mercurial/sparse.py

sparse-read: move from a recursive-based approach to a heap-based one

The previous recursive approach was trying to optimise each read slice to have
a good density. It had the tendency to over-optimize smaller slices while
leaving larger hole in others.

The new approach focuses on improving the combined density of all the reads,
instead of the individual slices. It slices at the largest gaps first, as they
reduce the total amount of read data the most efficiently.

Another benefit of this approach is that we iterate over the delta chain only
once, reducing the overhead of slicing long delta chains.

On the repository we use for tests, the new approach shows similar or faster
performance than the current default linear full read.

The repository contains about 450,000 revisions with many concurrent
topological branches. Tests have been run on two versions of the repository:
one built with the current delta constraint, and the other with an unlimited
delta span (using 'experimental.maxdeltachainspan=0')

Below are timings for building 1% of all the revision in the manifest log using
'hg perfrevlogrevisions -m'. Times are given in seconds. They include the new
couple of follow-up changeset in this series.

delta-span  standard    unlimited
linear-read     922s         632s
sparse-read     814s         566s

# sparse.py - functionality for sparse checkouts
#
# Copyright 2014 Facebook, Inc.
#
# 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 collections
import hashlib
import os

from .i18n import _
from .node import nullid
from . import (
    error,
    match as matchmod,
    merge as mergemod,
    pathutil,
    pycompat,
    scmutil,
    util,
)

# Whether sparse features are enabled. This variable is intended to be
# temporary to facilitate porting sparse to core. It should eventually be
# a per-repo option, possibly a repo requirement.
enabled = False

def parseconfig(ui, raw):
    """Parse sparse config file content.

    Returns a tuple of includes, excludes, and profiles.
    """
    includes = set()
    excludes = set()
    profiles = set()
    current = None
    havesection = False

    for line in raw.split('\n'):
        line = line.strip()
        if not line or line.startswith('#'):
            # empty or comment line, skip
            continue
        elif line.startswith('%include '):
            line = line[9:].strip()
            if line:
                profiles.add(line)
        elif line == '[include]':
            if havesection and current != includes:
                # TODO pass filename into this API so we can report it.
                raise error.Abort(_('sparse config cannot have includes ' +
                                    'after excludes'))
            havesection = True
            current = includes
            continue
        elif line == '[exclude]':
            havesection = True
            current = excludes
        elif line:
            if current is None:
                raise error.Abort(_('sparse config entry outside of '
                                    'section: %s') % line,
                                  hint=_('add an [include] or [exclude] line '
                                         'to declare the entry type'))

            if line.strip().startswith('/'):
                ui.warn(_('warning: sparse profile cannot use' +
                          ' paths starting with /, ignoring %s\n') % line)
                continue
            current.add(line)

    return includes, excludes, profiles

# Exists as separate function to facilitate monkeypatching.
def readprofile(repo, profile, changeid):
    """Resolve the raw content of a sparse profile file."""
    # TODO add some kind of cache here because this incurs a manifest
    # resolve and can be slow.
    return repo.filectx(profile, changeid=changeid).data()

def patternsforrev(repo, rev):
    """Obtain sparse checkout patterns for the given rev.

    Returns a tuple of iterables representing includes, excludes, and
    patterns.
    """
    # Feature isn't enabled. No-op.
    if not enabled:
        return set(), set(), set()

    raw = repo.vfs.tryread('sparse')
    if not raw:
        return set(), set(), set()

    if rev is None:
        raise error.Abort(_('cannot parse sparse patterns from working '
                            'directory'))

    includes, excludes, profiles = parseconfig(repo.ui, raw)
    ctx = repo[rev]

    if profiles:
        visited = set()
        while profiles:
            profile = profiles.pop()
            if profile in visited:
                continue

            visited.add(profile)

            try:
                raw = readprofile(repo, profile, rev)
            except error.ManifestLookupError:
                msg = (
                    "warning: sparse profile '%s' not found "
                    "in rev %s - ignoring it\n" % (profile, ctx))
                # experimental config: sparse.missingwarning
                if repo.ui.configbool(
                        'sparse', 'missingwarning'):
                    repo.ui.warn(msg)
                else:
                    repo.ui.debug(msg)
                continue

            pincludes, pexcludes, subprofs = parseconfig(repo.ui, raw)
            includes.update(pincludes)
            excludes.update(pexcludes)
            profiles.update(subprofs)

        profiles = visited

    if includes:
        includes.add('.hg*')

    return includes, excludes, profiles

def activeconfig(repo):
    """Determine the active sparse config rules.

