Removed 'device' concept and introduced proxies

* zmq_device is now a wrapper that calls zmq_proxy
* zmq_proxy adds capture socket

src/proxy.cpp

@@ -0,0 +1,121 @@
+/*
+    Copyright (c) 2007-2012 iMatix Corporation
+    Copyright (c) 2007-2012 Other contributors as noted in the AUTHORS file
+
+    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 <stddef.h>
+#include "../include/zmq.h"
+#include "platform.hpp"
+#include "proxy.hpp"
+#include "socket_base.hpp"
+#include "likely.hpp"
+#include "err.hpp"
+
+int zmq::proxy (
+    class socket_base_t *frontend_,
+    class socket_base_t *backend_,
+    class socket_base_t *capture_)
+{
+    msg_t msg;
+    int rc = msg.init ();
+    if (rc != 0)
+        return -1;
+
+    //  The algorithm below assumes ratio of requests and replies processed
+    //  under full load to be 1:1.
+
+    int more;
+    size_t moresz;
+    zmq_pollitem_t items [] = {
+        { frontend_, 0, ZMQ_POLLIN, 0 },
+        { backend_, 0, ZMQ_POLLIN, 0 }
+    };
+    while (true) {
+        //  Wait while there are either requests or replies to process.
+        rc = zmq_poll (&items [0], 2, -1);
+        if (unlikely (rc < 0))
+            return -1;
+
+        //  Process a request
+        if (items [0].revents & ZMQ_POLLIN) {
+            while (true) {
+                rc = frontend_->recv (&msg, 0);
+                if (unlikely (rc < 0))
+                    return -1;
+
+                moresz = sizeof more;
+                rc = frontend_->getsockopt (ZMQ_RCVMORE, &more, &moresz);
+                if (unlikely (rc < 0))
+                    return -1;
+
+                //  Copy message to capture socket if any
+                if (capture_) {
+                    msg_t ctrl;
+                    rc = ctrl.init ();
+                    if (unlikely (rc < 0))
+                        return -1;
+                    rc = ctrl.copy (msg);
+                    if (unlikely (rc < 0))
+                        return -1;
+                    rc = capture_->send (&ctrl, more? ZMQ_SNDMORE: 0);
+                    if (unlikely (rc < 0))
+                        return -1;
+                }
+                rc = backend_->send (&msg, more? ZMQ_SNDMORE: 0);
+                if (unlikely (rc < 0))
+                    return -1;
+                if (more == 0)
+                    break;
+            }
+        }
+        //  Process a reply
+        if (items [1].revents & ZMQ_POLLIN) {
+            while (true) {
+                rc = backend_->recv (&msg, 0);
+                if (unlikely (rc < 0))
+                    return -1;
+
+                moresz = sizeof more;
+                rc = backend_->getsockopt (ZMQ_RCVMORE, &more, &moresz);
+                if (unlikely (rc < 0))
+                    return -1;
+
+                //  Copy message to capture socket if any
+                if (capture_) {
+                    msg_t ctrl;
+                    rc = ctrl.init ();
+                    if (unlikely (rc < 0))
+                        return -1;
+                    rc = ctrl.copy (msg);
+                    if (unlikely (rc < 0))
+                        return -1;
+                    rc = capture_->send (&ctrl, more? ZMQ_SNDMORE: 0);
+                    if (unlikely (rc < 0))
+                        return -1;
+                }
+                rc = frontend_->send (&msg, more? ZMQ_SNDMORE: 0);
+                if (unlikely (rc < 0))
+                    return -1;
+                if (more == 0)
+                    break;
+            }
+        }
+
+    }
+    return 0;
+}