Clean-up of session termination process

Specifically, shutdown of child objects is initiated *before* termination
handshake with socket object.
Signed-off-by: Martin Sustrik <sustrik@250bpm.com>

src/fq.cpp

@@ -73,6 +73,10 @@ void zmq::fq_t::terminated (reader_t *pipe_)
         sink->unregister_term_ack ();
 }
 
+void zmq::fq_t::delimited (reader_t *pipe_)
+{
+}
+
 void zmq::fq_t::terminate ()
 {
     zmq_assert (!terminating);

src/fq.hpp

@@ -45,6 +45,7 @@ namespace zmq
         //  i_reader_events implementation.
         void activated (reader_t *pipe_);
         void terminated (reader_t *pipe_);
+        void delimited (reader_t *pipe_);
 
     private:
 

src/pair.cpp

@@ -42,8 +42,8 @@ zmq::pair_t::~pair_t ()
     zmq_assert (!outpipe);
 }
 
-void zmq::pair_t::xattach_pipes (class reader_t *inpipe_,
-    class writer_t *outpipe_, const blob_t &peer_identity_)
+void zmq::pair_t::xattach_pipes (reader_t *inpipe_, writer_t *outpipe_,
+    const blob_t &peer_identity_)
 {
     zmq_assert (!inpipe && !outpipe);
 
@@ -62,7 +62,7 @@ void zmq::pair_t::xattach_pipes (class reader_t *inpipe_,
     }
 }
 
-void zmq::pair_t::terminated (class reader_t *pipe_)
+void zmq::pair_t::terminated (reader_t *pipe_)
 {
     zmq_assert (pipe_ == inpipe);
     inpipe = NULL;
@@ -72,7 +72,7 @@ void zmq::pair_t::terminated (class reader_t *pipe_)
         unregister_term_ack ();
 }
 
-void zmq::pair_t::terminated (class writer_t *pipe_)
+void zmq::pair_t::terminated (writer_t *pipe_)
 {
     zmq_assert (pipe_ == outpipe);
     outpipe = NULL;
@@ -82,6 +82,10 @@ void zmq::pair_t::terminated (class writer_t *pipe_)
         unregister_term_ack ();
 }
 
+void  zmq::pair_t::delimited (reader_t *pipe_)
+{
+}
+
 void zmq::pair_t::process_term ()
 {
     terminating = true;

src/pair.hpp

@@ -47,6 +47,7 @@ namespace zmq
         //  i_reader_events interface implementation.
         void activated (class reader_t *pipe_);
         void terminated (class reader_t *pipe_);
+        void delimited (class reader_t *pipe_);
 
         //  i_writer_events interface implementation.
         void activated (class writer_t *pipe_);

src/pipe.cpp

@@ -89,6 +89,11 @@ bool zmq::reader_t::check_read ()
     //  If the next item in the pipe is message delimiter,
     //  initiate its termination.
     if (pipe->probe (is_delimiter)) {
+        zmq_msg_t msg;
+        bool ok = pipe->read (&msg);
+        zmq_assert (ok);
+        if (sink)
+            sink->delimited (this);
         terminate ();
         return false;
     }
@@ -109,6 +114,8 @@ bool zmq::reader_t::read (zmq_msg_t *msg_)
     //  If delimiter was read, start termination process of the pipe.
     unsigned char *offset = 0;
     if (msg_->content == (void*) (offset + ZMQ_DELIMITER)) {
+        if (sink)
+            sink->delimited (this);
         terminate ();
         return false;
     }

src/pipe.hpp

@@ -52,6 +52,7 @@ namespace zmq
 
         virtual void terminated (class reader_t *pipe_) = 0;
         virtual void activated (class reader_t *pipe_) = 0;
+        virtual void delimited (class reader_t *pipe_) = 0;
     };
 
     class reader_t : public object_t, public array_item_t

src/session.cpp

@@ -35,9 +35,9 @@ zmq::session_t::session_t (class io_thread_t *io_thread_,
     engine (NULL),
     socket (socket_),
     io_thread (io_thread_),
-    attach_processed (false),
-    term_processed (false),
-    finalised (false)
+    delimiter_processed (false),
+    force_terminate (false),
+    state (active)
 {    
 }
 
