XPUB and XSUB socket types added.

These are just placeholders. At the moment XPUB behaves th same
as PUB and XSUB as SUB.

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

11 files changed, 506 insertions, 346 deletions

diff --git a/include/zmq.h b/include/zmq.h
index 692f1c1..997595b 100644
--- a/include/zmq.h
+++ b/include/zmq.h
@@ -68,7 +68,7 @@ ZMQ_EXPORT void zmq_version (int *major, int *minor, int *patch);
 /*  0MQ errors.                                                               */
 /******************************************************************************/
 
-/*  A number random anough not to collide with different errno ranges on      */
+/*  A number random enough not to collide with different errno ranges on      */
 /*  different OSes. The assumption is that error_t is at least 32-bit type.   */
 #define ZMQ_HAUSNUMERO 156384712
 
@@ -178,6 +178,8 @@ ZMQ_EXPORT int zmq_term (void *context);
 #define ZMQ_XREP 6
 #define ZMQ_PULL 7
 #define ZMQ_PUSH 8
+#define ZMQ_XPUB 9
+#define ZMQ_XSUB 10
 #define ZMQ_UPSTREAM ZMQ_PULL      /*  Old alias, remove in 3.x               */
 #define ZMQ_DOWNSTREAM ZMQ_PUSH    /*  Old alias, remove in 3.x               */
 
diff --git a/src/Makefile.am b/src/Makefile.am
index a857ee7..eea7d35 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -126,8 +126,10 @@ libzmq_la_SOURCES = \
     uuid.hpp \
     windows.hpp \
     wire.hpp \
+    xpub.hpp \
     xrep.hpp \
     xreq.hpp \
+    xsub.hpp \
     ypipe.hpp \
     yqueue.hpp \
     zmq_connecter.hpp \
@@ -181,8 +183,10 @@ libzmq_la_SOURCES = \
     transient_session.cpp \
     trie.cpp \
     uuid.cpp \
+    xpub.cpp \
     xrep.cpp \
     xreq.cpp \
+    xsub.cpp \
     zmq.cpp \
     zmq_connecter.cpp \
     zmq_engine.cpp \
diff --git a/src/pub.cpp b/src/pub.cpp
index 84bd9e1..25d397c 100644
--- a/src/pub.cpp
+++ b/src/pub.cpp
@@ -17,155 +17,13 @@
     along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
-#include "../include/zmq.h"
-
 #include "pub.hpp"
-#include "err.hpp"
-#include "msg_content.hpp"
-#include "pipe.hpp"
 
 zmq::pub_t::pub_t (class ctx_t *parent_, uint32_t tid_) :
-    socket_base_t (parent_, tid_),
-    active (0),
-    terminating (false)
+    xpub_t (parent_, tid_)
 {
-    options.type = ZMQ_PUB;
-    options.requires_in = false;
-    options.requires_out = true;
 }
 
