view mercurial/narrowspec.py @ 48687:f8f2ecdde4b5

branchmap: skip obsolete revisions while computing heads

It's time to make this part of core Mercurial obsolescence-aware.

Not considering obsolete revisions when computing heads is clearly what
Mercurial should do. But there are a couple of small issues:

- Let's say tip of the repo is obsolete. There are two ways of finding tiprev
  for branchcache (both are in use): looking at input data for update() and
  looking at computed heads after update(). Previously, repo tip would be
  tiprev of the branchcache. With this patch, an obsolete revision can no
  longer be tiprev. And depending on what way we use for finding tiprev (input
  data vs computed heads) we'll get a different result. This is relevant when
  recomputing cache key from cache contents, and may lead to updating cache for
  obsolete revisions multiple times (not from scratch, because it still would
  be considered valid for a subset of revisions in the repo).

- If all commits on a branch are obsolete, the branchcache will include that
  branch, but the list of heads will be empty (that's why there's now `if not
  heads` when recomputing tiprev/tipnode from cache contents). Having an entry
  for every branch is currently required for notify extension (and
  test-notify.t to pass), because notify doesn't handle revsets in its
  subscription config very well and will throw an error if e.g. a branch
  doesn't exist.

- Cloning static HTTP repos may try to stat() a non-existent obsstore file. The
  issue is that we now care about obsolescence during clone, but statichttpvfs
  doesn't implement a stat method, so a regular vfs.stat() is used, and it
  assumes that file is local and calls os.stat().  During a clone, we're trying
  to stat() .hg/store/obsstore, but in static HTTP case we provide a literal
  URL to the obsstore file on the remote as if it were a local file path. On
  windows it actually results in a failure in test-static-http.t.

The first issue is going to be addressed in a series dedicated to making sure
branchcache is properly and timely written on disk (it wasn't perfect even
before this patch, but there aren't enough tests to demonstrate that). The
second issue will be addressed in a future patch for notify extension that will
make it not raise an exception if a branch doesn't exist. And the third one was
partially addressed in the previous patch in this series and will be properly
fixed in a future patch when this series is accepted.

filteredhash() grows a keyword argument to make sure that branchcache is also
invalidated when there are new obsolete revisions in its repo view. This way
the on-disk cache format is unchanged and compatible between versions (although
it will obviously be recomputed when switching versions before/after this patch
and the repo has obsolete revisions).

There's one test that uses plain `hg up` without arguments while updated to a
pruned commit. To make this test pass, simply return current working directory
parent. Later in this series this code will be replaced by what prune command
does: updating to the closest non-obsolete ancestor.

Test changes:

test-branch-change.t: update branch head and cache update message. The head of
default listed in hg heads is changed because revision 2 was rewritten as 7,
and 1 is the closest ancestor on the same branch, so it's the head of default
now.

The cache invalidation message appears now because of the cache hash change,
since we're now accounting for obsolete revisions. Here's some context:

"served.hidden" repo filter means everything is visible (no filtered
revisions), so before this series branch2-served.hidden file would not contain
any cache hash, only revnum and node. Now it also has a hash when there are
obsolete changesets in the repo. The command that the message appears for is
changing branch of 5 and 6, which are now obsolete, so the cache hash changes.

In general, when cache is simply out-of-date, it can be updated using the old
version as a base. But if cache hash differs, then the cache for that
particular repo filter is recomputed (at least with the current
implementation). This is what happens here.

test-obsmarker-template.t: the pull reports 2 heads changed, but after that the
repo correctly sees only 1. The new message could be better, but it's still an
improvement over the previous one where hg pull suggested merging with an
obsolete revision.

test-obsolete.t: we can see these revisions in hg log --hidden, but they
shouldn't be considered heads even with --hidden.

test-rebase-obsolete{,2}.t: there were new heads created previously after
making new orphan changesets, but they weren't detected. Now we are properly
detecting and reporting them.

test-rebase-obsolete4.t: there's only one head now because the other head is
pruned and was falsely reported before.

test-static-http.t: add obsstore to the list of requested files. This file
doesn't exist on the remotes, but clients want it anyway (they get 404). This
is fine, because there are other nonexistent files that clients request, like
.hg/bookmarks or .hg/cache/tags2-served.

