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¶
This function polls on all file descriptors used by the curl easy handles
contained in the given multi handle set. It will block until activity 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 will 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 supplied, it will be populated with the total
number of file descriptors on which interesting events occured. 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 will return immediately.
This function is encouraged to be used instead of
select(3) when using the multi
interface to allow applications to easier circumvent the common 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.
RETURN VALUE¶
CURLMcode type, general libcurl multi interface error code. See
libcurl-errors(3)
AVAILABILITY¶
This function was added in libcurl 7.28.0.
SEE ALSO¶
curl_multi_fdset(3),
curl_multi_perform(3)