 zmq::pub_t::~pub_t ()
 {
-    zmq_assert (pipes.empty ());
-}
-
-void zmq::pub_t::xattach_pipes (class reader_t *inpipe_,
-    class writer_t *outpipe_, const blob_t &peer_identity_)
-{
-    zmq_assert (!inpipe_);
-
-    outpipe_->set_event_sink (this);
-
-    pipes.push_back (outpipe_);
-    pipes.swap (active, pipes.size () - 1);
-    active++;
-
-    if (terminating) {
-        register_term_acks (1);
-        outpipe_->terminate ();
-    }
 }
-
-void zmq::pub_t::process_term (int linger_)
-{
-    terminating = true;
-
-    //  Start shutdown process for all the pipes.
-    for (pipes_t::size_type i = 0; i != pipes.size (); i++)
-        pipes [i]->terminate ();
-
-    //  Wait for pipes to terminate before terminating yourself.
-    register_term_acks (pipes.size ());
-
-    //  Continue with the termination immediately.
-    socket_base_t::process_term (linger_);
-}
-
-void zmq::pub_t::activated (writer_t *pipe_)
-{
-    //  Move the pipe to the list of active pipes.
-    pipes.swap (pipes.index (pipe_), active);
-    active++;
-}
-
-void zmq::pub_t::terminated (writer_t *pipe_)
-{
-    //  Remove the pipe from the list; adjust number of active pipes
-    //  accordingly.
-    if (pipes.index (pipe_) < active)
-        active--;
-    pipes.erase (pipe_);
-
-    //  If we are already terminating, wait for one term ack less.
-    if (terminating)
-        unregister_term_ack ();
-}
-
-int zmq::pub_t::xsend (zmq_msg_t *msg_, int flags_)
-{
-    //  If there are no active pipes available, simply drop the message.
-    if (active == 0) {
-        int rc = zmq_msg_close (msg_);
-        zmq_assert (rc == 0);
-        rc = zmq_msg_init (msg_);
-        zmq_assert (rc == 0);
-        return 0;
-    }
-
-    msg_content_t *content = (msg_content_t*) msg_->content;
-
-    //  For VSMs the copying is straighforward.
-    if (content == (msg_content_t*) ZMQ_VSM) {
-        for (pipes_t::size_type i = 0; i < active;)
-            if (write (pipes [i], msg_))
-                i++;
-        int rc = zmq_msg_init (msg_);
-        zmq_assert (rc == 0);
-        return 0;
-    }
-
-    //  Optimisation for the case when there's only a single pipe
-    //  to send the message to - no refcount adjustment i.e. no atomic
-    //  operations are needed.
-    if (active == 1) {
-        if (!write (pipes [0], msg_)) {
-            int rc = zmq_msg_close (msg_);
-            zmq_assert (rc == 0);
-        }
-        int rc = zmq_msg_init (msg_);
-        zmq_assert (rc == 0);
-        return 0;
-    }
-
-    //  There are at least 2 destinations for the message. That means we have
-    //  to deal with reference counting. First add N-1 references to
-    //  the content (we are holding one reference anyway, that's why -1).
-    if (msg_->flags & ZMQ_MSG_SHARED)
-        content->refcnt.add (active - 1);
-    else {
-        content->refcnt.set (active);
-        msg_->flags |= ZMQ_MSG_SHARED;
-    }
-
-    //  Push the message to all destinations.
-    for (pipes_t::size_type i = 0; i < active;) {
-        if (!write (pipes [i], msg_))
-            content->refcnt.sub (1);
-        else
-            i++;
-    }
-
-    //  Detach the original message from the data buffer.
-    int rc = zmq_msg_init (msg_);
-    zmq_assert (rc == 0);
-
-    return 0;
-}
-
-bool zmq::pub_t::xhas_out ()
-{
-    return true;
-}
-
-bool zmq::pub_t::write (class writer_t *pipe_, zmq_msg_t *msg_)
-{
-    if (!pipe_->write (msg_)) {
-        active--;
-        pipes.swap (pipes.index (pipe_), active);
-        return false;
-    }
-    if (!(msg_->flags & ZMQ_MSG_MORE))
-        pipe_->flush ();
-    return true;
-}
-
diff --git a/src/pub.hpp b/src/pub.hpp
index 270bda5..f398526 100644
--- a/src/pub.hpp
+++ b/src/pub.hpp
@@ -20,50 +20,20 @@
 #ifndef __ZMQ_PUB_HPP_INCLUDED__
 #define __ZMQ_PUB_HPP_INCLUDED__
 
-#include "socket_base.hpp"
-#include "array.hpp"
-#include "pipe.hpp"
+#include "xpub.hpp"
 
 namespace zmq
 {
 
-    class pub_t : public socket_base_t, public i_writer_events
+    class pub_t : public xpub_t
     {
     public:
 
         pub_t (class ctx_t *parent_, uint32_t tid_);
         ~pub_t ();
 
