From f0dce000b2184b87318016022efe14a9618e74a9 Mon Sep 17 00:00:00 2001
From: Min RK <benjaminrk@gmail.com>
Date: Thu, 21 Jan 2016 16:21:07 +0100
Subject: [PATCH] stop previous monitor socket before starting new one

avoids leaking sockets due to multiple monitor calls on one socket

Alternative: raise error (not sure what errno; EADDRINUSE?) if collision detected; force manual stop.
---
 src/socket_base.cpp | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/socket_base.cpp b/src/socket_base.cpp
index 3f969367..32ddeb5a 100644
--- a/src/socket_base.cpp
+++ b/src/socket_base.cpp
@@ -1537,6 +1537,10 @@ int zmq::socket_base_t::monitor (const char *addr_, int events_)
         errno = EPROTONOSUPPORT;
         return -1;
     }
+    // already monitoring. Stop previous monitor before starting new one.
+    if (monitor_socket != NULL) {
+        stop_monitor (true);
+    }
     //  Register events to monitor
     monitor_events = events_;
     monitor_socket = zmq_socket (get_ctx (), ZMQ_PAIR);