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0f147887b0
Introducing a number of options to the multi interface that allows for multiple pipelines to the same host, in order to optimize the balance between the penalty for opening new connections and the potential pipelining latency. Two new options for limiting the number of connections: CURLMOPT_MAX_HOST_CONNECTIONS - Limits the number of running connections to the same host. When adding a handle that exceeds this limit, that handle will be put in a pending state until another handle is finished, so we can reuse the connection. CURLMOPT_MAX_TOTAL_CONNECTIONS - Limits the number of connections in total. When adding a handle that exceeds this limit, that handle will be put in a pending state until another handle is finished. The free connection will then be reused, if possible, or closed if the pending handle can't reuse it. Several new options for pipelining: CURLMOPT_MAX_PIPELINE_LENGTH - Limits the pipeling length. If a pipeline is "full" when a connection is to be reused, a new connection will be opened if the CURLMOPT_MAX_xxx_CONNECTIONS limits allow it. If not, the handle will be put in a pending state until a connection is ready (either free or a pipe got shorter). CURLMOPT_CONTENT_LENGTH_PENALTY_SIZE - A pipelined connection will not be reused if it is currently processing a transfer with a content length that is larger than this. CURLMOPT_CHUNK_LENGTH_PENALTY_SIZE - A pipelined connection will not be reused if it is currently processing a chunk larger than this. CURLMOPT_PIPELINING_SITE_BL - A blacklist of hosts that don't allow pipelining. CURLMOPT_PIPELINING_SERVER_BL - A blacklist of server types that don't allow pipelining. See the curl_multi_setopt() man page for details.
213 lines
9.4 KiB
Groff
213 lines
9.4 KiB
Groff
.\" **************************************************************************
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.\" * _ _ ____ _
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.\" * Project ___| | | | _ \| |
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.\" * / __| | | | |_) | |
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.\" * | (__| |_| | _ <| |___
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.\" * \___|\___/|_| \_\_____|
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.\" *
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.\" * Copyright (C) 1998 - 2011, Daniel Stenberg, <daniel@haxx.se>, et al.
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.\" *
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.\" * This software is licensed as described in the file COPYING, which
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.\" * you should have received as part of this distribution. The terms
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.\" * are also available at http://curl.haxx.se/docs/copyright.html.
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.\" *
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.\" * You may opt to use, copy, modify, merge, publish, distribute and/or sell
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.\" * copies of the Software, and permit persons to whom the Software is
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.\" * furnished to do so, under the terms of the COPYING file.
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.\" *
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.\" * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
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.\" * KIND, either express or implied.
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.\" *
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.\" **************************************************************************
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.TH curl_multi_setopt 3 "10 Oct 2006" "libcurl 7.16.0" "libcurl Manual"
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.SH NAME
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curl_multi_setopt \- set options for a curl multi handle
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.SH SYNOPSIS
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#include <curl/curl.h>
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CURLMcode curl_multi_setopt(CURLM * multi_handle, CURLMoption option, param);
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.SH DESCRIPTION
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curl_multi_setopt() is used to tell a libcurl multi handle how to behave. By
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using the appropriate options to \fIcurl_multi_setopt(3)\fP, you can change
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libcurl's behaviour when using that multi handle. All options are set with
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the \fIoption\fP followed by the parameter \fIparam\fP. That parameter can be
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a \fBlong\fP, a \fBfunction pointer\fP, an \fBobject pointer\fP or a
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\fBcurl_off_t\fP type, depending on what the specific option expects. Read
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this manual carefully as bad input values may cause libcurl to behave badly!
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You can only set one option in each function call.
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.SH OPTIONS
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.IP CURLMOPT_SOCKETFUNCTION
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Pass a pointer to a function matching the \fBcurl_socket_callback\fP
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prototype. The \fIcurl_multi_socket_action(3)\fP function informs the
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application about updates in the socket (file descriptor) status by doing
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none, one, or multiple calls to the curl_socket_callback given in the
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\fBparam\fP argument. They update the status with changes since the previous
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time a \fIcurl_multi_socket(3)\fP function was called. If the given callback
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pointer is NULL, no callback will be called. Set the callback's \fBuserp\fP
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argument with \fICURLMOPT_SOCKETDATA\fP. See \fIcurl_multi_socket(3)\fP for
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more callback details.