    Rules are constructed by reading the current sparse config and bringing in
    referenced profiles from parents of the working directory.
    """
    revs = [repo.changelog.rev(node) for node in
            repo.dirstate.parents() if node != nullid]

    allincludes = set()
    allexcludes = set()
    allprofiles = set()

    for rev in revs:
        includes, excludes, profiles = patternsforrev(repo, rev)
        allincludes |= includes
        allexcludes |= excludes
        allprofiles |= profiles

    return allincludes, allexcludes, allprofiles

def configsignature(repo, includetemp=True):
    """Obtain the signature string for the current sparse configuration.

    This is used to construct a cache key for matchers.
    """
    cache = repo._sparsesignaturecache

    signature = cache.get('signature')

    if includetemp:
        tempsignature = cache.get('tempsignature')
    else:
        tempsignature = '0'

    if signature is None or (includetemp and tempsignature is None):
        signature = hashlib.sha1(repo.vfs.tryread('sparse')).hexdigest()
        cache['signature'] = signature

        if includetemp:
            raw = repo.vfs.tryread('tempsparse')
            tempsignature = hashlib.sha1(raw).hexdigest()
            cache['tempsignature'] = tempsignature

    return '%s %s' % (signature, tempsignature)

def writeconfig(repo, includes, excludes, profiles):
    """Write the sparse config file given a sparse configuration."""
    with repo.vfs('sparse', 'wb') as fh:
        for p in sorted(profiles):
            fh.write('%%include %s\n' % p)

        if includes:
            fh.write('[include]\n')
            for i in sorted(includes):
                fh.write(i)
                fh.write('\n')

        if excludes:
            fh.write('[exclude]\n')
            for e in sorted(excludes):
                fh.write(e)
                fh.write('\n')

    repo._sparsesignaturecache.clear()

def readtemporaryincludes(repo):
    raw = repo.vfs.tryread('tempsparse')
    if not raw:
        return set()

    return set(raw.split('\n'))

def writetemporaryincludes(repo, includes):
    repo.vfs.write('tempsparse', '\n'.join(sorted(includes)))
    repo._sparsesignaturecache.clear()

def addtemporaryincludes(repo, additional):
    includes = readtemporaryincludes(repo)
    for i in additional:
        includes.add(i)
    writetemporaryincludes(repo, includes)

def prunetemporaryincludes(repo):
    if not enabled or not repo.vfs.exists('tempsparse'):
        return

    s = repo.status()
    if s.modified or s.added or s.removed or s.deleted:
        # Still have pending changes. Don't bother trying to prune.
        return

    sparsematch = matcher(repo, includetemp=False)
    dirstate = repo.dirstate
    actions = []
    dropped = []
    tempincludes = readtemporaryincludes(repo)
    for file in tempincludes:
        if file in dirstate and not sparsematch(file):
            message = _('dropping temporarily included sparse files')
            actions.append((file, None, message))
            dropped.append(file)

    typeactions = collections.defaultdict(list)
    typeactions['r'] = actions
    mergemod.applyupdates(repo, typeactions, repo[None], repo['.'], False)

    # Fix dirstate
    for file in dropped:
        dirstate.drop(file)

    repo.vfs.unlink('tempsparse')
    repo._sparsesignaturecache.clear()
    msg = _('cleaned up %d temporarily added file(s) from the '
            'sparse checkout\n')
    repo.ui.status(msg % len(tempincludes))

def forceincludematcher(matcher, includes):
    """Returns a matcher that returns true for any of the forced includes
    before testing against the actual matcher."""
    kindpats = [('path', include, '') for include in includes]
    includematcher = matchmod.includematcher('', '', kindpats)
    return matchmod.unionmatcher([includematcher, matcher])

def matcher(repo, revs=None, includetemp=True):
    """Obtain a matcher for sparse working directories for the given revs.

    If multiple revisions are specified, the matcher is the union of all
    revs.

    ``includetemp`` indicates whether to use the temporary sparse profile.
    """
    # If sparse isn't enabled, sparse matcher matches everything.
    if not enabled:
        return matchmod.always(repo.root, '')

    if not revs or revs == [None]:
        revs = [repo.changelog.rev(node)
                for node in repo.dirstate.parents() if node != nullid]

    signature = configsignature(repo, includetemp=includetemp)

    key = '%s %s' % (signature, ' '.join(map(pycompat.bytestr, revs)))

    result = repo._sparsematchercache.get(key)
    if result:
        return result

    matchers = []
    for rev in revs:
        try:
            includes, excludes, profiles = patternsforrev(repo, rev)

