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From: "Lavrentiev, Anton (NIH/NLM/NCBI) [C]" <lavr@ncbi.nlm.nih.gov>
To: James Johnston <JamesJ@motionview3d.com>
CC: "cygwin@cygwin.com" <cygwin@cygwin.com>
Subject: RE: Pipe syncronization and incompatibility between Cygwin and .NET Framework 4.0
Date: Fri, 20 Dec 2013 22:39:18 +0000
Message-ID: <5F8AAC04F9616747BC4CC0E803D5907D0C455040@MLBXv04.nih.gov>
References: <02ee01cefdce$9c343300$d49c9900$@motionview3d.com>
In-Reply-To: <02ee01cefdce$9c343300$d49c9900$@motionview3d.com>
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MSDN does not list pipe handles as waitable with WaitForMultipleObjectsEx
(only a user comment at the end does).  If you trace execution without
PeekNamedPipe(), you'll see that WaitForMultipleObjectsEx() returns
immediately, and that it is ReadFile() that blocks and waits for
the input (which will be supplied after 3 seconds).

--quote--
The WaitForMultipleObjectsEx function can specify handles of any of the following object types in the lpHandles array:

    Change notification
    Console input
    Event
    Memory resource notification
    Mutex
    Process
    Semaphore
    Thread
    Waitable timer
--quote--

Also from here:

http://stackoverflow.com/questions/14203618/windows-api-wait-for-data-to-be-available-on-non-gui-console-input-pipe-based

--quote--
Is it possible to wait for data to be available on a non-GUI-based console input? The issue is that WaitFor* methods do not support PIPE handles and therefore STDIN is not supported if the process input is fed from another process, e.g. using the pipe | functionality of cmd.

The only way I know to query a pipe for data without actually reading the data is to use PeekNamedPipe(), but then you lose the ability to wait on a timeout effectively, because it has no timeout so you would have to implement a manual loop instead.
--quote--

HTH,

Anton Lavrentiev
Contractor NIH/NLM/NCBI


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