-        //  Implementations of virtual functions from socket_base_t.
-        void xattach_pipes (class reader_t *inpipe_, class writer_t *outpipe_,
-            const blob_t &peer_identity_);
-        int xsend (zmq_msg_t *msg_, int flags_);
-        bool xhas_out ();
-
-        //  i_writer_events interface implementation.
-        void activated (writer_t *pipe_);
-        void terminated (writer_t *pipe_);
-
     private:
 
-        //  Hook into the termination process.
-        void process_term (int linger_);
-
-        //  Write the message to the pipe. Make the pipe inactive if writing
-        //  fails. In such a case false is returned.
-        bool write (class writer_t *pipe_, zmq_msg_t *msg_);
-
-        //  Outbound pipes, i.e. those the socket is sending messages to.
-        typedef array_t <class writer_t> pipes_t;
-        pipes_t pipes;
-
-        //  Number of active pipes. All the active pipes are located at the
-        //  beginning of the pipes array.
-        pipes_t::size_type active;
-
-        //  True if termination process is already underway.
-        bool terminating;
-
         pub_t (const pub_t&);
         void operator = (const pub_t&);
     };
diff --git a/src/socket_base.cpp b/src/socket_base.cpp
index bfaacb7..2fe7bfd 100644
--- a/src/socket_base.cpp
+++ b/src/socket_base.cpp
@@ -46,6 +46,8 @@
 #include "ctx.hpp"
 #include "platform.hpp"
 #include "likely.hpp"
+#include "uuid.hpp"
+
 #include "pair.hpp"
 #include "pub.hpp"
 #include "sub.hpp"
@@ -55,7 +57,8 @@
 #include "push.hpp"
 #include "xreq.hpp"
 #include "xrep.hpp"
-#include "uuid.hpp"
+#include "xpub.hpp"
+#include "xsub.hpp"
 
 zmq::socket_base_t *zmq::socket_base_t::create (int type_, class ctx_t *parent_,
     uint32_t tid_)
@@ -90,6 +93,12 @@ zmq::socket_base_t *zmq::socket_base_t::create (int type_, class ctx_t *parent_,
     case ZMQ_PUSH:
         s = new (std::nothrow) push_t (parent_, tid_);
         break;
+    case ZMQ_XPUB:
+        s = new (std::nothrow) xpub_t (parent_, tid_);
+        break;
+    case ZMQ_XSUB:
+        s = new (std::nothrow) xsub_t (parent_, tid_);
+        break;    
     default:
         errno = EINVAL;
         return NULL;
diff --git a/src/sub.cpp b/src/sub.cpp
index 096fbc7..f763558 100644
--- a/src/sub.cpp
+++ b/src/sub.cpp
@@ -17,145 +17,13 @@
     along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
-#include <string.h>
-
-#include "../include/zmq.h"
-
 #include "sub.hpp"
-#include "err.hpp"
 
 zmq::sub_t::sub_t (class ctx_t *parent_, uint32_t tid_) :
-    socket_base_t (parent_, tid_),
-    fq (this),
-    has_message (false),
-    more (false)
+    xsub_t (parent_, tid_)
 {
-    options.type = ZMQ_SUB;
-    options.requires_in = true;
-    options.requires_out = false;
-    zmq_msg_init (&message);
 }
 
