view mercurial/grep.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- Let's say tip of the repo is obsolete.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

# grep.py - logic for history walk and grep
#
# Copyright 2005-2007 Olivia 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 difflib
import errno

from .i18n import _

from . import (
    error,
    match as matchmod,
    pycompat,
    scmutil,
    util,
)


def matchlines(body, regexp):
    begin = 0
    linenum = 0
    while begin < len(body):
        match = regexp.search(body, begin)
        if not match:
            break
        mstart, mend = match.span()
        linenum += body.count(b'\n', begin, mstart) + 1
        lstart = body.rfind(b'\n', begin, mstart) + 1 or begin
        begin = body.find(b'\n', mend) + 1 or len(body) + 1
        lend = begin - 1
        yield linenum, mstart - lstart, mend - lstart, body[lstart:lend]


class linestate(object):
    def __init__(self, line, linenum, colstart, colend):
        self.line = line
        self.linenum = linenum
        self.colstart = colstart
        self.colend = colend

    def __hash__(self):
        return hash(self.line)

    def __eq__(self, other):
        return self.line == other.line

    def findpos(self, regexp):
        """Iterate all (start, end) indices of matches"""
        yield self.colstart, self.colend
        p = self.colend
        while p < len(self.line):
            m = regexp.search(self.line, p)
            if not m:
                break
            if m.end() == p:
                p += 1
            else:
                yield m.span()
                p = m.end()


def difflinestates(a, b):
    sm = difflib.SequenceMatcher(None, a, b)
    for tag, alo, ahi, blo, bhi in sm.get_opcodes():
        if tag == 'insert':
            for i in pycompat.xrange(blo, bhi):
                yield (b'+', b[i])
        elif tag == 'delete':
            for i in pycompat.xrange(alo, ahi):
                yield (b'-', a[i])
        elif tag == 'replace':
            for i in pycompat.xrange(alo, ahi):
                yield (b'-', a[i])
            for i in pycompat.xrange(blo, bhi):
                yield (b'+', b[i])


class grepsearcher(object):
    """Search files and revisions for lines matching the given pattern

    Options:
    - all_files to search unchanged files at that revision.
    - diff to search files in the parent revision so diffs can be generated.
    - follow to skip files across copies and renames.
    """

    def __init__(
        self, ui, repo, regexp, all_files=False, diff=False, follow=False
    ):
        self._ui = ui
        self._repo = repo
        self._regexp = regexp
        self._all_files = all_files
        self._diff = diff
        self._follow = follow

        self._getfile = util.lrucachefunc(repo.file)
        self._getrenamed = scmutil.getrenamedfn(repo)

        self._matches = {}
        self._copies = {}
        self._skip = set()
        self._revfiles = {}

    def skipfile(self, fn, rev):
        """Exclude the given file (and the copy at the specified revision)
        from future search"""
        copy = self._copies.get(rev, {}).get(fn)
        self._skip.add(fn)
        if copy:
            self._skip.add(copy)

    def searchfiles(self, revs, makefilematcher):
        """Walk files and revisions to yield (fn, ctx, pstates, states)
        matches

        states is a list of linestate objects. pstates may be empty unless
        diff is True.
        """
        for ctx in scmutil.walkchangerevs(
            self._repo, revs, makefilematcher, self._prep
        ):
            rev = ctx.rev()
            parent = ctx.p1().rev()
            for fn in sorted(self._revfiles.get(rev, [])):
                states = self._matches[rev][fn]
                copy = self._copies.get(rev, {}).get(fn)
                if fn in self._skip:
                    if copy:
                        self._skip.add(copy)
                    continue
                pstates = self._matches.get(parent, {}).get(copy or fn, [])
                if pstates or states:
                    yield fn, ctx, pstates, states
            del self._revfiles[rev]
            # We will keep the matches dict for the duration of the window
            # clear the matches dict once the window is over
            if not self._revfiles:
                self._matches.clear()

    def _grepbody(self, fn, rev, body):
        self._matches[rev].setdefault(fn, [])
        m = self._matches[rev][fn]
        if body is None:
            return

        for lnum, cstart, cend, line in matchlines(body, self._regexp):
            s = linestate(line, lnum, cstart, cend)
            m.append(s)

    def _readfile(self, ctx, fn):
        rev = ctx.rev()
        if rev is None:
            fctx = ctx[fn]
            try:
                return fctx.data()
            except IOError as e:
                if e.errno != errno.ENOENT:
                    raise
        else:
            flog = self._getfile(fn)
            fnode = ctx.filenode(fn)
            try:
                return flog.read(fnode)
            except error.CensoredNodeError:
                self._ui.warn(
                    _(
                        b'cannot search in censored file: '
                        b'%(filename)s:%(revnum)s\n'
                    )
                    % {b'filename': fn, b'revnum': pycompat.bytestr(rev)}
                )

    def _prep(self, ctx, fmatch):
        rev = ctx.rev()
        pctx = ctx.p1()
        self._matches.setdefault(rev, {})
        if self._diff:
            parent = pctx.rev()
            self._matches.setdefault(parent, {})
        files = self._revfiles.setdefault(rev, [])
        if rev is None:
            # in `hg grep pattern`, 2/3 of the time is spent is spent in
            # pathauditor checks without this in mozilla-central
            contextmanager = self._repo.wvfs.audit.cached
        else:
            contextmanager = util.nullcontextmanager
        with contextmanager():
            # TODO: maybe better to warn missing files?
            if self._all_files:
                fmatch = matchmod.badmatch(fmatch, lambda f, msg: None)
                filenames = ctx.matches(fmatch)
            else:
                filenames = (f for f in ctx.files() if fmatch(f))
            for fn in filenames:
                # fn might not exist in the revision (could be a file removed by
                # the revision). We could check `fn not in ctx` even when rev is
                # None, but it's less racy to protect againt that in readfile.
                if rev is not None and fn not in ctx:
                    continue

                copy = None
                if self._follow:
                    copy = self._getrenamed(fn, rev)
                    if copy:
                        self._copies.setdefault(rev, {})[fn] = copy
                        if fn in self._skip:
                            self._skip.add(copy)
                if fn in self._skip:
                    continue
                files.append(fn)

                if fn not in self._matches[rev]:
                    self._grepbody(fn, rev, self._readfile(ctx, fn))

                if self._diff:
                    pfn = copy or fn
                    if pfn not in self._matches[parent] and pfn in pctx:
                        self._grepbody(pfn, parent, self._readfile(pctx, pfn))