Differential Revision: https://phab.mercurial-scm.org/D12097

# narrowspec.py - methods for working with a narrow view of a repository
#
# Copyright 2017 Google, 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

from .i18n import _
from .pycompat import getattr
from . import (
    error,
    match as matchmod,
    merge,
    mergestate as mergestatemod,
    requirements,
    scmutil,
    sparse,
    util,
)

# The file in .hg/store/ that indicates which paths exit in the store
FILENAME = b'narrowspec'
# The file in .hg/ that indicates which paths exit in the dirstate
DIRSTATE_FILENAME = b'narrowspec.dirstate'

# Pattern prefixes that are allowed in narrow patterns. This list MUST
# only contain patterns that are fast and safe to evaluate. Keep in mind
# that patterns are supplied by clients and executed on remote servers
# as part of wire protocol commands. That means that changes to this
# data structure influence the wire protocol and should not be taken
# lightly - especially removals.
VALID_PREFIXES = (
    b'path:',
    b'rootfilesin:',
)


def normalizesplitpattern(kind, pat):
    """Returns the normalized version of a pattern and kind.

    Returns a tuple with the normalized kind and normalized pattern.
    """
    pat = pat.rstrip(b'/')
    _validatepattern(pat)
    return kind, pat


def _numlines(s):
    """Returns the number of lines in s, including ending empty lines."""
    # We use splitlines because it is Unicode-friendly and thus Python 3
    # compatible. However, it does not count empty lines at the end, so trick
    # it by adding a character at the end.
    return len((s + b'x').splitlines())


def _validatepattern(pat):
    """Validates the pattern and aborts if it is invalid.

    Patterns are stored in the narrowspec as newline-separated
    POSIX-style bytestring paths. There's no escaping.
    """

    # We use newlines as separators in the narrowspec file, so don't allow them
    # in patterns.
    if _numlines(pat) > 1:
        raise error.Abort(_(b'newlines are not allowed in narrowspec paths'))

    components = pat.split(b'/')
    if b'.' in components or b'..' in components:
        raise error.Abort(
            _(b'"." and ".." are not allowed in narrowspec paths')
        )


def normalizepattern(pattern, defaultkind=b'path'):
    """Returns the normalized version of a text-format pattern.

    If the pattern has no kind, the default will be added.
    """
    kind, pat = matchmod._patsplit(pattern, defaultkind)
    return b'%s:%s' % normalizesplitpattern(kind, pat)


def parsepatterns(pats):
    """Parses an iterable of patterns into a typed pattern set.

    Patterns are assumed to be ``path:`` if no prefix is present.
    For safety and performance reasons, only some prefixes are allowed.
    See ``validatepatterns()``.

    This function should be used on patterns that come from the user to
    normalize and validate them to the internal data structure used for
    representing patterns.
    """
    res = {normalizepattern(orig) for orig in pats}
    validatepatterns(res)
    return res


def validatepatterns(pats):
    """Validate that patterns are in the expected data structure and format.

    And that is a set of normalized patterns beginning with ``path:`` or
    ``rootfilesin:``.