 zmq::sub_t::~sub_t ()
 {
-    zmq_msg_close (&message);
-}
-
-void zmq::sub_t::xattach_pipes (class reader_t *inpipe_,
-    class writer_t *outpipe_, const blob_t &peer_identity_)
-{
-    zmq_assert (inpipe_ && !outpipe_);
-    fq.attach (inpipe_);
-}
-
-void zmq::sub_t::process_term (int linger_)
-{
-    fq.terminate ();
-    socket_base_t::process_term (linger_);
-}
-
-int zmq::sub_t::xsetsockopt (int option_, const void *optval_,
-    size_t optvallen_)
-{
-    if (option_ == ZMQ_SUBSCRIBE) {
-        subscriptions.add ((unsigned char*) optval_, optvallen_);
-        return 0;
-    }
-    
-    if (option_ == ZMQ_UNSUBSCRIBE) {
-        if (!subscriptions.rm ((unsigned char*) optval_, optvallen_)) {
-            errno = EINVAL;
-            return -1;
-        }
-        return 0;
-    }
-
-    errno = EINVAL;
-    return -1;
-}
-
-int zmq::sub_t::xrecv (zmq_msg_t *msg_, int flags_)
-{
-    //  If there's already a message prepared by a previous call to zmq_poll,
-    //  return it straight ahead.
-    if (has_message) {
-        zmq_msg_move (msg_, &message);
-        has_message = false;
-        more = msg_->flags & ZMQ_MSG_MORE;
-        return 0;
-    }
-
-    //  TODO: This can result in infinite loop in the case of continuous
-    //  stream of non-matching messages which breaks the non-blocking recv
-    //  semantics.
-    while (true) {
-
-        //  Get a message using fair queueing algorithm.
-        int rc = fq.recv (msg_, flags_);
-
-        //  If there's no message available, return immediately.
-        //  The same when error occurs.
-        if (rc != 0)
-            return -1;
-
-        //  Check whether the message matches at least one subscription.
-        //  Non-initial parts of the message are passed 
-        if (more || match (msg_)) {
-            more = msg_->flags & ZMQ_MSG_MORE;
-            return 0;
-        }
-
-        //  Message doesn't match. Pop any remaining parts of the message
-        //  from the pipe.
-        while (msg_->flags & ZMQ_MSG_MORE) {
-            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 (more)
-        return true;
-
-    //  If there's already a message prepared by a previous call to zmq_poll,
-    //  return straight ahead.
-    if (has_message)
-        return true;
-
-    //  TODO: This can result in infinite loop in the case of continuous
-    //  stream of non-matching messages.
-    while (true) {
-
-        //  Get a message using fair queueing algorithm.
-        int rc = fq.recv (&message, ZMQ_NOBLOCK);
-
-        //  If there's no message available, return immediately.
-        //  The same when error occurs.
-        if (rc != 0) {
-            zmq_assert (errno == EAGAIN);
-            return false;
-        }
-
-        //  Check whether the message matches at least one subscription.
-        if (match (&message)) {
-            has_message = true;
-            return true;
-        }
-
-        //  Message doesn't match. Pop any remaining parts of the message
-        //  from the pipe.
-        while (message.flags & ZMQ_MSG_MORE) {
-            rc = fq.recv (&message, ZMQ_NOBLOCK);
-            zmq_assert (rc == 0);
-        }
-    }
-}
-
-bool zmq::sub_t::match (zmq_msg_t *msg_)
-{
-    return subscriptions.check ((unsigned char*) zmq_msg_data (msg_),
-        zmq_msg_size (msg_));
 }
diff --git a/src/sub.hpp b/src/sub.hpp
index 3f8ced0..0ea1fc4 100644
--- a/src/sub.hpp
+++ b/src/sub.hpp
@@ -20,54 +20,20 @@
 #ifndef __ZMQ_SUB_HPP_INCLUDED__
 #define __ZMQ_SUB_HPP_INCLUDED__
 
-#include "../include/zmq.h"
-
-#include "trie.hpp"
-#include "socket_base.hpp"
-#include "fq.hpp"
+#include "xsub.hpp"
 
 namespace zmq
 {
 
-    class sub_t : public socket_base_t
+    class sub_t : public xsub_t
     {
     public:
 
         sub_t (class ctx_t *parent_, uint32_t tid_);
         ~sub_t ();
 
