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# transaction.py - simple journaling scheme for mercurial
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#
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# This transaction scheme is intended to gracefully handle program
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# errors and interruptions. More serious failures like system crashes
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# can be recovered with an fsck-like tool. As the whole repository is
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# effectively log-structured, this should amount to simply truncating
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# anything that isn't referenced in the changelog.
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#
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# Copyright 2005, 2006 Matt Mackall <mpm@selenic.com>
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#
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# This software may be used and distributed according to the terms of the
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# GNU General Public License version 2 or any later version.
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from i18n import _
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import errno
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import error, util
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version = 2
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def active(func):
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def _active(self, *args, **kwds):
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if self.count == 0:
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raise error.Abort(_(
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'cannot use transaction when it is already committed/aborted'))
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return func(self, *args, **kwds)
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return _active
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def _playback(journal, report, opener, vfsmap, entries, backupentries,
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unlink=True):
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for f, o, _ignore in entries:
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if o or not unlink:
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try:
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fp = opener(f, 'a')
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fp.truncate(o)
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fp.close()
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except IOError:
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report(_("failed to truncate %s\n") % f)
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raise
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else:
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try:
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opener.unlink(f)
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except (IOError, OSError), inst:
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if inst.errno != errno.ENOENT:
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raise
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backupfiles = []
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for l, f, b, c in backupentries:
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if l not in vfsmap and c:
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report("couldn't handle %s: unknown cache location %s\n"
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% (b, l))
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vfs = vfsmap[l]
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try:
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if f and b:
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filepath = vfs.join(f)
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backuppath = vfs.join(b)
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try:
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util.copyfile(backuppath, filepath)
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backupfiles.append(b)
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except IOError:
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report(_("failed to recover %s\n") % f)
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else:
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target = f or b
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try:
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vfs.unlink(target)
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except (IOError, OSError), inst:
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if inst.errno != errno.ENOENT:
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raise
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except (IOError, OSError, util.Abort), inst:
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if not c:
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raise
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opener.unlink(journal)
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backuppath = "%s.backupfiles" % journal
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if opener.exists(backuppath):
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opener.unlink(backuppath)
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try:
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for f in backupfiles:
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if opener.exists(f):
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opener.unlink(f)
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except (IOError, OSError, util.Abort), inst:
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# only pure backup file remains, it is sage to ignore any error
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pass
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class transaction(object):
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def __init__(self, report, opener, vfsmap, journal, after=None,
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createmode=None):
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"""Begin a new transaction
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Begins a new transaction that allows rolling back writes in the event of
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an exception.
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* `after`: called after the transaction has been committed
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* `createmode`: the mode of the journal file that will be created
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"""
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self.count = 1
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self.usages = 1
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self.report = report
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# a vfs to the store content
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self.opener = opener
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# a map to access file in various {location -> vfs}
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vfsmap = vfsmap.copy()
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vfsmap[''] = opener # set default value
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self._vfsmap = vfsmap
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self.after = after
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self.entries = []
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self.map = {}
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self.journal = journal
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self._queue = []
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# a dict of arguments to be passed to hooks
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self.hookargs = {}
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self.file = opener.open(self.journal, "w")
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# a list of ('location', 'path', 'backuppath', cache) entries.
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# - if 'backuppath' is empty, no file existed at backup time
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# - if 'path' is empty, this is a temporary transaction file
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# - if 'location' is not empty, the path is outside main opener reach.
