common heads:          1
       also local heads:          0
       also remote heads:         0
       both:                      0
     local heads:                 1
       common:                    0
       missing:                   1
     remote heads:                1
       common:                    0
       unknown:                   1
   local changesets:             32
     common:                      2
       heads:                     1
       roots:                     1
     missing:                    30
       heads:                     1
       roots:                     1
     first undecided set:        32
       heads:                     1
       roots:                     1
       common:                    2
       missing:                  30
   common heads: 66f7d451a68b
   
   % -- a -> b set (tip only)
   comparing with b
   query 1; heads
   searching for changes
   taking quick initial sample
   searching: 2 queries
   query 2; still undecided: 31, sample size is: 31
   2 total queries in *.????s (glob)
   elapsed time:  * seconds (glob)
   round-trips:                   2
   heads summary:
     total common heads:          1
       also local heads:          0
       also remote heads:         0
       both:                      0
     local heads:                 1
       common:                    0
       missing:                   1
     remote heads:                1
       common:                    0
       unknown:                   1
   local changesets:             32
     common:                      2
       heads:                     1
       roots:                     1
     missing:                    30
       heads:                     1
       roots:                     1
     first undecided set:        32
       heads:                     1
       roots:                     1
       common:                    2
       missing:                  30
   common heads: 66f7d451a68b
   
   % -- b -> a tree
   comparing with a
   searching for changes
   unpruned common: 66f7d451a68b
   elapsed time:  * seconds (glob)
   round-trips:                   4
   heads summary:
     total common heads:          1
       also local heads:          0
       also remote heads:         0
       both:                      0
     local heads:                 1
       common:                    0
       missing:                   1
     remote heads:                1
       common:                    0
       unknown:                   1
   local changesets:             32
     common:                      2
       heads:                     1
       roots:                     1
     missing:                    30
       heads:                     1
       roots:                     1
     first undecided set:        32
       heads:                     1
       roots:                     1
       common:                    2
       missing:                  30
   common heads: 66f7d451a68b
   
   % -- b -> a set
   comparing with a
   query 1; heads
   searching for changes
   taking quick initial sample
   searching: 2 queries
   query 2; still undecided: 31, sample size is: 31
   2 total queries in *.????s (glob)
   elapsed time:  * seconds (glob)
   round-trips:                   2
   heads summary:
     total common heads:          1
       also local heads:          0
       also remote heads:         0
       both:                      0
     local heads:                 1
       common:                    0
       missing:                   1
     remote heads:                1
       common:                    0
       unknown:                   1
   local changesets:             32
     common:                      2
       heads:                     1
       roots:                     1
     missing:                    30
       heads:                     1
       roots:                     1
     first undecided set:        32
       heads:                     1
       roots:                     1
       common:                    2
       missing:                  30
   common heads: 66f7d451a68b
   
   % -- b -> a set (tip only)
   comparing with a
   query 1; heads
   searching for changes
   taking quick initial sample
   searching: 2 queries
   query 2; still undecided: 31, sample size is: 31
   2 total queries in *.????s (glob)
   elapsed time:  * seconds (glob)
   round-trips:                   2
   heads summary:
     total common heads:          1
       also local heads:          0
       also remote heads:         0
       both:                      0
     local heads:                 1
       common:                    0
       missing:                   1
     remote heads:                1
       common:                    0
       unknown:                   1
   local changesets:             32
     common:                      2
       heads:                     1
       roots:                     1
     missing:                    30
       heads:                     1
       roots:                     1
     first undecided set:        32
       heads:                     1
       roots:                     1
       common:                    2
       missing:                  30
   common heads: 66f7d451a68b
 
 
 Both many new skewed:
 
   $ testdesc '-ra' '-rb' '
   > +2:f +30 :b
   > <f +50 :a'
   
   % -- a -> b tree
   comparing with b
   searching for changes
   unpruned common: 66f7d451a68b
   elapsed time:  * seconds (glob)
   round-trips:                   4
   heads summary:
     total common heads:          1
       also local heads:          0
       also remote heads:         0
       both:                      0
     local heads:                 1
       common:                    0
       missing:                   1
     remote heads:                1
       common:                    0
       unknown:                   1
   local changesets:             52
     common:                      2
       heads:                     1
       roots:                     1
     missing:                    50
       heads:                     1
       roots:                     1
     first undecided set:        52
       heads:                     1
       roots:                     1
       common:                    2
       missing:                  50
   common heads: 66f7d451a68b
   
