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From: Ivan Zhakov <ivan@visualsvn.com>
Date: Sat, 14 Sep 2013 23:19:12 +0400
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Subject: Re: Using AcceptEx on Windows
To: dev@httpd.apache.org, kyanha@kyanha.net, christophe.jaillet@wanadoo.fr
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On Sat, Sep 14, 2013 at 10:26 PM, Kyle Hamilton <kyanha@kyanha.net> wrote:
>>> Hi,
>>>
>>> The mpm_winnt uses AcceptEx API call to accept incoming connections.
>>> But MSDN documentation states [1] that consumer should use WSAIoctl()
>>> to get pointer to AcceptEx function instead calling it directly:
>>> [[[
>>> Note  The function pointer for the AcceptEx function must be obtained
>>> at run time by making a call to the WSAIoctl function with the
>>> SIO_GET_EXTENSION_FUNCTION_POINTER opcode specified. The input buffer
>>> passed to the WSAIoctl function must contain WSAID_ACCEPTEX, a
>>> globally unique identifier (GUID) whose value identifies the AcceptEx
>>> extension function. On success, the output returned by the WSAIoctl
>>> function contains a pointer to the AcceptEx function. The
>>> WSAID_ACCEPTEX GUID is defined in the Mswsock.h header file.
>>> ]]]
>>>
>>> Is any reason why WSAIoctl() is not used or just mistake and I should
>>> prepare the patch to fix it?>
> Calling WSAIoctl is necessary and useful in certain circumstances to
> reduce duplicate work performed on every AcceptEx call (i.e., AcceptEx
> calls WSAIoctl on every call, to ensure that the proper implementation
> of AcceptEx for the given socket through the proper network provider
> is property routed).
>
> Calling WSAIoctl and using AcceptEx through the pointer returned
> bypasses this duplicate work.  But, if httpd ever allows a single
> instance to be used across multiple network providers (my presumption
> is, like IPv4 and IPv6), this duplicate work cannot be avoided, and so
> it's easiest and most effective to simply use AcceptEx without the
> pointer and let the system figure out how to route it.
>
> This is digested solely from documentation, and I have done no testing
> of the assumptions or validity of the documentation.
>
I was looking to httpd 2.4.x source code, while trunk code already
resolves AcceptEx pointer dynamically using WSAIoctl() since r1363312
[1].

Sorry for noise :(

[1]  http://svn.apache.org/r1363312

-- 
Ivan Zhakov