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+.\" **************************************************************************
+.\" *                                  _   _ ____  _
+.\" *  Project                     ___| | | |  _ \| |
+.\" *                             / __| | | | |_) | |
+.\" *                            | (__| |_| |  _ <| |___
+.\" *                             \___|\___/|_| \_\_____|
+.\" *
+.\" * Copyright (C) 1998 - 2019, Daniel Stenberg, <daniel@haxx.se>, et al.
+.\" *
+.\" * This software is licensed as described in the file COPYING, which
+.\" * you should have received as part of this distribution. The terms
+.\" * are also available at https://curl.haxx.se/docs/copyright.html.
+.\" *
+.\" * You may opt to use, copy, modify, merge, publish, distribute and/or sell
+.\" * copies of the Software, and permit persons to whom the Software is
+.\" * furnished to do so, under the terms of the COPYING file.
+.\" *
+.\" * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+.\" * KIND, either express or implied.
+.\" *
+.\" **************************************************************************
+.TH curl_multi_socket_action 3 "9 Jul 2006" "libcurl 7.16.0" "libcurl Manual"
+.SH NAME
+curl_multi_socket_action \- reads/writes available data given an action
+.SH SYNOPSIS
+.nf
+#include <curl/curl.h>
+
+CURLMcode curl_multi_socket_action(CURLM * multi_handle,
+                                   curl_socket_t sockfd,
+                                   int ev_bitmask,
+                                   int *running_handles);
+.fi
+.SH DESCRIPTION
+When the application has detected action on a socket handled by libcurl, it
+should call \fIcurl_multi_socket_action(3)\fP with the \fBsockfd\fP argument
+set to the socket with the action. When the events on a socket are known, they
+can be passed as an events bitmask \fBev_bitmask\fP by first setting
+\fBev_bitmask\fP to 0, and then adding using bitwise OR (|) any combination of
+events to be chosen from CURL_CSELECT_IN, CURL_CSELECT_OUT or
+CURL_CSELECT_ERR. When the events on a socket are unknown, pass 0 instead, and
+libcurl will test the descriptor internally. It is also permissible to pass
+CURL_SOCKET_TIMEOUT to the \fBsockfd\fP parameter in order to initiate the
+whole process or when a timeout occurs.
+
+At return, \fBrunning_handles\fP points to the number of running easy handles
+within the multi handle. When this number reaches zero, all transfers are
+complete/done. When you call \fIcurl_multi_socket_action(3)\fP on a specific
+socket and the counter decreases by one, it DOES NOT necessarily mean that
+this exact socket/transfer is the one that completed. Use
+\fIcurl_multi_info_read(3)\fP to figure out which easy handle that completed.
+
+The \fIcurl_multi_socket_action(3)\fP function informs the application about
+updates in the socket (file descriptor) status by doing none, one, or multiple
+calls to the socket callback function set with the
+\fICURLMOPT_SOCKETFUNCTION(3)\fP option to \fIcurl_multi_setopt(3)\fP. They
+update the status with changes since the previous time the callback was
+called.
+
+Get the timeout time by setting the \fICURLMOPT_TIMERFUNCTION(3)\fP option
+with \fIcurl_multi_setopt(3)\fP. Your application will then get called with
+information on how long to wait for socket actions at most before doing the
+timeout action: call the \fIcurl_multi_socket_action(3)\fP function with the
+\fBsockfd\fP argument set to CURL_SOCKET_TIMEOUT. You can also use the
+\fIcurl_multi_timeout(3)\fP function to poll the value at any given time, but
+for an event-based system using the callback is far better than relying on
+polling the timeout value.
+.SH "TYPICAL USAGE"
+1. Create a multi handle
+
+2. Set the socket callback with \fICURLMOPT_SOCKETFUNCTION(3)\fP
+
+3. Set the timeout callback with \fICURLMOPT_TIMERFUNCTION(3)\fP, to get to
+know what timeout value to use when waiting for socket activities.
+
+4. Add easy handles with curl_multi_add_handle()
+
+5. Provide some means to manage the sockets libcurl is using, so you can check
+them for activity. This can be done through your application code, or by way
+of an external library such as libevent or glib.
+
+6. Call curl_multi_socket_action(..., CURL_SOCKET_TIMEOUT, 0, ...)
+to kickstart everything. To get one or more callbacks called.
+
+7. Wait for activity on any of libcurl's sockets, use the timeout value your
+callback has been told.
+
+8, When activity is detected, call curl_multi_socket_action() for the
+socket(s) that got action. If no activity is detected and the timeout expires,
+call \fIcurl_multi_socket_action(3)\fP with \fICURL_SOCKET_TIMEOUT\fP.
+.SH AVAILABILITY
+This function was added in libcurl 7.15.4, and is deemed stable since 7.16.0.
+.SH "SEE ALSO"
+.BR curl_multi_cleanup "(3), " curl_multi_init "(3), "
+.BR curl_multi_fdset "(3), " curl_multi_info_read "(3), "
+.BR "the hiperfifo.c example"