            if includes or excludes:
                # Explicitly include subdirectories of includes so
                # status will walk them down to the actual include.
                subdirs = set()
                for include in includes:
                    # TODO consider using posix path functions here so Windows
                    # \ directory separators don't come into play.
                    dirname = os.path.dirname(include)
                    # basename is used to avoid issues with absolute
                    # paths (which on Windows can include the drive).
                    while os.path.basename(dirname):
                        subdirs.add(dirname)
                        dirname = os.path.dirname(dirname)

                matcher = matchmod.match(repo.root, '', [],
                                         include=includes, exclude=excludes,
                                         default='relpath')
                if subdirs:
                    matcher = forceincludematcher(matcher, subdirs)
                matchers.append(matcher)
        except IOError:
            pass

    if not matchers:
        result = matchmod.always(repo.root, '')
    elif len(matchers) == 1:
        result = matchers[0]
    else:
        result = matchmod.unionmatcher(matchers)

    if includetemp:
        tempincludes = readtemporaryincludes(repo)
        result = forceincludematcher(result, tempincludes)

    repo._sparsematchercache[key] = result

    return result

def filterupdatesactions(repo, wctx, mctx, branchmerge, actions):
    """Filter updates to only lay out files that match the sparse rules."""
    if not enabled:
        return actions

    oldrevs = [pctx.rev() for pctx in wctx.parents()]
    oldsparsematch = matcher(repo, oldrevs)

    if oldsparsematch.always():
        return actions

    files = set()
    prunedactions = {}

    if branchmerge:
        # If we're merging, use the wctx filter, since we're merging into
        # the wctx.
        sparsematch = matcher(repo, [wctx.parents()[0].rev()])
    else:
        # If we're updating, use the target context's filter, since we're
        # moving to the target context.
        sparsematch = matcher(repo, [mctx.rev()])

    temporaryfiles = []
    for file, action in actions.iteritems():
        type, args, msg = action
        files.add(file)
        if sparsematch(file):
            prunedactions[file] = action
        elif type == 'm':
            temporaryfiles.append(file)
            prunedactions[file] = action
        elif branchmerge:
            if type != 'k':
                temporaryfiles.append(file)
                prunedactions[file] = action
        elif type == 'f':
            prunedactions[file] = action
        elif file in wctx:
            prunedactions[file] = ('r', args, msg)

    if len(temporaryfiles) > 0:
        repo.ui.status(_('temporarily included %d file(s) in the sparse '
                         'checkout for merging\n') % len(temporaryfiles))
        addtemporaryincludes(repo, temporaryfiles)

        # Add the new files to the working copy so they can be merged, etc
        actions = []
        message = 'temporarily adding to sparse checkout'
        wctxmanifest = repo[None].manifest()
        for file in temporaryfiles:
            if file in wctxmanifest:
                fctx = repo[None][file]
                actions.append((file, (fctx.flags(), False), message))

        typeactions = collections.defaultdict(list)
        typeactions['g'] = actions
        mergemod.applyupdates(repo, typeactions, repo[None], repo['.'],
                              False)

        dirstate = repo.dirstate
        for file, flags, msg in actions:
            dirstate.normal(file)

    profiles = activeconfig(repo)[2]
    changedprofiles = profiles & files
    # If an active profile changed during the update, refresh the checkout.
    # Don't do this during a branch merge, since all incoming changes should
    # have been handled by the temporary includes above.
    if changedprofiles and not branchmerge:
        mf = mctx.manifest()
        for file in mf:
            old = oldsparsematch(file)
            new = sparsematch(file)
            if not old and new:
                flags = mf.flags(file)
                prunedactions[file] = ('g', (flags, False), '')
            elif old and not new:
                prunedactions[file] = ('r', [], '')

    return prunedactions

def refreshwdir(repo, origstatus, origsparsematch, force=False):
    """Refreshes working directory by taking sparse config into account.

    The old status and sparse matcher is compared against the current sparse
    matcher.

