Mercurial > hg > mercurial-crew-with-dirclash
annotate mercurial/transaction.py @ 535:fba26990604a
Deal with failed clone/transaction interaction
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Deal with failed clone/transaction interaction
> What is happening is that something in the transaction machinery is
> causing the directory to be completely recreated.
The transaction gets rolled back by its destructor. This is critical
so it happens whenever an exception occurs that unwinds the stack.
Unfortunately, what's happening with clone is we're trying to delete
the directory during exception propagation. And a reference to the
transaction is held in the exception backtrace stack frames so it
still exists until the exception is completely resolved.
So there's no way to do the directory delete inside the exception
handling cleanly.
But we can handle it similarly to the transaction itself: use an
object with a destructor.
manifest hash: fc38550a20d64d08333f256bbedc312493c1390b
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author | mpm@selenic.com |
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date | Thu, 30 Jun 2005 10:07:50 -0800 |
parents | 03f27b1381f9 |
children | 0ceea19182a9 |
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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: |
95 | 18 def __init__(self, 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 | |
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25 self.opener = opener |
95 | 26 self.after = after |
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27 self.entries = [] |
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28 self.map = {} |
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29 self.journal = journal |
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30 |
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31 self.file = open(self.journal, "w") |
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32 |
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33 def __del__(self): |
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34 if self.entries: self.abort() |
13 | 35 try: os.unlink(self.journal) |
36 except: pass | |
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37 |
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38 def add(self, file, offset): |
42
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39 if file in self.map: return |
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40 self.entries.append((file, offset)) |
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41 self.map[file] = 1 |
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42 # add enough data to the journal to do the truncate |
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43 self.file.write("%s\0%d\n" % (file, offset)) |
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44 self.file.flush() |
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45 |
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46 def close(self): |
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47 self.file.close() |
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48 self.entries = [] |
95 | 49 if self.after: |
421 | 50 util.rename(self.journal, self.after) |
95 | 51 else: |
52 os.unlink(self.journal) | |
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53 |
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54 def abort(self): |
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55 if not self.entries: return |
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56 |
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57 print "transaction abort!" |
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58 |
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59 for f, o in self.entries: |
108 | 60 try: |
61 self.opener(f, "a").truncate(o) | |
62 except: | |
63 print "failed to truncate", f | |
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64 |
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65 self.entries = [] |
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66 |
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67 print "rollback completed" |
515 | 68 |
162 | 69 def rollback(opener, file): |
70 for l in open(file).readlines(): | |
71 f, o = l.split('\0') | |
72 opener(f, "a").truncate(int(o)) | |
73 os.unlink(file) | |
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74 |