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# use 'location' value as a key in a vfsmap to find the right 'vfs'
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# (cache is currently unused)
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self._backupentries = []
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self._backupmap = {}
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self._backupjournal = "%s.backupfiles" % journal
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self._backupsfile = opener.open(self._backupjournal, 'w')
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self._backupsfile.write('%d\n' % version)
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if createmode is not None:
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opener.chmod(self.journal, createmode & 0666)
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opener.chmod(self._backupjournal, createmode & 0666)
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# hold file generations to be performed on commit
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self._filegenerators = {}
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# hold callback to write pending data for hooks
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self._pendingcallback = {}
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# True is any pending data have been written ever
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self._anypending = False
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# holds callback to call when writing the transaction
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self._finalizecallback = {}
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# hold callback for post transaction close
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self._postclosecallback = {}
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# holds callbacks to call during abort
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self._abortcallback = {}
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def __del__(self):
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if self.journal:
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self._abort()
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@active
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def startgroup(self):
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"""delay registration of file entry
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This is used by strip to delay vision of strip offset. The transaction
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sees either none or all of the strip actions to be done."""
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self._queue.append([])
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@active
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def endgroup(self):
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"""apply delayed registration of file entry.
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This is used by strip to delay vision of strip offset. The transaction
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sees either none or all of the strip actions to be done."""
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q = self._queue.pop()
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for f, o, data in q:
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self._addentry(f, o, data)
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@active
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def add(self, file, offset, data=None):
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"""record the state of an append-only file before update"""
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if file in self.map or file in self._backupmap:
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return
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if self._queue:
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self._queue[-1].append((file, offset, data))
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return
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self._addentry(file, offset, data)
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def _addentry(self, file, offset, data):
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"""add a append-only entry to memory and on-disk state"""
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if file in self.map or file in self._backupmap:
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return
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self.entries.append((file, offset, data))
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self.map[file] = len(self.entries) - 1
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# add enough data to the journal to do the truncate
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self.file.write("%s\0%d\n" % (file, offset))
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self.file.flush()
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@active
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def addbackup(self, file, hardlink=True, location=''):
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"""Adds a backup of the file to the transaction
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Calling addbackup() creates a hardlink backup of the specified file
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that is used to recover the file in the event of the transaction
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aborting.
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* `file`: the file path, relative to .hg/store
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* `hardlink`: use a hardlink to quickly create the backup
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"""
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if self._queue:
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msg = 'cannot use transaction.addbackup inside "group"'
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raise RuntimeError(msg)
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if file in self.map or file in self._backupmap:
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return
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vfs = self._vfsmap[location]
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dirname, filename = vfs.split(file)
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backupfilename = "%s.backup.%s" % (self.journal, filename)
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backupfile = vfs.reljoin(dirname, backupfilename)
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if vfs.exists(file):
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filepath = vfs.join(file)
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backuppath = vfs.join(backupfile)
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util.copyfiles(filepath, backuppath, hardlink=hardlink)
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else:
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backupfile = ''
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self._addbackupentry((location, file, backupfile, False))
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def _addbackupentry(self, entry):
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"""register a new backup entry and write it to disk"""
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self._backupentries.append(entry)
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self._backupmap[file] = len(self._backupentries) - 1
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self._backupsfile.write("%s\0%s\0%s\0%d\n" % entry)
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self._backupsfile.flush()
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@active
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def registertmp(self, tmpfile, location=''):
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"""register a temporary transaction file
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Such files will be deleted when the transaction exits (on both
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failure and success).
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"""
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self._addbackupentry((location, '', tmpfile, False))
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@active
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def addfilegenerator(self, genid, filenames, genfunc, order=0,
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location=''):
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"""add a function to generates some files at transaction commit
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The `genfunc` argument is a function capable of generating proper
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content of each entry in the `filename` tuple.
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At transaction close time, `genfunc` will be called with one file
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object argument per entries in `filenames`.
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The transaction itself is responsible for the backup, creation and
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final write of such file.
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The `genid` argument is used to ensure the same set of file is only
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generated once. Call to `addfilegenerator` for a `genid` already
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present will overwrite the old entry.
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The `order` argument may be used to control the order in which multiple
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generator will be executed.
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The `location` arguments may be used to indicate the files are located
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outside of the the standard directory for transaction. It should match
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one of the key of the `transaction.vfsmap` dictionary.