   % -- a -> b set
   comparing with b
   query 1; heads
   searching for changes
   taking quick initial sample
   searching: 2 queries
   query 2; still undecided: 51, sample size is: 51
   2 total queries in *.????s (glob)
   elapsed time:  * seconds (glob)
   round-trips:                   2
   heads summary:
     total common heads:          1
       also local heads:          0
       also remote heads:         0
       both:                      0
     local heads:                 1
       common:                    0
       missing:                   1
     remote heads:                1
       common:                    0
       unknown:                   1
   local changesets:             52
     common:                      2
       heads:                     1
       roots:                     1
     missing:                    50
       heads:                     1
       roots:                     1
     first undecided set:        52
       heads:                     1
       roots:                     1
       common:                    2
       missing:                  50
   common heads: 66f7d451a68b
   
   % -- a -> b set (tip only)
   comparing with b
   query 1; heads
   searching for changes
   taking quick initial sample
   searching: 2 queries
   query 2; still undecided: 51, sample size is: 51
   2 total queries in *.????s (glob)
   elapsed time:  * seconds (glob)
   round-trips:                   2
   heads summary:
     total common heads:          1
       also local heads:          0
       also remote heads:         0
       both:                      0
     local heads:                 1
       common:                    0
       missing:                   1
     remote heads:                1
       common:                    0
       unknown:                   1
   local changesets:             52
     common:                      2
       heads:                     1
       roots:                     1
     missing:                    50
       heads:                     1
       roots:                     1
     first undecided set:        52
       heads:                     1
       roots:                     1
       common:                    2
       missing:                  50
   common heads: 66f7d451a68b
   
   % -- b -> a tree
   comparing with a
   searching for changes
   unpruned common: 66f7d451a68b
   elapsed time:  * seconds (glob)
   round-trips:                   3
   heads summary:
     total common heads:          1
       also local heads:          0
       also remote heads:         0
       both:                      0
     local heads:                 1
       common:                    0
       missing:                   1
     remote heads:                1
       common:                    0
       unknown:                   1
   local changesets:             32
     common:                      2
       heads:                     1
       roots:                     1
     missing:                    30
       heads:                     1
       roots:                     1
     first undecided set:        32
       heads:                     1
       roots:                     1
       common:                    2
       missing:                  30
   common heads: 66f7d451a68b
   
   % -- b -> a set
   comparing with a
   query 1; heads
   searching for changes
   taking quick initial sample
   searching: 2 queries
   query 2; still undecided: 31, sample size is: 31
   2 total queries in *.????s (glob)
   elapsed time:  * seconds (glob)
   round-trips:                   2
   heads summary:
     total common heads:          1
       also local heads:          0
       also remote heads:         0
       both:                      0
     local heads:                 1
       common:                    0
       missing:                   1
     remote heads:                1
       common:                    0
       unknown:                   1
   local changesets:             32
     common:                      2
       heads:                     1
       roots:                     1
     missing:                    30
       heads:                     1
       roots:                     1
     first undecided set:        32
       heads:                     1
       roots:                     1
       common:                    2
       missing:                  30
   common heads: 66f7d451a68b
   
   % -- b -> a set (tip only)
   comparing with a
   query 1; heads
   searching for changes
   taking quick initial sample
   searching: 2 queries
   query 2; still undecided: 31, sample size is: 31
   2 total queries in *.????s (glob)
   elapsed time:  * seconds (glob)
   round-trips:                   2
   heads summary:
     total common heads:          1
       also local heads:          0
       also remote heads:         0
       both:                      0
     local heads:                 1
       common:                    0
       missing:                   1
     remote heads:                1
       common:                    0
       unknown:                   1
   local changesets:             32
     common:                      2
       heads:                     1
       roots:                     1
     missing:                    30
       heads:                     1
       roots:                     1
     first undecided set:        32
       heads:                     1
       roots:                     1
       common:                    2
       missing:                  30
   common heads: 66f7d451a68b
 
 
 Both many new on top of long history:
 
   $ testdesc '-ra' '-rb' '
   > +1000:f +30 :b
   > <f +50 :a'
   
