view mercurial/sparse.py @ 47965:f9e6f2bb721d

rhg: Don’t compare ambiguous files one byte at a time

Even though the use of `BufReader` reduces the number of syscalls to read
the file from disk, `.bytes()` yields a separate `Result` for every byte.
Creating those results and dispatching on them is most likely costly.

Instead, this commit opts for simplicity by reading the entire file into memory
and comparing a single pair of byte strings. Note that memory already needs to
contain the entire previous contents of the file, as read from the filelog.
So with an extremely large file this doubles memory use but does not make it
grow by orders of magnitude.

At first I wrote code that still avoids reading the entire file into memory
and compares one buffer at a time with `BufReader`. Find this code below for
posterity. However its correctness is subtle. I ended up preferring the
simplicity of the obviously-correct single comparison.

```rust
let mut reader = BufReader::new(fobj);
let mut expected = &contents_in_p1[..];
loop {
    let buf = reader.fill_buf().when_reading_file(&fs_path)?;
    if buf.is_empty() {
        // Found EOF
        return Ok(expected.is_empty());
    } else if let Some(rest) = expected.drop_prefix(buf) {
        // What we read so far matches the expected content, continue reading
        let buf_len = buf.len();
        reader.consume(buf_len);
        expected = rest
    } else {
        // Found different content
        return Ok(false);
    }
}
```

Differential Revision: https://phab.mercurial-scm.org/D11412

# 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 os

from .i18n import _
from .node import hex
from . import (
    error,
    match as matchmod,
    merge as mergemod,
    mergestate as mergestatemod,
    pathutil,
    pycompat,
    requirements,
    scmutil,
    util,
)
from .utils import hashutil


# 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, action):
    """Parse sparse config file content.

    action is the command which is trigerring this read, can be narrow, sparse

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

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

            if line.strip().startswith(b'/'):
                ui.warn(
                    _(
                        b'warning: %(action)s profile cannot use'
                        b' paths starting with /, ignoring %(line)s\n'
                    )
                    % {b'action': action, b'line': 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(b'sparse')
    if not raw:
        return set(), set(), set()

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

    includes, excludes, profiles = parseconfig(repo.ui, raw, b'sparse')
    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 = (
                    b"warning: sparse profile '%s' not found "
                    b"in rev %s - ignoring it\n" % (profile, ctx)
                )
                # experimental config: sparse.missingwarning
                if repo.ui.configbool(b'sparse', b'missingwarning'):
                    repo.ui.warn(msg)
                else:
                    repo.ui.debug(msg)
                continue

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

        profiles = visited

    if includes:
        includes.add(b'.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 != repo.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(b'signature')

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

    if signature is None or (includetemp and tempsignature is None):
        signature = hex(hashutil.sha1(repo.vfs.tryread(b'sparse')).digest())
        cache[b'signature'] = signature

        if includetemp:
            raw = repo.vfs.tryread(b'tempsparse')
            tempsignature = hex(hashutil.sha1(raw).digest())
            cache[b'tempsignature'] = tempsignature

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


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

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

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

    repo._sparsesignaturecache.clear()


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

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


def writetemporaryincludes(repo, includes):
    repo.vfs.write(b'tempsparse', b'\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(b'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
    mresult = mergemod.mergeresult()
    dropped = []
    tempincludes = readtemporaryincludes(repo)
    for file in tempincludes:
        if file in dirstate and not sparsematch(file):
            message = _(b'dropping temporarily included sparse files')
            mresult.addfile(file, mergestatemod.ACTION_REMOVE, None, message)
            dropped.append(file)

    mergemod.applyupdates(
        repo, mresult, repo[None], repo[b'.'], False, wantfiledata=False
    )

    # Fix dirstate
    for file in dropped:
        dirstate.update_file(file, p1_tracked=False, wc_tracked=False)

    repo.vfs.unlink(b'tempsparse')
    repo._sparsesignaturecache.clear()
    msg = _(
        b'cleaned up %d temporarily added file(s) from the '
        b'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 = [(b'path', include, b'') for include in includes]
    includematcher = matchmod.includematcher(b'', 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()

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

    signature = configsignature(repo, includetemp=includetemp)

    key = b'%s %s' % (signature, b' '.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:
                matcher = matchmod.match(
                    repo.root,
                    b'',
                    [],
                    include=includes,
                    exclude=excludes,
                    default=b'relpath',
                )
                matchers.append(matcher)
        except IOError:
            pass

    if not matchers:
        result = matchmod.always()
    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, mresult):
    """Filter updates to only lay out files that match the sparse rules."""
    if not enabled:
        return

