NAME¶
curl_multi_setopt - set options for a curl multi handle
SYNOPSIS¶
#include <curl/curl.h>
CURLMcode curl_multi_setopt(CURLM * multi_handle, CURLMoption option, param);
DESCRIPTION¶
curl_multi_setopt() is used to tell a libcurl multi handle how to behave. By
using the appropriate options to
curl_multi_setopt(3), you can change
libcurl's behaviour when using that multi handle. All options are set with the
option followed by the parameter
param. That parameter can be a
long, a
function pointer, an
object pointer or a
curl_off_t type, depending on what the specific option expects. Read
this manual carefully as bad input values may cause libcurl to behave badly!
You can only set one option in each function call.
OPTIONS¶
- CURLMOPT_SOCKETFUNCTION
- Pass a pointer to a function matching the
curl_socket_callback prototype. The
curl_multi_socket_action(3) function informs the application about
updates in the socket (file descriptor) status by doing none, one, or
multiple calls to the curl_socket_callback given in the param
argument. They update the status with changes since the previous time a
curl_multi_socket(3) function was called. If the given callback
pointer is NULL, no callback will be called. Set the callback's
userp argument with CURLMOPT_SOCKETDATA. See
curl_multi_socket(3) for more callback details.
- CURLMOPT_SOCKETDATA
- Pass a pointer to whatever you want passed to the
curl_socket_callback's forth argument, the userp pointer. This is
not used by libcurl but only passed-thru as-is. Set the callback pointer
with CURLMOPT_SOCKETFUNCTION.
- CURLMOPT_PIPELINING
- Pass a long set to 1 to enable or 0 to disable. Enabling
pipelining on a multi handle will make it attempt to perform HTTP
Pipelining as far as possible for transfers using this handle. This means
that if you add a second request that can use an already existing
connection, the second request will be "piped" on the same
connection rather than being executed in parallel. (Added in 7.16.0)
- CURLMOPT_TIMERFUNCTION
- Pass a pointer to a function matching the
curl_multi_timer_callback prototype. This function will then be
called when the timeout value changes. The timeout value is at what latest
time the application should call one of the "performing"
functions of the multi interface ( curl_multi_socket_action(3) and
curl_multi_perform(3)) - to allow libcurl to keep timeouts and
retries etc to work. A timeout value of -1 means that there is no timeout
at all, and 0 means that the timeout is already reached. Libcurl attempts
to limit calling this only when the fixed future timeout time actually
changes. See also CURLMOPT_TIMERDATA. This callback can be used
instead of, or in addition to, curl_multi_timeout(3). (Added in
7.16.0)
- CURLMOPT_TIMERDATA
- Pass a pointer to whatever you want passed to the
curl_multi_timer_callback's third argument, the userp pointer. This
is not used by libcurl but only passed-thru as-is. Set the callback
pointer with CURLMOPT_TIMERFUNCTION. (Added in 7.16.0)
- CURLMOPT_MAXCONNECTS
- Pass a long. The set number will be used as the maximum
amount of simultaneously open connections that libcurl may cache. Default
is 10, and libcurl will enlarge the size for each added easy handle to
make it fit 4 times the number of added easy handles.
By setting this option, you can prevent the cache size from growing beyond
the limit set by you.
When the cache is full, curl closes the oldest one in the cache to prevent
the number of open connections from increasing.
This option is for the multi handle's use only, when using the easy
interface you should instead use the CURLOPT_MAXCONNECTS option.
(Added in 7.16.3)
RETURNS¶
The standard CURLMcode for multi interface error codes. Note that it returns a
CURLM_UNKNOWN_OPTION if you try setting an option that this version of libcurl
doesn't know of.
AVAILABILITY¶
This function was added in libcurl 7.15.4.
SEE ALSO¶
curl_multi_cleanup(3),
curl_multi_init(3),
curl_multi_socket(3),
curl_multi_info_read(3)