Ubuntu Manpage: curl_multi_setopt - set options for a curl multi handle

Provided by: libcurl4-doc_7.35.0-1ubuntu2.20_all

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.

(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.

NAME

SYNOPSIS

DESCRIPTION

OPTIONS

RETURNS

AVAILABILITY

SEE ALSO