Adapted man page to API.

doc/zmq_socket_monitor.txt

@@ -17,168 +17,100 @@ DESCRIPTION
 -----------
 The _zmq_socket_monitor()_ function shall spawn a 'PAIR' socket that publishes
 socket state changes (events) over the inproc:// transport to a given endpoint.
-Messages are 'zmq_event_t' structs. It's recommended to connect via a 'PAIR'
-socket in another application thread and handle monitoring events there. It's
-possible to also supply a bitmask ('ZMQ_EVENT_ALL' or any combination of the
-'ZMQ_EVENT_*' constants) of the events you're interested in.
 
-----
+Messages consist of 2 Frames, the first containing the event-id and the
-// monitoring thread
+associated value. The second frame holds the affected endpoint as string.
-static void *req_socket_monitor (void *ctx)
-{
-    zmq_event_t event;
-    int rc;
 
-    void *s = zmq_socket (ctx, ZMQ_PAIR);
+The layout of the first Frame is:
-    assert (s);
+  16 bit event id
+  32 bit event value
 
-    rc = zmq_connect (s, "inproc://monitor.req");
+event id and value are in the native byte order (for the machine the
-    assert (rc == 0);
+application is running on). There is no padding between the fields.
-    while (true) {
-        zmq_msg_t msg;
-        zmq_msg_init (&msg);
-        rc = zmq_msg_recv (s, &msg, 0);
-        if (rc == -1 && zmq_errno() == ETERM) break;
-        assert (rc != -1);
-        memcpy (&event, zmq_msg_data (&msg), sizeof (event));
-        switch (event.event) {
-        case ZMQ_EVENT_CONNECTED:
-            // handle socket connected event
-            break;
-        case ZMQ_EVENT_CLOSED:
-            // handle socket closed event
-            break;
-        }
-    }
-    zmq_close (s);
-    return NULL;
-}
 
-// register a monitor endpoint for all socket events
+The event value has to be interpreted in the context of the event id.
-rc = zmq_socket_monitor (req, "inproc://monitor.req", ZMQ_EVENT_ALL);
+See 'Supported events' below for details.
-assert (rc == 0);
 
-// spawn a monitoring thread
-rc = pthread_create (&threads [0], NULL, req_socket_monitor, ctx);
-assert (rc == 0);
 ----
 
 Only connection oriented (tcp and ipc) transports are supported in this initial
 implementation.
 
-Supported events are:
+----
 
+Supported events
+----------------
 
 ZMQ_EVENT_CONNECTED: connection established
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 The 'ZMQ_EVENT_CONNECTED' event triggers when a connection has been established
 to a remote peer. This can happen either synchronous or asynchronous.
+value is the FD of the newly connected socket.
 
-.Event metadata:
-----
-data.connected.addr // peer address
-data.connected.fd // socket descriptor
-----
 
 ZMQ_EVENT_CONNECT_DELAYED: synchronous connect failed, it's being polled
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 The 'ZMQ_EVENT_CONNECT_DELAYED' event triggers when an immediate connection
 attempt is delayed and it's completion's being polled for.
+value has no meaning.
 
-.Event metadata:
-----
-data.connect_delayed.addr // peer address
-data.connect_delayed.err // errno value
-----
 
 ZMQ_EVENT_CONNECT_RETRIED: asynchronous connect / reconnection attempt
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 The 'ZMQ_EVENT_CONNECT_RETRIED' event triggers when a connection attempt
 is being handled by reconnect timer. The reconnect interval's recomputed
 for each attempt.
+value is the reconnect interval.
 
-.Event metadata:
-----
-data.connect_retried.addr // peer address
-data.connect_retried.interval // computed reconnect interval
-----
 
 ZMQ_EVENT_LISTENING: socket bound to an address, ready to accept connections
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 The 'ZMQ_EVENT_LISTENING' event triggers when a socket's successfully bound
 to a an interface.
+value is the FD of the newly bound socket.
 
-.Event metadata:
-----
-data.listening.addr //  listen address
-data.listening.fd // socket descriptor
-----
 
 ZMQ_EVENT_BIND_FAILED: socket could not bind to an address
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 The 'ZMQ_EVENT_BIND_FAILED' event triggers when a socket could not bind to
 a given interface.
+value is the errno generated by the bind call.
 