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"""
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# For now, we are unable to do proper backup and restore of custom vfs
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# but for bookmarks that are handled outside this mechanism.
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self._filegenerators[genid] = (order, filenames, genfunc, location)
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def _generatefiles(self, suffix=''):
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# write files registered for generation
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any = False
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for entry in sorted(self._filegenerators.values()):
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any = True
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order, filenames, genfunc, location = entry
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vfs = self._vfsmap[location]
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files = []
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try:
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for name in filenames:
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name += suffix
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if suffix:
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self.registertmp(name, location=location)
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else:
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self.addbackup(name, location=location)
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files.append(vfs(name, 'w', atomictemp=True))
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genfunc(*files)
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finally:
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for f in files:
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f.close()
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return any
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@active
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def find(self, file):
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if file in self.map:
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return self.entries[self.map[file]]
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if file in self._backupmap:
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return self._backupentries[self._backupmap[file]]
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return None
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@active
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def replace(self, file, offset, data=None):
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'''
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replace can only replace already committed entries
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that are not pending in the queue
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'''
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if file not in self.map:
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raise KeyError(file)
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index = self.map[file]
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self.entries[index] = (file, offset, data)
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self.file.write("%s\0%d\n" % (file, offset))
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self.file.flush()
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@active
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def nest(self):
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self.count += 1
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self.usages += 1
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return self
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def release(self):
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if self.count > 0:
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self.usages -= 1
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# if the transaction scopes are left without being closed, fail
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if self.count > 0 and self.usages == 0:
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self._abort()
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def running(self):
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return self.count > 0
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def addpending(self, category, callback):
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"""add a callback to be called when the transaction is pending
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The transaction will be given as callback's first argument.
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Category is a unique identifier to allow overwriting an old callback
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with a newer callback.
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"""
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self._pendingcallback[category] = callback
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@active
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def writepending(self):
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'''write pending file to temporary version
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This is used to allow hooks to view a transaction before commit'''
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categories = sorted(self._pendingcallback)
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for cat in categories:
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# remove callback since the data will have been flushed
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any = self._pendingcallback.pop(cat)(self)
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self._anypending = self._anypending or any
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self._anypending |= self._generatefiles(suffix='.pending')
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return self._anypending
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@active
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def addfinalize(self, category, callback):
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"""add a callback to be called when the transaction is closed
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The transaction will be given as callback's first argument.
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Category is a unique identifier to allow overwriting old callbacks with
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newer callbacks.
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"""
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self._finalizecallback[category] = callback
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@active
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def addpostclose(self, category, callback):
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"""add a callback to be called after the transaction is closed
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The transaction will be given as callback's first argument.
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Category is a unique identifier to allow overwriting an old callback
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with a newer callback.
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"""
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self._postclosecallback[category] = callback
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@active
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def addabort(self, category, callback):
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"""add a callback to be called when the transaction is aborted.
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The transaction will be given as the first argument to the callback.
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Category is a unique identifier to allow overwriting an old callback
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with a newer callback.
