Mercurial > hg
view mercurial/transaction.py @ 13750:7eb82f88e157
# User Dan Villiom Podlaski Christiansen <danchr@gmail.com>
# Date 1289564504 -3600
# Node ID b75264c15cc888cf38c3c7b8f619801e3c2589c7
# Parent 89b2e5d940f669e590096c6be70eee61c9172fff
revsets: overload the branch() revset to also take a branch name.
This should only change semantics in the specific case of a tag/branch
conflict where the tag wasn't done on the branch with the same
name. Previously, branch(whatever) would resolve to the branch of the
tag in that case, whereas now it will resolve to the branch of the
name. The previous behaviour, while documented, seemed very
counter-intuitive to me.
An alternate approach would be to introduce a new revset such as
branchname() or namedbranch(). While this would retain backwards
compatibility, the distinction between it and branch() would not be
readily apparent to users. The most intuitive behaviour would be to
have branch(x) require 'x' to be a branch name, and something like
branchof(x) or samebranch(x) do what branch(x) currently
does. Unfortunately, our backwards compatibility guarantees prevent us
from doing that.
Please note that while 'hg tag' guards against shadowing a branch, 'hg
branch' does not. Besides, even if it did, that wouldn't solve the
issue of conversions with such tags and branches...
author | Matt Mackall <mpm@selenic.com> |
---|---|
date | Wed, 23 Mar 2011 19:28:16 -0500 |
parents | 19ad316e5be3 |
children | f366d4c2ff34 |
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# transaction.py - simple journalling scheme for mercurial # # This transaction scheme is intended to gracefully handle program # errors and interruptions. More serious failures like system crashes # can be recovered with an fsck-like tool. As the whole repository is # effectively log-structured, this should amount to simply truncating # anything that isn't referenced in the changelog. # # Copyright 2005, 2006 Matt Mackall <mpm@selenic.com> # # This software may be used and distributed according to the terms of the # GNU General Public License version 2 or any later version. from i18n import _ import os, errno import error, util def active(func): def _active(self, *args, **kwds): if self.count == 0: raise error.Abort(_( 'cannot use transaction when it is already committed/aborted')) return func(self, *args, **kwds) return _active def _playback(journal, report, opener, entries, unlink=True): for f, o, ignore in entries: if o or not unlink: try: fp = opener(f, 'a') fp.truncate(o) fp.close() except IOError: report(_("failed to truncate %s\n") % f) raise else: try: fp = opener(f) fn = fp.name fp.close() util.unlink(fn) except (IOError, OSError), inst: if inst.errno != errno.ENOENT: raise util.unlink(journal) class transaction(object): def __init__(self, report, opener, journal, after=None, createmode=None): self.count = 1 self.usages = 1 self.report = report self.opener = opener self.after = after self.entries = [] self.map = {} self.journal = journal self._queue = [] self.file = util.posixfile(self.journal, "w") if createmode is not None: os.chmod(self.journal, createmode & 0666) def __del__(self): if self.journal: self._abort() @active def startgroup(self): self._queue.append([]) @active def endgroup(self): q = self._queue.pop() d = ''.join(['%s\0%d\n' % (x[0], x[1]) for x in q]) self.entries.extend(q) self.file.write(d) self.file.flush() @active def add(self, file, offset, data=None): if file in self.map: return if self._queue: self._queue[-1].append((file, offset, data)) return self.entries.append((file, offset, data)) self.map[file] = len(self.entries) - 1 # add enough data to the journal to do the truncate self.file.write("%s\0%d\n" % (file, offset)) self.file.flush() @active def find(self, file): if file in self.map: return self.entries[self.map[file]] return None @active def replace(self, file, offset, data=None): ''' replace can only replace already committed entries that are not pending in the queue ''' if file not in self.map: raise KeyError(file) index = self.map[file] self.entries[index] = (file, offset, data) self.file.write("%s\0%d\n" % (file, offset)) self.file.flush() @active def nest(self): self.count += 1 self.usages += 1 return self def release(self): if self.count > 0: self.usages -= 1 # if the transaction scopes are left without being closed, fail if self.count > 0 and self.usages == 0: self._abort() def running(self): return self.count > 0 @active def close(self): '''commit the transaction''' self.count -= 1 if self.count != 0: return self.file.close() self.entries = [] if self.after: self.after() if os.path.isfile(self.journal): util.unlink(self.journal) self.journal = None @active def abort(self): '''abort the transaction (generally called on error, or when the transaction is not explicitly committed before going out of scope)''' self._abort() def _abort(self): self.count = 0 self.usages = 0 self.file.close() try: if not self.entries: if self.journal: util.unlink(self.journal) return self.report(_("transaction abort!\n")) try: _playback(self.journal, self.report, self.opener, self.entries, False) self.report(_("rollback completed\n")) except: self.report(_("rollback failed - please run hg recover\n")) finally: self.journal = None def rollback(opener, file, report): entries = [] fp = util.posixfile(file) lines = fp.readlines() fp.close() for l in lines: f, o = l.split('\0') entries.append((f, int(o), None)) _playback(file, report, opener, entries)