-.Event metadata:
-----
-data.bind_failed.addr // listen address
-data.bind_failed.err // errno value
-----
 
 ZMQ_EVENT_ACCEPTED: connection accepted to bound interface
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 The 'ZMQ_EVENT_ACCEPTED' event triggers when a connection from a remote peer
 has been established with a socket's listen address.
+value is the FD of the accepted socket.
 
-.Event metadata:
-----
-data.accepted.addr // listen address
-data.accepted.fd // socket descriptor
-----
 
 ZMQ_EVENT_ACCEPT_FAILED: could not accept client connection
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 The 'ZMQ_EVENT_ACCEPT_FAILED' event triggers when a connection attempt to
 a socket's bound address fails.
+value is the errno generated by accept.
 
-.Event metadata:
-----
-data.accept_failed.addr // listen address
-data.accept_failed.err // errno value
-----
 
 ZMQ_EVENT_CLOSED: connection closed
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 The 'ZMQ_EVENT_CLOSED' event triggers when a connection's underlying descriptor
-has been closed. 
+has been closed.
+value is the former FD of the for the closed socket. FD has been closed already!
 
-.Event metadata:
-----
-data.closed.addr // address
-data.closed.fd // socket descriptor
-----
 
 ZMQ_EVENT_CLOSE_FAILED: connection couldn't be closed
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 The 'ZMQ_EVENT_CLOSE_FAILED' event triggers when a descriptor could not be
-released back to the OS.
+released back to the OS. Implementation note: ONLY FOR IPC SOCKETS.
+value is the errno generated by unlink.
 
-.Event metadata:
-----
-data.close_failed.addr // address
-data.close_failed.err // errno value
-----
 
 ZMQ_EVENT_DISCONNECTED: broken session
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 The 'ZMQ_EVENT_DISCONNECTED' event triggers when the stream engine (tcp and ipc
 specific) detects a corrupted / broken session.
+value is the FD of the socket.
 
-.Event metadata:
-----
-data.disconnected.addr // address
-data.disconnected.fd // socket descriptor
-----
 
 RETURN VALUE
 ------------
@@ -203,78 +135,116 @@ EXAMPLE
 -------
 .Observing a 'REP' socket's connection state 
 ----
+#include <stdio.h>
+#include <zmq.h>
+#include <pthread.h>
+#include <string.h>
+#include <assert.h>
+
+static int read_msg(void* s, zmq_event_t* event, char* ep)
+{
+    int rc ;
+    zmq_msg_t msg1;  // binary part
+    zmq_msg_init (&msg1);
+    zmq_msg_t msg2;  //  address part
+    zmq_msg_init (&msg2);
+    rc = zmq_msg_recv (&msg1, s, 0);
+    if (rc == -1 && zmq_errno() == ETERM)
+	return 1 ;
+    assert (rc != -1);
+    assert (zmq_msg_more(&msg1) != 0);
+    rc = zmq_msg_recv (&msg2, s, 0);
+    if (rc == -1 && zmq_errno() == ETERM)
+	return 1;
+    assert (rc != -1);
+    assert (zmq_msg_more(&msg2) == 0);
+    // copy binary data to event struct
+    const char* data = (char*)zmq_msg_data(&msg1);
+    memcpy(&(event->event), data, sizeof(event->event));
+    memcpy(&(event->value), data+sizeof(event->event), sizeof(event->value));
+    // copy address part
+    const size_t len = zmq_msg_size(&msg2) ;
+    ep = memcpy(ep, zmq_msg_data(&msg2), len);
+    *(ep + len) = 0 ;
+    return 0 ;
+}
+
 // REP socket monitor thread
 static void *rep_socket_monitor (void *ctx)
 {
     zmq_event_t event;
+    static char addr[1025] ;
     int rc;
 
