Add new socket monitor event for when socket monitoring is stopped.

include/zmq.h

@@ -314,12 +314,14 @@ ZMQ_EXPORT int zmq_msg_set (zmq_msg_t *msg, int option, int optval);
 #define ZMQ_EVENT_CLOSED 128
 #define ZMQ_EVENT_CLOSE_FAILED 256
 #define ZMQ_EVENT_DISCONNECTED 512
+#define ZMQ_EVENT_MONITOR_STOPPED 1024
 
 #define ZMQ_EVENT_ALL ( ZMQ_EVENT_CONNECTED | ZMQ_EVENT_CONNECT_DELAYED | \
                         ZMQ_EVENT_CONNECT_RETRIED | ZMQ_EVENT_LISTENING | \
                         ZMQ_EVENT_BIND_FAILED | ZMQ_EVENT_ACCEPTED | \
                         ZMQ_EVENT_ACCEPT_FAILED | ZMQ_EVENT_CLOSED | \
-                        ZMQ_EVENT_CLOSE_FAILED | ZMQ_EVENT_DISCONNECTED )
+                        ZMQ_EVENT_CLOSE_FAILED | ZMQ_EVENT_DISCONNECTED | \
+                        ZMQ_EVENT_MONITOR_STOPPED)
 
 /*  Socket event data  */
 typedef struct {

src/socket_base.cpp

@@ -1221,6 +1221,12 @@ void zmq::socket_base_t::monitor_event (zmq_event_t event_, const std::string& a
 void zmq::socket_base_t::stop_monitor()
 {
     if (monitor_socket) {
+        if (monitor_events & ZMQ_EVENT_MONITOR_STOPPED) {
+            zmq_event_t event;
+            event.event = ZMQ_EVENT_MONITOR_STOPPED;
+            event.value = 0;
+            monitor_event (event, "");
+        }
         zmq_close (monitor_socket);
         monitor_socket = NULL;
         monitor_events = 0;