##// END OF EJS Templates
wireproto: add streams to frame-based protocol...
wireproto: add streams to frame-based protocol Previously, the frame-based protocol was just a series of frames, with each frame associated with a request ID. In order to scale the protocol, we'll want to enable the use of compression. While it is possible to enable compression at the socket/pipe level, this has its disadvantages. The big one is it undermines the point of frames being standalone, atomic units that can be read and written: if you add compression above the framing protocol, you are back to having a stream-based protocol as opposed to something frame-based. So in order to preserve frames, compression needs to occur at the frame payload level. Compressing each frame's payload individually will limit compression ratios because the window size of the compressor will be limited by the max frame size, which is 32-64kb as currently defined. It will also add CPU overhead, as it is more efficient for compressors to operate on fewer, larger blocks of data than more, smaller blocks. So compressing each frame independently is out. This means we need to compress each frame's payload as if it is part of a larger stream. The simplest approach is to have 1 stream per connection. This could certainly work. However, it has disadvantages (documented below). We could also have 1 stream per RPC/command invocation. (This is the model HTTP/2 goes with.) This also has disadvantages. The main disadvantage to one global stream is that it has the very real potential to create CPU bottlenecks doing compression. Networks are only getting faster and the performance of single CPU cores has been relatively flat. Newer compression formats like zstandard offer better CPU cycle efficiency than predecessors like zlib. But it still all too common to saturate your CPU with compression overhead long before you saturate the network pipe. The main disadvantage with streams per request is that you can't reap the benefits of the compression context for multiple requests. For example, if you send 1000 RPC requests (or HTTP/2 requests for that matter), the response to each would have its own compression context. The overall size of the raw responses would be larger because compression contexts wouldn't be able to reference data from another request or response. The approach for streams as implemented in this commit is to support N streams per connection and for streams to potentially span requests and responses. As explained by the added internals docs, this facilitates servers and clients delegating independent streams and compression to independent threads / CPU cores. This helps alleviate the CPU bottleneck of compression. This design also allows compression contexts to be reused across requests/responses. This can result in improved compression ratios and less overhead for compressors and decompressors having to build new contexts. Another feature that was defined was the ability for individual frames within a stream to declare whether that individual frame's payload uses the content encoding (read: compression) defined by the stream. The idea here is that some servers may serve data from a combination of caches and dynamic resolution. Data coming from caches may be pre-compressed. We want to facilitate servers being able to essentially stream bytes from caches to the wire with minimal overhead. Being able to mix and match with frames are compressed within a stream enables these types of advanced server functionality. This commit defines the new streams mechanism. Basic code for supporting streams in frames has been added. But that code is seriously lacking and doesn't fully conform to the defined protocol. For example, we don't close any streams. And support for content encoding within streams is not yet implemented. The change was rather invasive and I didn't think it would be reasonable to implement the entire feature in a single commit. For the record, I would have loved to reuse an existing multiplexing protocol to build the new wire protocol on top of. However, I couldn't find a protocol that offers the performance and scaling characteristics that I desired. Namely, it should support multiple compression contexts to facilitate scaling out to multiple CPU cores and compression contexts should be able to live longer than single RPC requests. HTTP/2 *almost* fits the bill. But the semantics of HTTP message exchange state that streams can only live for a single request-response. We /could/ tunnel on top of HTTP/2 streams and frames with HEADER and DATA frames. But there's no guarantee that HTTP/2 libraries and proxies would allow us to use HTTP/2 streams and frames without the HTTP message exchange semantics defined in RFC 7540 Section 8. Other RPC protocols like gRPC tunnel are built on top of HTTP/2 and thus preserve its semantics of stream per RPC invocation. Even QUIC does this. We could attempt to invent a higher-level stream that spans HTTP/2 streams. But this would be violating HTTP/2 because there is no guarantee that HTTP/2 streams are routed to the same server. The best we can do - which is what this protocol does - is shoehorn all request and response data into a single HTTP message and create streams within. At that point, we've defined a Content-Type in HTTP parlance. It just so happens our media type can also work as a standalone, stream-based protocol, without leaning on HTTP or similar protocol. Differential Revision: https://phab.mercurial-scm.org/D2907

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verify.py
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# verify.py - repository integrity checking for Mercurial
#
# Copyright 2006, 2007 Matt Mackall <mpm@selenic.com>
#
# 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 os
from .i18n import _
from .node import (
nullid,
short,
)
from . import (
error,
pycompat,
revlog,
scmutil,
util,
)
def verify(repo):
with repo.lock():
return verifier(repo).verify()
def _normpath(f):
# under hg < 2.4, convert didn't sanitize paths properly, so a
# converted repo may contain repeated slashes
while '//' in f:
f = f.replace('//', '/')
return f
class verifier(object):