+    printf("starting monitor...\n");
+
     void *s = zmq_socket (ctx, ZMQ_PAIR);
     assert (s);
 
     rc = zmq_connect (s, "inproc://monitor.rep");
     assert (rc == 0);
-    while (true) {
+    while (!read_msg(s, &event, addr)) {
-        zmq_msg_t msg;
-        zmq_msg_init (&msg);
-        rc = zmq_msg_recv (s, &msg, 0);
-        if (rc == -1 && zmq_errno() == ETERM) break;
-        assert (rc != -1);
-        memcpy (&event, zmq_msg_data (&msg), sizeof (event));
         switch (event.event) {
         case ZMQ_EVENT_LISTENING:
-            printf ("listening socket descriptor %d\n", event.data.listening.fd);
+            printf ("listening socket descriptor %d\n", event.value);
-            printf ("listening socket address %s\n", event.data.listening.addr);
+            printf ("listening socket address %s\n", addr);
             break;
         case ZMQ_EVENT_ACCEPTED:
-            printf ("accepted socket descriptor %d\n", event.data.accepted.fd);
+            printf ("accepted socket descriptor %d\n", event.value);
-            printf ("accepted socket address %s\n", event.data.accepted.addr);
+            printf ("accepted socket address %s\n", addr);
             break;
         case ZMQ_EVENT_CLOSE_FAILED:
-            printf ("socket close failure error code %d\n", event.data.close_failed.err);
+            printf ("socket close failure error code %d\n", event.value);
-            printf ("socket address %s\n", event.data.close_failed.addr);
+            printf ("socket address %s\n", addr);
             break;
         case ZMQ_EVENT_CLOSED:
-            printf ("closed socket descriptor %d\n", event.data.closed.fd);
+            printf ("closed socket descriptor %d\n", event.value);
-            printf ("closed socket address %s\n", event.data.closed.addr);
+            printf ("closed socket address %s\n", addr);
             break;
         case ZMQ_EVENT_DISCONNECTED:
-            printf ("disconnected socket descriptor %d\n", event.data.disconnected.fd);
+            printf ("disconnected socket descriptor %d\n", event.value);
-            printf ("disconnected socket address %s\n", event.data.disconnected.addr);
+            printf ("disconnected socket address %s\n", addr);
             break;
         }
-        zmq_msg_close (&msg);
     }
     zmq_close (s);
     return NULL;
 }
 
 
-//  Create the infrastructure
+int main()
-void *ctx = zmq_init (1);
+{
-assert (ctx);
+    const char* addr = "tcp://127.0.0.1:6666" ;
+    pthread_t thread ;
 
-// REP socket
+    //  Create the infrastructure
-rep = zmq_socket (ctx, ZMQ_REP);
+    void *ctx = zmq_init (1);
-assert (rep);
+    assert (ctx);
 
-// REP socket monitor, all events
+    // REP socket
-rc = zmq_socket_monitor (rep, "inproc://monitor.rep", ZMQ_EVENT_ALL);
+    void* rep = zmq_socket (ctx, ZMQ_REP);
-assert (rc == 0);
+    assert (rep);
-rc = pthread_create (&threads [0], NULL, rep_socket_monitor, ctx);
-assert (rc == 0);
 
-rc = zmq_bind (rep, addr);
+    // REP socket monitor, all events
-assert (rc == 0);
+    int rc = zmq_socket_monitor (rep, "inproc://monitor.rep", ZMQ_EVENT_ALL);
+    assert (rc == 0);
+    rc = pthread_create (&thread, NULL, rep_socket_monitor, ctx);
+    assert (rc == 0);
 
-// Allow some time for event detection
+    rc = zmq_bind (rep, addr);
-zmq_sleep (1);
+    assert (rc == 0);
 
-// Close the REP socket
+    // Allow some time for event detection
-rc = zmq_close (rep);
+    zmq_sleep (1);
-assert (rc == 0);
 
-zmq_term (ctx);
+    // Close the REP socket
+    rc = zmq_close (rep);
+    assert (rc == 0);
+
+    zmq_term (ctx);
+
+    return 0 ;
+}
 ----
 
 
@@ -286,3 +256,4 @@ linkzmq:zmq[7]
 AUTHORS
 -------
 This 0MQ manual page was written by Lourens Naudé <lourens@methodmissing.com>
+Changes by Guido Goldstein <github@a-nugget.de>