   % -- a -> b tree
   comparing with b
   searching for changes
   unpruned common: 7ead0cba2838
   elapsed time:  * seconds (glob)
   round-trips:                   4
   heads summary:
     total common heads:          1
       also local heads:          0
       also remote heads:         0
       both:                      0
     local heads:                 1
       common:                    0
       missing:                   1
     remote heads:                1
       common:                    0
       unknown:                   1
   local changesets:           1050
     common:                   1000
       heads:                     1
       roots:                     1
     missing:                    50
       heads:                     1
       roots:                     1
     first undecided set:      1050
       heads:                     1
       roots:                     1
       common:                 1000
       missing:                  50
   common heads: 7ead0cba2838
   
   % -- a -> b set
   comparing with b
   query 1; heads
   searching for changes
   taking quick initial sample
   searching: 2 queries
   query 2; still undecided: 1049, sample size is: 11
   sampling from both directions
   searching: 3 queries
   query 3; still undecided: 31, sample size is: 31
   3 total queries in *.????s (glob)
   elapsed time:  * seconds (glob)
   round-trips:                   3
   heads summary:
     total common heads:          1
       also local heads:          0
       also remote heads:         0
       both:                      0
     local heads:                 1
       common:                    0
       missing:                   1
     remote heads:                1
       common:                    0
       unknown:                   1
   local changesets:           1050
     common:                   1000
       heads:                     1
       roots:                     1
     missing:                    50
       heads:                     1
       roots:                     1
     first undecided set:      1050
       heads:                     1
       roots:                     1
       common:                 1000
       missing:                  50
   common heads: 7ead0cba2838
   
   % -- a -> b set (tip only)
   comparing with b
   query 1; heads
   searching for changes
   taking quick initial sample
   searching: 2 queries
   query 2; still undecided: 1049, sample size is: 11
   sampling from both directions
   searching: 3 queries
   query 3; still undecided: 31, sample size is: 31
   3 total queries in *.????s (glob)
   elapsed time:  * seconds (glob)
   round-trips:                   3
   heads summary:
     total common heads:          1
       also local heads:          0
       also remote heads:         0
       both:                      0
     local heads:                 1
       common:                    0
       missing:                   1
     remote heads:                1
       common:                    0
       unknown:                   1
   local changesets:           1050
     common:                   1000
       heads:                     1
       roots:                     1
     missing:                    50
       heads:                     1
       roots:                     1
     first undecided set:      1050
       heads:                     1
       roots:                     1
       common:                 1000
       missing:                  50
   common heads: 7ead0cba2838
   
   % -- b -> a tree
   comparing with a
   searching for changes
   unpruned common: 7ead0cba2838
   elapsed time:  * seconds (glob)
   round-trips:                   3
   heads summary:
     total common heads:          1
       also local heads:          0
       also remote heads:         0
       both:                      0
     local heads:                 1
       common:                    0
       missing:                   1
     remote heads:                1
       common:                    0
       unknown:                   1
   local changesets:           1030
     common:                   1000
       heads:                     1
       roots:                     1
     missing:                    30
       heads:                     1
       roots:                     1
     first undecided set:      1030
       heads:                     1
       roots:                     1
       common:                 1000
       missing:                  30
   common heads: 7ead0cba2838
   
   % -- b -> a set
   comparing with a
   query 1; heads
   searching for changes
   taking quick initial sample
   searching: 2 queries
   query 2; still undecided: 1029, sample size is: 11
   sampling from both directions
   searching: 3 queries
   query 3; still undecided: 15, sample size is: 15
   3 total queries in *.????s (glob)
   elapsed time:  * seconds (glob)
   round-trips:                   3
   heads summary:
     total common heads:          1
       also local heads:          0
       also remote heads:         0
       both:                      0
     local heads:                 1
       common:                    0
       missing:                   1
     remote heads:                1
       common:                    0
       unknown:                   1
   local changesets:           1030
     common:                   1000
       heads:                     1
       roots:                     1
     missing:                    30
       heads:                     1
       roots:                     1
     first undecided set:      1030
       heads:                     1
       roots:                     1
       common:                 1000
       missing:                  30
   common heads: 7ead0cba2838
   
