Mercurial > hg
view mercurial/transaction.py @ 13180:a79e0688a5ee
subrepo: fix git archive parsing of directories and symfiles
author | Eric Eisner <ede@mit.edu> |
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date | Mon, 20 Dec 2010 13:59:33 -0500 |
parents | aade8f133d11 |
children | 14f3795a5ed7 |
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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 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: opener(f, 'a').truncate(o) except IOError: report(_("failed to truncate %s\n") % f) raise else: try: fn = opener(f).name os.unlink(fn) except (IOError, OSError), inst: if inst.errno != errno.ENOENT: raise os.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 = open(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): os.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: os.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 = [] for l in open(file).readlines(): f, o = l.split('\0') entries.append((f, int(o), None)) _playback(file, report, opener, entries)