Mercurial > hg
view mercurial/transaction.py @ 24217:d2b81256db1e
error: add a new UnknownIdentifier error type
This will be used by the revset and fileset code to communicate more
specific errors to higher levels so that we might be able to offer
suggestions about what function might have been similar.
author | Augie Fackler <augie@google.com> |
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date | Mon, 26 Jan 2015 14:31:01 -0500 |
parents | d251da5e0e84 |
children | ef22cfff7052 |
line wrap: on
line source
# transaction.py - simple journaling 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 errno import error, util version = 2 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, vfsmap, entries, backupentries, 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: opener.unlink(f) except (IOError, OSError), inst: if inst.errno != errno.ENOENT: raise backupfiles = [] for l, f, b, c in backupentries: if l not in vfsmap and c: report("couldn't handle %s: unknown cache location %s\n" % (b, l)) vfs = vfsmap[l] try: if f and b: filepath = vfs.join(f) backuppath = vfs.join(b) try: util.copyfile(backuppath, filepath) backupfiles.append(b) except IOError: report(_("failed to recover %s\n") % f) else: target = f or b try: vfs.unlink(target) except (IOError, OSError), inst: if inst.errno != errno.ENOENT: raise except (IOError, OSError, util.Abort), inst: if not c: raise opener.unlink(journal) backuppath = "%s.backupfiles" % journal if opener.exists(backuppath): opener.unlink(backuppath) try: for f in backupfiles: if opener.exists(f): opener.unlink(f) except (IOError, OSError, util.Abort), inst: # only pure backup file remains, it is sage to ignore any error pass class transaction(object): def __init__(self, report, opener, vfsmap, journalname, undoname=None, after=None, createmode=None): """Begin a new transaction Begins a new transaction that allows rolling back writes in the event of an exception. * `after`: called after the transaction has been committed * `createmode`: the mode of the journal file that will be created """ self.count = 1 self.usages = 1 self.report = report # a vfs to the store content self.opener = opener # a map to access file in various {location -> vfs} vfsmap = vfsmap.copy() vfsmap[''] = opener # set default value self._vfsmap = vfsmap self.after = after self.entries = [] self.map = {} self.journal = journalname self.undoname = undoname self._queue = [] # a dict of arguments to be passed to hooks self.hookargs = {} self.file = opener.open(self.journal, "w") # a list of ('location', 'path', 'backuppath', cache) entries. # - if 'backuppath' is empty, no file existed at backup time # - if 'path' is empty, this is a temporary transaction file # - if 'location' is not empty, the path is outside main opener reach. # use 'location' value as a key in a vfsmap to find the right 'vfs' # (cache is currently unused) self._backupentries = [] self._backupmap = {} self._backupjournal = "%s.backupfiles" % self.journal self._backupsfile = opener.open(self._backupjournal, 'w') self._backupsfile.write('%d\n' % version) if createmode is not None: opener.chmod(self.journal, createmode & 0666) opener.chmod(self._backupjournal, createmode & 0666) # hold file generations to be performed on commit self._filegenerators = {} # hold callback to write pending data for hooks self._pendingcallback = {} # True is any pending data have been written ever self._anypending = False # holds callback to call when writing the transaction self._finalizecallback = {} # hold callback for post transaction close self._postclosecallback = {} # holds callbacks to call during abort self._abortcallback = {} def __del__(self): if self.journal: self._abort() @active def startgroup(self): """delay registration of file entry This is used by strip to delay vision of strip offset. The transaction sees either none or all of the strip actions to be done.""" self._queue.append([]) @active def endgroup(self): """apply delayed registration of file entry. This is used by strip to delay vision of strip offset. The transaction sees either none or all of the strip actions to be done.""" q = self._queue.pop() for f, o, data in q: self._addentry(f, o, data) @active def add(self, file, offset, data=None): """record the state of an append-only file before update""" if file in self.map or file in self._backupmap: return if self._queue: self._queue[-1].append((file, offset, data)) return self._addentry(file, offset, data) def _addentry(self, file, offset, data): """add a append-only entry to memory and on-disk state""" if file in self.map or file in self._backupmap: 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 addbackup(self, file, hardlink=True, location=''): """Adds a backup of the file to the transaction Calling addbackup() creates a hardlink backup of the specified file that is used to recover the file in the event of the transaction aborting. * `file`: the file path, relative to .hg/store * `hardlink`: use a hardlink to quickly create the backup """ if self._queue: msg = 'cannot use transaction.addbackup inside "group"' raise RuntimeError(msg) if file in self.map or file in self._backupmap: return vfs = self._vfsmap[location] dirname, filename = vfs.split(file) backupfilename = "%s.backup.