mirror of
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e3fe020089
Remove the PROTOCOLS section from the source files completely and instead generate them based on the header data in the curldown files. It also generates TLS backend information for options marked for TLS as protocol. Closes #13175
131 lines
3.4 KiB
Markdown
131 lines
3.4 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: curl_multi_poll
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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_perform (3)
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- curl_multi_wait (3)
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- curl_multi_wakeup (3)
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Protocol:
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- All
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---
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# NAME
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curl_multi_poll - polls on all easy handles in a multi handle
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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_poll(CURLM *multi_handle,
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struct curl_waitfd extra_fds[],
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unsigned int extra_nfds,
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int timeout_ms,
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int *numfds);
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~~~
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# DESCRIPTION
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curl_multi_poll(3) polls all file descriptors used by the curl easy
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handles contained in the given multi handle set. It blocks until activity is
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detected on at least one of the handles or *timeout_ms* has passed.
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Alternatively, if the multi handle has a pending internal timeout that has a
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shorter expiry time than *timeout_ms*, that shorter time is used instead
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to make sure timeout accuracy is reasonably kept.
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The calling application may pass additional curl_waitfd structures which are
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similar to *poll(2)*'s *pollfd* structure to be waited on in the same
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call.
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On completion, if *numfds* is non-NULL, it gets populated with the total
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number of file descriptors on which interesting events occurred. This number
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can include both libcurl internal descriptors as well as descriptors provided
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in *extra_fds*.
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The curl_multi_wakeup(3) function can be used from another thread to
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wake up this function and return faster. This is one of the details
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that makes this function different than curl_multi_wait(3) which cannot
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be woken up this way.
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If no extra file descriptors are provided and libcurl has no file descriptor
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to offer to wait for, this function instead waits during *timeout_ms*
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milliseconds (or shorter if an internal timer indicates so). This is the other
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detail that makes this function different than curl_multi_wait(3).
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This function is encouraged to be used instead of select(3) when using the
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multi interface to allow applications to easier circumvent the common problem
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with 1024 maximum file descriptors.
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# curl_waitfd
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~~~c
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struct curl_waitfd {
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curl_socket_t fd;
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short events;
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short revents;
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};
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~~~
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## CURL_WAIT_POLLIN
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Bit flag to curl_waitfd.events indicating the socket should poll on read
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events such as new data received.
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## CURL_WAIT_POLLPRI
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Bit flag to curl_waitfd.events indicating the socket should poll on high
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priority read events such as out of band data.
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## CURL_WAIT_POLLOUT
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Bit flag to curl_waitfd.events indicating the socket should poll on write
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events such as the socket being clear to write without blocking.
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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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CURL *easy_handle;
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CURLM *multi_handle;
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int still_running = 0;
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/* add the individual easy handle */
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curl_multi_add_handle(multi_handle, easy_handle);
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do {
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CURLMcode mc;
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int numfds;
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mc = curl_multi_perform(multi_handle, &still_running);
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if(mc == CURLM_OK) {
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/* wait for activity or timeout */
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mc = curl_multi_poll(multi_handle, NULL, 0, 1000, &numfds);
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}
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if(mc != CURLM_OK) {
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fprintf(stderr, "curl_multi failed, code %d.\n", mc);
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break;
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}
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} while(still_running);
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curl_multi_remove_handle(multi_handle, easy_handle);
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}
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~~~
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# AVAILABILITY
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Added in 7.66.0.
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# RETURN VALUE
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CURLMcode type, general libcurl multi interface error code. See
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libcurl-errors(3)
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