# The match argument is always None in hg core, but e.g. the narrowhg
# extension will pass in a matcher here.
def __init__(self, repo, match=None):
self.repo = repo.unfiltered()
self.ui = repo.ui
self.match = match or scmutil.matchall(repo)
self.badrevs = set()
self.errors = 0
self.warnings = 0
self.havecl = len(repo.changelog) > 0
self.havemf = len(repo.manifestlog._revlog) > 0
self.revlogv1 = repo.changelog.version != revlog.REVLOGV0
self.lrugetctx = util.lrucachefunc(repo.changectx)
self.refersmf = False
self.fncachewarned = False
# developer config: verify.skipflags
self.skipflags = repo.ui.configint('verify', 'skipflags')
def warn(self, msg):
self.ui.warn(msg + "\n")
self.warnings += 1
def err(self, linkrev, msg, filename=None):
if linkrev is not None:
self.badrevs.add(linkrev)
linkrev = "%d" % linkrev
else:
linkrev = '?'
msg = "%s: %s" % (linkrev, msg)
if filename:
msg = "%s@%s" % (filename, msg)
self.ui.warn(" " + msg + "\n")
self.errors += 1
def exc(self, linkrev, msg, inst, filename=None):
fmsg = pycompat.bytestr(inst)
if not fmsg:
fmsg = pycompat.byterepr(inst)
self.err(linkrev, "%s: %s" % (msg, fmsg), filename)
def checklog(self, obj, name, linkrev):
if not len(obj) and (self.havecl or self.havemf):
self.err(linkrev, _("empty or missing %s") % name)
return
d = obj.checksize()
if d[0]:
self.err(None, _("data length off by %d bytes") % d[0], name)
if d[1]:
self.err(None, _("index contains %d extra bytes") % d[1], name)
if obj.version != revlog.REVLOGV0:
if not self.revlogv1:
self.warn(_("warning: `%s' uses revlog format 1") % name)
elif self.revlogv1:
self.warn(_("warning: `%s' uses revlog format 0") % name)
def checkentry(self, obj, i, node, seen, linkrevs, f):
lr = obj.linkrev(obj.rev(node))
if lr < 0 or (self.havecl and lr not in linkrevs):
if lr < 0 or lr >= len(self.repo.changelog):
msg = _("rev %d points to nonexistent changeset %d")
else:
msg = _("rev %d points to unexpected changeset %d")
self.err(None, msg % (i, lr), f)
if linkrevs:
if f and len(linkrevs) > 1:
try:
# attempt to filter down to real linkrevs
linkrevs = [l for l in linkrevs
if self.lrugetctx(l)[f].filenode() == node]
except Exception:
pass
self.warn(_(" (expected %s)") % " ".join
(map(pycompat.bytestr, linkrevs)))
lr = None # can't be trusted
try:
p1, p2 = obj.parents(node)
if p1 not in seen and p1 != nullid:
self.err(lr, _("unknown parent 1 %s of %s") %
(short(p1), short(node)), f)
if p2 not in seen and p2 != nullid:
self.err(lr, _("unknown parent 2 %s of %s") %
(short(p2), short(node)), f)
