eefcc1bda4
curldown is this new file format for libcurl man pages. It is markdown inspired with differences: - Each file has a set of leading headers with meta-data - Supports a small subset of markdown - Uses .md file extensions for editors/IDE/GitHub to treat them nicely - Generates man pages very similar to the previous ones - Generates man pages that still convert nicely to HTML on the website - Detects and highlights mentions of curl symbols automatically (when their man page section is specified) tools: - cd2nroff: converts from curldown to nroff man page - nroff2cd: convert an (old) nroff man page to curldown - cdall: convert many nroff pages to curldown versions - cd2cd: verifies and updates a curldown to latest curldown This setup generates .3 versions of all the curldown versions at build time. CI: Since the documentation is now technically markdown in the eyes of many things, the CI runs many more tests and checks on this documentation, including proselint, link checkers and tests that make sure we capitalize the first letter after a period... Closes #12730
129 lines
3.4 KiB
Markdown
129 lines
3.4 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_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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---
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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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