multi-part messages work with PUB/SUB

src/fq.cpp

@@ -25,7 +25,8 @@
 
 zmq::fq_t::fq_t () :
     active (0),
-    current (0)
+    current (0),
+    tbc (false)
 {
 }
 
@@ -44,6 +45,8 @@ void zmq::fq_t::attach (reader_t *pipe_)
 
 void zmq::fq_t::detach (reader_t *pipe_)
 {
+    zmq_assert (!tbc || pipes [current] != pipe_);
+
     //  Remove the pipe from the list; adjust number of active pipes
     //  accordingly.
     if (pipes.index (pipe_) < active) {
@@ -75,15 +78,27 @@ int zmq::fq_t::recv (zmq_msg_t *msg_, int flags_)
     //  Deallocate old content of the message.
     zmq_msg_close (msg_);
 
-    //  Round-robin over the pipes to get next message.
+    //  Round-robin over the pipes to get the next message.
     for (int count = active; count != 0; count--) {
+
+        //  Try to fetch new message. If we've already read part of the message
+        //  subsequent part should be immediately available.
         bool fetched = pipes [current]->read (msg_);
+        zmq_assert (!(tbc && !fetched));
+
+        //  Note that when message is not fetched, current pipe is killed and
+        //  replaced by another active pipe. Thus we don't have to increase
+        //  the 'current' pointer.
+        if (fetched) {
+            tbc = msg_->flags & ZMQ_MSG_TBC;
+            if (!tbc) {
                 current++;
                 if (current >= active)
                     current = 0;
-        if (fetched)
+            }
             return 0;
         }
+    }
 
     //  No message is available. Initialise the output parameter
     //  to be a 0-byte message.
@@ -94,6 +109,10 @@ int zmq::fq_t::recv (zmq_msg_t *msg_, int flags_)
 
 bool zmq::fq_t::has_in ()
 {
+    //  There are subsequent parts of the partly-read message available.
+    if (tbc)
+        return true;
+
     //  Note that messing with current doesn't break the fairness of fair
     //  queueing algorithm. If there are no messages available current will
     //  get back to its original value. Otherwise it'll point to the first

src/fq.hpp

@@ -55,6 +55,10 @@ namespace zmq
         //  Index of the next bound pipe to read a message from.
         pipes_t::size_type current;
 
+        //  If true, part of a multipart message was already received, but
+        //  there are following parts still waiting in the current pipe.
+        bool tbc;
+
         fq_t (const fq_t&);
         void operator = (const fq_t&);
     };

src/pipe.cpp

@@ -77,7 +77,9 @@ bool zmq::reader_t::read (zmq_msg_t *msg_)
         return false;
     }
 
+    if (!(msg_->flags & ZMQ_MSG_TBC))
         msgs_read++;
+
     if (lwm > 0 && msgs_read % lwm == 0)
         send_reader_info (peer, msgs_read);
 
@@ -161,6 +163,7 @@ bool zmq::writer_t::write (zmq_msg_t *msg_)
     }
 
     pipe->write (*msg_);
+    if (!(msg_->flags & ZMQ_MSG_TBC))
         msgs_written++;
     return true;
 }
@@ -194,6 +197,9 @@ void zmq::writer_t::term ()
 {
     endpoint = NULL;
 
+    //  Rollback any unfinished messages.
+    rollback ();
+
     //  Push delimiter into the pipe.
     //  Trick the compiler to belive that the tag is a valid pointer.
     zmq_msg_t msg;

src/pub.cpp

@@ -170,6 +170,7 @@ bool zmq::pub_t::write (class writer_t *pipe_, zmq_msg_t *msg_)
         pipes.swap (pipes.index (pipe_), active);
         return false;
     }
+    if (!(msg_->flags & ZMQ_MSG_TBC))
         pipe_->flush ();
     return true;
 }

src/sub.cpp

@@ -26,7 +26,8 @@
 
 zmq::sub_t::sub_t (class app_thread_t *parent_) :
     socket_base_t (parent_),
-    has_message (false)
+    has_message (false),
+    tbc (false)
 {
     options.requires_in = true;
     options.requires_out = false;
@@ -105,6 +106,7 @@ int zmq::sub_t::xrecv (zmq_msg_t *msg_, int flags_)
     if (has_message) {
         zmq_msg_move (msg_, &message);
         has_message = false;
+        tbc = msg_->flags & ZMQ_MSG_TBC;
         return 0;
     }
 
@@ -122,13 +124,27 @@ int zmq::sub_t::xrecv (zmq_msg_t *msg_, int flags_)
             return -1;
 
         //  Check whether the message matches at least one subscription.
-        if (match (msg_))
+        //  Non-initial parts of the message are passed 
+        if (tbc || match (msg_)) {
+            tbc = msg_->flags & ZMQ_MSG_TBC;
             return 0;
         }
+
+        //  Message doesn't match. Pop any remaining parts of the message
+        //  from the pipe.
+        while (msg_->flags & ZMQ_MSG_TBC) {
+            rc = fq.recv (msg_, ZMQ_NOBLOCK);
+            zmq_assert (rc == 0);
+        }
+    }
 }
 
 bool zmq::sub_t::xhas_in ()
 {
+    //  There are subsequent parts of the partly-read message available.
+    if (tbc)
+        return true;
+
     //  If there's already a message prepared by a previous call to zmq_poll,
     //  return straight ahead.
     if (has_message)
@@ -153,6 +169,13 @@ bool zmq::sub_t::xhas_in ()
             has_message = true;
             return true;
         }
+
+        //  Message doesn't match. Pop any remaining parts of the message
+        //  from the pipe.
+        while (message.flags & ZMQ_MSG_TBC) {
+            rc = fq.recv (&message, ZMQ_NOBLOCK);
+            zmq_assert (rc == 0);
+        }
     }
 }
 

src/sub.hpp

@@ -68,6 +68,10 @@ namespace zmq
         bool has_message;
         zmq_msg_t message;
 
+        //  If true, part of a multipart message was already received, but
+        //  there are following parts still waiting.
+        bool tbc;
+
         sub_t (const sub_t&);
         void operator = (const sub_t&);
     };

src/ypipe.hpp

@@ -84,8 +84,8 @@ namespace zmq
         {
             if (w == &queue.back ())
                 return false;
-            *value_ = queue.back ();
             queue.unpush ();
+            *value_ = queue.back ();
             return true;
         }