view mercurial/verify.py @ 39506:b66ea3fc3a86

sparse-revlog: set max delta chain length to on thousand

The new snapshot system used in the sparse-revlog case gave us some small size
benefit so far. However its most important property is to gracefully handle
harder limit on delta chainlength.

Long delta chain has a very detrimental impact on read (and write) performance
in revlog. Being able to shorter them provide a great boost. However, shorting
delta used to result significantly lower compression ratio. The intermediate
snapshots effectively suppress most of this effect (even all in some case).

# Effect on the test repository

The repository we use for test is not "realistic" but can still show this in
action using an unreasonably low chain limit. Limiting the chain length show a
sizeable increase but stay under control: +6% for limit=15; +15% for limit=10.
Without the snapshot system the increase is significantly bigger: +45% for
limit=15; +80% for limit=10. Even slightly larger than without delta chain
limit, the resulting size is still smaller than before we started doing
snapshots.

Here is a table for comparison. *Since the repository is not branchy, the
initial sparse-revlog version does not bring much benefit compare to the
non-sparse one):

       chain length limit |     none   |   limit=15  |   limit=10  |
    without sparse-revlog | 62 818 987 | 112 664 615 | 131 222 574 |
    without snapshot      | 74 365 490 | 108 211 410 | 133 857 764 |
    with    snapshot      | 59 230 936 |  63 002 924 |  68 415 329 |


# Effect On Real Life Repositories

The series provides significant benefits on all kind of repositories.

Using `hg debugupgraderepo -o redeltaparent --run`, we recomputed delta chain
for various repositories with different settings:
  - delta chain length: unlimited or 1000 limit
  - sparse-revlog:      enabled or disabled
  - this series:        applied or not applied

We can observe multiple types of effect:

 - On very branchy repositories:
   * The delta chain limit as low impact on the repo size.
   * Intermediate snapshot greatly reduces manifest size:
     - pypy:     -80%
     - netbeans: -95%
   * The delta chain limit is effective, without a size impact:
     - netbeans average:      613 -> 282
     - private #1 average:  1 068 -> 307

 - On more linear repository:
   * Intermediate snapshot limit the impact of delta chain limit:
     - mozilla:
         without the series: +360%
         with the series:     +25%
   * The delta chain limit provides large improvement:
     - mozilla's average chain length:
        unlimited: 15 338
        limited:      469
   * Despite the chain length limit, the manifest size is reduced:
     - mercurial: -25%
     - mozilla:   -30%

It is clear that the use of chains of intermediate snapshots provide large
benefits both in storage size and delta chains quality. We should now switch our
effort toward making sure the write performance are acceptable. Then,
`sparse-revlog` will be a suitable format for all new repository.

# Raw Statistic

  * no-sparse:   general delta repository not using sparse-revlog
  * no-snapshot: sparse-revlog repository not using this series
  * snapshot:    sparse-revlog repository using this series

mercurial

    Manifest Size:
        limit       | none        |        1000
        ------------|-------------|------------
        no-sparse   |   8 021 373 |  8 199 366
        no-snapshot |   8 103 561 |  8 259 719
        snapshot    |   6 137 116 |  6 126 433

    Manifest Chain length data
        limit       ||       none        ||       1000        ||
        value       || average |   max   || average |   max   ||
        ------------||---------|---------||---------|---------||
        no-sparse   ||     307 |    1456 ||     279 |    1000 ||
        no-snapshot ||     312 |    1456 ||     283 |    1000 ||
        snapshot    ||     248 |    1208 ||     241 |    1000 ||

    Full Store Size
        limit       | none        |        1000
        ------------|-------------|------------
        no-sparse   |  51 013 198 | 51 201 574
        no-snapshot |  50 930 795 | 51 141 006
        snapshot    |  48 072 037 | 48 093 572

pypy

    Manifest Size:
        limit       | none        |        1000
        ------------|-------------|------------
        no-sparse   | 193 987 784 | 193 987 784
        no-snapshot | 163 171 745 | 163 312 229
        snapshot    |  34 605 900 |  34 600 750

    Manifest Chain length data
        limit       ||       none        ||       1000        ||
        value       || average |   max   || average |   max   ||
        ------------||---------|---------||---------|---------||
        no-sparse   ||     101 |     692 ||     101 |     692 ||
        no-snapshot ||     151 |    1307 ||     148 |    1000 ||
        snapshot    ||     128 |    1309 ||     125 |    1000 ||

    Full Store Size
        limit       | none        |        1000
        ------------|-------------|------------
        no-sparse   | 495 931 473 | 495 931 473
        no-snapshot | 465 441 017 | 465 581 501
        snapshot    | 355 467 301 | 355 472 451

Mozilla

    Manifest Size:
        limit       | none           |        1000
        ------------|----------------|---------------
        no-sparse   |    416 757 148 |  1 869 009 668
        no-snapshot |    401 592 370 |  1 843 493 795
        snapshot    |    224 359 521 |    284 615 500

    Manifest Chain length data
        limit       ||       none        ||       1000        ||
        value       || average |   max   || average |   max   ||
        ------------||---------|---------||---------|---------||
        no-sparse   ||  15 333 |  58 980 ||     468 |   1 000 ||
        no-snapshot ||  15 336 |  58 980 ||     469 |   1 000 ||
        snapshot    ||  15 338 |  58 983 ||     469 |   1 000 ||