%s" % (self.journal, filename) backupfile = vfs.reljoin(dirname, backupfilename) if vfs.exists(file): filepath = vfs.join(file) backuppath = vfs.join(backupfile) util.copyfile(filepath, backuppath, hardlink=hardlink) else: backupfile = '' self._addbackupentry((location, file, backupfile, False)) def _addbackupentry(self, entry): """register a new backup entry and write it to disk""" self._backupentries.append(entry) self._backupmap[file] = len(self._backupentries) - 1 self._backupsfile.write("%s\0%s\0%s\0%d\n" % entry) self._backupsfile.flush() @active def registertmp(self, tmpfile, location=''): """register a temporary transaction file Such files will be deleted when the transaction exits (on both failure and success). """ self._addbackupentry((location, '', tmpfile, False)) @active def addfilegenerator(self, genid, filenames, genfunc, order=0, location=''): """add a function to generates some files at transaction commit The `genfunc` argument is a function capable of generating proper content of each entry in the `filename` tuple. At transaction close time, `genfunc` will be called with one file object argument per entries in `filenames`. The transaction itself is responsible for the backup, creation and final write of such file. The `genid` argument is used to ensure the same set of file is only generated once. Call to `addfilegenerator` for a `genid` already present will overwrite the old entry. The `order` argument may be used to control the order in which multiple generator will be executed. The `location` arguments may be used to indicate the files are located outside of the the standard directory for transaction. It should match one of the key of the `transaction.vfsmap` dictionary. """ # For now, we are unable to do proper backup and restore of custom vfs # but for bookmarks that are handled outside this mechanism. self._filegenerators[genid] = (order, filenames, genfunc, location) def _generatefiles(self, suffix=''): # write files registered for generation any = False for entry in sorted(self._filegenerators.values()): any = True order, filenames, genfunc, location = entry vfs = self._vfsmap[location] files = [] try: for name in filenames: name += suffix if suffix: self.registertmp(name, location=location) else: self.addbackup(name, location=location) files.append(vfs(name, 'w', atomictemp=True)) genfunc(*files) finally: for f in files: f.close() return any @active def find(self, file): if file in self.map: return self.entries[self.map[file]] if file in self._backupmap: return self._backupentries[self._backupmap[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 def addpending(self, category, callback): """add a callback to be called when the transaction is pending The transaction will be given as callback's first argument. Category is a unique identifier to allow overwriting an old callback with a newer callback. """ self._pendingcallback[category] = callback @active def writepending(self): '''write pending file to temporary version This is used to allow hooks to view a transaction before commit''' categories = sorted(self._pendingcallback) for cat in categories: # remove callback since the data will have been flushed any = self._pendingcallback.pop(cat)(self) self._anypending = self._anypending or any self._anypending |= self._generatefiles(suffix='.pending') return self._anypending @active def addfinalize(self, category, callback): """add a callback to be called when the transaction is closed The transaction will be given as callback's first argument. Category is a unique identifier to allow overwriting old callbacks with newer callbacks. """ self._finalizecallback[category] = callback @active def addpostclose(self, category, callback): """add a callback to be called after the transaction is closed The transaction will be given as callback's first argument. Category is a unique identifier to allow overwriting an old callback with a newer callback. """ self._postclosecallback[category] = callback @active def addabort(self, category, callback): """add a callback to be called when the transaction is aborted. The transaction will be given as the first argument to the callback. Category is a unique identifier to allow overwriting an old callback with a newer callback. """ self._abortcallback[category] = callback @active def close(self): '''commit the transaction''' if self.count == 1: self._generatefiles() categories = sorted(self._finalizecallback) for cat in categories: self._finalizecallback[cat](self) self.count -= 1 if self.count != 0: return self.file.close() self._backupsfile.close() # cleanup temporary files for l, f, b, c in self._backupentries: if l not in self._vfsmap and c: self.report("couldn't remote %s: unknown cache location %s\n" % (b, l)) continue vfs = self._vfsmap[l] if not f and b and vfs.exists(b): try: vfs.unlink(b) except (IOError, OSError, util.Abort), inst: if not c: raise # Abort may be raise by read only opener self.report("couldn't remote %s: %s\n" % (vfs.join(b), inst)) self.entries = [] self._writeundo() if self.after: self.after() if self.opener.isfile(self.journal): self.opener.unlink(self.journal) if self.opener.isfile(self._backupjournal): self.opener.unlink(self._backupjournal) for l, _f, b, c in self._backupentries: if l not in self._vfsmap and c: self.report("couldn't remote %s: unknown cache location" "%s\n" % (b, l)) continue vfs = self._vfsmap[l] if b and vfs.exists(b): try: vfs.unlink(b) except (IOError, OSError, util.Abort), inst: if not c: raise # Abort may be raise by read only opener self.report("couldn't remote %s: %s\n" % (vfs.join(b), inst)) self._backupentries = [] self.journal = None # run post close action categories = sorted(self._postclosecallback) for cat in categories: self._postclosecallback[cat](self) @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 _writeundo(self): """write transaction data for possible future undo call""" if self.undoname is None: return undobackupfile = self.opener.open("%s.backupfiles" % self.undoname, 'w') undobackupfile.write('%d\n' % version) for l, f, b, c in self._backupentries: if not f: # temporary file continue if not b: u = '' else: if l not in self._vfsmap and c: self.report("couldn't remote %s: unknown cache location" "%s\n" % (b, l)) continue vfs = self._vfsmap[l] base, name = vfs.split(b) assert name.startswith(self.journal), name uname = name.replace(self.journal, self.undoname, 1) u = vfs.reljoin(base, uname) util.copyfile(vfs.join(b), vfs.join(u), hardlink=True) undobackupfile.write("%s\0%s\0%s\0%d\n" % (l, f, u, c)) undobackupfile.close() def _abort(self): self.count = 0 self.usages = 0 self.file.close() self._backupsfile.close() try: if not self.entries and not self._backupentries: if self.journal: 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)