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.IP CURLMOPT_SOCKETDATA
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Pass a pointer to whatever you want passed to the \fBcurl_socket_callback\fP's
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fourth argument, the userp pointer. This is not used by libcurl but only
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passed-thru as-is. Set the callback pointer with
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\fICURLMOPT_SOCKETFUNCTION\fP.
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.IP CURLMOPT_PIPELINING
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Pass a long set to 1 to enable or 0 to disable. Enabling pipelining on a multi
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handle will make it attempt to perform HTTP Pipelining as far as possible for
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transfers using this handle. This means that if you add a second request that
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can use an already existing connection, the second request will be \&"piped"
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on the same connection rather than being executed in parallel. (Added in
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7.16.0)
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.IP CURLMOPT_TIMERFUNCTION
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Pass a pointer to a function matching the \fBcurl_multi_timer_callback\fP
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prototype: int curl_multi_timer_callback(CURLM *multi /* multi handle */,
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long timeout_ms /* timeout in milliseconds */, void *userp /* TIMERDATA */).
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This function will then be called when the timeout value
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changes. The timeout value is at what latest time the application should call
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one of the \&"performing" functions of the multi interface
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(\fIcurl_multi_socket_action(3)\fP and \fIcurl_multi_perform(3)\fP) - to allow
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libcurl to keep timeouts and retries etc to work. A timeout value of -1 means
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that there is no timeout at all, and 0 means that the timeout is already
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reached. Libcurl attempts to limit calling this only when the fixed future
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timeout time actually changes. See also \fICURLMOPT_TIMERDATA\fP. The callback
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should return 0 on success, and -1 on error. This
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callback can be used instead of, or in addition to,
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\fIcurl_multi_timeout(3)\fP. (Added in 7.16.0)
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.IP CURLMOPT_TIMERDATA
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Pass a pointer to whatever you want passed to the
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\fBcurl_multi_timer_callback\fP's third argument, the userp pointer. This is
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not used by libcurl but only passed-thru as-is. Set the callback pointer with
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\fICURLMOPT_TIMERFUNCTION\fP. (Added in 7.16.0)
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.IP CURLMOPT_MAXCONNECTS
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Pass a long. The set number will be used as the maximum amount of
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simultaneously open connections that libcurl may cache. Default is 10, and
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libcurl will enlarge the size for each added easy handle to make it fit 4
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times the number of added easy handles.
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By setting this option, you can prevent the cache size from growing beyond the
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limit set by you.
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When the cache is full, curl closes the oldest one in the cache to prevent the
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number of open connections from increasing.
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This option is for the multi handle's use only, when using the easy interface
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you should instead use the \fICURLOPT_MAXCONNECTS\fP option.
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(Added in 7.16.3)
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.IP CURLMOPT_MAX_HOST_CONNECTIONS
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Pass a long. The set number will be used as the maximum amount of
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simultaneously open connections to a single host. For each new session to
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a host, libcurl will open a new connection up to the limit set by
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CURLMOPT_MAX_HOST_CONNECTIONS. When the limit is reached, the sessions will
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be pending until there are available connections. If CURLMOPT_PIPELINING is
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1, libcurl will try to pipeline if the host is capable of it.
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The default value is 0, which means that there is no limit.
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However, for backwards compatibility, setting it to 0 when CURLMOPT_PIPELINING
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is 1 will not be treated as unlimited. Instead it will open only 1 connection
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and try to pipeline on it.
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(Added in 7.30.0)
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.IP CURLMOPT_MAX_PIPELINE_LENGTH
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Pass a long. The set number will be used as the maximum amount of requests
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in a pipelined connection. When this limit is reached, libcurl will use another
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connection to the same host (see CURLMOPT_MAX_HOST_CONNECTIONS), or queue the
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requests until one of the pipelines to the host is ready to accept a request.
