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accept-process-output doc string vs. lispref

From: Kim F. Storm
Subject: accept-process-output doc string vs. lispref
Date: Wed, 22 Mar 2006 22:36:34 +0100
User-agent: Gnus/5.11 (Gnus v5.11) Emacs/22.0.50 (gnu/linux)

There is a _BIG_ problem between the doc string and lispref 
for the accept-process-output function:


(accept-process-output &optional process timeout timeout-msecs just-this-one)
Non-nil second arg timeout and third arg timeout-msecs are number of
seconds and microseconds to wait; return after that much time whether
or not there is input.


 - Function: accept-process-output &optional process seconds millisec 

     The arguments SECONDS and MILLISEC let you specify timeout
     periods.  The former specifies a period measured in seconds and the
     latter specifies one measured in milliseconds.  The two time
     periods thus specified are added together, and
     `accept-process-output' returns after that much time whether or
     not there has been any subprocess output.

So doc string says that "timeout-msecs" is in MICRO seconds, while
the lisp ref says "millisec" is in MILLI seconds.

The doc string has been like that since 1991, and the lisp ref since 1994.

The C-code interprets it as MICRO seconds, so the doc string is correct.

However, the name of the parameter "msecs" is misleading.

I also checked Xemacs, and it interprets the argument as MILLI seconds.

The recently reported problem with gnus looping in gettimeofday and
accept-process-output (IIRC) can probably be attributed to gnus
using a timeout on accept-process-output of msec=100, i.e. 0.0001 second.

Looking at the code, it clearly expects the arg to be interpreted as
100 MILLI seconds.  I have also checked all other uses of
accept-process-output, and all code that sets timeout-msec expects it
to be MILLI seconds.

On Linux [the kernel], the minimum time-difference is typically 0.01
second, so having a resolution in MICRO seconds is pretty useless;
MILLI seconds is fully adequate

I will change the interpretation from MICRO to MILLI seconds to align
the code and doc string with 1) the LISP REF, and 2) all uses of the

Kim F. Storm <address@hidden> http://www.cua.dk

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