    This function should be used to validate internal data structures
    and patterns that are loaded from sources that use the internal,
    prefixed pattern representation (but can't necessarily be fully trusted).
    """
    if not isinstance(pats, set):
        raise error.ProgrammingError(
            b'narrow patterns should be a set; got %r' % pats
        )

    for pat in pats:
        if not pat.startswith(VALID_PREFIXES):
            # Use a Mercurial exception because this can happen due to user
            # bugs (e.g. manually updating spec file).
            raise error.Abort(
                _(b'invalid prefix on narrow pattern: %s') % pat,
                hint=_(
                    b'narrow patterns must begin with one of '
                    b'the following: %s'
                )
                % b', '.join(VALID_PREFIXES),
            )


def format(includes, excludes):
    output = b'[include]\n'
    for i in sorted(includes - excludes):
        output += i + b'\n'
    output += b'[exclude]\n'
    for e in sorted(excludes):
        output += e + b'\n'
    return output


def match(root, include=None, exclude=None):
    if not include:
        # Passing empty include and empty exclude to matchmod.match()
        # gives a matcher that matches everything, so explicitly use
        # the nevermatcher.
        return matchmod.never()
    return matchmod.match(
        root, b'', [], include=include or [], exclude=exclude or []
    )


def parseconfig(ui, spec):
    # maybe we should care about the profiles returned too
    includepats, excludepats, profiles = sparse.parseconfig(ui, spec, b'narrow')
    if profiles:
        raise error.Abort(
            _(
                b"including other spec files using '%include' is not"
                b" supported in narrowspec"
            )
        )

    validatepatterns(includepats)
    validatepatterns(excludepats)

    return includepats, excludepats


def load(repo):
    # Treat "narrowspec does not exist" the same as "narrowspec file exists
    # and is empty".
    spec = repo.svfs.tryread(FILENAME)
    return parseconfig(repo.ui, spec)


def save(repo, includepats, excludepats):
    validatepatterns(includepats)
    validatepatterns(excludepats)
    spec = format(includepats, excludepats)
    repo.svfs.write(FILENAME, spec)


def copytoworkingcopy(repo):
    spec = repo.svfs.read(FILENAME)
    repo.vfs.write(DIRSTATE_FILENAME, spec)


def savebackup(repo, backupname):
    if requirements.NARROW_REQUIREMENT not in repo.requirements:
        return
    svfs = repo.svfs
    svfs.tryunlink(backupname)
    util.copyfile(svfs.join(FILENAME), svfs.join(backupname), hardlink=True)


def restorebackup(repo, backupname):
    if requirements.NARROW_REQUIREMENT not in repo.requirements:
        return
    util.rename(repo.svfs.join(backupname), repo.svfs.join(FILENAME))


def savewcbackup(repo, backupname):
    if requirements.NARROW_REQUIREMENT not in repo.requirements:
        return
    vfs = repo.vfs
    vfs.tryunlink(backupname)
    # It may not exist in old repos
    if vfs.exists(DIRSTATE_FILENAME):
        util.copyfile(
            vfs.join(DIRSTATE_FILENAME), vfs.join(backupname), hardlink=True
        )


def restorewcbackup(repo, backupname):
    if requirements.NARROW_REQUIREMENT not in repo.requirements:
        return
    # It may not exist in old repos
    if repo.vfs.exists(backupname):
        util.rename(repo.vfs.join(backupname), repo.vfs.join(DIRSTATE_FILENAME))


def clearwcbackup(repo, backupname):
    if requirements.NARROW_REQUIREMENT not in repo.requirements:
        return
    repo.vfs.tryunlink(backupname)


def restrictpatterns(req_includes, req_excludes, repo_includes, repo_excludes):
    r"""Restricts the patterns according to repo settings,
    results in a logical AND operation

    :param req_includes: requested includes
    :param req_excludes: requested excludes
    :param repo_includes: repo includes
    :param repo_excludes: repo excludes
    :return: include patterns, exclude patterns, and invalid include patterns.
    """
    res_excludes = set(req_excludes)
    res_excludes.update(repo_excludes)
    invalid_includes = []
    if not req_includes:
        res_includes = set(repo_includes)
    elif b'path:.' not in repo_includes:
        res_includes = []
        for req_include in req_includes:
            req_include = util.expandpath(util.normpath(req_include))
            if req_include in repo_includes:
                res_includes.append(req_include)
                continue
            valid = False
            for repo_include in repo_includes:
                if req_include.startswith(repo_include + b'/'):
                    valid = True
                    res_includes.append(req_include)
                    break
            if not valid:
                invalid_includes.append(req_include)
        if len(res_includes) == 0:
            res_excludes = {b'path:.'}
        else:
            res_includes = set(res_includes)
    else:
        res_includes = set(req_includes)
    return res_includes, res_excludes, invalid_includes


