90 lines
2.4 KiB
Markdown
90 lines
2.4 KiB
Markdown
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c: Copyright (C) Daniel Stenberg, <daniel.se>, et al.
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SPDX-License-Identifier: curl
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Title: curl_multi_timeout
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Section: 3
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Source: libcurl
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See-also:
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- curl_multi_fdset (3)
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- curl_multi_info_read (3)
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- curl_multi_setopt (3)
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- curl_multi_socket (3)
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---
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# NAME
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curl_multi_timeout - how long to wait for action before proceeding
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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_timeout(CURLM *multi_handle, long *timeout);
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~~~
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# DESCRIPTION
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An application using the libcurl multi interface should call
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curl_multi_timeout(3) to figure out how long it should wait for socket
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actions - at most - before proceeding.
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Proceeding means either doing the socket-style timeout action: call the
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curl_multi_socket_action(3) function with the **sockfd** argument set
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to CURL_SOCKET_TIMEOUT, or call curl_multi_perform(3) if you are using
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the simpler and older multi interface approach.
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The timeout value returned in the long **timeout** points to, is in number
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of milliseconds at this moment. If 0, it means you should proceed immediately
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without waiting for anything. If it returns -1, there is no timeout at all set.
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An application that uses the *multi_socket* API should not use this function.
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It should instead use the CURLMOPT_TIMERFUNCTION(3) option for proper and
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desired behavior.
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Note: if libcurl returns a -1 timeout here, it just means that libcurl
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currently has no stored timeout value. You must not wait too long (more than a
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few seconds perhaps) before you call curl_multi_perform(3) again.
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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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struct timeval timeout;
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long timeo;
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fd_set fdread;
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fd_set fdwrite;
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fd_set fdexcep;
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int maxfd;
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CURLM *multi = curl_multi_init();
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curl_multi_timeout(multi, &timeo);
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if(timeo < 0)
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/* no set timeout, use a default */
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timeo = 980;
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timeout.tv_sec = timeo / 1000;
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timeout.tv_usec = (timeo % 1000) * 1000;
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/* wait for activities no longer than the set timeout */
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select(maxfd + 1, &fdread, &fdwrite, &fdexcep, &timeout);
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}
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~~~
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# TYPICAL USAGE
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Call curl_multi_timeout(3), then wait for action on the sockets. Figure
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out which sockets to wait for by calling curl_multi_fdset(3).
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When there is activity or timeout, call curl_multi_perform(3) and then
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loop - until all transfers are complete.
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# AVAILABILITY
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This function was added in libcurl 7.15.4.
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# RETURN VALUE
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The standard CURLMcode for multi interface error codes.
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