Mercurial > hg > mercurial-crew-with-dirclash
view mercurial/transaction.py @ 847:f1555f48f884
Update the TODO file to the help changes, and the output of test-help.
author | kreijack@inwind.REMOVEME.it |
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date | Sat, 06 Aug 2005 13:33:14 +0100 |
parents | 0902ffece4b4 |
children | 6d5a62a549fa |
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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 import util class transaction: def __init__(self, report, opener, journal, after = None): self.journal = None # abort here if the journal already exists if os.path.exists(journal): raise "journal already exists - run hg recover" self.report = report self.opener = opener self.after = after self.entries = [] self.map = {} self.journal = journal self.file = open(self.journal, "w") def __del__(self): if self.journal: if self.entries: self.abort() self.file.close() try: os.unlink(self.journal) except: pass def add(self, file, offset): if file in self.map: return self.entries.append((file, offset)) self.map[file] = 1 # 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 = [] if self.after: self.after() else: os.unlink(self.journal) self.journal = None def abort(self): if not self.entries: return self.report("transaction abort!\n") for f, o in self.entries: try: self.opener(f, "a").truncate(o) except: self.report("failed to truncate %s\n" % f) self.entries = [] self.report("rollback completed\n") def rollback(opener, file): for l in open(file).readlines(): f, o = l.split('\0') opener(f, "a").truncate(int(o)) os.unlink(file)