trusty (3) curl_multi_setopt.3.gz
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 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)
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)