/usr/share/pyshared/mercurial/transaction.py is in mercurial-common 2.0.2-1ubuntu1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 | # 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, 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, 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:
fp = opener(f)
fn = fp.name
fp.close()
util.unlink(fn)
except (IOError, OSError), inst:
if inst.errno != errno.ENOENT:
raise
util.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 = util.posixfile(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):
util.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:
util.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 = []
fp = util.posixfile(file)
lines = fp.readlines()
fp.close()
for l in lines:
f, o = l.split('\0')
entries.append((f, int(o), None))
_playback(file, report, opener, entries)
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