transaction.py
102 lines
| 2.8 KiB
| text/x-python
|
PythonLexer
/ mercurial / transaction.py
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r0 | # 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. | ||||
# | ||||
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r2859 | # Copyright 2005, 2006 Matt Mackall <mpm@selenic.com> | ||
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r0 | # | ||
# This software may be used and distributed according to the terms | ||||
# of the GNU General Public License, incorporated herein by reference. | ||||
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r3891 | from i18n import _ | ||
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r3877 | import os | ||
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r0 | |||
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r1559 | class transaction(object): | ||
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r1062 | def __init__(self, report, opener, journal, after=None): | ||
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r162 | self.journal = None | ||
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r1806 | self.count = 1 | ||
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r582 | self.report = report | ||
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r0 | self.opener = opener | ||
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r95 | self.after = after | ||
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r0 | self.entries = [] | ||
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r42 | self.map = {} | ||
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r0 | self.journal = journal | ||
self.file = open(self.journal, "w") | ||||
def __del__(self): | ||||
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r558 | if self.journal: | ||
if self.entries: self.abort() | ||||
self.file.close() | ||||
try: os.unlink(self.journal) | ||||
except: pass | ||||
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r0 | |||
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r2084 | def add(self, file, offset, data=None): | ||
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r42 | if file in self.map: return | ||
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r2084 | self.entries.append((file, offset, data)) | ||
self.map[file] = len(self.entries) - 1 | ||||
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r0 | # add enough data to the journal to do the truncate | ||
self.file.write("%s\0%d\n" % (file, offset)) | ||||
self.file.flush() | ||||
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r2084 | def find(self, file): | ||
if file in self.map: | ||||
return self.entries[self.map[file]] | ||||
return None | ||||
def replace(self, file, offset, data=None): | ||||
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() | ||||
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r1806 | def nest(self): | ||
self.count += 1 | ||||
return self | ||||
def running(self): | ||||
return self.count > 0 | ||||
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r0 | def close(self): | ||
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r1806 | self.count -= 1 | ||
if self.count != 0: | ||||
return | ||||
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r0 | self.file.close() | ||
self.entries = [] | ||||
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r95 | if self.after: | ||
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r785 | self.after() | ||
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r95 | else: | ||
os.unlink(self.journal) | ||||
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r573 | self.journal = None | ||
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r0 | |||
def abort(self): | ||||
if not self.entries: return | ||||
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r1402 | self.report(_("transaction abort!\n")) | ||
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r0 | |||
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r2084 | for f, o, ignore in self.entries: | ||
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r108 | try: | ||
self.opener(f, "a").truncate(o) | ||||
except: | ||||
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r1402 | self.report(_("failed to truncate %s\n") % f) | ||
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r0 | |||
self.entries = [] | ||||
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r1402 | self.report(_("rollback completed\n")) | ||
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r515 | |||
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r162 | def rollback(opener, file): | ||
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r2084 | files = {} | ||
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r162 | for l in open(file).readlines(): | ||
f, o = l.split('\0') | ||||
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r2084 | files[f] = o | ||
for f in files: | ||||
o = files[f] | ||||
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r162 | opener(f, "a").truncate(int(o)) | ||
os.unlink(file) | ||||
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r0 | |||