mercurial/grep.py

transaction: use the standard transaction mechanism to backup branch

Branch is a bit special :
- It currently does not collaborate with the transaction (or any scoping) for
  writing (this is bad)
- It can change without the lock being taken (it is protected by `wlock`)

So we rely on the same mechanism as for the backup of the other dirstate file:
- we only do a backup if we hold the wlock
- we force a backup though the transaction


Since "branch" write does not collaborate with the transaction, we cannot back
it up "at the last minute" as we do for the dirstate. We have to back it up
"upfront". Since we have a backup, the transaction is no longer doing its
"quick_abort" and get noisy. Which is quite annoying. To work around this, and
to avoid jumping in yet-another-rabbit-hole of "getting branch written
properly", I am doing horrible things to the transaction in the meantime.
We should be able to get this code go away during the next cycle.

In the meantime, I prefer to take this small stop so that we stop abusing the
"journal" and "undo" mechanism instead of the proper backup mechanism of the
transaction.


Also note that this change regress the warning message for the legacy fallback
introduced in 2008 when issue902 got fixed in dd5a501cb97f (Mercurial 1.0).

I feel like this is fine as issue 902 remains fixed, and this would only affect
people deploying a mix of 15 year old Mercurial and modern mercurial, and using
branch and rollback extensively.

# 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.


import difflib

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:
    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 range(blo, bhi):
                yield (b'+', b[i])
        elif tag == 'delete':
            for i in range(alo, ahi):
                yield (b'-', a[i])
        elif tag == 'replace':
            for i in range(alo, ahi):
                yield (b'-', a[i])
            for i in range(blo, bhi):
                yield (b'+', b[i])


class grepsearcher:
    """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 FileNotFoundError:
                pass
        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))