-    protected:
-
-        //  Overloads of functions from socket_base_t.
-        void xattach_pipes (class reader_t *inpipe_, class writer_t *outpipe_,
-            const blob_t &peer_identity_);
-        int xsetsockopt (int option_, const void *optval_, size_t optvallen_);
-        int xrecv (zmq_msg_t *msg_, int flags_);
-        bool xhas_in ();
-
     private:
 
-        //  Hook into the termination process.
-        void process_term (int linger_);
-
-        //  Check whether the message matches at least one subscription.
-        bool match (zmq_msg_t *msg_);
-
-        //  Fair queueing object for inbound pipes.
-        fq_t fq;
-
-        //  The repository of subscriptions.
-        trie_t subscriptions;
-
-        //  If true, 'message' contains a matching message to return on the
-        //  next recv call.
-        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 more;
-
         sub_t (const sub_t&);
         void operator = (const sub_t&);
     };
diff --git a/src/xpub.cpp b/src/xpub.cpp
new file mode 100644
index 0000000..1659d6f
--- /dev/null
+++ b/src/xpub.cpp
@@ -0,0 +1,171 @@
+/*
+    Copyright (c) 2007-2010 iMatix Corporation
+
+    This file is part of 0MQ.
+
+    0MQ is free software; you can redistribute it and/or modify it under
+    the terms of the GNU Lesser General Public License as published by
+    the Free Software Foundation; either version 3 of the License, or
+    (at your option) any later version.
+
+    0MQ is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Lesser General Public License for more details.
+
+    You should have received a copy of the GNU Lesser General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#include "../include/zmq.h"
+
+#include "xpub.hpp"
+#include "err.hpp"
+#include "msg_content.hpp"
+#include "pipe.hpp"
+
+zmq::xpub_t::xpub_t (class ctx_t *parent_, uint32_t tid_) :
+    socket_base_t (parent_, tid_),
+    active (0),
+    terminating (false)
+{
+    options.type = ZMQ_PUB;
+    options.requires_in = false;
+    options.requires_out = true;
+}
+
+zmq::xpub_t::~xpub_t ()
+{
+    zmq_assert (pipes.empty ());
+}
+
+void zmq::xpub_t::xattach_pipes (class reader_t *inpipe_,
+    class writer_t *outpipe_, const blob_t &peer_identity_)
+{
+    zmq_assert (!inpipe_);
+
+    outpipe_->set_event_sink (this);
+
+    pipes.push_back (outpipe_);
+    pipes.swap (active, pipes.size () - 1);
+    active++;
+
+    if (terminating) {
+        register_term_acks (1);
+        outpipe_->terminate ();
+    }
+}
+
+void zmq::xpub_t::process_term (int linger_)
+{
+    terminating = true;
+
+    //  Start shutdown process for all the pipes.
+    for (pipes_t::size_type i = 0; i != pipes.size (); i++)
+        pipes [i]->terminate ();
+
+    //  Wait for pipes to terminate before terminating yourself.
+    register_term_acks (pipes.size ());
+
+    //  Continue with the termination immediately.
+    socket_base_t::process_term (linger_);
+}
+
+void zmq::xpub_t::activated (writer_t *pipe_)
+{
+    //  Move the pipe to the list of active pipes.
+    pipes.swap (pipes.index (pipe_), active);
+    active++;
+}
+
+void zmq::xpub_t::terminated (writer_t *pipe_)
+{
+    //  Remove the pipe from the list; adjust number of active pipes
+    //  accordingly.
+    if (pipes.index (pipe_) < active)
+        active--;
+    pipes.erase (pipe_);
+
+    //  If we are already terminating, wait for one term ack less.
+    if (terminating)
+        unregister_term_ack ();
+}
+
+int zmq::xpub_t::xsend (zmq_msg_t *msg_, int flags_)
+{
+    //  If there are no active pipes available, simply drop the message.
+    if (active == 0) {
