signaler renamed to mailbox

For historical reasons queue to transfer commands between
threads was called 'signaler'. Given that it was used to
pass commands rather than signals it was renamed to 'mailbox',
see Erlang mailboxes.

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

src/mailbox.hpp

@@ -0,0 +1,61 @@
+/*
+    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_MAILBOX_HPP_INCLUDED__
+#define __ZMQ_MAILBOX_HPP_INCLUDED__
+
+#include <stddef.h>
+
+#include "platform.hpp"
+#include "fd.hpp"
+#include "stdint.hpp"
+#include "config.hpp"
+#include "command.hpp"
+
+namespace zmq
+{
+
+    class mailbox_t
+    {
+    public:
+
+        mailbox_t ();
+        ~mailbox_t ();
+
+        fd_t get_fd ();
+        void send (const command_t &cmd_);
+        int recv (command_t *cmd_, bool block_);
+        
+    private:
+
+        //  Write & read end of the socketpair.
+        fd_t w;
+        fd_t r;
+
+        //  Platform-dependent function to create a socketpair.
+        static int make_socketpair (fd_t *r_, fd_t *w_);
+
+        //  Disable copying of mailbox_t object.
+        mailbox_t (const mailbox_t&);
+        void operator = (const mailbox_t&);
+    };
+
+}
+
+#endif