mirror of
https://github.com/facebook/sapling.git
synced 2024-10-09 00:14:35 +03:00
92bf4dcbdc
The callback will likely need to perform some operation related to the transaction (eg: backing files up). So we better pass the current transaction as the callback argument. Otherwise callback that needs it has to rely on horrible weak reference trick. The first foreseen user of this is changelog._writepending. We would like it to register the temporary file it create for cleanup purpose.
432 lines
15 KiB
Python
432 lines
15 KiB
Python
# 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 = 1
|
|
|
|
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, 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 f, b in backupentries:
|
|
if b:
|
|
filepath = opener.join(f)
|
|
backuppath = opener.join(b)
|
|
try:
|
|
util.copyfile(backuppath, filepath)
|
|
backupfiles.append(b)
|
|
except IOError:
|
|
report(_("failed to recover %s\n") % f)
|
|
raise
|
|
else:
|
|
try:
|
|
opener.unlink(f)
|
|
except (IOError, OSError), inst:
|
|
if inst.errno != errno.ENOENT:
|
|
raise
|
|
|
|
opener.unlink(journal)
|
|
backuppath = "%s.backupfiles" % journal
|
|
if opener.exists(backuppath):
|
|
opener.unlink(backuppath)
|
|
for f in backupfiles:
|
|
opener.unlink(f)
|
|
|
|
class transaction(object):
|
|
def __init__(self, report, opener, journal, after=None, createmode=None,
|
|
onclose=None, onabort=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
|
|
* `onclose`: called as the transaction is closing, but before it is
|
|
closed
|
|
* `onabort`: called as the transaction is aborting, but before any files
|
|
have been truncated
|
|
"""
|
|
self.count = 1
|
|
self.usages = 1
|
|
self.report = report
|
|
self.opener = opener
|
|
self.after = after
|
|
self.onclose = onclose
|
|
self.onabort = onabort
|
|
self.entries = []
|
|
self.map = {}
|
|
self.journal = journal
|
|
self._queue = []
|
|
# a dict of arguments to be passed to hooks
|
|
self.hookargs = {}
|
|
self.file = opener.open(self.journal, "w")
|
|
|
|
# a list of ('path', 'backuppath') entries.
|
|
# if 'backuppath' is empty, no file existed at backup time
|
|
self._backupentries = []
|
|
self._backupmap = {}
|
|
self._backupjournal = "%s.backupfiles" % 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 callbalk 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 callbalk for post transaction close
|
|
self._postclosecallback = {}
|
|
|
|
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, vfs=None):
|
|
"""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
|
|
backupfile = "%s.backup.%s" % (self.journal, file)
|
|
if vfs is None:
|
|
vfs = self.opener
|
|
if vfs.exists(file):
|
|
filepath = vfs.join(file)
|
|
backuppath = self.opener.join(backupfile)
|
|
util.copyfiles(filepath, backuppath, hardlink=hardlink)
|
|
else:
|
|
backupfile = ''
|
|
|
|
self._backupentries.append((file, backupfile))
|
|
self._backupmap[file] = len(self._backupentries) - 1
|
|
self._backupsfile.write("%s\0%s\n" % (file, backupfile))
|
|
self._backupsfile.flush()
|
|
|
|
@active
|
|
def addfilegenerator(self, genid, filenames, genfunc, order=0, vfs=None):
|
|
"""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.
|
|
"""
|
|
# For now, we are unable to do proper backup and restore of custom vfs
|
|
# but for bookmarks that are handled outside this mechanism.
|
|
assert vfs is None or filenames == ('bookmarks',)
|
|
self._filegenerators[genid] = (order, filenames, genfunc, vfs)
|
|
|
|
def _generatefiles(self):
|
|
# write files registered for generation
|
|
for entry in sorted(self._filegenerators.values()):
|
|
order, filenames, genfunc, vfs = entry
|
|
if vfs is None:
|
|
vfs = self.opener
|
|
files = []
|
|
try:
|
|
for name in filenames:
|
|
# Some files are already backed up when creating the
|
|
# localrepo. Until this is properly fixed we disable the
|
|
# backup for them.
|
|
if name not in ('phaseroots', 'bookmarks'):
|
|
self.addbackup(name)
|
|
files.append(vfs(name, 'w', atomictemp=True))
|
|
genfunc(*files)
|
|
finally:
|
|
for f in files:
|
|
f.close()
|
|
|
|
@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
|
|
return self._anypending
|
|
|
|
@active
|
|
def addfinalize(self, category, callback):
|
|
"""add a callback to be called when the transaction is closed
|
|
|
|
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
|
|
|
|
Category is a unique identifier to allow overwriting an old callback
|
|
with a newer callback.
|
|
"""
|
|
self._postclosecallback[category] = callback
|
|
|
|
@active
|
|
def close(self):
|
|
'''commit the transaction'''
|
|
if self.count == 1 and self.onclose is not None:
|
|
self._generatefiles()
|
|
categories = sorted(self._finalizecallback)
|
|
for cat in categories:
|
|
self._finalizecallback[cat]()
|
|
self.onclose()
|
|
|
|
self.count -= 1
|
|
if self.count != 0:
|
|
return
|
|
self.file.close()
|
|
self._backupsfile.close()
|
|
self.entries = []
|
|
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 _f, b in self._backupentries:
|
|
if b:
|
|
self.opener.unlink(b)
|
|
self._backupentries = []
|
|
self.journal = None
|
|
# run post close action
|
|
categories = sorted(self._postclosecallback)
|
|
for cat in categories:
|
|
self._postclosecallback[cat]()
|
|
|
|
@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()
|
|
self._backupsfile.close()
|
|
|
|
if self.onabort is not None:
|
|
self.onabort()
|
|
|
|
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:
|
|
_playback(self.journal, self.report, self.opener,
|
|
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, 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]
|
|
f, b = line.split('\0')
|
|
backupentries.append((f, b))
|
|
else:
|
|
report(_("journal was created by a newer version of "
|
|
"Mercurial"))
|
|
|
|
_playback(file, report, opener, entries, backupentries)
|