ZMQII-59: TCP server crashes sometimes when message is send and socket is closed immediately

src/dispatcher.cpp

@@ -67,6 +67,12 @@ zmq::dispatcher_t::dispatcher_t (int app_threads_, int io_threads_,
         signalers.push_back (io_thread->get_signaler ());
     }
 
+    //  Create the administrative thread. Nothing special is needed. NULL
+    //  is used instead of signaler given that as for now, administrative
+    //  thread doesn't receive any commands. The only thing it is used for
+    //  is sending 'stop' command to I/O threads on shutdown.
+    signalers.push_back (NULL);
+
     //  Create command pipe matrix.
     command_pipes = new  (std::nothrow) command_pipe_t [signalers.size () *
          signalers.size ()];
@@ -159,6 +165,23 @@ void zmq::dispatcher_t::destroy_socket ()
        delete this;
 }
 
+void zmq::dispatcher_t::write (int source_, int destination_,
+    const command_t &command_)
+{
+    command_pipe_t &pipe =
+        command_pipes [source_ * signalers.size () + destination_];
+    pipe.write (command_);
+    if (!pipe.flush ())
+        signalers [destination_]->signal (source_);
+}
+
+bool zmq::dispatcher_t::read (int source_,  int destination_,
+    command_t *command_)
+{
+    return command_pipes [source_ * signalers.size () +
+        destination_].read (command_);
+}
+
 zmq::app_thread_t *zmq::dispatcher_t::choose_app_thread ()
 {
     //  Check whether thread ID is already assigned. If so, return it.

src/dispatcher.hpp

@@ -70,23 +70,11 @@ namespace zmq
         int thread_slot_count ();
 
         //  Send command from the source to the destination.
-        inline void write (int source_, int destination_,
+        void write (int source_, int destination_, const command_t &command_);
-            const command_t &command_)
-        {
-            command_pipe_t &pipe =
-                command_pipes [source_ * signalers.size () + destination_];
-            pipe.write (command_);
-            if (!pipe.flush ())
-                signalers [destination_]->signal (source_);
-        }
 
         //  Receive command from the source. Returns false if there is no
         //  command available.
-        inline bool read (int source_,  int destination_, command_t *command_)
+        bool read (int source_,  int destination_, command_t *command_);
-        {
-            return command_pipes [source_ * signalers.size () +
-                destination_].read (command_);
-        }
 
         //  Returns the I/O thread that is the least busy at the moment.
         //  Taskset specifies which I/O threads are eligible (0 = all).

src/object.cpp

@@ -146,12 +146,13 @@ zmq::io_thread_t *zmq::object_t::choose_io_thread (uint64_t taskset_)
 
 void zmq::object_t::send_stop ()
 {
-    //  Send command goes always to the current object. To-self pipe is
+    //  'stop' command goes always from administrative thread to
-    //  used exclusively for sending this command.
+    //  the current object. 
+    int admin_thread_id = dispatcher->thread_slot_count () - 1;
     command_t cmd;
     cmd.destination = this;
     cmd.type = command_t::stop;
-    dispatcher->write (thread_slot, thread_slot, cmd);
+    dispatcher->write (admin_thread_id, thread_slot, cmd);
 }
 
 void zmq::object_t::send_plug (owned_t *destination_, bool inc_seqnum_)
@@ -314,9 +315,6 @@ void zmq::object_t::process_seqnum ()
 void zmq::object_t::send_command (command_t &cmd_)
 {
     int destination_thread_slot = cmd_.destination->get_thread_slot ();
-    if (destination_thread_slot == thread_slot)
+    dispatcher->write (thread_slot, destination_thread_slot, cmd_);
-        cmd_.destination->process_command (cmd_);
-    else 
-        dispatcher->write (thread_slot, destination_thread_slot, cmd_);
 }