+        int rc = zmq_msg_close (msg_);
+        zmq_assert (rc == 0);
+        rc = zmq_msg_init (msg_);
+        zmq_assert (rc == 0);
+        return 0;
+    }
+
+    msg_content_t *content = (msg_content_t*) msg_->content;
+
+    //  For VSMs the copying is straighforward.
+    if (content == (msg_content_t*) ZMQ_VSM) {
+        for (pipes_t::size_type i = 0; i < active;)
+            if (write (pipes [i], msg_))
+                i++;
+        int rc = zmq_msg_init (msg_);
+        zmq_assert (rc == 0);
+        return 0;
+    }
+
+    //  Optimisation for the case when there's only a single pipe
+    //  to send the message to - no refcount adjustment i.e. no atomic
+    //  operations are needed.
+    if (active == 1) {
+        if (!write (pipes [0], msg_)) {
+            int rc = zmq_msg_close (msg_);
+            zmq_assert (rc == 0);
+        }
+        int rc = zmq_msg_init (msg_);
+        zmq_assert (rc == 0);
+        return 0;
+    }
+
+    //  There are at least 2 destinations for the message. That means we have
+    //  to deal with reference counting. First add N-1 references to
+    //  the content (we are holding one reference anyway, that's why -1).
+    if (msg_->flags & ZMQ_MSG_SHARED)
+        content->refcnt.add (active - 1);
+    else {
+        content->refcnt.set (active);
+        msg_->flags |= ZMQ_MSG_SHARED;
+    }
+
+    //  Push the message to all destinations.
+    for (pipes_t::size_type i = 0; i < active;) {
+        if (!write (pipes [i], msg_))
+            content->refcnt.sub (1);
+        else
+            i++;
+    }
+
+    //  Detach the original message from the data buffer.
+    int rc = zmq_msg_init (msg_);
+    zmq_assert (rc == 0);
+
+    return 0;
+}
+
+bool zmq::xpub_t::xhas_out ()
+{
+    return true;
+}
+
+bool zmq::xpub_t::write (class writer_t *pipe_, zmq_msg_t *msg_)
+{
+    if (!pipe_->write (msg_)) {
+        active--;
+        pipes.swap (pipes.index (pipe_), active);
+        return false;
+    }
+    if (!(msg_->flags & ZMQ_MSG_MORE))
+        pipe_->flush ();
+    return true;
+}
+
diff --git a/src/xpub.hpp b/src/xpub.hpp
new file mode 100644
index 0000000..13dd405
--- /dev/null
+++ b/src/xpub.hpp
@@ -0,0 +1,73 @@
+/*
+    Copyright (c) 2007-2010 iMatix Corporation
+
+    This file is part of 0MQ.
+
+    0MQ is free software; you can redistribute it and/or modify it under
+    the terms of the GNU Lesser General Public License as published by
+    the Free Software Foundation; either version 3 of the License, or
+    (at your option) any later version.
+
+    0MQ is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Lesser General Public License for more details.
+
+    You should have received a copy of the GNU Lesser General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#ifndef __ZMQ_XPUB_HPP_INCLUDED__
+#define __ZMQ_XPUB_HPP_INCLUDED__
+
+#include "socket_base.hpp"
+#include "array.hpp"
+#include "pipe.hpp"
+
+namespace zmq
+{
+
+    class xpub_t : public socket_base_t, public i_writer_events
+    {
+    public:
+
+        xpub_t (class ctx_t *parent_, uint32_t tid_);
+        ~xpub_t ();
+
+        //  Implementations of virtual functions from socket_base_t.
+        void xattach_pipes (class reader_t *inpipe_, class writer_t *outpipe_,
+            const blob_t &peer_identity_);
+        int xsend (zmq_msg_t *msg_, int flags_);
+        bool xhas_out ();
+
+        //  i_writer_events interface implementation.
+        void activated (writer_t *pipe_);
+        void terminated (writer_t *pipe_);
+
+    private:
+
+        //  Hook into the termination process.
+        void process_term (int linger_);
+
