Mercurial > hg > mercurial-crew-with-dirclash
annotate mercurial/transaction.py @ 595:c2c2c6d617bd
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author | mpm@selenic.com |
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date | Sun, 03 Jul 2005 11:41:43 -0800 |
parents | df8a5a0098d4 |
children | 46a8dd3145cc 445970ccf57a |
rev | line source |
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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 |
421 | 15 import util |
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16 |
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17 class transaction: |
582 | 18 def __init__(self, report, opener, journal, after = None): |
162 | 19 self.journal = None |
20 | |
21 # abort here if the journal already exists | |
22 if os.path.exists(journal): | |
23 raise "journal already exists - run hg recover" | |
24 | |
582 | 25 self.report = report |
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26 self.opener = opener |
95 | 27 self.after = after |
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28 self.entries = [] |
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29 self.map = {} |
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30 self.journal = journal |
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31 |
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32 self.file = open(self.journal, "w") |
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33 |
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34 def __del__(self): |
558
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35 if self.journal: |
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36 if self.entries: self.abort() |
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37 self.file.close() |
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38 try: os.unlink(self.journal) |
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39 except: pass |
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40 |
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41 def add(self, file, offset): |
42
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42 if file in self.map: return |
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43 self.entries.append((file, offset)) |
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44 self.map[file] = 1 |
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45 # add enough data to the journal to do the truncate |
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46 self.file.write("%s\0%d\n" % (file, offset)) |
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47 self.file.flush() |
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48 |
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49 def close(self): |
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50 self.file.close() |
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51 self.entries = [] |
95 | 52 if self.after: |
421 | 53 util.rename(self.journal, self.after) |
95 | 54 else: |
55 os.unlink(self.journal) | |
573 | 56 self.journal = None |
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57 |
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58 def abort(self): |
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59 if not self.entries: return |
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60 |
582 | 61 self.report("transaction abort!\n") |
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62 |
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63 for f, o in self.entries: |
108 | 64 try: |
65 self.opener(f, "a").truncate(o) | |
66 except: | |
582 | 67 self.report("failed to truncate %s\n" % f) |
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68 |
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69 self.entries = [] |
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70 |
582 | 71 self.report("rollback completed\n") |
515 | 72 |
162 | 73 def rollback(opener, file): |
74 for l in open(file).readlines(): | |
75 f, o = l.split('\0') | |
76 opener(f, "a").truncate(int(o)) | |
77 os.unlink(file) | |
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78 |