mirror of
https://github.com/zeromq/libzmq.git
synced 2024-12-27 15:41:05 +08:00
87 lines
3.1 KiB
Plaintext
87 lines
3.1 KiB
Plaintext
= zmq_recv(3)
|
|
|
|
|
|
== NAME
|
|
zmq_recv - receive a message part from a socket
|
|
|
|
|
|
== SYNOPSIS
|
|
*int zmq_recv (void '*socket', void '*buf', size_t 'len', int 'flags');*
|
|
|
|
|
|
== DESCRIPTION
|
|
The _zmq_recv()_ function shall receive a message from the socket referenced
|
|
by the 'socket' argument and store it in the buffer referenced by the 'buf'
|
|
argument. Any bytes exceeding the length specified by the 'len' argument shall
|
|
be truncated. 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: The 'buf'
|
|
argument may be null if len is zero.
|
|
|
|
*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_recv()_
|
|
function shall fail with 'errno' set to EAGAIN.
|
|
|
|
|
|
Multi-part messages
|
|
~~~~~~~~~~~~~~~~~~~
|
|
A 0MQ message is composed of 1 or more message parts. 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 multi-part messages must use the _ZMQ_RCVMORE_
|
|
xref:zmq_getsockopt.adoc[zmq_getsockopt] option after calling _zmq_recv()_ to determine if
|
|
there are further parts to receive.
|
|
|
|
== RETURN VALUE
|
|
The _zmq_recv()_ function shall return number of bytes in the message
|
|
if successful. Note that the value can exceed the value of the 'len' parameter
|
|
in case the message was truncated. If not successful the function shall return
|
|
`-1` and set 'errno' to one of the values defined below.
|
|
|
|
|
|
== ERRORS
|
|
*EAGAIN*::
|
|
Either the timeout set via the socket-option ZMQ_RCVTIMEO (see xref:zmq_setsockopt.adoc[zmq_setsockopt])
|
|
has been reached (flag ZMQ_DONTWAIT not set) without being able to read a message
|
|
from the socket or there are no messages available at the moment (flag ZMQ_DONTWAIT set)
|
|
and the operation would block.
|
|
*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 xref:zmq_socket.adoc[zmq_socket] 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.
|
|
|
|
|
|
== EXAMPLE
|
|
.Receiving a message from a socket
|
|
----
|
|
char buf [256];
|
|
nbytes = zmq_recv (socket, buf, 256, 0);
|
|
assert (nbytes != -1);
|
|
----
|
|
|
|
|
|
== SEE ALSO
|
|
* xref:zmq_send.adoc[zmq_send]
|
|
* xref:zmq_getsockopt.adoc[zmq_getsockopt]
|
|
* xref:zmq_setsockopt.adoc[zmq_setsockopt]
|
|
* xref:zmq_socket.adoc[zmq_socket]
|
|
* xref:zmq.adoc[zmq]
|
|
|
|
|
|
== AUTHORS
|
|
This page was written by the 0MQ community. To make a change please
|
|
read the 0MQ Contribution Policy at <http://www.zeromq.org/docs:contributing>.
|