21
24
Alternative versions of \fIcurl_multi_perform(3)\fP that allows the
22
25
application to pass in the file descriptor/socket that has been detected to
23
have \&"action" on it and let libcurl perform. This allows libcurl to not have
24
to scan through all possible file descriptors to check for action. When the
25
application has detected action on a socket handled by libcurl, it should call
26
\fIcurl_multi_socket_action(3)\fP with the \fBsockfd\fP argument set to the
27
socket with the action. When the events on a socket are known, they can be
28
passed as an events bitmask \fBev_bitmask\fP by first setting \fBev_bitmask\fP
29
to 0, and then adding using bitwise OR (|) any combination of events to be
30
chosen from CURL_CSELECT_IN, CURL_CSELECT_OUT or CURL_CSELECT_ERR. When the
31
events on a socket are unknown, pass 0 instead, and libcurl will test the
32
descriptor internally.
34
At return, the int \fBrunning_handles\fP points to will contain the number of
35
still running easy handles within the multi handle. When this number reaches
36
zero, all transfers are complete/done. Note that when you call
26
have \&"action" on it and let libcurl perform. This lets libcurl avoid having
27
to scan through all possible file descriptors to check for action.
29
When the application has detected action on a socket handled by libcurl, it
30
should call \fIcurl_multi_socket_action(3)\fP with the \fBsockfd\fP argument
31
set to the socket with the action. When the events on a socket are known, they
32
can be passed as an events bitmask \fBev_bitmask\fP by first setting
33
\fBev_bitmask\fP to 0, and then adding using bitwise OR (|) any combination of
34
events to be chosen from CURL_CSELECT_IN, CURL_CSELECT_OUT or
35
CURL_CSELECT_ERR. When the events on a socket are unknown, pass 0 instead, and
36
libcurl will test the descriptor internally.
38
At return, the integer \fBrunning_handles\fP points to will contain the number
39
of still running easy handles within the multi handle. When this number
40
reaches zero, all transfers are complete/done. Note that when you call
37
41
\fIcurl_multi_socket_action(3)\fP on a specific socket and the counter
38
42
decreases by one, it DOES NOT necessarily mean that this exact socket/transfer
39
43
is the one that completed. Use \fIcurl_multi_info_read(3)\fP to figure out
40
44
which easy handle that completed.
42
The curl_multi_socket functions inform the application about updates in the
43
socket (file descriptor) status by doing none, one or multiple calls to the
44
socket callback function set with the CURLMOPT_SOCKETFUNCTION option to
45
\fIcurl_multi_setopt(3)\fP. They update the status with changes since the
46
previous time this function was called.
46
The \fBcurl_multi_socket_action(3)\fP functions inform the application about
47
updates in the socket (file descriptor) status by doing none, one, or multiple
48
calls to the socket callback function set with the CURLMOPT_SOCKETFUNCTION
49
option to \fIcurl_multi_setopt(3)\fP. They update the status with changes
50
since the previous time the callback was called.
52
Get the timeout time by setting the \fICURLMOPT_TIMERFUNCTION\fP option with
53
\fIcurl_multi_setopt(3)\fP. Your application will then get called with
54
information on how long to wait for socket actions at most before doing the
55
timeout action: call the \fBcurl_multi_socket_action(3)\fP function with the
56
\fBsockfd\fP argument set to CURL_SOCKET_TIMEOUT. You can also use the
57
\fIcurl_multi_timeout(3)\fP function to poll the value at any given time, but
58
for an event-based system using the callback is far better than relying on
59
polling the timeout value.
61
Usage of \fIcurl_multi_socket(3)\fP is deprecated, whereas the function is
62
equivalent to \fIcurl_multi_socket_action(3)\fP with \fBev_bitmask\fP set to
48
65
Force libcurl to (re-)check all its internal sockets and transfers instead of
49
66
just a single one by calling \fBcurl_multi_socket_all(3)\fP. Note that there
50
should rarely be reasons to use this function!
52
Get the timeout time - how long to wait for socket actions at most before
53
doing the timeout action: call the \fBcurl_multi_socket(3)\fP function with
54
the \fBsockfd\fP argument set to CURL_SOCKET_TIMEOUT, by setting the
55
\fICURLMOPT_TIMERFUNCTION\fP option with \fIcurl_multi_setopt(3)\fP. You can
56
also use the \fIcurl_multi_timeout(3)\fP function to poll the value at any
57
given time, but for an event-based system using the callback is far better
58
than relying on polling the timeout value.
60
Usage of \fIcurl_multi_socket(3)\fP is deprecated, whereas the function is
61
equivalent to \fIcurl_multi_socket_action(3)\fP, when \fBev_bitmask\fP is set
67
should not be any reason to use this function!
64
68
.SH "CALLBACK DETAILS"
66
70
The socket \fBcallback\fP function uses a prototype like this
107
111
.SH "RETURN VALUE"
108
112
CURLMcode type, general libcurl multi interface error code.
110
If you receive \fICURLM_CALL_MULTI_PERFORM\fP, this basically means that you
111
should call \fIcurl_multi_socket(3)\fP again, before you wait for more actions
112
on libcurl's sockets. You don't have to do it immediately, but the return code
113
means that libcurl may have more data available to return or that there may be
114
more data to send off before it is "satisfied".
116
NOTE that this only returns errors etc regarding the whole multi stack. There
117
might still have occurred problems on individual transfers even when this
114
Legacy: If you receive \fICURLM_CALL_MULTI_PERFORM\fP, this basically means
115
that you should call \fIcurl_multi_socket(3)\fP again, before you wait for
116
more actions on libcurl's sockets. You don't have to do it immediately, but
117
the return code means that libcurl may have more data available to return or
118
that there may be more data to send off before it is "satisfied".
120
In modern libcurls, \fICURLM_CALL_MULTI_PERFORM\fP or
121
\fICURLM_CALL_MULTI_SOKCET\fP should not be returned and no application needs
124
NOTE that the return code is for the whole multi stack. Problems still might have
125
occurred on individual transfers even when one of these functions
119
127
.SH "TYPICAL USAGE"
120
128
1. Create a multi handle
added
removed
docs/libcurl/curl_multi_socket.3
