From ad6fa9d0d4f1cf29ce63998d7efe337b1a784ef6 Mon Sep 17 00:00:00 2001
From: Martin Sustrik <sustrik@250bpm.com>
Date: Tue, 27 Apr 2010 17:36:00 +0200
Subject: initial version of multi-hop REQ/REP

---
 src/rep.cpp | 97 +++++++++++++++++++++++++++++++++++++++++--------------------
 1 file changed, 65 insertions(+), 32 deletions(-)

(limited to 'src/rep.cpp')

diff --git a/src/rep.cpp b/src/rep.cpp
index f77dfce..6711509 100644
--- a/src/rep.cpp
+++ b/src/rep.cpp
@@ -167,15 +167,15 @@ int zmq::rep_t::xsend (zmq_msg_t *msg_, int flags_)
 
     if (reply_pipe) {
 
-        //  Push message to the reply pipe.
+        // Push message to the reply pipe.
         bool written = reply_pipe->write (msg_);
         zmq_assert (!more || written);
 
-        //  The pipe is full...
-        //  When this happens, we simply return an error.
-        //  This makes REP sockets vulnerable to DoS attack when
-        //  misbehaving requesters stop collecting replies.
-        //  TODO: Tear down the underlying connection (?)
+        // The pipe is full...
+        // When this happens, we simply return an error.
+        // This makes REP sockets vulnerable to DoS attack when
+        // misbehaving requesters stop collecting replies.
+        // TODO: Tear down the underlying connection (?)
         if (!written) {
             errno = EAGAIN;
             return -1;
@@ -185,12 +185,12 @@ int zmq::rep_t::xsend (zmq_msg_t *msg_, int flags_)
     }
     else {
 
-        //  If the requester have disconnected in the meantime, drop the reply.
+        // If the requester have disconnected in the meantime, drop the reply.
         more = msg_->flags & ZMQ_MSG_MORE;
         zmq_msg_close (msg_);
     }
 
-    //  Flush the reply to the requester.
+    // Flush the reply to the requester.
     if (!more) {
         if (reply_pipe)
             reply_pipe->flush ();
@@ -198,7 +198,7 @@ int zmq::rep_t::xsend (zmq_msg_t *msg_, int flags_)
         reply_pipe = NULL;
     }
 
-    //  Detach the message from the data buffer.
+    // Detach the message from the data buffer.
     int rc = zmq_msg_init (msg_);
     zmq_assert (rc == 0);
 
@@ -207,37 +207,70 @@ int zmq::rep_t::xsend (zmq_msg_t *msg_, int flags_)
 
 int zmq::rep_t::xrecv (zmq_msg_t *msg_, int flags_)
 {
-    //  Deallocate old content of the message.
-    zmq_msg_close (msg_);
-
+    //  If we are in middle of sending a reply, we cannot receive next request.
     if (sending_reply) {
         errno = EFSM;
         return -1;
     }
 
-    //  Round-robin over the pipes to get next message.
-    for (int count = active; count != 0; count--) {
-        bool fetched = in_pipes [current]->read (msg_);
-        zmq_assert (!(more && !fetched));
-        
-        if (fetched) {
-            more = msg_->flags & ZMQ_MSG_MORE;
-            if (!more) {
-                reply_pipe = out_pipes [current];
-                sending_reply = true;
-                current++;
-                if (current >= active)
-                    current = 0;
-            }
-            return 0;
+    //  Deallocate old content of the message.
+    zmq_msg_close (msg_);
+
+    //  We haven't started reading a request yet...
+    if (!more) {
+
+        //  Round-robin over the pipes to get next message.
+        int count;
+        for (count = active; count != 0; count--) {
+            if (in_pipes [current]->read (msg_))
+                break;
+            current++;
+            if (current >= active)
+                current = 0;
+        }
+
+        //  No message is available. Initialise the output parameter
+        //  to be a 0-byte message.
+        if (count == 0) {
+            zmq_msg_init (msg_);
+            errno = EAGAIN;
+            return -1;
+        }
+
+        //  We are aware of a new message now. Setup the reply pipe.
+        reply_pipe = out_pipes [current];
+
+        //  Copy the routing info to the reply pipe.
+        while (true) {
+
+            //  Push message to the reply pipe.
+            //  TODO: What if the pipe is full?
+            //  Tear down the underlying connection?
+            bool written = reply_pipe->write (msg_);
+            zmq_assert (written);
+
+            //  Message part of zero size delimits the traceback stack.
+            if (zmq_msg_size (msg_) == 0)
+                break;
+
+            //  Get next part of the message.
+            bool fetched = in_pipes [current]->read (msg_);
+            zmq_assert (fetched);
         }
     }
 
-    //  No message is available. Initialise the output parameter
-    //  to be a 0-byte message.
-    zmq_msg_init (msg_);
-    errno = EAGAIN;
-    return -1;
+    //  Now the routing info is processed. Get the first part
+    //  of the message payload and exit.
+    bool fetched = in_pipes [current]->read (msg_);
+    zmq_assert (fetched);
+    more = msg_->flags & ZMQ_MSG_MORE;
+    if (!more) {
+        current++;
+        if (current >= active)
+            current = 0;
+        sending_reply = true;
+    }
+    return 0;
 }
 
 bool zmq::rep_t::xhas_in ()
-- 
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