Lock recipe sorts sequenced children incorrectly
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Key: ZOOKEEPER-1329
URL: https://issues.apache.org/jira/browse/ZOOKEEPER-1329
Project: ZooKeeper
Issue Type: Bug
Components: recipes
Affects Versions: 3.3.3
Environment: Mac OS X Version 10.6.8
Darwin emcclure-lt-mac.local 10.8.0 Darwin Kernel Version 10.8.0: Tue Jun 7
16:33:36 PDT 2011; root:xnu-1504.15.3~1/RELEASE_I386 i386
Homebrew 0.8
Reporter: Evan McClure
The lock recipe sorts sequenced children lexicographically. When the sequence
number wraps, a lexicographical comparison will always place 2147483648 ahead
of -2147483649, place -2147483648 ahead of -2147483649, and place -1 ahead of
-2. Clearly, we want 2147483648 < -2147483649, -2147483649 < -2147483648, and
-2 placed ahead of -1, since those sequence numbers were generated in that
order.
I suggest that the sequence numbers be converted to unsigned numbers before
being compared in the comparison functor that gets passed to qsort().
This leaves us with another issue. When comparing unsigned sequence numbers,
there is a slim chance that 4294967296 < 0. So, I suggest that a fudge range
be used--say, the number of nodes in the quorum * some fudge factor--in order
to handle this comparison.
Please close this if I'm way off base here.
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