   % -- b -> a set (tip only)
   comparing with a
   query 1; heads
   searching for changes
   taking quick initial sample
   searching: 2 queries
   query 2; still undecided: 1029, sample size is: 11
   sampling from both directions
   searching: 3 queries
   query 3; still undecided: 15, sample size is: 15
   3 total queries in *.????s (glob)
   elapsed time:  * seconds (glob)
   round-trips:                   3
   heads summary:
     total common heads:          1
       also local heads:          0
       also remote heads:         0
       both:                      0
     local heads:                 1
       common:                    0
       missing:                   1
     remote heads:                1
       common:                    0
       unknown:                   1
   local changesets:           1030
     common:                   1000
       heads:                     1
       roots:                     1
     missing:                    30
       heads:                     1
       roots:                     1
     first undecided set:      1030
       heads:                     1
       roots:                     1
       common:                 1000
       missing:                  30
   common heads: 7ead0cba2838
 
 
 One with >200 heads. We now switch to send them all in the initial roundtrip, but still do sampling for the later request.
 
   $ hg init manyheads
   $ cd manyheads
   $ echo "+300:r @a" >dagdesc
   $ echo "*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3 *r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3" >>dagdesc # 20 heads
   $ echo "*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3 *r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3" >>dagdesc # 20 heads
   $ echo "*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3 *r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3" >>dagdesc # 20 heads
   $ echo "*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3 *r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3" >>dagdesc # 20 heads
   $ echo "*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3 *r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3" >>dagdesc # 20 heads
   $ echo "*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3 *r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3" >>dagdesc # 20 heads
   $ echo "*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3 *r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3" >>dagdesc # 20 heads
   $ echo "*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3 *r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3" >>dagdesc # 20 heads
   $ echo "*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3 *r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3" >>dagdesc # 20 heads
   $ echo "*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3 *r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3" >>dagdesc # 20 heads
   $ echo "*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3 *r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3" >>dagdesc # 20 heads
   $ echo "*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3 *r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3" >>dagdesc # 20 heads
   $ echo "*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3 *r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3" >>dagdesc # 20 heads
   $ echo "@b *r+3" >>dagdesc # one more head
   $ hg debugbuilddag <dagdesc
   reading DAG from stdin
 
   $ hg heads -t --template . | wc -c
   \s*261 (re)
 
   $ hg clone -b a . a
   adding changesets
   adding manifests
   adding file changes
   added 1340 changesets with 0 changes to 0 files (+259 heads)
   new changesets 1ea73414a91b:1c51e2c80832
   updating to branch a
   0 files updated, 0 files merged, 0 files removed, 0 files unresolved
   $ hg clone -b b . b
   adding changesets
   adding manifests
   adding file changes
   added 304 changesets with 0 changes to 0 files
   new changesets 1ea73414a91b:513314ca8b3a
   updating to branch b
   0 files updated, 0 files merged, 0 files removed, 0 files unresolved
 
   $ hg -R a debugdiscovery b --debug --verbose --config progress.debug=true --config devel.discovery.randomize=false
   comparing with b
   query 1; heads
   searching for changes
   taking quick initial sample
   searching: 2 queries
   query 2; still undecided: 1080, sample size is: 100
   sampling from both directions
   searching: 3 queries
   query 3; still undecided: 980, sample size is: 200
   sampling from both directions
   searching: 4 queries
   query 4; still undecided: 497, sample size is: 210
   sampling from both directions
   searching: 5 queries
   query 5; still undecided: 285, sample size is: 220
   sampling from both directions
   searching: 6 queries
   query 6; still undecided: 63, sample size is: 63
   6 total queries in *.????s (glob)
   elapsed time:  * seconds (glob)
   round-trips:                   6
   heads summary:
     total common heads:          1
       also local heads:          0
       also remote heads:         0
       both:                      0
     local heads:               260
       common:                    0
       missing:                 260
     remote heads:                1
       common:                    0
       unknown:                   1
   local changesets:           1340
     common:                    300
       heads:                     1
       roots:                     1
     missing:                  1040
       heads:                   260
       roots:                   260
     first undecided set:      1340
       heads:                   260
       roots:                     1
       common:                  300
       missing:                1040
   common heads: 3ee37d65064a
   $ hg -R a debugdiscovery b --debug --verbose --config progress.debug=true --rev tip
   comparing with b
   query 1; heads
   searching for changes
   taking quick initial sample
   searching: 2 queries
   query 2; still undecided: 303, sample size is: 9
   sampling from both directions
   searching: 3 queries
   query 3; still undecided: 3, sample size is: 3
   3 total queries in *.????s (glob)
   elapsed time:  * seconds (glob)
   round-trips:                   3
   heads summary:
     total common heads:          1
       also local heads:          0
       also remote heads:         0
       both:                      0
     local heads:               260
       common:                    0
       missing:                 260
     remote heads:                1
       common:                    0
       unknown:                   1
   local changesets:           1340
     common:                    300
       heads:                     1
       roots:                     1
     missing:                  1040
       heads:                   260
       roots:                   260
     first undecided set:      1340
       heads:                   260
       roots:                     1
       common:                  300
       missing:                1040
   common heads: 3ee37d65064a
 