+        //  Write the message to the pipe. Make the pipe inactive if writing
+        //  fails. In such a case false is returned.
+        bool write (class writer_t *pipe_, zmq_msg_t *msg_);
+
+        //  Outbound pipes, i.e. those the socket is sending messages to.
+        typedef array_t <class writer_t> pipes_t;
+        pipes_t pipes;
+
+        //  Number of active pipes. All the active pipes are located at the
+        //  beginning of the pipes array.
+        pipes_t::size_type active;
+
+        //  True if termination process is already underway.
+        bool terminating;
+
+        xpub_t (const xpub_t&);
+        void operator = (const xpub_t&);
+    };
+
+}
+
+#endif
diff --git a/src/xsub.cpp b/src/xsub.cpp
new file mode 100644
index 0000000..16e1042
--- /dev/null
+++ b/src/xsub.cpp
@@ -0,0 +1,161 @@
+/*
+    Copyright (c) 2007-2010 iMatix Corporation
+
+    This file is part of 0MQ.
+
+    0MQ is free software; you can redistribute it and/or modify it under
+    the terms of the GNU Lesser General Public License as published by
+    the Free Software Foundation; either version 3 of the License, or
+    (at your option) any later version.
+
+    0MQ is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Lesser General Public License for more details.
+
+    You should have received a copy of the GNU Lesser General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#include <string.h>
+
+#include "../include/zmq.h"
+
+#include "xsub.hpp"
+#include "err.hpp"
+
+zmq::xsub_t::xsub_t (class ctx_t *parent_, uint32_t tid_) :
+    socket_base_t (parent_, tid_),
+    fq (this),
+    has_message (false),
+    more (false)
+{
+    options.type = ZMQ_SUB;
+    options.requires_in = true;
+    options.requires_out = false;
+    zmq_msg_init (&message);
+}
+
+zmq::xsub_t::~xsub_t ()
+{
+    zmq_msg_close (&message);
+}
+
+void zmq::xsub_t::xattach_pipes (class reader_t *inpipe_,
+    class writer_t *outpipe_, const blob_t &peer_identity_)
+{
+    zmq_assert (inpipe_ && !outpipe_);
+    fq.attach (inpipe_);
+}
+
+void zmq::xsub_t::process_term (int linger_)
+{
+    fq.terminate ();
+    socket_base_t::process_term (linger_);
+}
+
+int zmq::xsub_t::xsetsockopt (int option_, const void *optval_,
+    size_t optvallen_)
+{
+    if (option_ == ZMQ_SUBSCRIBE) {
+        subscriptions.add ((unsigned char*) optval_, optvallen_);
+        return 0;
+    }
+    
+    if (option_ == ZMQ_UNSUBSCRIBE) {
+        if (!subscriptions.rm ((unsigned char*) optval_, optvallen_)) {
+            errno = EINVAL;
+            return -1;
+        }
+        return 0;
+    }
+
+    errno = EINVAL;
+    return -1;
+}
+
+int zmq::xsub_t::xrecv (zmq_msg_t *msg_, int flags_)
+{
+    //  If there's already a message prepared by a previous call to zmq_poll,
+    //  return it straight ahead.
+    if (has_message) {
+        zmq_msg_move (msg_, &message);
+        has_message = false;
+        more = msg_->flags & ZMQ_MSG_MORE;
+        return 0;
+    }
+
+    //  TODO: This can result in infinite loop in the case of continuous
+    //  stream of non-matching messages which breaks the non-blocking recv
+    //  semantics.
+    while (true) {
+
+        //  Get a message using fair queueing algorithm.
+        int rc = fq.recv (msg_, flags_);
+
+        //  If there's no message available, return immediately.
+        //  The same when error occurs.
+        if (rc != 0)
+            return -1;
+
+        //  Check whether the message matches at least one subscription.
+        //  Non-initial parts of the message are passed 
+        if (more || match (msg_)) {
+            more = msg_->flags & ZMQ_MSG_MORE;
+            return 0;
+        }
+