except Exception as inst:
self.exc(lr, _("checking parents of %s") % short(node), inst, f)
if node in seen:
self.err(lr, _("duplicate revision %d (%d)") % (i, seen[node]), f)
seen[node] = i
return lr
def verify(self):
repo = self.repo
ui = repo.ui
if not repo.url().startswith('file:'):
raise error.Abort(_("cannot verify bundle or remote repos"))
if os.path.exists(repo.sjoin("journal")):
ui.warn(_("abandoned transaction found - run hg recover\n"))
if ui.verbose or not self.revlogv1:
ui.status(_("repository uses revlog format %d\n") %
(self.revlogv1 and 1 or 0))
mflinkrevs, filelinkrevs = self._verifychangelog()
filenodes = self._verifymanifest(mflinkrevs)
del mflinkrevs
self._crosscheckfiles(filelinkrevs, filenodes)
totalfiles, filerevisions = self._verifyfiles(filenodes, filelinkrevs)
ui.status(_("%d files, %d changesets, %d total revisions\n") %
(totalfiles, len(repo.changelog), filerevisions))
if self.warnings:
ui.warn(_("%d warnings encountered!\n") % self.warnings)
if self.fncachewarned:
ui.warn(_('hint: run "hg debugrebuildfncache" to recover from '
'corrupt fncache\n'))
if self.errors:
ui.warn(_("%d integrity errors encountered!\n") % self.errors)
if self.badrevs:
ui.warn(_("(first damaged changeset appears to be %d)\n")
% min(self.badrevs))
return 1
def _verifychangelog(self):
ui = self.ui
repo = self.repo
match = self.match
cl = repo.changelog
ui.status(_("checking changesets\n"))
mflinkrevs = {}
filelinkrevs = {}
seen = {}
self.checklog(cl, "changelog", 0)
total = len(repo)
for i in repo:
ui.progress(_('checking'), i, total=total, unit=_('changesets'))
n = cl.node(i)
self.checkentry(cl, i, n, seen, [i], "changelog")
try:
changes = cl.read(n)
if changes[0] != nullid:
mflinkrevs.setdefault(changes[0], []).append(i)
self.refersmf = True
for f in changes[3]:
if match(f):
filelinkrevs.setdefault(_normpath(f), []).append(i)
except Exception as inst:
self.refersmf = True
self.exc(i, _("unpacking changeset %s") % short(n), inst)
ui.progress(_('checking'), None)
return mflinkrevs, filelinkrevs
def _verifymanifest(self, mflinkrevs, dir="", storefiles=None,
progress=None):
repo = self.repo
ui = self.ui
match = self.match
mfl = self.repo.manifestlog
mf = mfl._revlog.dirlog(dir)
if not dir:
self.ui.status(_("checking manifests\n"))
filenodes = {}
subdirnodes = {}
seen = {}
label = "manifest"
if dir:
label = dir
revlogfiles = mf.files()
storefiles.difference_update(revlogfiles)
if progress: # should be true since we're in a subdirectory
progress()
if self.refersmf:
# Do not check manifest if there are only changelog entries with
# null manifests.
self.checklog(mf, label, 0)
total = len(mf)
for i in mf:
if not dir:
ui.progress(_('checking'), i, total=total, unit=_('manifests'))
n = mf.node(i)
lr = self.checkentry(mf, i, n, seen, mflinkrevs.get(n, []), label)
if n in mflinkrevs:
del mflinkrevs[n]
elif dir:
self.err(lr, _("%s not in parent-directory manifest") %
short(n), label)
else:
self.err(lr, _("%s not in changesets") % short(n), label)
try:
mfdelta = mfl.get(dir, n).readdelta(shallow=True)
for f, fn, fl in mfdelta.iterentries():
if not f:
self.err(lr, _("entry without name in manifest"))
elif f == "/dev/null": # ignore this in very old repos
continue
fullpath = dir + _normpath(f)
if fl == 't':
if not match.visitdir(fullpath):
continue
subdirnodes.setdefault(fullpath + '/', {}).setdefault(
fn, []).append(lr)
else:
if not match(fullpath):
continue
filenodes.setdefault(fullpath, {}).setdefault(fn, lr)
except Exception as inst:
self.exc(lr, _("reading delta %s") % short(n), inst, label)
if not dir:
ui.progress(_('checking'), None)
if self.havemf:
for c, m in sorted([(c, m) for m in mflinkrevs
for c in mflinkrevs[m]]):
if dir:
self.err(c, _("parent-directory manifest refers to unknown "
"revision %s") % short(m), label)
else:
self.err(c, _("changeset refers to unknown revision %s") %
short(m), label)
if not dir and subdirnodes:
self.ui.status(_("checking directory manifests\n"))
storefiles = set()
subdirs = set()
revlogv1 = self.revlogv1
for f, f2, size in repo.store.datafiles():
if not f:
self.err(None, _("cannot decode filename '%s'") % f2)
elif (size > 0 or not revlogv1) and f.startswith('meta/'):
storefiles.add(_normpath(f))
subdirs.add(os.path.dirname(f))
subdircount = len(subdirs)
currentsubdir = [0]
def progress():
currentsubdir[0] += 1
ui.progress(_('checking'), currentsubdir[0], total=subdircount,
unit=_('manifests'))
for subdir, linkrevs in subdirnodes.iteritems():
subdirfilenodes = self._verifymanifest(linkrevs, subdir, storefiles,
progress)
for f, onefilenodes in subdirfilenodes.iteritems():
filenodes.setdefault(f, {}).update(onefilenodes)
if not dir and subdirnodes:
ui.progress(_('checking'), None)
for f in sorted(storefiles):
self.warn(_("warning: orphan revlog '%s'") % f)
return filenodes
def _crosscheckfiles(self, filelinkrevs, filenodes):
repo = self.repo
ui = self.ui
ui.status(_("crosschecking files in changesets and manifests\n"))
total = len(filelinkrevs) + len(filenodes)
count = 0
if self.havemf:
for f in sorted(filelinkrevs):
count += 1
ui.progress(_('crosschecking'), count, total=total)
if f not in filenodes:
lr = filelinkrevs[f][0]
self.err(lr, _("in changeset but not in manifest"), f)
if self.havecl:
for f in sorted(filenodes):
count += 1
ui.progress(_('crosschecking'), count, total=total)
if f not in filelinkrevs:
try:
fl = repo.file(f)
lr = min([fl.linkrev(fl.rev(n)) for n in filenodes[f]])
except Exception:
lr = None
self.err(lr, _("in manifest but not in changeset"), f)
ui.progress(_('crosschecking'), None)
def _verifyfiles(self, filenodes, filelinkrevs):
repo = self.repo
ui = self.ui
lrugetctx = self.lrugetctx
revlogv1 = self.revlogv1
havemf = self.havemf
ui.status(_("checking files\n"))
storefiles = set()
for f, f2, size in repo.store.datafiles():
if not f:
self.err(None, _("cannot decode filename '%s'") % f2)
elif (size > 0 or not revlogv1) and f.startswith('data/'):
storefiles.add(_normpath(f))
files = sorted(set(filenodes) | set(filelinkrevs))
total = len(files)
revisions = 0
for i, f in enumerate(files):
ui.progress(_('checking'), i, item=f, total=total, unit=_('files'))
try:
linkrevs = filelinkrevs[f]
except KeyError:
# in manifest but not in changelog
linkrevs = []
if linkrevs:
lr = linkrevs[0]
else:
lr = None
try:
fl = repo.file(f)
except error.RevlogError as e:
self.err(lr, _("broken revlog! (%s)") % e, f)
continue
for ff in fl.files():
try:
storefiles.remove(ff)
except KeyError:
self.warn(_(" warning: revlog '%s' not in fncache!") % ff)
self.fncachewarned = True
self.checklog(fl, f, lr)
seen = {}
rp = None
for i in fl:
revisions += 1
n = fl.node(i)
lr = self.checkentry(fl, i, n, seen, linkrevs, f)
if f in filenodes:
if havemf and n not in filenodes[f]:
self.err(lr, _("%s not in manifests") % (short(n)), f)
else:
del filenodes[f][n]