-  $ hg -R a debugdiscovery b --debug --config devel.discovery.randomize=false --config devel.discovery.grow-sample.rate=1.01
+  $ hg -R a debugdiscovery b --debug --config devel.discovery.exchange-heads=false --config devel.discovery.randomize=false --config devel.discovery.grow-sample.rate=1.01
   comparing with b
-  query 1; heads
   searching for changes
-  taking quick initial sample
-  query 2; still undecided: 1080, sample size is: 100
   sampling from both directions
-  query 3; still undecided: 980, sample size is: 200
+  query 1; still undecided: 1340, sample size is: 200
+  sampling from both directions
+  query 2; still undecided: 795, sample size is: 202
   sampling from both directions
-  query 4; still undecided: 497, sample size is: 202
+  query 3; still undecided: 525, sample size is: 204
   sampling from both directions
-  query 5; still undecided: 294, sample size is: 204
+  query 4; still undecided: 252, sample size is: 206
   sampling from both directions
-  query 6; still undecided: 90, sample size is: 90
-  6 total queries in *s (glob)
+  query 5; still undecided: 44, sample size is: 44
+  5 total queries in *s (glob)
   elapsed time: * seconds (glob)
-  round-trips:                   6
+  round-trips:                   5
   heads summary:
     total common heads:          1
       also local heads:          0
       also remote heads:         0
       both:                      0
     local heads:               260
       common:                    0
       missing:                 260
     remote heads:                1
       common:                    0
       unknown:                   1
   local changesets:           1340
     common:                    300
       heads:                     1
       roots:                     1
     missing:                  1040
       heads:                   260
       roots:                   260
     first undecided set:      1340
       heads:                   260
       roots:                     1
       common:                  300
       missing:                1040
   common heads: 3ee37d65064a
 
 Test actual protocol when pulling one new head in addition to common heads
 
   $ hg clone -U b c
   $ hg -R c id -ir tip
   513314ca8b3a
   $ hg -R c up -qr default
   $ touch c/f
   $ hg -R c ci -Aqm "extra head"
   $ hg -R c id -i
   e64a39e7da8b
 
   $ hg serve -R c -p $HGPORT -d --pid-file=hg.pid -A access.log -E errors.log
   $ cat hg.pid >> $DAEMON_PIDS
 
   $ hg -R b incoming http://localhost:$HGPORT/ -T '{node|short}\n'
   comparing with http://localhost:$HGPORT/
   searching for changes
   e64a39e7da8b
 
   $ killdaemons.py
   $ cut -d' ' -f6- access.log | grep -v cmd=known # cmd=known uses random sampling
   "GET /?cmd=capabilities HTTP/1.1" 200 -
   "GET /?cmd=batch HTTP/1.1" 200 - x-hgarg-1:cmds=heads+%3Bknown+nodes%3D513314ca8b3ae4dac8eec56966265b00fcf866db x-hgproto-1:0.1 0.2 comp=$USUAL_COMPRESSIONS$ partial-pull
   "GET /?cmd=getbundle HTTP/1.1" 200 - x-hgarg-1:$USUAL_BUNDLE_CAPS$&cg=1&common=513314ca8b3ae4dac8eec56966265b00fcf866db&heads=e64a39e7da8b0d54bc63e81169aff001c13b3477 x-hgproto-1:0.1 0.2 comp=$USUAL_COMPRESSIONS$ partial-pull
   "GET /?cmd=listkeys HTTP/1.1" 200 - x-hgarg-1:namespace=phases x-hgproto-1:0.1 0.2 comp=$USUAL_COMPRESSIONS$ partial-pull
   $ cat errors.log
 
   $ cd ..
 
