Mercurial > hg
view mercurial/transaction.py @ 12:8b64243ee17b
Delete journal on destruction even if there are no entries to replay.
author | mpm@selenic.com |
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date | Wed, 04 May 2005 09:30:56 -0800 |
parents | 9117c6561b0b |
children | eb87b7dc4236 |
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# 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 Matt Mackall <mpm@selenic.com> # # This software may be used and distributed according to the terms # of the GNU General Public License, incorporated herein by reference. import os class transaction: def __init__(self, opener, journal): self.opener = opener self.entries = [] self.journal = journal # abort here if the journal already exists if os.path.exists(self.journal): raise "Journal already exists!" self.file = open(self.journal, "w") def __del__(self): if self.entries: self.abort() self.close() def add(self, file, offset): self.entries.append((file, offset)) # add enough data to the journal to do the truncate self.file.write("%s\0%d\n" % (file, offset)) self.file.flush() def close(self): self.file.close() self.entries = [] os.unlink(self.journal) def abort(self): if not self.entries: return print "transaction abort!" for f, o in self.entries: self.opener(f, "a").truncate(o) self.entries = [] print "rollback completed" def recover(self): for l in open(self.journal).readlines(): f, o = l.split('\0') self.opener(f, "a").truncate(int(o))