mirror of
https://github.com/zeromq/libzmq.git
synced 2024-12-13 10:52:56 +01:00
b6cdd369e3
* Fixed zmq_term, zmq_socket, zmq_close, zmq_setsockopt, * zmq_getsockopt, zmq_bind, zmq_connect, zmq_send, * zmq_recv, zmq_poll, zmq_device, zmq_stopwatch_stop * Updated Reference Manual for these methods
110 lines
3.2 KiB
Plaintext
110 lines
3.2 KiB
Plaintext
zmq_recv(3)
|
|
===========
|
|
|
|
|
|
NAME
|
|
----
|
|
zmq_recv - receive a message from a socket
|
|
|
|
|
|
SYNOPSIS
|
|
--------
|
|
*int zmq_recv (void '*socket', zmq_msg_t '*msg', int 'flags');*
|
|
|
|
|
|
DESCRIPTION
|
|
-----------
|
|
The _zmq_recv()_ function shall receive a message from the socket referenced by
|
|
the 'socket' argument and store it in the message referenced by the 'msg'
|
|
argument. Any content previously stored in 'msg' shall be properly deallocated.
|
|
If there are no messages available on the specified 'socket' the _zmq_recv()_
|
|
function shall block until the request can be satisfied. The 'flags' argument
|
|
is a combination of the flags defined below:
|
|
|
|
*ZMQ_NOBLOCK*::
|
|
Specifies that the operation should be performed in non-blocking mode. If there
|
|
are no messages available on the specified 'socket', the _zmq_recv()_ function
|
|
shall fail with 'errno' set to EAGAIN.
|
|
|
|
|
|
Multi-part messages
|
|
~~~~~~~~~~~~~~~~~~~
|
|
A 0MQ message is composed of 1 or more message parts; each message part is an
|
|
independent 'zmq_msg_t' in its own right. 0MQ ensures atomic delivery of
|
|
messages; peers shall receive either all _message parts_ of a message or none
|
|
at all.
|
|
|
|
The total number of message parts is unlimited.
|
|
|
|
An application wishing to determine if a message is composed of multiple parts
|
|
does so by retrieving the value of the _ZMQ_RCVMORE_ socket option on the
|
|
'socket' it is receiving the message from. If there are no message parts to
|
|
follow, or if the message is not composed of multiple parts, _ZMQ_RCVMORE_
|
|
shall report a value of zero. Otherwise, _ZMQ_RCVMORE_ shall report a value of
|
|
1, indicating that more message parts are to follow.
|
|
|
|
|
|
RETURN VALUE
|
|
------------
|
|
The _zmq_recv()_ function shall return zero if successful. Otherwise it shall
|
|
return `-1` and set 'errno' to one of the values defined below.
|
|
|
|
|
|
ERRORS
|
|
------
|
|
*EAGAIN*::
|
|
Non-blocking mode was requested and no messages are available at the moment.
|
|
*ENOTSUP*::
|
|
The _zmq_recv()_ operation is not supported by this socket type.
|
|
*EFSM*::
|
|
The _zmq_recv()_ operation cannot be performed on this socket at the moment due
|
|
to the socket not being in the appropriate state. This error may occur with
|
|
socket types that switch between several states, such as ZMQ_REP. See the
|
|
_messaging patterns_ section of linkzmq:zmq_socket[3] for more information.
|
|
*ETERM*::
|
|
The 0MQ 'context' associated with the specified 'socket' was terminated.
|
|
*EFAULT*::
|
|
The provided 'socket' was not valid (NULL).
|
|
|
|
|
|
EXAMPLE
|
|
-------
|
|
.Receiving a message from a socket
|
|
----
|
|
/* Create an empty 0MQ message */
|
|
zmq_msg_t msg;
|
|
int rc = zmq_msg_init (&msg);
|
|
assert (rc == 0);
|
|
/* Block until a message is available to be received from socket */
|
|
rc = zmq_recv (socket, &msg, 0);
|
|
assert (rc == 0);
|
|
----
|
|
|
|
.Receiving a multi-part message
|
|
----
|
|
int64_t more;
|
|
int64_t more_size = sizeof more;
|
|
do {
|
|
/* Create an empty 0MQ message to hold the message part */
|
|
zmq_msg_t part;
|
|
int rc = zmq_msg_init (&part);
|
|
assert (rc == 0);
|
|
/* Block until a message is available to be received from socket */
|
|
rc = zmq_recv (socket, &part, 0);
|
|
assert (rc == 0);
|
|
/* Determine if more message parts are to follow */
|
|
rc = zmq_getsockopt (socket, ZMQ_RCVMORE, &more, &more_size);
|
|
assert (rc == 0);
|
|
} while (more);
|
|
----
|
|
|
|
|
|
SEE ALSO
|
|
--------
|
|
linkzmq:zmq_send[3]
|
|
linkzmq:zmq_getsockopt[3]
|
|
linkzmq:zmq_socket[7]
|
|
linkzmq:zmq[7]
|
|
|
|
|