mirror of
https://github.com/zeromq/libzmq.git
synced 2024-12-13 18:55:10 +01:00
122 lines
3.5 KiB
Plaintext
122 lines
3.5 KiB
Plaintext
zmq_recvmsg(3)
|
|
==============
|
|
|
|
|
|
NAME
|
|
----
|
|
zmq_recvmsg - receive a message part from a socket
|
|
|
|
|
|
SYNOPSIS
|
|
--------
|
|
*int zmq_recvmsg (void '*socket', zmq_msg_t '*msg', int 'flags');*
|
|
|
|
|
|
DESCRIPTION
|
|
-----------
|
|
The _zmq_recvmsg()_ function shall receive a message part 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 message parts available on the specified 'socket'
|
|
the _zmq_recvmsg()_ function shall block until the request can be satisfied.
|
|
The 'flags' argument is a combination of the flags defined below:
|
|
|
|
*ZMQ_DONTWAIT*::
|
|
Specifies that the operation should be performed in non-blocking mode. If there
|
|
are no messages available on the specified 'socket', the _zmq_recvmsg()_
|
|
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 except
|
|
by available memory.
|
|
|
|
An application that processes multipart messages must use the _ZMQ_RCVMORE_
|
|
linkzmq:zmq_getsockopt[3] option after calling _zmq_recvmsg()_ to determine if
|
|
there are further parts to receive.
|
|
|
|
|
|
RETURN VALUE
|
|
------------
|
|
The _zmq_recvmsg()_ function shall return number of bytes in the message
|
|
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_recvmsg()_ operation is not supported by this socket type.
|
|
*EFSM*::
|
|
The _zmq_recvmsg()_ 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.
|
|
*ENOTSOCK*::
|
|
The provided 'socket' was invalid.
|
|
*EINTR*::
|
|
The operation was interrupted by delivery of a signal before a message was
|
|
available.
|
|
*EFAULT*::
|
|
The message passed to the function was invalid.
|
|
|
|
|
|
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_recvmsg (socket, &msg, 0);
|
|
assert (rc != -1);
|
|
/* Release message */
|
|
zmq_msg_close (&msg);
|
|
----
|
|
|
|
.Receiving a multi-part message
|
|
----
|
|
int64_t more;
|
|
size_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_recvmsg (socket, &part, 0);
|
|
assert (rc != -1);
|
|
/* Determine if more message parts are to follow */
|
|
rc = zmq_getsockopt (socket, ZMQ_RCVMORE, &more, &more_size);
|
|
assert (rc == 0);
|
|
zmq_msg_close (&part);
|
|
} while (more);
|
|
----
|
|
|
|
|
|
SEE ALSO
|
|
--------
|
|
linkzmq:zmq_recv[3]
|
|
linkzmq:zmq_send[3]
|
|
linkzmq:zmq_sendmsg[3]
|
|
linkzmq:zmq_getsockopt[3]
|
|
linkzmq:zmq_socket[7]
|
|
linkzmq:zmq[7]
|
|
|
|
|
|
AUTHORS
|
|
-------
|
|
This man page was written by Martin Sustrik <sustrik@250bpm.com>, Martin
|
|
Lucina <mato@kotelna.sk> and Pieter Hintjens <ph@imatix.com>.
|
|
|