Problem: relicensing forced to remove support for ZMQ_RECONNECT_IVL_MAX option

Solution: reimplement support for ZMQ_RECONNECT_IVL_MAX without knowledge of the previous code.

src/options.cpp

@@ -186,6 +186,7 @@ zmq::options_t::options_t () :
     tcp_maxrt (0),
     reconnect_stop (0),
     reconnect_ivl (100),
+    reconnect_ivl_max (0),
     backlog (100),
     maxmsgsize (-1),
     rcvtimeo (-1),
@@ -400,11 +401,11 @@ int zmq::options_t::setsockopt (int option_,
             break;
 
         case ZMQ_RECONNECT_IVL_MAX:
-#ifdef ZMQ_HAVE_WINDOWS
+            if (is_int && value >= 0) {
-            return WSAEOPNOTSUPP;
+                reconnect_ivl_max = value;
-#else
+                return 0;
-            return -EOPNOTSUPP;
+            }
-#endif
+            break;
 
         case ZMQ_BACKLOG:
             if (is_int && value >= 0) {
@@ -1048,11 +1049,11 @@ int zmq::options_t::getsockopt (int option_,
             break;
 
         case ZMQ_RECONNECT_IVL_MAX:
-#ifdef ZMQ_HAVE_WINDOWS
+            if (is_int) {
-            return WSAEOPNOTSUPP;
+                *value = reconnect_ivl_max;
-#else
+                return 0;
-            return -EOPNOTSUPP;
+            }
-#endif
+            break;
 
         case ZMQ_BACKLOG:
             if (is_int) {

src/options.hpp

@@ -100,6 +100,10 @@ struct options_t
     //  Default 100ms
     int reconnect_ivl;
     
+    //  Maximum interval between attempts to reconnect, in milliseconds.
+    //  Default 0ms (meaning maximum interval is disabled)
+    int reconnect_ivl_max;
+
     //  Maximum backlog for pending connections.
     int backlog;
 

src/stream_connecter_base.cpp

@@ -30,7 +30,7 @@ zmq::stream_connecter_base_t::stream_connecter_base_t (
     _socket (session_->get_socket ()),
     _delayed_start (delayed_start_),
     _reconnect_timer_started (false),
-    _current_reconnect_ivl (options.reconnect_ivl),
+    _current_reconnect_ivl (-1),
     _session (session_)
 {
     zmq_assert (_addr);
@@ -85,19 +85,33 @@ void zmq::stream_connecter_base_t::add_reconnect_timer ()
 
 int zmq::stream_connecter_base_t::get_new_reconnect_ivl ()
 {
-    //  TODO should the random jitter be really based on the configured initial
+    if (options.reconnect_ivl_max > 0) {
-    //  reconnect interval options.reconnect_ivl, or better on the
+        int candidate_interval = 0;
-    //  _current_reconnect_ivl?
+        if (_current_reconnect_ivl == -1)
+            candidate_interval = options.reconnect_ivl;
+        else if (_current_reconnect_ivl > std::numeric_limits<int>::max () / 2)
+            candidate_interval = std::numeric_limits<int>::max ();
+        else
+            candidate_interval = _current_reconnect_ivl * 2;
 
-    //  The new interval is the current interval + random value.
+        if (candidate_interval > options.reconnect_ivl_max)
+            _current_reconnect_ivl = options.reconnect_ivl_max;
+        else
+            _current_reconnect_ivl = candidate_interval;
+        return _current_reconnect_ivl;
+    } else {
+        if (_current_reconnect_ivl == -1)
+            _current_reconnect_ivl = options.reconnect_ivl;
+        //  The new interval is the base interval + random value.
         const int random_jitter = generate_random () % options.reconnect_ivl;
         const int interval =
-      _current_reconnect_ivl < std::numeric_limits<int>::max () - random_jitter
+          _current_reconnect_ivl
+              < std::numeric_limits<int>::max () - random_jitter
             ? _current_reconnect_ivl + random_jitter
             : std::numeric_limits<int>::max ();
-
         return interval;
     }
+}
 
 void zmq::stream_connecter_base_t::rm_handle ()
 {