160 lines
6.7 KiB
Groff
160 lines
6.7 KiB
Groff
.\" **************************************************************************
|
|
.\" * _ _ ____ _
|
|
.\" * Project ___| | | | _ \| |
|
|
.\" * / __| | | | |_) | |
|
|
.\" * | (__| |_| | _ <| |___
|
|
.\" * \___|\___/|_| \_\_____|
|
|
.\" *
|
|
.\" * Copyright (C) 1998 - 2018, 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 3 "9 Jul 2006" "libcurl 7.16.0" "libcurl Manual"
|
|
.SH NAME
|
|
curl_multi_socket \- reads/writes available data
|
|
.SH SYNOPSIS
|
|
.nf
|
|
#include <curl/curl.h>
|
|
CURLMcode curl_multi_socket(CURLM * multi_handle, curl_socket_t sockfd,
|
|
int *running_handles);
|
|
|
|
CURLMcode curl_multi_socket_all(CURLM *multi_handle,
|
|
int *running_handles);
|
|
.fi
|
|
.SH DESCRIPTION
|
|
These functions are deprecated. Do not use! See
|
|
\fIcurl_multi_socket_action(3)\fP instead!
|
|
|
|
At return, the integer \fBrunning_handles\fP points to will contain the number
|
|
of still running easy handles within the multi handle. When this number
|
|
reaches zero, all transfers are complete/done. Note that 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 functions inform 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.
|
|
|
|
Usage of \fIcurl_multi_socket(3)\fP is deprecated, whereas the function is
|
|
equivalent to \fIcurl_multi_socket_action(3)\fP with \fBev_bitmask\fP set to
|
|
0.
|
|
|
|
Force libcurl to (re-)check all its internal sockets and transfers instead of
|
|
just a single one by calling \fIcurl_multi_socket_all(3)\fP. Note that there
|
|
should not be any reason to use this function!
|
|
.SH "CALLBACK DETAILS"
|
|
|
|
The socket \fBcallback\fP function uses a prototype like this
|
|
.nf
|
|
|
|
int curl_socket_callback(CURL *easy, /* easy handle */
|
|
curl_socket_t s, /* socket */
|
|
int action, /* see values below */
|
|
void *userp, /* private callback pointer */
|
|
void *socketp); /* private socket pointer */
|
|
|
|
.fi
|
|
The callback MUST return 0.
|
|
|
|
The \fIeasy\fP argument is a pointer to the easy handle that deals with this
|
|
particular socket. Note that a single handle may work with several sockets
|
|
simultaneously.
|
|
|
|
The \fIs\fP argument is the actual socket value as you use it within your
|
|
system.
|
|
|
|
The \fIaction\fP argument to the callback has one of five values:
|
|
.RS
|
|
.IP "CURL_POLL_NONE (0)"
|
|
register, not interested in readiness (yet)
|
|
.IP "CURL_POLL_IN (1)"
|
|
register, interested in read readiness
|
|
.IP "CURL_POLL_OUT (2)"
|
|
register, interested in write readiness
|
|
.IP "CURL_POLL_INOUT (3)"
|
|
register, interested in both read and write readiness
|
|
.IP "CURL_POLL_REMOVE (4)"
|
|
unregister
|
|
.RE
|
|
|
|
The \fIsocketp\fP argument is a private pointer you have previously set with
|
|
\fIcurl_multi_assign(3)\fP to be associated with the \fIs\fP socket. If no
|
|
pointer has been set, socketp will be NULL. This argument is of course a
|
|
service to applications that want to keep certain data or structs that are
|
|
strictly associated to the given socket.
|
|
|
|
The \fIuserp\fP argument is a private pointer you have previously set with
|
|
\fIcurl_multi_setopt(3)\fP and the \fICURLMOPT_SOCKETDATA(3)\fP option.
|
|
.SH "RETURN VALUE"
|
|
CURLMcode type, general libcurl multi interface error code.
|
|
|
|
Legacy: If you receive \fICURLM_CALL_MULTI_PERFORM\fP, this basically means
|
|
that you should call \fIcurl_multi_socket(3)\fP again, before you wait for
|
|
more actions on libcurl's sockets. You don't have to do it immediately, but
|
|
the return code means that libcurl may have more data available to return or
|
|
that there may be more data to send off before it is "satisfied".
|
|
|
|
In modern libcurls, \fICURLM_CALL_MULTI_PERFORM\fP or
|
|
\fICURLM_CALL_MULTI_SOCKET\fP should not be returned and no application needs
|
|
to care about them.
|
|
|
|
NOTE that the return code is for the whole multi stack. Problems still might have
|
|
occurred on individual transfers even when one of these functions
|
|
return OK.
|
|
.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. Wait for activity on any of libcurl's sockets, use the timeout value your
|
|
callback has been told
|
|
|
|
7, 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
|
|
|
|
8. Go back to step 6.
|
|
.SH AVAILABILITY
|
|
This function was added in libcurl 7.15.4, and is deemed stable since
|
|
7.16.0.
|
|
|
|
\fIcurl_multi_socket(3)\fP is deprecated, use
|
|
\fIcurl_multi_socket_action(3)\fP instead!
|
|
.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"
|