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https://issues.apache.org/jira/browse/ZOOKEEPER-1643?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13575632#comment-13575632
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Benjamin Reed commented on ZOOKEEPER-1643:
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ah you are correct. the comment // result = ebx is correct, but i think the
actual code mov result, ecx is incorrect as you point out. the
fix/simplification is to use the intrinsic. we should probably also use
__sync_fetch_and_add in the non windows case.
> Windows: fetch_and_add not 64bit-compatible, may not be correct
> ---------------------------------------------------------------
>
> Key: ZOOKEEPER-1643
> URL: https://issues.apache.org/jira/browse/ZOOKEEPER-1643
> Project: ZooKeeper
> Issue Type: Bug
> Components: c client
> Affects Versions: 3.3.3
> Environment: Windows 7
> Microsoft Visual Studio 2005
> Reporter: Erik Anderson
>
> Note: While I am using a really old version of ZK, I did do enough "SVN
> Blame" operations to realize that this code hasn't changed.
> I am currently attempting to compile the C client under MSVC 2005 arch=x64.
> There are three things I can see with fetch_and_add() inside of
> /src/c/src/mt_adapter.c
> (1) MSVC 2005 64bit will not compile inline _asm sections. I'm moderately
> sure this code is x86-specific so I'm unsure whether it should attempt to
> either.
> (2) The Windows intrinsic InterlockedExchangeAdd
> [http://msdn.microsoft.com/en-us/library/windows/desktop/ms683597(v=vs.85).aspx]
> appears to do the same thing this code is attempting to do
> (3) I'm really rusty on my assembly, but why are we doing two separate XADD
> operations here, and is the code as-written anything approaching atomicity?
> If you want an official patch I likely can do an SVN checkout and submit a
> patch the replaces the entire #else on lines 495-505 with a "return
> InterlockedExchangeAdd(operand, incr);"
> Usually when I'm scratching my head this badly there's something I'm missing
> though. As far as I can tell there has been no prior discussion on this code.
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