    Will abort if a file with pending changes is being excluded or included
    unless ``force`` is True.
    """
    # Verify there are no pending changes
    pending = set()
    pending.update(origstatus.modified)
    pending.update(origstatus.added)
    pending.update(origstatus.removed)
    sparsematch = matcher(repo)
    abort = False

    for f in pending:
        if not sparsematch(f):
            repo.ui.warn(_("pending changes to '%s'\n") % f)
            abort = not force

    if abort:
        raise error.Abort(_('could not update sparseness due to pending '
                            'changes'))

    # Calculate actions
    dirstate = repo.dirstate
    ctx = repo['.']
    added = []
    lookup = []
    dropped = []
    mf = ctx.manifest()
    files = set(mf)

    actions = {}

    for file in files:
        old = origsparsematch(file)
        new = sparsematch(file)
        # Add files that are newly included, or that don't exist in
        # the dirstate yet.
        if (new and not old) or (old and new and not file in dirstate):
            fl = mf.flags(file)
            if repo.wvfs.exists(file):
                actions[file] = ('e', (fl,), '')
                lookup.append(file)
            else:
                actions[file] = ('g', (fl, False), '')
                added.append(file)
        # Drop files that are newly excluded, or that still exist in
        # the dirstate.
        elif (old and not new) or (not old and not new and file in dirstate):
            dropped.append(file)
            if file not in pending:
                actions[file] = ('r', [], '')

    # Verify there are no pending changes in newly included files
    abort = False
    for file in lookup:
        repo.ui.warn(_("pending changes to '%s'\n") % file)
        abort = not force
    if abort:
        raise error.Abort(_('cannot change sparseness due to pending '
                            'changes (delete the files or use '
                            '--force to bring them back dirty)'))

    # Check for files that were only in the dirstate.
    for file, state in dirstate.iteritems():
        if not file in files:
            old = origsparsematch(file)
            new = sparsematch(file)
            if old and not new:
                dropped.append(file)

    # Apply changes to disk
    typeactions = dict((m, [])
                       for m in 'a f g am cd dc r dm dg m e k p pr'.split())
    for f, (m, args, msg) in actions.iteritems():
        if m not in typeactions:
            typeactions[m] = []
        typeactions[m].append((f, args, msg))

    mergemod.applyupdates(repo, typeactions, repo[None], repo['.'], False)

    # Fix dirstate
    for file in added:
        dirstate.normal(file)

    for file in dropped:
        dirstate.drop(file)

    for file in lookup:
        # File exists on disk, and we're bringing it back in an unknown state.
        dirstate.normallookup(file)

    return added, dropped, lookup

def aftercommit(repo, node):
    """Perform actions after a working directory commit."""
    # This function is called unconditionally, even if sparse isn't
    # enabled.
    ctx = repo[node]

    profiles = patternsforrev(repo, ctx.rev())[2]

    # profiles will only have data if sparse is enabled.
    if profiles & set(ctx.files()):
        origstatus = repo.status()
        origsparsematch = matcher(repo)
        refreshwdir(repo, origstatus, origsparsematch, force=True)

    prunetemporaryincludes(repo)

def _updateconfigandrefreshwdir(repo, includes, excludes, profiles,
                                force=False, removing=False):
    """Update the sparse config and working directory state."""
    raw = repo.vfs.tryread('sparse')
    oldincludes, oldexcludes, oldprofiles = parseconfig(repo.ui, raw)

    oldstatus = repo.status()
    oldmatch = matcher(repo)
    oldrequires = set(repo.requirements)

    # TODO remove this try..except once the matcher integrates better
    # with dirstate. We currently have to write the updated config
    # because that will invalidate the matcher cache and force a
    # re-read. We ideally want to update the cached matcher on the
    # repo instance then flush the new config to disk once wdir is
    # updated. But this requires massive rework to matcher() and its
    # consumers.

    if 'exp-sparse' in oldrequires and removing:
        repo.requirements.discard('exp-sparse')
        scmutil.writerequires(repo.vfs, repo.requirements)
    elif 'exp-sparse' not in oldrequires:
        repo.requirements.add('exp-sparse')
        scmutil.writerequires(repo.vfs, repo.requirements)

    try:
        writeconfig(repo, includes, excludes, profiles)
        return refreshwdir(repo, oldstatus, oldmatch, force=force)
    except Exception:
        if repo.requirements != oldrequires:
            repo.requirements.clear()
            repo.requirements |= oldrequires
            scmutil.writerequires(repo.vfs, repo.requirements)
        writeconfig(repo, oldincludes, oldexcludes, oldprofiles)
        raise

def clearrules(repo, force=False):
    """Clears include/exclude rules from the sparse config.

    The remaining sparse config only has profiles, if defined. The working
    directory is refreshed, as needed.
    """
    with repo.wlock():
        raw = repo.vfs.tryread('sparse')
        includes, excludes, profiles = parseconfig(repo.ui, raw)

        if not includes and not excludes:
            return

        _updateconfigandrefreshwdir(repo, set(), set(), profiles, force=force)

def importfromfiles(repo, opts, paths, force=False):
    """Import sparse config rules from files.