@@ -50,12 +50,24 @@ zmq::session_t::~session_t ()
         engine->terminate ();
 }
 
-void zmq::session_t::terminate ()
+void zmq::session_t::proceed_with_term ()
 {
-    if (in_pipe)
+    if (state == terminating)
+        return;
+
+    zmq_assert (state == pending);
+    state = terminating;
+
+    if (in_pipe) {
+        register_term_acks (1);
         in_pipe->terminate ();
-    if (out_pipe)
+    }
+    if (out_pipe) {
+        register_term_acks (1);
         out_pipe->terminate ();
+    }
+
+    own_t::process_term ();
 }
 
 bool zmq::session_t::read (::zmq_msg_t *msg_)
@@ -125,46 +137,44 @@ void zmq::session_t::attach_pipes (class reader_t *inpipe_,
     }
 
     //  If we are already terminating, terminate the pipes straight away.
-    if (finalised) {
+    if (state == terminating) {
         if (in_pipe) {
-            register_term_acks (1);
             in_pipe->terminate ();
+            register_term_acks (1);
         }
         if (out_pipe) {
-            register_term_acks (1);
             out_pipe->terminate ();
+            register_term_acks (1);
         }
-        return;
     }
+}
+
+void zmq::session_t::delimited (reader_t *pipe_)
+{
+    zmq_assert (in_pipe == pipe_);
+    zmq_assert (!delimiter_processed);
+    delimiter_processed = true;
 
-    attach_processed = true;
-    finalise ();
+    //  If we are in process of being closed, but still waiting for all
+    //  pending messeges being sent, we can terminate here.
+    if (state == pending)
+        proceed_with_term ();
 }
 
 void zmq::session_t::terminated (reader_t *pipe_)
 {
     zmq_assert (in_pipe == pipe_);
     in_pipe = NULL;
-
-    if (finalised) {
+    if (state == terminating)
         unregister_term_ack ();
-        return;
-    }
-
-    finalise ();
 }
 
 void zmq::session_t::terminated (writer_t *pipe_)
 {
     zmq_assert (out_pipe == pipe_);
     out_pipe = NULL;
-
-    if (finalised) {
+    if (state == terminating)
         unregister_term_ack ();
-        return;
-    }
-
-    finalise ();
 }
 
 void zmq::session_t::activated (reader_t *pipe_)
@@ -186,27 +196,6 @@ void zmq::session_t::process_plug ()
 {
 }
 
-void zmq::session_t::finalise ()
-{
-    //  There may be delimiter waiting in the inbound pipe, never to be read
-    //  because the connection cannot be established. In order to terminate
-    //  decently in such case, do check_read which will in turn start the pipe
-    //  termination process if there's delimiter in it.
-    if (in_pipe)
-        in_pipe->check_read ();
-
-    //  If all conditions are met, proceed with termination:
-    //  1. Owner object already asked us to terminate.
-    //  2. The pipes were already attached to the session.
-    //  3. Both pipes have already terminated. Note that inbound pipe
-    //     is terminated after delimiter is read, i.e. all messages
-    //     were already sent to the wire.
-    if (term_processed && attach_processed && !in_pipe && !out_pipe) {
-        finalised = true;
-        own_t::process_term ();
-    }
-}
-
 void zmq::session_t::process_attach (i_engine *engine_,
     const blob_t &peer_identity_)
 {
@@ -219,7 +208,7 @@ void zmq::session_t::process_attach (i_engine *engine_,
     }
 
     //  If we are already terminating, we destroy the engine straight away.
-    if (finalised) {
+    if (state == terminating) {
         delete engine;
         return;
     }
@@ -229,18 +218,19 @@ void zmq::session_t::process_attach (i_engine *engine_,
     reader_t *socket_reader = NULL;
     writer_t *socket_writer = NULL;
 
+    //  Create the pipes, if required.
     if (options.requires_in && !out_pipe) {
         create_pipe (socket, this, options.hwm, options.swap, &socket_reader,
             &out_pipe);
         out_pipe->set_event_sink (this);
     }
-
     if (options.requires_out && !in_pipe) {
         create_pipe (this, socket, options.hwm, options.swap, &in_pipe,
             &socket_writer);
         in_pipe->set_event_sink (this);
     }
 