# Verify contents. 4 cases to care about:
#
# common: the most common case
# rename: with a rename
# meta: file content starts with b'\1\n', the metadata
# header defined in filelog.py, but without a rename
# ext: content stored externally
#
# More formally, their differences are shown below:
#
# | common | rename | meta | ext
# -------------------------------------------------------
# flags() | 0 | 0 | 0 | not 0
# renamed() | False | True | False | ?
# rawtext[0:2]=='\1\n'| False | True | True | ?
#
# "rawtext" means the raw text stored in revlog data, which
# could be retrieved by "revision(rev, raw=True)". "text"
# mentioned below is "revision(rev, raw=False)".
#
# There are 3 different lengths stored physically:
# 1. L1: rawsize, stored in revlog index
# 2. L2: len(rawtext), stored in revlog data
# 3. L3: len(text), stored in revlog data if flags==0, or
# possibly somewhere else if flags!=0
#
# L1 should be equal to L2. L3 could be different from them.
# "text" may or may not affect commit hash depending on flag
# processors (see revlog.addflagprocessor).
#
# | common | rename | meta | ext
# -------------------------------------------------
# rawsize() | L1 | L1 | L1 | L1
# size() | L1 | L2-LM | L1(*) | L1 (?)
# len(rawtext) | L2 | L2 | L2 | L2
# len(text) | L2 | L2 | L2 | L3
# len(read()) | L2 | L2-LM | L2-LM | L3 (?)
#
# LM: length of metadata, depending on rawtext
# (*): not ideal, see comment in filelog.size
# (?): could be "- len(meta)" if the resolved content has
# rename metadata
#
# Checks needed to be done:
# 1. length check: L1 == L2, in all cases.
# 2. hash check: depending on flag processor, we may need to
# use either "text" (external), or "rawtext" (in revlog).
try:
skipflags = self.skipflags
if skipflags:
skipflags &= fl.flags(i)
if not skipflags:
fl.read(n) # side effect: read content and do checkhash
rp = fl.renamed(n)
# the "L1 == L2" check
l1 = fl.rawsize(i)
l2 = len(fl.revision(n, raw=True))
if l1 != l2:
self.err(lr, _("unpacked size is %s, %s expected") %
(l2, l1), f)
except error.CensoredNodeError:
# experimental config: censor.policy
if ui.config("censor", "policy") == "abort":
self.err(lr, _("censored file data"), f)
except Exception as inst:
self.exc(lr, _("unpacking %s") % short(n), inst, f)
# check renames
try:
if rp:
if lr is not None and ui.verbose:
ctx = lrugetctx(lr)
if not any(rp[0] in pctx for pctx in ctx.parents()):
self.warn(_("warning: copy source of '%s' not"
" in parents of %s") % (f, ctx))
fl2 = repo.file(rp[0])
if not len(fl2):
self.err(lr, _("empty or missing copy source "
"revlog %s:%s") % (rp[0], short(rp[1])), f)
elif rp[1] == nullid:
ui.note(_("warning: %s@%s: copy source"
" revision is nullid %s:%s\n")
% (f, lr, rp[0], short(rp[1])))
else:
fl2.rev(rp[1])
except Exception as inst:
self.exc(lr, _("checking rename of %s") % short(n), inst, f)
# cross-check
if f in filenodes:
fns = [(v, k) for k, v in filenodes[f].iteritems()]
for lr, node in sorted(fns):
self.err(lr, _("manifest refers to unknown revision %s") %
short(node), f)
ui.progress(_('checking'), None)
for f in sorted(storefiles):
self.warn(_("warning: orphan revlog '%s'") % f)
return len(files), revisions