    The updated sparse config is written out and the working directory
    is refreshed, as needed.
    """
    with repo.wlock():
        # read current configuration
        raw = repo.vfs.tryread('sparse')
        includes, excludes, profiles = parseconfig(repo.ui, raw)
        aincludes, aexcludes, aprofiles = activeconfig(repo)

        # Import rules on top; only take in rules that are not yet
        # part of the active rules.
        changed = False
        for p in paths:
            with util.posixfile(util.expandpath(p)) as fh:
                raw = fh.read()

            iincludes, iexcludes, iprofiles = parseconfig(repo.ui, raw)
            oldsize = len(includes) + len(excludes) + len(profiles)
            includes.update(iincludes - aincludes)
            excludes.update(iexcludes - aexcludes)
            profiles.update(iprofiles - aprofiles)
            if len(includes) + len(excludes) + len(profiles) > oldsize:
                changed = True

        profilecount = includecount = excludecount = 0
        fcounts = (0, 0, 0)

        if changed:
            profilecount = len(profiles - aprofiles)
            includecount = len(includes - aincludes)
            excludecount = len(excludes - aexcludes)

            fcounts = map(len, _updateconfigandrefreshwdir(
                repo, includes, excludes, profiles, force=force))

        printchanges(repo.ui, opts, profilecount, includecount, excludecount,
                     *fcounts)

def updateconfig(repo, pats, opts, include=False, exclude=False, reset=False,
                 delete=False, enableprofile=False, disableprofile=False,
                 force=False, usereporootpaths=False):
    """Perform a sparse config update.

    Only one of the actions may be performed.

    The new config is written out and a working directory refresh is performed.
    """
    with repo.wlock():
        raw = repo.vfs.tryread('sparse')
        oldinclude, oldexclude, oldprofiles = parseconfig(repo.ui, raw)

        if reset:
            newinclude = set()
            newexclude = set()
            newprofiles = set()
        else:
            newinclude = set(oldinclude)
            newexclude = set(oldexclude)
            newprofiles = set(oldprofiles)

        if any(os.path.isabs(pat) for pat in pats):
            raise error.Abort(_('paths cannot be absolute'))

        if not usereporootpaths:
            # let's treat paths as relative to cwd
            root, cwd = repo.root, repo.getcwd()
            abspats = []
            for kindpat in pats:
                kind, pat = matchmod._patsplit(kindpat, None)
                if kind in matchmod.cwdrelativepatternkinds or kind is None:
                    ap = (kind + ':' if kind else '') +\
                            pathutil.canonpath(root, cwd, pat)
                    abspats.append(ap)
                else:
                    abspats.append(kindpat)
            pats = abspats

        if include:
            newinclude.update(pats)
        elif exclude:
            newexclude.update(pats)
        elif enableprofile:
            newprofiles.update(pats)
        elif disableprofile:
            newprofiles.difference_update(pats)
        elif delete:
            newinclude.difference_update(pats)
            newexclude.difference_update(pats)

        profilecount = (len(newprofiles - oldprofiles) -
                        len(oldprofiles - newprofiles))
        includecount = (len(newinclude - oldinclude) -
                        len(oldinclude - newinclude))
        excludecount = (len(newexclude - oldexclude) -
                        len(oldexclude - newexclude))

        fcounts = map(len, _updateconfigandrefreshwdir(
            repo, newinclude, newexclude, newprofiles, force=force,
            removing=reset))

        printchanges(repo.ui, opts, profilecount, includecount,
                     excludecount, *fcounts)

def printchanges(ui, opts, profilecount=0, includecount=0, excludecount=0,
                 added=0, dropped=0, conflicting=0):
    """Print output summarizing sparse config changes."""
    with ui.formatter('sparse', opts) as fm:
        fm.startitem()
        fm.condwrite(ui.verbose, 'profiles_added', _('Profiles changed: %d\n'),
                     profilecount)
        fm.condwrite(ui.verbose, 'include_rules_added',
                     _('Include rules changed: %d\n'), includecount)
        fm.condwrite(ui.verbose, 'exclude_rules_added',
                     _('Exclude rules changed: %d\n'), excludecount)

        # In 'plain' verbose mode, mergemod.applyupdates already outputs what
        # files are added or removed outside of the templating formatter
        # framework. No point in repeating ourselves in that case.
        if not fm.isplain():
            fm.condwrite(ui.verbose, 'files_added', _('Files added: %d\n'),
                         added)
            fm.condwrite(ui.verbose, 'files_dropped', _('Files dropped: %d\n'),
                         dropped)
            fm.condwrite(ui.verbose, 'files_conflicting',
                         _('Files conflicting: %d\n'), conflicting)