+    //  Bind the pipes to the socket object.
     if (socket_reader || socket_writer)
         send_bind (socket, socket_reader, socket_writer, peer_identity_);
 
@@ -250,8 +240,6 @@ void zmq::session_t::process_attach (i_engine *engine_,
     engine = engine_;
     engine->plug (io_thread, this);
 
-    attach_processed = true;
-
     //  Trigger the notfication about the attachment.
     attached (peer_identity_);
 }
@@ -266,11 +254,21 @@ void zmq::session_t::detach ()
 
 void zmq::session_t::process_term ()
 {
-    //  Here we are pugging into the own_t's termination mechanism.
-    //  The goal is to postpone the termination till all the pending messages
-    //  are sent to the peer.
-    term_processed = true;
-    finalise ();
+    zmq_assert (state == active);
+    state = pending;
+
+    //  If there's no engine and there's only delimiter in the pipe it wouldn't
+    //  be ever read. Thus we check for it explicitly.
+    if (in_pipe)
+        in_pipe->check_read ();
+
+    //  If there's no in pipe there are no pending messages to send.
+    //  We can proceed with the shutdown straight away. Also, if there is
+    //  inbound pipe, but the delimiter was already processed, we can
+    //  terminate immediately. Alternatively, if the derived session type have
+    //  called 'terminate' we'll finish straight away.
+    if (!options.requires_out || delimiter_processed || force_terminate)
+        proceed_with_term ();
 }
 
 bool zmq::session_t::register_session (const blob_t &name_, session_t *session_)
@@ -291,3 +289,8 @@ void zmq::session_t::detached ()
 {
 }
 
+void zmq::session_t::terminate ()
+{
+    force_terminate = true;
+    own_t::terminate ();
+}

src/session.hpp

@@ -54,6 +54,7 @@ namespace zmq
         //  i_reader_events interface implementation.
         void activated (class reader_t *pipe_);
         void terminated (class reader_t *pipe_);
+        void delimited (class reader_t *pipe_);
 
         //  i_writer_events interface implementation.
         void activated (class writer_t *pipe_);
@@ -61,8 +62,8 @@ namespace zmq
 
     protected:
 
-        //  Forcefully close this session (without sending
-        //  outbound messages to the wire).
+        //  This function allows to shut down the session even though
+        //  there are pending messages in the inbound pipe.
         void terminate ();
 
         //  Two events for the derived session type. Attached is triggered
@@ -93,9 +94,8 @@ namespace zmq
             const blob_t &peer_identity_);
         void process_term ();
 
-        //  Check whether object is ready for termination. If so proceed
-        //  with closing child objects.
-        void finalise ();
+        //  Call this function to move on with the delayed process_term.
+        void proceed_with_term ();
 
         //  Inbound pipe, i.e. one the session is getting messages from.
         class reader_t *in_pipe;
@@ -117,13 +117,18 @@ namespace zmq
         //  the engines into the same thread.
         class io_thread_t *io_thread;
 
-        //  True if pipes were already attached.
-        bool attach_processed;
+        //  If true, delimiter was already read from the inbound pipe.
+        bool delimiter_processed;
 
-        //  True if term command was already processed.
-        bool term_processed;
+        //  If true, we should terminate the session even though there are
+        //  pending messages in the inbound pipe.
+        bool force_terminate;
 
-        bool finalised;
+        enum {
+            active,
+            pending,
+            terminating
+        } state;
 
         session_t (const session_t&);
         void operator = (const session_t&);

src/xrep.cpp

@@ -135,6 +135,10 @@ void zmq::xrep_t::terminated (writer_t *pipe_)
     zmq_assert (false);
 }
 
+void zmq::xrep_t::delimited (reader_t *pipe_)
+{
+}
+
 void zmq::xrep_t::activated (reader_t *pipe_)
 {
     for (inpipes_t::iterator it = inpipes.begin (); it != inpipes.end ();

src/xrep.hpp

@@ -57,6 +57,7 @@ namespace zmq
         //  i_reader_events interface implementation.
         void activated (reader_t *pipe_);
         void terminated (reader_t *pipe_);
+        void delimited (reader_t *pipe_);
 
         //  i_writer_events interface implementation.
         void activated (writer_t *pipe_);