mirror of
https://github.com/moparisthebest/curl
synced 2024-11-06 01:25:33 -05:00
154 lines
6.4 KiB
Groff
154 lines
6.4 KiB
Groff
.\" $Id$
|
|
.\"
|
|
.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_action(CURLM * multi_handle,
|
|
curl_socket_t sockfd, int ev_bitmask,
|
|
int *running_handles);
|
|
|
|
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
|
|
Alternative versions of \fIcurl_multi_perform(3)\fP that allows the
|
|
application to pass in the file descriptor/socket that has been detected to
|
|
have \&"action" on it and let libcurl perform. This allows libcurl to not have
|
|
to scan through all possible file descriptors to check for action. 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.
|
|
|
|
At return, the int \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 curl_multi_socket 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 CURLMOPT_SOCKETFUNCTION option to
|
|
\fIcurl_multi_setopt(3)\fP. They update the status with changes since the
|
|
previous time this function was called.
|
|
|
|
Force libcurl to (re-)check all its internal sockets and transfers instead of
|
|
just a single one by calling \fBcurl_multi_socket_all(3)\fP. This is typically
|
|
done as the first function call before the application has any knowledge about
|
|
what sockets libcurl uses.
|
|
|
|
Get the timeout time - how long to wait for socket actions at most before
|
|
doing the timeout action: call the \fBcurl_multi_socket(3)\fP function with
|
|
the \fBsockfd\fP argument set to CURL_SOCKET_TIMEOUT, by setting the
|
|
\fICURLMOPT_TIMERFUNCTION\fP option with \fIcurl_multi_setopt(3)\fP. 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, when \fBev_bitmask\fP is set
|
|
to 0.
|
|
|
|
.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 CURLMOPT_SOCKETDATA option.
|
|
.SH "RETURN VALUE"
|
|
CURLMcode type, general libcurl multi interface error code.
|
|
|
|
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".
|
|
|
|
NOTE that this only returns errors etc regarding the whole multi stack. There
|
|
might still have occurred problems on individual transfers even when this
|
|
function returns OK.
|
|
.SH "TYPICAL USAGE"
|
|
1. Create a multi handle
|
|
|
|
2. Set the socket callback with CURLMOPT_SOCKETFUNCTION
|
|
|
|
3. Set the timeout callback with CURLMOPT_TIMERFUNCTION, to get to know what
|
|
timeout value to use when waiting for socket activities.
|
|
|
|
4. Add easy handles
|
|
|
|
5. Call curl_multi_socket_all() first once
|
|
|
|
6. 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.
|
|
|
|
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(3)\fP with \fICURL_SOCKET_TIMEOUT\fP
|
|
|
|
9. Go back to step 7.
|
|
.SH AVAILABILITY
|
|
This function was added in libcurl 7.15.4, although 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"
|