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

    if oldsparsematch.always():
        return

    files = set()
    prunedactions = {}

    if branchmerge:
        # If we're merging, use the wctx filter, since we're merging into
        # the wctx.
        sparsematch = matcher(repo, [wctx.p1().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 mresult.filemap():
        type, args, msg = action
        files.add(file)
        if sparsematch(file):
            prunedactions[file] = action
        elif type == mergestatemod.ACTION_MERGE:
            temporaryfiles.append(file)
            prunedactions[file] = action
        elif branchmerge:
            if type not in mergestatemod.NO_OP_ACTIONS:
                temporaryfiles.append(file)
                prunedactions[file] = action
        elif type == mergestatemod.ACTION_FORGET:
            prunedactions[file] = action
        elif file in wctx:
            prunedactions[file] = (mergestatemod.ACTION_REMOVE, args, msg)

        # in case or rename on one side, it is possible that f1 might not
        # be present in sparse checkout we should include it
        # TODO: should we do the same for f2?
        # exists as a separate check because file can be in sparse and hence
        # if we try to club this condition in above `elif type == ACTION_MERGE`
        # it won't be triggered
        if branchmerge and type == mergestatemod.ACTION_MERGE:
            f1, f2, fa, move, anc = args
            if not sparsematch(f1):
                temporaryfiles.append(f1)

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

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

        with repo.dirstate.parentchange():
            mergemod.applyupdates(
                repo,
                tmresult,
                repo[None],
                repo[b'.'],
                False,
                wantfiledata=False,
            )

            dirstate = repo.dirstate
            for file, flags, msg in tmresult.getactions(
                [mergestatemod.ACTION_GET]
            ):
                dirstate.update_file(file, p1_tracked=True, wc_tracked=True)

    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] = (
                    mergestatemod.ACTION_GET,
                    (flags, False),
                    b'',
                )
            elif old and not new:
                prunedactions[file] = (mergestatemod.ACTION_REMOVE, [], b'')

    mresult.setactions(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(_(b"pending changes to '%s'\n") % f)
            abort = not force

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

    # Calculate merge result
    dirstate = repo.dirstate
    ctx = repo[b'.']
    added = []
    lookup = []
    dropped = []
    mf = ctx.manifest()
    files = set(mf)
    mresult = mergemod.mergeresult()

    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):
                mresult.addfile(file, mergestatemod.ACTION_EXEC, (fl,), b'')
                lookup.append(file)
            else:
                mresult.addfile(
                    file, mergestatemod.ACTION_GET, (fl, False), b''
                )
                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:
                mresult.addfile(file, mergestatemod.ACTION_REMOVE, [], b'')

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

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

    mergemod.applyupdates(
        repo, mresult, repo[None], repo[b'.'], False, wantfiledata=False
    )

    # Fix dirstate
    for file in added:
        dirstate.update_file(file, p1_tracked=True, wc_tracked=True)

    for file in dropped:
        dirstate.update_file(file, p1_tracked=False, wc_tracked=False)

    for file in lookup:
        # File exists on disk, and we're bringing it back in an unknown state.
        dirstate.update_file(
            file, p1_tracked=True, wc_tracked=True, possibly_dirty=True
        )

    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(b'sparse')
    oldincludes, oldexcludes, oldprofiles = parseconfig(repo.ui, raw, b'sparse')

    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 requirements.SPARSE_REQUIREMENT in oldrequires and removing:
        repo.requirements.discard(requirements.SPARSE_REQUIREMENT)
        scmutil.writereporequirements(repo)
    elif requirements.SPARSE_REQUIREMENT not in oldrequires:
        repo.requirements.add(requirements.SPARSE_REQUIREMENT)
        scmutil.writereporequirements(repo)

    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.writereporequirements(repo)
        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(), repo.dirstate.parentchange():
        raw = repo.vfs.tryread(b'sparse')
        includes, excludes, profiles = parseconfig(repo.ui, raw, b'sparse')

        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(), repo.dirstate.parentchange():
        # read current configuration
        raw = repo.vfs.tryread(b'sparse')
        includes, excludes, profiles = parseconfig(repo.ui, raw, b'sparse')
        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), mode=b'rb') as fh:
                raw = fh.read()

            iincludes, iexcludes, iprofiles = parseconfig(
                repo.ui, raw, b'sparse'
            )
            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(), repo.dirstate.parentchange():
        raw = repo.vfs.tryread(b'sparse')
        oldinclude, oldexclude, oldprofiles = parseconfig(
            repo.ui, raw, b'sparse'
        )

        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(_(b'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 + b':' if kind else b'') + 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(b'sparse', opts) as fm:
        fm.startitem()
        fm.condwrite(
            ui.verbose,
            b'profiles_added',
            _(b'Profiles changed: %d\n'),
            profilecount,
        )
        fm.condwrite(
            ui.verbose,
            b'include_rules_added',
            _(b'Include rules changed: %d\n'),
            includecount,
        )
        fm.condwrite(
            ui.verbose,
            b'exclude_rules_added',
            _(b'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, b'files_added', _(b'Files added: %d\n'), added
            )
            fm.condwrite(
                ui.verbose, b'files_dropped', _(b'Files dropped: %d\n'), dropped
            )
            fm.condwrite(
                ui.verbose,
                b'files_conflicting',
                _(b'Files conflicting: %d\n'),
                conflicting,
            )