# These two are extracted for extensions (specifically for Google's CitC file
# system)
def _deletecleanfiles(repo, files):
    for f in files:
        repo.wvfs.unlinkpath(f)


def _writeaddedfiles(repo, pctx, files):
    mresult = merge.mergeresult()
    mf = repo[b'.'].manifest()
    for f in files:
        if not repo.wvfs.exists(f):
            mresult.addfile(
                f,
                mergestatemod.ACTION_GET,
                (mf.flags(f), False),
                b"narrowspec updated",
            )
    merge.applyupdates(
        repo,
        mresult,
        wctx=repo[None],
        mctx=repo[b'.'],
        overwrite=False,
        wantfiledata=False,
    )


def checkworkingcopynarrowspec(repo):
    # Avoid infinite recursion when updating the working copy
    if getattr(repo, '_updatingnarrowspec', False):
        return
    storespec = repo.svfs.tryread(FILENAME)
    wcspec = repo.vfs.tryread(DIRSTATE_FILENAME)
    if wcspec != storespec:
        raise error.StateError(
            _(b"working copy's narrowspec is stale"),
            hint=_(b"run 'hg tracked --update-working-copy'"),
        )


def updateworkingcopy(repo, assumeclean=False):
    """updates the working copy and dirstate from the store narrowspec

    When assumeclean=True, files that are not known to be clean will also
    be deleted. It is then up to the caller to make sure they are clean.
    """
    oldspec = repo.vfs.tryread(DIRSTATE_FILENAME)
    newspec = repo.svfs.tryread(FILENAME)
    repo._updatingnarrowspec = True

    oldincludes, oldexcludes = parseconfig(repo.ui, oldspec)
    newincludes, newexcludes = parseconfig(repo.ui, newspec)
    oldmatch = match(repo.root, include=oldincludes, exclude=oldexcludes)
    newmatch = match(repo.root, include=newincludes, exclude=newexcludes)
    addedmatch = matchmod.differencematcher(newmatch, oldmatch)
    removedmatch = matchmod.differencematcher(oldmatch, newmatch)

    ds = repo.dirstate
    lookup, status, _mtime_boundary = ds.status(
        removedmatch, subrepos=[], ignored=True, clean=True, unknown=True
    )
    trackeddirty = status.modified + status.added
    clean = status.clean
    if assumeclean:
        clean.extend(lookup)
    else:
        trackeddirty.extend(lookup)
    _deletecleanfiles(repo, clean)
    uipathfn = scmutil.getuipathfn(repo)
    for f in sorted(trackeddirty):
        repo.ui.status(
            _(b'not deleting possibly dirty file %s\n') % uipathfn(f)
        )
    for f in sorted(status.unknown):
        repo.ui.status(_(b'not deleting unknown file %s\n') % uipathfn(f))
    for f in sorted(status.ignored):
        repo.ui.status(_(b'not deleting ignored file %s\n') % uipathfn(f))
    for f in clean + trackeddirty:
        ds.update_file(f, p1_tracked=False, wc_tracked=False)

    pctx = repo[b'.']

    # only update added files that are in the sparse checkout
    addedmatch = matchmod.intersectmatchers(addedmatch, sparse.matcher(repo))
    newfiles = [f for f in pctx.manifest().walk(addedmatch) if f not in ds]
    for f in newfiles:
        ds.update_file(f, p1_tracked=True, wc_tracked=True, possibly_dirty=True)
    _writeaddedfiles(repo, pctx, newfiles)
    repo._updatingnarrowspec = False