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 fourth 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: int curl_multi_timer_callback(CURLM *multi /* multi handle */,
long timeout_ms /* timeout in milliseconds */, void *userp /* TIMERDATA
*/). 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. The callback should return 0 on success, and -1
on error. 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 keep in its connection
cache after completed use. By default 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(3) option.
See CURLMOPT_MAX_TOTAL_CONNECTIONS for limiting the number of active
connections.
(Added in 7.16.3)
- CURLMOPT_MAX_HOST_CONNECTIONS
- Pass a long. The set number will be used as the maximum amount of
simultaneously open connections to a single host. For each new session to
a host, libcurl will open a new connection up to the limit set by
CURLMOPT_MAX_HOST_CONNECTIONS. When the limit is reached, the sessions
will be pending until there are available connections. If
CURLMOPT_PIPELINING is 1, libcurl will try to pipeline if the host is
capable of it.
The default value is 0, which means that there is no limit. However, for
backwards compatibility, setting it to 0 when CURLMOPT_PIPELINING is 1
will not be treated as unlimited. Instead it will open only 1 connection
and try to pipeline on it.
(Added in 7.30.0)
- CURLMOPT_MAX_PIPELINE_LENGTH
- Pass a long. The set number will be used as the maximum amount of requests
in a pipelined connection. When this limit is reached, libcurl will use
another connection to the same host (see CURLMOPT_MAX_HOST_CONNECTIONS),
or queue the requests until one of the pipelines to the host is ready to
accept a request. Thus, the total number of requests in-flight is
CURLMOPT_MAX_HOST_CONNECTIONS * CURLMOPT_MAX_PIPELINE_LENGTH. The default
value is 5.
(Added in 7.30.0)
- CURLMOPT_CONTENT_LENGTH_PENALTY_SIZE
- Pass a long. If a pipelined connection is currently processing a request
with a Content-Length larger than CURLMOPT_CONTENT_LENGTH_PENALTY_SIZE,
that connection will not be considered for additional requests, even if it
is shorter than CURLMOPT_MAX_PIPELINE_LENGTH. The default value is 0,
which means that the penalization is inactive.
(Added in 7.30.0)
- CURLMOPT_CHUNK_LENGTH_PENALTY_SIZE
- Pass a long. If a pipelined connection is currently processing a chunked
(Transfer-encoding: chunked) request with a current chunk length larger
than CURLMOPT_CHUNK_LENGTH_PENALTY_SIZE, that connection will not be
considered for additional requests, even if it is shorter than
CURLMOPT_MAX_PIPELINE_LENGTH. The default value is 0, which means that the
penalization is inactive.
(Added in 7.30.0)
- CURLMOPT_PIPELINING_SITE_BL
- Pass an array of char *, ending with NULL. This is a list of sites that
are blacklisted from pipelining, i.e sites that are known to not support
HTTP pipelining. The array is copied by libcurl.
The default value is NULL, which means that there is no blacklist.
Pass a NULL pointer to clear the blacklist.
Example:
site_blacklist[] =
{
"www.haxx.se",
"www.example.com:1234",
NULL
};
curl_multi_setopt(m, CURLMOPT_PIPELINE_SITE_BL, site_blacklist);
(Added in 7.30.0)
- CURLMOPT_PIPELINING_SERVER_BL
- Pass an array of char *, ending with NULL. This is a list of server types
prefixes (in the Server: HTTP header) that are blacklisted from
pipelining, i.e server types that are known to not support HTTP
pipelining. The array is copied by libcurl.
Note that the comparison matches if the Server: header begins with the
string in the blacklist, i.e "Server: Ninja 1.2.3" and
"Server: Ninja 1.4.0" can both be blacklisted by having
"Ninja" in the backlist.
The default value is NULL, which means that there is no blacklist.
Pass a NULL pointer to clear the blacklist.
Example:
server_blacklist[] =
{
"Microsoft-IIS/6.0",
"nginx/0.8.54",
NULL
};
curl_multi_setopt(m, CURLMOPT_PIPELINE_SERVER_BL, server_blacklist);
(Added in 7.30.0)
- CURLMOPT_MAX_TOTAL_CONNECTIONS
- Pass a long. The set number will be used as the maximum amount of
simultaneously open connections in total. For each new session, libcurl
will open a new connection up to the limit set by
CURLMOPT_MAX_TOTAL_CONNECTIONS. When the limit is reached, the sessions
will be pending until there are available connections. If
CURLMOPT_PIPELINING is 1, libcurl will try to pipeline if the host is
capable of it.
The default value is 0, which means that there is no limit. However, for
backwards compatibility, setting it to 0 when CURLMOPT_PIPELINING is 1
will not be treated as unlimited. Instead it will open only 1 connection
and try to pipeline on it.
(Added in 7.30.0)
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)