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"""
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self._abortcallback[category] = callback
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@active
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def close(self):
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'''commit the transaction'''
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if self.count == 1:
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self._generatefiles()
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categories = sorted(self._finalizecallback)
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for cat in categories:
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self._finalizecallback[cat](self)
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self.count -= 1
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if self.count != 0:
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return
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self.file.close()
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self._backupsfile.close()
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# cleanup temporary files
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for l, f, b, c in self._backupentries:
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if l not in self._vfsmap and c:
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self.report("couldn't remote %s: unknown cache location %s\n"
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% (b, l))
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continue
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vfs = self._vfsmap[l]
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if not f and b and vfs.exists(b):
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try:
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vfs.unlink(b)
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except (IOError, OSError, util.Abort), inst:
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if not c:
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raise
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# Abort may be raise by read only opener
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self.report("couldn't remote %s: %s\n"
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% (vfs.join(b), inst))
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self.entries = []
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if self.after:
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self.after()
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if self.opener.isfile(self.journal):
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self.opener.unlink(self.journal)
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if self.opener.isfile(self._backupjournal):
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self.opener.unlink(self._backupjournal)
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for l, _f, b, c in self._backupentries:
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if l not in self._vfsmap and c:
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self.report("couldn't remote %s: unknown cache location"
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"%s\n" % (b, l))
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continue
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vfs = self._vfsmap[l]
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if b and vfs.exists(b):
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try:
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vfs.unlink(b)
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except (IOError, OSError, util.Abort), inst:
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if not c:
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raise
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# Abort may be raise by read only opener
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self.report("couldn't remote %s: %s\n"
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% (vfs.join(b), inst))
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self._backupentries = []
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self.journal = None
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# run post close action
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categories = sorted(self._postclosecallback)
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for cat in categories:
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self._postclosecallback[cat](self)
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@active
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def abort(self):
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'''abort the transaction (generally called on error, or when the
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transaction is not explicitly committed before going out of
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scope)'''
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self._abort()
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def _abort(self):
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self.count = 0
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self.usages = 0
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self.file.close()
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self._backupsfile.close()
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try:
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if not self.entries and not self._backupentries:
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if self.journal:
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|
self.opener.unlink(self.journal)
|
|
|
if self._backupjournal:
|
|
|
self.opener.unlink(self._backupjournal)
|
|
|
return
|
|
|
|
|
|
self.report(_("transaction abort!\n"))
|
|
|
|
|
|
try:
|
|
|
for cat in sorted(self._abortcallback):
|
|
|
self._abortcallback[cat](self)
|
|
|
_playback(self.journal, self.report, self.opener, self._vfsmap,
|
|
|
self.entries, self._backupentries, False)
|
|
|
self.report(_("rollback completed\n"))
|
|
|
except Exception:
|
|
|
self.report(_("rollback failed - please run hg recover\n"))
|
|
|
finally:
|
|
|
self.journal = None
|
|
|
|
|
|
|
|
|
def rollback(opener, vfsmap, file, report):
|
|
|
"""Rolls back the transaction contained in the given file
|
|
|
|
|
|
Reads the entries in the specified file, and the corresponding
|
|
|
'*.backupfiles' file, to recover from an incomplete transaction.
|
|
|
|
|
|
* `file`: a file containing a list of entries, specifying where
|
|
|
to truncate each file. The file should contain a list of
|
|
|
file\0offset pairs, delimited by newlines. The corresponding
|
|
|
'*.backupfiles' file should contain a list of file\0backupfile
|
|
|
pairs, delimited by \0.
|
|
|
"""
|
|
|
entries = []
|
|
|
backupentries = []
|
|
|
|
|
|
fp = opener.open(file)
|
|
|
lines = fp.readlines()
|
|
|
fp.close()
|
|
|
for l in lines:
|
|
|
try:
|
|
|
f, o = l.split('\0')
|
|
|
entries.append((f, int(o), None))
|
|
|
except ValueError:
|
|
|
report(_("couldn't read journal entry %r!\n") % l)
|
|
|
|
|
|
backupjournal = "%s.backupfiles" % file
|
|
|
if opener.exists(backupjournal):
|
|
|
fp = opener.open(backupjournal)
|
|
|
lines = fp.readlines()
|
|
|
if lines:
|
|
|
ver = lines[0][:-1]
|
|
|
if ver == str(version):
|
|
|
for line in lines[1:]:
|
|
|
if line:
|
|
|
# Shave off the trailing newline
|
|
|
line = line[:-1]
|
|
|
l, f, b, c = line.split('\0')
|
|
|
backupentries.append((l, f, b, bool(c)))
|
|
|
else:
|
|
|
report(_("journal was created by a different version of "
|
|
|
"Mercurial"))
|
|
|
|
|
|
_playback(file, report, opener, vfsmap, entries, backupentries)
|
|
|
|
