78 lines
2.2 KiB
Markdown
78 lines
2.2 KiB
Markdown
---
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c: Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
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SPDX-License-Identifier: curl
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Title: CURLMOPT_MAX_HOST_CONNECTIONS
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Section: 3
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Source: libcurl
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See-also:
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- CURLMOPT_MAXCONNECTS (3)
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- CURLMOPT_MAX_TOTAL_CONNECTIONS (3)
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Protocol:
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- All
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Added-in: 7.30.0
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---
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# NAME
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CURLMOPT_MAX_HOST_CONNECTIONS - max number of connections to a single host
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# SYNOPSIS
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~~~c
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#include <curl/curl.h>
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CURLMcode curl_multi_setopt(CURLM *handle, CURLMOPT_MAX_HOST_CONNECTIONS,
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long max);
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~~~
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# DESCRIPTION
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Pass a long to indicate **max**, the maximum amount of simultaneously open
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connections libcurl may hold a single host (a host being the same as a
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hostname + port number pair). For each new transfer to the same host, libcurl
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might open a new connection up to the limit set by
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CURLMOPT_MAX_HOST_CONNECTIONS(3). When the limit is reached, new sessions are
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kept pending until a connection becomes available.
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The default **max** value is 0, unlimited. This set limit is also used for
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proxy connections, and then the proxy is considered to be the host for which
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this limit counts.
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When more transfers are added to the multi handle than what can be performed
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due to the set limit, they are queued up waiting for their chance.
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While a transfer is queued up internally waiting for a connection, the
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CURLOPT_TIMEOUT_MS(3) timeout is counted inclusive of the waiting time,
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meaning that if you set a too narrow timeout the transfer might never even
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start before it times out. The CURLOPT_CONNECTTIMEOUT_MS(3) time is also
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similarly still treated as a per-connect timeout and might expire even before
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making a new connection is permitted.
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Changing this value while there are transfers in progress is possible. The new
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value is then used the next time checks are performed. Lowering the value does
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not close down any active transfers, it simply does not allow new ones to get
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made.
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# DEFAULT
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0
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# %PROTOCOLS%
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# EXAMPLE
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~~~c
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int main(void)
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{
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CURLM *m = curl_multi_init();
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/* do no more than 2 connections per host */
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curl_multi_setopt(m, CURLMOPT_MAX_HOST_CONNECTIONS, 2L);
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}
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~~~
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# %AVAILABILITY%
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# RETURN VALUE
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Returns CURLM_OK if the option is supported, and CURLM_UNKNOWN_OPTION if not.
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