+        //  Message doesn't match. Pop any remaining parts of the message
+        //  from the pipe.
+        while (msg_->flags & ZMQ_MSG_MORE) {
+            rc = fq.recv (msg_, ZMQ_NOBLOCK);
+            zmq_assert (rc == 0);
+        }
+    }
+}
+
+bool zmq::xsub_t::xhas_in ()
+{
+    //  There are subsequent parts of the partly-read message available.
+    if (more)
+        return true;
+
+    //  If there's already a message prepared by a previous call to zmq_poll,
+    //  return straight ahead.
+    if (has_message)
+        return true;
+
+    //  TODO: This can result in infinite loop in the case of continuous
+    //  stream of non-matching messages.
+    while (true) {
+
+        //  Get a message using fair queueing algorithm.
+        int rc = fq.recv (&message, ZMQ_NOBLOCK);
+
+        //  If there's no message available, return immediately.
+        //  The same when error occurs.
+        if (rc != 0) {
+            zmq_assert (errno == EAGAIN);
+            return false;
+        }
+
+        //  Check whether the message matches at least one subscription.
+        if (match (&message)) {
+            has_message = true;
+            return true;
+        }
+
+        //  Message doesn't match. Pop any remaining parts of the message
+        //  from the pipe.
+        while (message.flags & ZMQ_MSG_MORE) {
+            rc = fq.recv (&message, ZMQ_NOBLOCK);
+            zmq_assert (rc == 0);
+        }
+    }
+}
+
+bool zmq::xsub_t::match (zmq_msg_t *msg_)
+{
+    return subscriptions.check ((unsigned char*) zmq_msg_data (msg_),
+        zmq_msg_size (msg_));
+}
diff --git a/src/xsub.hpp b/src/xsub.hpp
new file mode 100644
index 0000000..3d7b08f
--- /dev/null
+++ b/src/xsub.hpp
@@ -0,0 +1,78 @@
+/*
+    Copyright (c) 2007-2010 iMatix Corporation
+
+    This file is part of 0MQ.
+
+    0MQ is free software; you can redistribute it and/or modify it under
+    the terms of the GNU Lesser General Public License as published by
+    the Free Software Foundation; either version 3 of the License, or
+    (at your option) any later version.
+
+    0MQ is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Lesser General Public License for more details.
+
+    You should have received a copy of the GNU Lesser General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#ifndef __ZMQ_XSUB_HPP_INCLUDED__
+#define __ZMQ_XSUB_HPP_INCLUDED__
+
+#include "../include/zmq.h"
+
+#include "trie.hpp"
+#include "socket_base.hpp"
+#include "fq.hpp"
+
+namespace zmq
+{
+
+    class xsub_t : public socket_base_t
+    {
+    public:
+
+        xsub_t (class ctx_t *parent_, uint32_t tid_);
+        ~xsub_t ();
+
+    protected:
+
+        //  Overloads of functions from socket_base_t.
+        void xattach_pipes (class reader_t *inpipe_, class writer_t *outpipe_,
+            const blob_t &peer_identity_);
+        int xsetsockopt (int option_, const void *optval_, size_t optvallen_);
+        int xrecv (zmq_msg_t *msg_, int flags_);
+        bool xhas_in ();
+
+    private:
+
+        //  Hook into the termination process.
+        void process_term (int linger_);
+
+        //  Check whether the message matches at least one subscription.
+        bool match (zmq_msg_t *msg_);
+
+        //  Fair queueing object for inbound pipes.
+        fq_t fq;
+
+        //  The repository of subscriptions.
+        trie_t subscriptions;
+
+        //  If true, 'message' contains a matching message to return on the
+        //  next recv call.
+        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 more;
+
+        xsub_t (const xsub_t&);
+        void operator = (const xsub_t&);
+    };
+
+}
+
+#endif
+