 
 Issue 4438 - test coverage for 3ef893520a85 issues.
 
   $ mkdir issue4438
   $ cd issue4438
 #if false
 generate new bundles:
   $ hg init r1
   $ for i in `"$PYTHON" $TESTDIR/seq.py 101`; do hg -R r1 up -qr null && hg -R r1 branch -q b$i && hg -R r1 ci -qmb$i; done
   $ hg clone -q r1 r2
   $ for i in `"$PYTHON" $TESTDIR/seq.py 10`; do hg -R r1 up -qr null && hg -R r1 branch -q c$i && hg -R r1 ci -qmc$i; done
   $ hg -R r2 branch -q r2change && hg -R r2 ci -qmr2change
   $ hg -R r1 bundle -qa $TESTDIR/bundles/issue4438-r1.hg
   $ hg -R r2 bundle -qa $TESTDIR/bundles/issue4438-r2.hg
 #else
 use existing bundles:
   $ hg init r1
   $ hg -R r1 -q unbundle $TESTDIR/bundles/issue4438-r1.hg
   $ hg -R r1 -q up
   $ hg init r2
   $ hg -R r2 -q unbundle $TESTDIR/bundles/issue4438-r2.hg
   $ hg -R r2 -q up
 #endif
 
 Set iteration order could cause wrong and unstable results - fixed in 73cfaa348650:
 
   $ hg -R r1 outgoing r2 -T'{rev} '
   comparing with r2
   searching for changes
   101 102 103 104 105 106 107 108 109 110  (no-eol)
 
 The case where all the 'initialsamplesize' samples already were common would
 give 'all remote heads known locally' without checking the remaining heads -
 fixed in 86c35b7ae300:
 
   $ cat >> r1/.hg/hgrc << EOF
   > [devel]
   > discovery.randomize = False
   > EOF
 
   $ hg -R r1 outgoing r2 -T'{rev} ' --config extensions.blackbox= \
   > --config blackbox.track='command commandfinish discovery'
   comparing with r2
   searching for changes
   101 102 103 104 105 106 107 108 109 110  (no-eol)
   $ hg -R r1 --config extensions.blackbox= blackbox --config blackbox.track=
   * @5d0b986a083e0d91f116de4691e2aaa54d5bbec0 (*)> serve --cmdserver chgunix * (glob) (chg !)
   * @5d0b986a083e0d91f116de4691e2aaa54d5bbec0 (*)> -R r1 outgoing r2 *-T{rev} * --config *extensions.blackbox=* (glob)
   * @5d0b986a083e0d91f116de4691e2aaa54d5bbec0 (*)> found 101 common and 1 unknown server heads, 1 roundtrips in *.????s (glob)
   * @5d0b986a083e0d91f116de4691e2aaa54d5bbec0 (*)> -R r1 outgoing r2 *-T{rev} * --config *extensions.blackbox=* exited 0 after *.?? seconds (glob)
   $ cd ..
 
 Even if the set of revs to discover is restricted, unrelated revs may be
 returned as common heads.
 
   $ mkdir ancestorsof
   $ cd ancestorsof
   $ hg init a
   $ hg clone a b -q
   $ cd b
   $ hg debugbuilddag '.:root *root *root'
   $ hg log -G -T '{node|short}'
   o  fa942426a6fd
   |
   | o  66f7d451a68b
   |/
   o  1ea73414a91b
   
   $ hg push -r 66f7d451a68b -q
   $ hg debugdiscovery --verbose --rev fa942426a6fd
   comparing with $TESTTMP/ancestorsof/a
   searching for changes
   elapsed time:  * seconds (glob)
   round-trips:                   1
   heads summary:
     total common heads:          1
       also local heads:          1
       also remote heads:         1
       both:                      1
     local heads:                 2
       common:                    1
       missing:                   1
     remote heads:                1
       common:                    1
       unknown:                   0
   local changesets:              3
     common:                      2
       heads:                     1
       roots:                     1
     missing:                     1
       heads:                     1
       roots:                     1
     first undecided set:         1
       heads:                     1
       roots:                     1
       common:                    0
       missing:                   1
   common heads: 66f7d451a68b