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Remove file-locking in MH.pack() method. 

This change looks massive but it's mostly a re-indenting after
removing some try...finally blocks.

Also adds a test case that does a pack() while the mailbox is locked; this
test would have turned up bugs in the original code on some platforms.

In both nmh and GNU Mailutils' implementation of MH-format mailboxes,
no locking is done of individual message files when renaming them.

The original mailbox.py code did do locking, which meant that message
files had to be opened.  This code was buggy on certain platforms
(found through reading the code); there were code paths that closed
the file object and then called _unlock_file() on it.

Will backport to 25-maint once I see how the buildbots react to this patch.
This commit is contained in:
Andrew M. Kuchling 2006-11-17 13:30:25 +00:00
parent 25aabf4cbb
commit 8c456f3b57
2 changed files with 22 additions and 21 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

28
Lib/mailbox.py
View File

@ -1054,27 +1054,13 @@ class MH(Mailbox):
for key in self.iterkeys():
if key - 1 != prev:
changes.append((key, prev + 1))
f = open(os.path.join(self._path, str(key)), 'r+')
try:
if self._locked:
_lock_file(f)
try:
if hasattr(os, 'link'):
os.link(os.path.join(self._path, str(key)),
os.path.join(self._path, str(prev + 1)))
if sys.platform == 'os2emx':
# cannot unlink an open file on OS/2
f.close()
os.unlink(os.path.join(self._path, str(key)))
else:
f.close()
os.rename(os.path.join(self._path, str(key)),
os.path.join(self._path, str(prev + 1)))
finally:
if self._locked:
_unlock_file(f)
finally:
f.close()
if hasattr(os, 'link'):
os.link(os.path.join(self._path, str(key)),
os.path.join(self._path, str(prev + 1)))
os.unlink(os.path.join(self._path, str(key)))
else:
os.rename(os.path.join(self._path, str(key)),
os.path.join(self._path, str(prev + 1)))
prev += 1
self._next_key = prev + 1
if len(changes) == 0:

15
Lib/test/test_mailbox.py
View File

@ -887,6 +887,21 @@ class TestMH(TestMailbox):
self.assert_(self._box.get_sequences() ==
{'foo':[1, 2, 3], 'unseen':[1], 'bar':[3], 'replied':[3]})
# Test case for packing while holding the mailbox locked.
key0 = self._box.add(msg1)
key1 = self._box.add(msg1)
key2 = self._box.add(msg1)
key3 = self._box.add(msg1)
self._box.remove(key0)
self._box.remove(key2)
self._box.lock()
self._box.pack()
self._box.unlock()
self.assert_(self._box.get_sequences() ==
{'foo':[1, 2, 3, 4, 5],
'unseen':[1], 'bar':[3], 'replied':[3]})
def _get_lock_path(self):
return os.path.join(self._path, '.mh_sequences.lock')