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mirror of https://github.com/zeromq/libzmq.git synced 2024-12-27 07:31:03 +08:00

Problem: disconnect & unbind doc is misleading

Make it explicit that the two functions are identical.
Also document the expected disconnect behavior extensively
and illustrate the difference between disconnecting a
connected vs. bound endpoint.
This commit is contained in:
jean-airoldie 2019-06-17 01:55:18 -04:00
parent b17e854f15
commit 4d933c28be
2 changed files with 57 additions and 70 deletions

View File

@ -4,7 +4,7 @@ zmq_disconnect(3)
NAME
----
zmq_disconnect - Disconnect a socket
zmq_disconnect - Disconnect a socket from an endpoint
SYNOPSIS
@ -16,11 +16,22 @@ DESCRIPTION
-----------
The _zmq_disconnect()_ function shall disconnect a socket specified
by the 'socket' argument from the endpoint specified by the 'endpoint'
argument. Any outstanding messages physically received from the network but not
yet received by the application with _zmq_recv()_ shall be discarded. The
behaviour for discarding messages sent by the application with _zmq_send()_ but
not yet physically transferred to the network depends on the value of the
_ZMQ_LINGER_ socket option for the specified 'socket'.
argument. Note the actual disconnect system call might occur at a later time.
Upon disconnection the will also stop receiving messages originating from
this endpoint. Moreover, the socket will no longuer be able
to queue outgoing messages to this endpoint. The outgoing message queue
associated with the endpoint will be discarded. However, if the socket's linger
period is non-zero, libzmq will still attempt to transmit these discarded messages,
until the linger period expires.
Addionally, if the disconnected endpoint was previously connected to
(as opposed to bound), the incoming message queue associated with the
endpoint will be discarded. This means that after unbinding an endpoint
using `disconnect`, it is possible to received messages originating
from that same endpoint if they were already present in the incoming message
queue before unbinding. However, this is not the case when disconnecting
from a connected endpoint.
The 'endpoint' argument is as described in linkzmq:zmq_connect[3]
@ -28,6 +39,12 @@ NOTE: The default setting of _ZMQ_LINGER_ does not discard unsent messages;
this behaviour may cause the application to block when calling _zmq_ctx_term()_.
For details refer to linkzmq:zmq_setsockopt[3] and linkzmq:zmq_ctx_term[3].
Unbinding wild-card address from a socket
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
When a wild-card `*` 'endpoint' (described in linkzmq:zmq_tcp[7],
linkzmq:zmq_ipc[7] and linkzmq:zmq_vmci[7]) was used in _zmq_bind()_, the caller
should use the real 'endpoint' obtained from the ZMQ_LAST_ENDPOINT socket option
to unbind this 'endpoint' from a socket.
RETURN VALUE
------------
@ -43,7 +60,7 @@ The 0MQ 'context' associated with the specified 'socket' was terminated.
*ENOTSOCK*::
The provided 'socket' was invalid.
*ENOENT*::
The provided endpoint is not connected.
The provided endpoint is not in use by the socket.
EXAMPLE
@ -61,6 +78,36 @@ rc = zmq_disconnect (socket, "tcp://server001:5555");
assert (rc == 0);
----
.Unbind a subscriber socket from a TCP transport
----
/* Create a ZMQ_SUB socket */
void *socket = zmq_socket (context, ZMQ_SUB);
assert (socket);
/* Connect it to the host server001, port 5555 using a TCP transport */
rc = zmq_bind (socket, "tcp://127.0.0.1:5555");
assert (rc == 0);
/* Disconnect from the previously connected endpoint */
rc = zmq_disconnect(socket, "tcp://127.0.0.1:5555");
assert (rc == 0);
----
.Unbind wild-card `*` binded socket
----
/* Create a ZMQ_SUB socket */
void *socket = zmq_socket (context, ZMQ_SUB);
assert (socket);
/* Bind it to the system-assigned ephemeral port using a TCP transport */
rc = zmq_bind (socket, "tcp://127.0.0.1:*");
assert (rc == 0);
/* Obtain real endpoint */
const size_t buf_size = 32;
char buf[buf_size];
rc = zmq_getsockopt (socket, ZMQ_LAST_ENDPOINT, buf, (size_t *)&buf_size);
assert (rc == 0);
/* Unbind socket by real endpoint */
rc = zmq_disconnect (socket, buf);
assert (rc == 0);
----
SEE ALSO
--------

View File

@ -4,7 +4,7 @@ zmq_unbind(3)
NAME
----
zmq_unbind - Stop accepting connections on a socket
zmq_unbind - Another name for zmq_disconnect
SYNOPSIS
@ -14,68 +14,8 @@ int zmq_unbind (void '*socket', const char '*endpoint');
DESCRIPTION
-----------
The _zmq_unbind()_ function shall unbind a socket specified
by the 'socket' argument from the endpoint specified by the 'endpoint'
argument.
The 'endpoint' argument is as described in linkzmq:zmq_bind[3]
Unbinding wild-card address from a socket
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
When wild-card `*` 'endpoint' (described in linkzmq:zmq_tcp[7],
linkzmq:zmq_ipc[7] and linkzmq:zmq_vmci[7]) was used in _zmq_bind()_, the caller should use
real 'endpoint' obtained from the ZMQ_LAST_ENDPOINT socket option
to unbind this 'endpoint' from a socket.
RETURN VALUE
------------
The _zmq_unbind()_ function shall return zero if successful. Otherwise it
shall return `-1` and set 'errno' to one of the values defined below.
ERRORS
------
*EINVAL*::
The endpoint supplied is invalid.
*ETERM*::
The 0MQ 'context' associated with the specified 'socket' was terminated.
*ENOTSOCK*::
The provided 'socket' was invalid.
*ENOENT*::
The endpoint supplied was not previously bound.
EXAMPLES
--------
.Unbind a subscriber socket from a TCP transport
----
/* Create a ZMQ_SUB socket */
void *socket = zmq_socket (context, ZMQ_SUB);
assert (socket);
/* Connect it to the host server001, port 5555 using a TCP transport */
rc = zmq_bind (socket, "tcp://127.0.0.1:5555");
assert (rc == 0);
/* Disconnect from the previously connected endpoint */
rc = zmq_unbind (socket, "tcp://127.0.0.1:5555");
assert (rc == 0);
----
.Unbind wild-card `*` binded socket
----
/* Create a ZMQ_SUB socket */
void *socket = zmq_socket (context, ZMQ_SUB);
assert (socket);
/* Bind it to the system-assigned ephemeral port using a TCP transport */
rc = zmq_bind (socket, "tcp://127.0.0.1:*");
assert (rc == 0);
/* Obtain real endpoint */
const size_t buf_size = 32;
char buf[buf_size];
rc = zmq_getsockopt (socket, ZMQ_LAST_ENDPOINT, buf, (size_t *)&buf_size);
assert (rc == 0);
/* Unbind socket by real endpoint */
rc = zmq_unbind (socket, buf);
assert (rc == 0);
----
The _zmq_unbind()_ has the same exact behavior as _zmq_disconnect()_.
Refer to linkzmq:zmq_disconnect[3].
SEE ALSO
--------