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Thus, the total number of requests in-flight is CURLMOPT_MAX_HOST_CONNECTIONS *
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CURLMOPT_MAX_PIPELINE_LENGTH.
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The default value is 5.
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(Added in 7.30.0)
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.IP CURLMOPT_CONTENT_LENGTH_PENALTY_SIZE
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Pass a long. If a pipelined connection is currently processing a request
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with a Content-Length larger than CURLMOPT_CONTENT_LENGTH_PENALTY_SIZE, that
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connection will not be considered for additional requests, even if it is
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shorter than CURLMOPT_MAX_PIPELINE_LENGTH.
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The default value is 0, which means that the penalization is inactive.
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(Added in 7.30.0)
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.IP CURLMOPT_CHUNK_LENGTH_PENALTY_SIZE
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Pass a long. If a pipelined connection is currently processing a
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chunked (Transfer-encoding: chunked) request with a current chunk length
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larger than CURLMOPT_CHUNK_LENGTH_PENALTY_SIZE, that connection will not be
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considered for additional requests, even if it is shorter than
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CURLMOPT_MAX_PIPELINE_LENGTH.
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The default value is 0, which means that the penalization is inactive.
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(Added in 7.30.0)
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.IP CURLMOPT_PIPELINING_SITE_BL
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Pass an array of char *, ending with NULL. This is a list of sites that are
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blacklisted from pipelining, i.e sites that are known to not support HTTP
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pipelining. The array is copied by libcurl.
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The default value is NULL, which means that there is no blacklist.
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Pass a NULL pointer to clear the blacklist.
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Example:
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.nf
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site_blacklist[] =
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{
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"www.haxx.se",
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"www.example.com:1234",
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NULL
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};
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curl_multi_setopt(m, CURLMOPT_PIPELINE_SITE_BL, site_blacklist);
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.fi
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(Added in 7.30.0)
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.IP CURLMOPT_PIPELINING_SERVER_BL
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Pass an array of char *, ending with NULL. This is a list of server types
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prefixes (in the Server: HTTP header) that are blacklisted from pipelining,
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i.e server types that are known to not support HTTP pipelining. The array is
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copied by libcurl.
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Note that the comparison matches if the Server: header begins with the string
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in the blacklist, i.e "Server: Ninja 1.2.3" and "Server: Ninja 1.4.0" can
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both be blacklisted by having "Ninja" in the backlist.
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The default value is NULL, which means that there is no blacklist.
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Pass a NULL pointer to clear the blacklist.
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Example:
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.nf
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server_blacklist[] =
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{
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"Microsoft-IIS/6.0",
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"nginx/0.8.54",
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NULL
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};
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curl_multi_setopt(m, CURLMOPT_PIPELINE_SERVER_BL, server_blacklist);
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.fi
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(Added in 7.30.0)
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.IP CURLMOPT_MAX_TOTAL_CONNECTIONS
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Pass a long. The set number will be used as the maximum amount of
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simultaneously open connections in total. For each new session, libcurl
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will open a new connection up to the limit set by
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CURLMOPT_MAX_TOTAL_CONNECTIONS. When the limit is reached, the sessions will
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be pending until there are available connections. If CURLMOPT_PIPELINING is
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1, libcurl will try to pipeline if the host is capable of it.
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The default value is 0, which means that there is no limit.
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However, for backwards compatibility, setting it to 0 when CURLMOPT_PIPELINING
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is 1 will not be treated as unlimited. Instead it will open only 1 connection
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and try to pipeline on it.
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(Added in 7.30.0)
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.SH RETURNS
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The standard CURLMcode for multi interface error codes. Note that it returns a
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CURLM_UNKNOWN_OPTION if you try setting an option that this version of libcurl
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doesn't know of.
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.SH AVAILABILITY
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This function was added in libcurl 7.15.4.
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.SH "SEE ALSO"
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.BR curl_multi_cleanup "(3), " curl_multi_init "(3), "
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.BR curl_multi_socket "(3), " curl_multi_info_read "(3)"
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