curl_multi_perform(3) libcurl Manual curl_multi_perform(3)NAMEcurl_multi_perform - reads/writes available data from each
CURLMcode curl_multi_perform(CURLM *multi_handle, int
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 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
When you call curl_multi_perform() and the amount of
running_handles 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 curl_multi_info_read(3) to
get information about each individual completed transfer,
and that returned info includes CURLcode and more.
CURLMcode type, general libcurl multi interface error code.
If you receive CURLM_CALL_MULTI_PERFORM, this basically
means that you should call curl_multi_perform again, before
you select() on more actions. You don't have to do it
immediately, but the return code means that libcurl may have
more data available to return or that there may be more data
to send off before it is "satisfied".
NOTE that this only returns errors etc regarding the whole
multi stack. There might still have occurred problems on
individual transfers even when this function returns OK.
Most application will use curl_multi_fdset(3) to get the
multi_handle's file descriptors, then it'll wait for action
on them using select() and as soon as one or more of them
are ready, curl_multi_perform(3) gets called.
SEE ALSOcurl_multi_cleanup(3), curl_multi_init(3),
curl_multi_fdset(3), curl_multi_info_read(3)libcurl 7.9.5 Last change: 1 March 2002 1