split off curl_multi_socket_action() into its own separate man page as this is

the function we should use, while both curl_multi_socket() and
curl_multi_socket_all() should be killed!

docs/libcurl/curl_multi_socket_action.3

@@ -0,0 +1,132 @@
+.\" $Id$
+.\"
+.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.
+
+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 \fBcurl_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 CURLMOPT_SOCKETFUNCTION
+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\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 \fBcurl_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 "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.
+
+Legacy: If you receive \fICURLM_CALL_MULTI_PERFORM\fP, this basically means
+that you should call \fIcurl_multi_socket_action(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_SOKCET\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 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 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.
+.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"