mirror of
https://github.com/facebook/sapling.git
synced 2024-10-09 08:18:15 +03:00
12b0405a08
We allow a vfs argument to `addfilegenerator`. This allows generating files outside of the store directory like bookmarks. However, this is not really working since we do not have the infrastructure to backup and restore files outside of store. By chance, the bookmark file is already backed up by another mechanism so we can restrict this new feature to bookmarks (which is our only interest here) and proceed.
357 lines
12 KiB
Python
357 lines
12 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
|
|
|
|
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, _ignore in backupentries:
|
|
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
|
|
|
|
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.backupentries = []
|
|
self.map = {}
|
|
self.backupmap = {}
|
|
self.journal = journal
|
|
self._queue = []
|
|
# a dict of arguments to be passed to hooks
|
|
self.hookargs = {}
|
|
|
|
self.backupjournal = "%s.backupfiles" % journal
|
|
self.file = opener.open(self.journal, "w")
|
|
self.backupsfile = opener.open(self.backupjournal, 'w')
|
|
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 = {}
|
|
|
|
def __del__(self):
|
|
if self.journal:
|
|
self._abort()
|
|
|
|
@active
|
|
def startgroup(self):
|
|
self._queue.append(([], []))
|
|
|
|
@active
|
|
def endgroup(self):
|
|
q = self._queue.pop()
|
|
self.entries.extend(q[0])
|
|
self.backupentries.extend(q[1])
|
|
|
|
offsets = []
|
|
backups = []
|
|
for f, o, _data in q[0]:
|
|
offsets.append((f, o))
|
|
|
|
for f, b, _data in q[1]:
|
|
backups.append((f, b))
|
|
|
|
d = ''.join(['%s\0%d\n' % (f, o) for f, o in offsets])
|
|
self.file.write(d)
|
|
self.file.flush()
|
|
|
|
d = ''.join(['%s\0%s\0' % (f, b) for f, b in backups])
|
|
self.backupsfile.write(d)
|
|
self.backupsfile.flush()
|
|
|
|
@active
|
|
def add(self, file, offset, data=None):
|
|
if file in self.map or file in self.backupmap:
|
|
return
|
|
if self._queue:
|
|
self._queue[-1][0].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 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 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:
|
|
self.add(file, 0)
|
|
return
|
|
|
|
if self._queue:
|
|
self._queue[-1][1].append((file, backupfile))
|
|
return
|
|
|
|
self.backupentries.append((file, backupfile, None))
|
|
self.backupmap[file] = len(self.backupentries) - 1
|
|
self.backupsfile.write("%s\0%s\0" % (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)
|
|
|
|
@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
|
|
|
|
@active
|
|
def close(self):
|
|
'''commit the transaction'''
|
|
# 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()
|
|
|
|
if self.count == 1 and self.onclose is not None:
|
|
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, _ignore in self.backupentries:
|
|
self.opener.unlink(b)
|
|
self.backupentries = []
|
|
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()
|
|
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)
|
|
data = fp.read()
|
|
if len(data) > 0:
|
|
parts = data.split('\0')
|
|
for i in xrange(0, len(parts), 2):
|
|
f, b = parts[i:i + 1]
|
|
backupentries.append((f, b, None))
|
|
|
|
_playback(file, report, opener, entries, backupentries)
|