mirror of
https://github.com/moparisthebest/curl
synced 2024-11-17 23:15:08 -05:00
127 lines
5.0 KiB
Groff
127 lines
5.0 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
|
|
#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);
|
|
.SH DESCRIPTION
|
|
Alternative versions of \fIcurl_multi_perform(3)\fP that allows the
|
|
application to pass in one of the file descriptors/sockets that have been
|
|
detected to have \&"action" on them 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(3)\fP with the \fBsockfd\fP
|
|
argument set to the socket with the action.
|
|
|
|
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(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.
|
|
|
|
To force libcurl to (re-)check all its internal sockets and transfers instead
|
|
of just a single one, you call \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.
|
|
|
|
Applications should call \fBcurl_multi_timeout(3)\fP to figure out 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.
|
|
|
|
.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)"
|
|
deregister
|
|
.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_perform\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. Add easy handles
|
|
|
|
4. Call curl_multi_socket_all() first once
|
|
|
|
5. Setup a "collection" of sockets to supervise when your socket
|
|
callback is called.
|
|
|
|
6. Use curl_multi_timeout() to figure out how long to wait for action
|
|
|
|
7. Wait for action on any of libcurl's sockets
|
|
|
|
8, When action happens, call curl_multi_socket() for the socket(s) that got
|
|
action.
|
|
|
|
9. Go back to step 6.
|
|
.SH AVAILABILITY
|
|
This function was added in libcurl 7.15.4, although not deemed stable yet.
|
|
.SH "SEE ALSO"
|
|
.BR curl_multi_cleanup "(3), " curl_multi_init "(3), "
|
|
.BR curl_multi_fdset "(3), " curl_multi_info_read "(3)"
|