    Full Store Size
        limit       | none           |        1000
        ------------|----------------|---------------
        no-sparse   |  2 712 477 887 | 4 164 995 451
        no-snapshot |  2 698 887 835 | 4 141 054 304
        snapshot    |  2 518 130 385 | 2 578 587 596

Netbeans

    Manifest Size:
        limit       | none           |        1000
        ------------|----------------|---------------
        no-sparse   |  4 766 794 101 |  4 870 642 687
        no-snapshot |  4 334 806 082 |  4 428 681 309
        snapshot    |    232 659 666 |    240 330 665

    Manifest Chain length data
        limit       ||       none        ||       1000        ||
        value       || average |   max   || average |   max   ||
        ------------||---------|---------||---------|---------||
        no-sparse   ||     597 |   6802  ||     254 |   1 000 ||
        no-snapshot ||     648 |   6 802 ||     305 |   1 000 ||
        snapshot    ||     613 |   6 804 ||     282 |   1 000 ||

    Full Store Size
        limit       | none           |        1000
        ------------|----------------|---------------
        no-sparse   |  5 807 347 998 |  5 911 196 584
        no-snapshot |  5 375 398 602 |  5 469 273 829
        snapshot    |  1 282 519 928 |  1 290 190 927

Private repo #1

    Manifest Size:
        limit       | none            |        1000
        ------------|-----------------|---------------
        no-sparse   | 41 389 010 840  | 41 398 162 091
        no-snapshot |  9 737 319 435  | 10 223 773 150
        snapshot    |    744 215 807  |    747 961 822

    Manifest Chain length data
        limit       ||       none        ||       1000        ||
        value       || average |   max   || average |   max   ||
        ------------||---------|---------||---------|---------||
        no-sparse   ||     245 |   8 885 ||     81  |   1 000 ||
        no-snapshot ||   1 225 |   8 885 ||    336  |   1 000 ||
        snapshot    ||   1 068 |   7 909 ||    307  |   1 000 ||

    Full Store Size
        limit       | none           |        1000
        ------------|----------------|---------------
        no-sparse   | 49 646 065 126 | 49 655 216 377
        no-snapshot | 17 924 862 856 | 18 411 316 571
        snapshot    |  9 009 024 710 |  9 012 770 725

Private repo #2

  We currently have less data available for that repository.
    * Before is a sparse-revlog repository without this series
    * After is a sparse-revlog repository with this series + 1000 chain limit


  Manifest Size:
    Before: 1 531 485 040 bytes
    After:  1 091 422 451 bytes
  Manifest Chain:
    Before: 2 218 avg; 6 575 Max
    After:    442 avg; 1 000 Max

  Full Store Size
    Before: 15 203 955 615
    after:   8 207 180 693

# verify.py - repository integrity checking for Mercurial
#
# Copyright 2006, 2007 Matt Mackall <[e-mail]>
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.

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.getstorage(b'')) > 0
        self.revlogv1 = repo.changelog.version != revlog.REVLOGV0
        self.lrugetctx = util.lrucachefunc(repo.__getitem__)
        self.refersmf = False
        self.fncachewarned = False
        # developer config: verify.skipflags
        self.skipflags = repo.ui.configint('verify', 'skipflags')
        self.warnorphanstorefiles = True

    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(_("checked %d changesets with %d changes to %d files\n") %
                       (len(repo.changelog), filerevisions, totalfiles))
        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)
        progress = ui.makeprogress(_('checking'), unit=_('changesets'),
                                   total=len(repo))
        for i in repo:
            progress.update(i)
            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)
        progress.complete()
        return mflinkrevs, filelinkrevs

    def _verifymanifest(self, mflinkrevs, dir="", storefiles=None,
                        subdirprogress=None):
        repo = self.repo
        ui = self.ui
        match = self.match
        mfl = self.repo.manifestlog
        mf = mfl.getstorage(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 subdirprogress: # should be true since we're in a subdirectory
                subdirprogress.increment()
        if self.refersmf:
            # Do not check manifest if there are only changelog entries with
            # null manifests.
            self.checklog(mf, label, 0)
        progress = ui.makeprogress(_('checking'), unit=_('manifests'),
                                   total=len(mf))
        for i in mf:
            if not dir:
                progress.update(i)
            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:
            progress.complete()

        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))
            subdirprogress = ui.makeprogress(_('checking'), unit=_('manifests'),
                                             total=len(subdirs))

        for subdir, linkrevs in subdirnodes.iteritems():
            subdirfilenodes = self._verifymanifest(linkrevs, subdir, storefiles,
                                                   subdirprogress)
            for f, onefilenodes in subdirfilenodes.iteritems():
                filenodes.setdefault(f, {}).update(onefilenodes)

        if not dir and subdirnodes:
            subdirprogress.complete()
            if self.warnorphanstorefiles:
                for f in sorted(storefiles):
                    self.warn(_("warning: orphan data file '%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)
        progress = ui.makeprogress(_('crosschecking'), total=total)
        if self.havemf:
            for f in sorted(filelinkrevs):
                progress.increment()
                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):
                progress.increment()
                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)

        progress.complete()

    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))
        revisions = 0
        progress = ui.makeprogress(_('checking'), unit=_('files'),
                                   total=len(files))
        for i, f in enumerate(files):
            progress.update(i, item=f)
            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:
                    if self.warnorphanstorefiles:
                        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)
        progress.complete()

        if self.warnorphanstorefiles:
            for f in sorted(storefiles):
                self.warn(_("warning: orphan data file '%s'") % f)

        return len(files), revisions