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curl_multi_perform.3: extended/clarified

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Daniel Stenberg 2012-08-27 00:16:03 +02:00
parent 0f76e492ae
commit ba569a27cc
1 changed files with 20 additions and 15 deletions
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35
docs/libcurl/curl_multi_perform.3
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@ -5,7 +5,7 @@
.\" * | (__| |_| | _ <| |___
.\" * \___|\___/|_| \_\_____|
.\" *
.\" * Copyright (C) 1998 - 2011, Daniel Stenberg, <daniel@haxx.se>, et al.
.\" * Copyright (C) 1998 - 2012, Daniel Stenberg, <daniel@haxx.se>, et al.
.\" *
.\" * This software is licensed as described in the file COPYING, which
.\" * you should have received as part of this distribution. The terms
@ -28,21 +28,24 @@ curl_multi_perform - reads/writes available data from each easy handle
CURLMcode curl_multi_perform(CURLM *multi_handle, int *running_handles);
.ad
.SH DESCRIPTION
When the app thinks there's data available for the multi_handle, it should
call this function to read/write whatever there is to read or write right
now. curl_multi_perform() returns as soon as the reads/writes are done. This
This function handles transfers on all the added handles that need attention
in an non-blocking fashion.
When an application has found out there's data available for the multi_handle
or a timeout has elapsed, the application should call this function to
read/write whatever there is to read or write right now etc.
curl_multi_perform() returns as soon as the reads/writes are done. This
function does not require that there actually is any data available for
reading or that data can be written, it can be called just in case. It will
write the number of handles that still transfer data in the second argument's
integer-pointer.
When you call curl_multi_perform() and the amount of \fIrunning_handles\fP is
changed from the previous call (or is less than the amount of easy handles
you've added to the multi handle), you know that there is one or more
transfers less "running". You can then call \fIcurl_multi_info_read(3)\fP to
get information about each individual completed transfer, and that returned
info includes CURLcode and more. If an added handle fails very quickly, it may
never be counted as a running_handle.
If the amount of \fIrunning_handles\fP is changed from the previous call (or
is less than the amount of easy handles you've added to the multi handle), you
know that there is one or more transfers less "running". You can then call
\fIcurl_multi_info_read(3)\fP to get information about each individual
completed transfer, and that returned info includes CURLcode and more. If an
added handle fails very quickly, it may never be counted as a running_handle.
When \fIrunning_handles\fP is set to zero (0) on the return of this function,
there is no longer any transfers in progress.
@ -61,12 +64,14 @@ need to wait for \&"action" and then call this function again.
This function only returns errors etc regarding the whole multi stack.
Problems still might have occurred on individual transfers even when this
function returns \fICURLM_OK\fP.
function returns \fICURLM_OK\fP. Use \fIcurl_multi_info_read(3)\fP to figure
out how individual transfers did.
.SH "TYPICAL USAGE"
Most applications will use \fIcurl_multi_fdset(3)\fP to get the multi_handle's
file descriptors, then it'll wait for action on them using \fBselect(3)\fP and
as soon as one or more of them are ready, \fIcurl_multi_perform(3)\fP gets
called.
file descriptors, and \fIcurl_multi_timeout(3)\fP to get a suitable timeout
period, then it'll wait for action on the file descriptors using
\fBselect(3)\fP. As soon as one or more file descriptor is ready,
\fIcurl_multi_perform(3)\fP gets called.
.SH "SEE ALSO"
.BR curl_multi_cleanup "(3), " curl_multi_init "(3), "
.BR curl_multi_fdset "(3), " curl_multi_info_read "(3), "