Mercurial > hg > gitserve

annotate mercurial/transaction.py @ 12:8b64243ee17b

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Delete journal on destruction even if there are no entries to replay.
author mpm@selenic.com
date Wed, 04 May 2005 09:30:56 -0800
parents 9117c6561b0b
children eb87b7dc4236
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1 # transaction.py - simple journalling scheme for mercurial
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2 #
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3 # This transaction scheme is intended to gracefully handle program
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4 # errors and interruptions. More serious failures like system crashes
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5 # can be recovered with an fsck-like tool. As the whole repository is
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6 # effectively log-structured, this should amount to simply truncating
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7 # anything that isn't referenced in the changelog.
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8 #
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9 # Copyright 2005 Matt Mackall <mpm@selenic.com>
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10 #
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11 # This software may be used and distributed according to the terms
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12 # of the GNU General Public License, incorporated herein by reference.
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13
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14 import os
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15
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16 class transaction:
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17 def __init__(self, opener, journal):
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18 self.opener = opener
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19 self.entries = []
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20 self.journal = journal
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21
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22 # abort here if the journal already exists
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23 if os.path.exists(self.journal):
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24 raise "Journal already exists!"
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25 self.file = open(self.journal, "w")
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27 def __del__(self):
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28 if self.entries: self.abort()
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29 self.close()
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31 def add(self, file, offset):
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32 self.entries.append((file, offset))
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33 # add enough data to the journal to do the truncate
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34 self.file.write("%s\0%d\n" % (file, offset))
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35 self.file.flush()
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36
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37 def close(self):
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38 self.file.close()
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39 self.entries = []
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40 os.unlink(self.journal)
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41
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42 def abort(self):
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43 if not self.entries: return
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44
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45 print "transaction abort!"
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46
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47 for f, o in self.entries:
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48 self.opener(f, "a").truncate(o)
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50 self.entries = []
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52 print "rollback completed"
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53
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54 def recover(self):
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55 for l in open(self.journal).readlines():
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56 f, o = l.split('\0')
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57 self.opener(f, "a").truncate(int(o))
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