x SuSE Linux 13.1-RELEASE x
x SuSE Linux 13.1-RELEASEx
curl_multi_wait(3) libcurl curl_multi_wait(3)
NAME
curl_multi_wait - polls on all easy handles in a multi handle
SYNOPSIS
#include <curl/curl.h>
CURLMcode curl_multi_wait(CURLM *multi_handle,
struct curl_waitfd extra_fds[],
unsigned int extra_nfds,
int timeout_ms,
int *numfds);
DESCRIPTION
curl_multi_wait(3) polls all file descriptors used by the curl easy
handles contained in the given multi handle set. It blocks until activ-
ity is detected on at least one of the handles or timeout_ms has
passed. Alternatively, if the multi handle has a pending internal
timeout that has a shorter expiry time than timeout_ms, that shorter
time is be used instead to make sure timeout accuracy is reasonably
kept.
The calling application may pass additional curl_waitfd structures
which are similar to poll(2)'s pollfd structure to be waited on in the
same call.
On completion, if numfds is non-NULL, it gets populated with the total
number of file descriptors on which interesting events occurred. This
number can include both libcurl internal descriptors as well as
descriptors provided in extra_fds.
If no extra file descriptors are provided and libcurl has no file
descriptor to offer to wait for, this function returns immediately.
(Consider using curl_multi_poll(3) to avoid this behavior.)
This function is encouraged to be used instead of select(3) when using
the multi interface to allow applications to easier circumvent the com-
mon problem with 1024 maximum file descriptors.
curl_waitfd
struct curl_waitfd {
curl_socket_t fd;
short events;
short revents;
};
CURL_WAIT_POLLIN
Bit flag to curl_waitfd.events indicating the socket should poll
on read events such as new data received.
CURL_WAIT_POLLPRI
Bit flag to curl_waitfd.events indicating the socket should poll
on high priority read events such as out of band data.
CURL_WAIT_POLLOUT
Bit flag to curl_waitfd.events indicating the socket should poll
on write events such as the socket being clear to write without
blocking.
EXAMPLE
CURL *easy_handle;
CURLM *multi_handle;
/* add the individual easy handle */
curl_multi_add_handle(multi_handle, easy_handle);
do {
CURLMcode mc;
int numfds;
mc = curl_multi_perform(multi_handle, &still_running);
if(mc == CURLM_OK ) {
/* wait for activity, timeout or "nothing" */
mc = curl_multi_wait(multi_handle, NULL, 0, 1000, &numfds);
}
if(mc != CURLM_OK) {
fprintf(stderr, "curl_multi failed, code %d.\n", mc);
break;
}
/* 'numfds' being zero means either a timeout or no file descriptors to
wait for. Try timeout on first occurrence, then assume no file
descriptors and no file descriptors to wait for means wait for 100
milliseconds. */
if(!numfds) {
repeats++; /* count number of repeated zero numfds */
if(repeats > 1) {
WAITMS(100); /* sleep 100 milliseconds */
}
}
else
repeats = 0;
} while(still_running);
curl_multi_remove_handle(multi_handle, easy_handle);
AVAILABILITY
This function was added in libcurl 7.28.0.
RETURN VALUE
CURLMcode type, general libcurl multi interface error code. See
libcurl-errors(3)
SEE ALSO
curl_multi_fdset(3), curl_multi_perform(3), curl_multi_poll(3)
libcurl 8.4.0 September 26, 2023 curl_multi_wait(3)
Want to link to this manual page? Use this URL:
<http://star2.abcm.com/cgi-bin/bsdi-man?query=curl_multi_wait&sektion=3&manpath=>