Fair queueing of subscriptions added to XPUB socket

Signed-off-by: Martin Sustrik <sustrik@250bpm.com>

src/xpub.cpp

@@ -25,10 +25,11 @@
 
 zmq::xpub_t::xpub_t (class ctx_t *parent_, uint32_t tid_) :
     socket_base_t (parent_, tid_),
-    dist (this)
+    dist (this),
+    fq (this)
 {
     options.type = ZMQ_XPUB;
-    options.requires_in = false;
+    options.requires_in = true;
     options.requires_out = true;
 }
 
@@ -39,14 +40,16 @@ zmq::xpub_t::~xpub_t ()
 void zmq::xpub_t::xattach_pipes (class reader_t *inpipe_,
     class writer_t *outpipe_, const blob_t &peer_identity_)
 {
-    zmq_assert (!inpipe_);
+    zmq_assert (inpipe_ && outpipe_);
     dist.attach (outpipe_);
+    fq.attach (inpipe_);
 }
 
 void zmq::xpub_t::process_term (int linger_)
 {
     //  Terminate the outbound pipes.
     dist.terminate ();
+    fq.terminate ();
 
     //  Continue with the termination immediately.
     socket_base_t::process_term (linger_);
@@ -62,3 +65,13 @@ bool zmq::xpub_t::xhas_out ()
     return dist.has_out ();
 }
 
+int zmq::xpub_t::xrecv (zmq_msg_t *msg_, int flags_)
+{
+    return fq.recv (msg_, flags_);
+}
+
+bool zmq::xpub_t::xhas_in ()
+{
+    return fq.has_in ();
+}
+

src/xpub.hpp

@@ -24,6 +24,7 @@
 #include "array.hpp"
 #include "pipe.hpp"
 #include "dist.hpp"
+#include "fq.hpp"
 
 namespace zmq
 {
@@ -40,6 +41,8 @@ namespace zmq
             const blob_t &peer_identity_);
         int xsend (zmq_msg_t *msg_, int flags_);
         bool xhas_out ();
+        int xrecv (zmq_msg_t *msg_, int flags_);
+        bool xhas_in ();
 
     private:
 
@@ -49,6 +52,9 @@ namespace zmq
         //  Distributor of messages holding the list of outbound pipes.
         dist_t dist;
 
+        //  Fair queuer for inbound subscriptions.
+        fq_t fq;
+
         xpub_t (const xpub_t&);
         const xpub_t &operator = (const xpub_t&);
     };