Mercurial > hg > mercurial-crew-with-dirclash

comparison mercurial/transaction.py @ 0:9117c6561b0b

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
Add back links from file revisions to changeset revisions Add simple transaction support Add hg verify Improve caching in revlog Fix a bunch of bugs Self-hosting now that the metadata is close to finalized
author mpm@selenic.com
date Tue, 03 May 2005 13:16:10 -0800
parents
children 8b64243ee17b
comparison
equal deleted inserted replaced
-1:000000000000 0:9117c6561b0b
1 # transaction.py - simple journalling scheme for mercurial
2 #
3 # This transaction scheme is intended to gracefully handle program
4 # errors and interruptions. More serious failures like system crashes
5 # can be recovered with an fsck-like tool. As the whole repository is
6 # effectively log-structured, this should amount to simply truncating
7 # anything that isn't referenced in the changelog.
8 #
9 # Copyright 2005 Matt Mackall <mpm@selenic.com>
10 #
11 # This software may be used and distributed according to the terms
12 # of the GNU General Public License, incorporated herein by reference.
13
14 import os
15
16 class transaction:
17 def __init__(self, opener, journal):
18 self.opener = opener
19 self.entries = []
20 self.journal = journal
21
22 # abort here if the journal already exists
23 if os.path.exists(self.journal):
24 raise "Journal already exists!"
25 self.file = open(self.journal, "w")
26
27 def __del__(self):
28 if self.entries: self.abort()
29
30 def add(self, file, offset):
31 self.entries.append((file, offset))
32 # add enough data to the journal to do the truncate
33 self.file.write("%s\0%d\n" % (file, offset))
34 self.file.flush()
35
36 def close(self):
37 self.file.close()
38 self.entries = []
39 os.unlink(self.journal)
40
41 def abort(self):
42 if not self.entries: return
43
44 print "transaction abort!"
45
46 for f, o in self.entries:
47 self.opener(f, "a").truncate(o)
48
49 self.entries = []
50
51 try:
52 os.unlink(self.journal)
53 self.file.close()
54 except: pass
55
56 print "rollback completed"
57
58 def recover(self):
59 for l in open(self.journal).readlines():
60 f, o = l.split('\0')
61 self.opener(f, "a").truncate(int(o))
62