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160 lines
6.7 KiB
Groff
160 lines
6.7 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 - 2018, 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 https://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_socket 3 "9 Jul 2006" "libcurl 7.16.0" "libcurl Manual"
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.SH NAME
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curl_multi_socket \- reads/writes available data
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.SH SYNOPSIS
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.nf
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#include <curl/curl.h>
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CURLMcode curl_multi_socket(CURLM * multi_handle, curl_socket_t sockfd,
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int *running_handles);
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CURLMcode curl_multi_socket_all(CURLM *multi_handle,
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int *running_handles);
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.fi
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.SH DESCRIPTION
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These functions are deprecated. Do not use! See
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\fIcurl_multi_socket_action(3)\fP instead!
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At return, the integer \fBrunning_handles\fP points to will contain the number
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of still running easy handles within the multi handle. When this number
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reaches zero, all transfers are complete/done. Note that when you call
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\fIcurl_multi_socket_action(3)\fP on a specific socket and the counter
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decreases by one, it DOES NOT necessarily mean that this exact socket/transfer
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is the one that completed. Use \fIcurl_multi_info_read(3)\fP to figure out
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which easy handle that completed.
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The \fIcurl_multi_socket_action(3)\fP functions inform the application about
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updates in the socket (file descriptor) status by doing none, one, or multiple
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calls to the socket callback function set with the
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\fICURLMOPT_SOCKETFUNCTION(3)\fP option to \fIcurl_multi_setopt(3)\fP. They
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update the status with changes since the previous time the callback was
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called.
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Get the timeout time by setting the \fICURLMOPT_TIMERFUNCTION(3)\fP option
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with \fIcurl_multi_setopt(3)\fP. Your application will then get called with
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information on how long to wait for socket actions at most before doing the
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timeout action: call the \fIcurl_multi_socket_action(3)\fP function with the
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\fBsockfd\fP argument set to CURL_SOCKET_TIMEOUT. You can also use the
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\fIcurl_multi_timeout(3)\fP function to poll the value at any given time, but
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for an event-based system using the callback is far better than relying on
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polling the timeout value.
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Usage of \fIcurl_multi_socket(3)\fP is deprecated, whereas the function is
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equivalent to \fIcurl_multi_socket_action(3)\fP with \fBev_bitmask\fP set to
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0.
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Force libcurl to (re-)check all its internal sockets and transfers instead of
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just a single one by calling \fIcurl_multi_socket_all(3)\fP. Note that there
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should not be any reason to use this function!
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.SH "CALLBACK DETAILS"
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The socket \fBcallback\fP function uses a prototype like this
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.nf
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int curl_socket_callback(CURL *easy, /* easy handle */
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curl_socket_t s, /* socket */
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int action, /* see values below */
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void *userp, /* private callback pointer */
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void *socketp); /* private socket pointer */
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.fi
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The callback MUST return 0.
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The \fIeasy\fP argument is a pointer to the easy handle that deals with this
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particular socket. Note that a single handle may work with several sockets
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simultaneously.
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The \fIs\fP argument is the actual socket value as you use it within your
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system.
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The \fIaction\fP argument to the callback has one of five values:
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.RS
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.IP "CURL_POLL_NONE (0)"
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register, not interested in readiness (yet)
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.IP "CURL_POLL_IN (1)"
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register, interested in read readiness
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.IP "CURL_POLL_OUT (2)"
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register, interested in write readiness
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.IP "CURL_POLL_INOUT (3)"
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register, interested in both read and write readiness
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.IP "CURL_POLL_REMOVE (4)"
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unregister
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.RE
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The \fIsocketp\fP argument is a private pointer you have previously set with
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\fIcurl_multi_assign(3)\fP to be associated with the \fIs\fP socket. If no
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pointer has been set, socketp will be NULL. This argument is of course a
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service to applications that want to keep certain data or structs that are
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strictly associated to the given socket.
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The \fIuserp\fP argument is a private pointer you have previously set with
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\fIcurl_multi_setopt(3)\fP and the \fICURLMOPT_SOCKETDATA(3)\fP option.
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.SH "RETURN VALUE"
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CURLMcode type, general libcurl multi interface error code.
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Legacy: If you receive \fICURLM_CALL_MULTI_PERFORM\fP, this basically means
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that you should call \fIcurl_multi_socket(3)\fP again, before you wait for
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more actions on libcurl's sockets. You don't have to do it immediately, but
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the return code means that libcurl may have more data available to return or
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that there may be more data to send off before it is "satisfied".
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In modern libcurls, \fICURLM_CALL_MULTI_PERFORM\fP or
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\fICURLM_CALL_MULTI_SOCKET\fP should not be returned and no application needs
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to care about them.
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NOTE that the return code is for the whole multi stack. Problems still might have
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occurred on individual transfers even when one of these functions
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return OK.
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.SH "TYPICAL USAGE"
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1. Create a multi handle
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2. Set the socket callback with \fICURLMOPT_SOCKETFUNCTION(3)\fP
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3. Set the timeout callback with \fICURLMOPT_TIMERFUNCTION(3)\fP, to get to
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know what timeout value to use when waiting for socket activities.
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4. Add easy handles with curl_multi_add_handle()
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5. Provide some means to manage the sockets libcurl is using, so you can check
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them for activity. This can be done through your application code, or by way
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of an external library such as libevent or glib.
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6. Wait for activity on any of libcurl's sockets, use the timeout value your
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callback has been told
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7, When activity is detected, call curl_multi_socket_action() for the
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socket(s) that got action. If no activity is detected and the timeout expires,
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call \fIcurl_multi_socket_action(3)\fP with \fICURL_SOCKET_TIMEOUT\fP
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8. Go back to step 6.
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.SH AVAILABILITY
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This function was added in libcurl 7.15.4, and is deemed stable since
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7.16.0.
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\fIcurl_multi_socket(3)\fP is deprecated, use
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\fIcurl_multi_socket_action(3)\fP instead!
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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_fdset "(3), " curl_multi_info_read "(3), "
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.BR "the hiperfifo.c example"
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