Session class separated into socket-type-specific sessions

This is a preliminary patch allowing for socket-type-specific
functionality in the I/O thread. For example, message format
can be checked asynchronously and misbehaved connections dropped
straight away.

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

src/session_base.hpp

@@ -0,0 +1,131 @@
+/*
+    Copyright (c) 2007-2011 iMatix Corporation
+    Copyright (c) 2007-2011 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/>.
+*/
+
+#ifndef __ZMQ_SESSION_BASE_HPP_INCLUDED__
+#define __ZMQ_SESSION_BASE_HPP_INCLUDED__
+
+#include <string>
+
+#include "own.hpp"
+#include "i_engine.hpp"
+#include "io_object.hpp"
+#include "pipe.hpp"
+
+namespace zmq
+{
+
+    class session_base_t :
+        public own_t,
+        public io_object_t,
+        public i_pipe_events
+    {
+    public:
+
+        //  Create a session of the particular type.
+        static session_base_t *create (class io_thread_t *io_thread_,
+            bool connect_, class socket_base_t *socket_,
+            const options_t &options_, const char *protocol_,
+            const char *address_);
+
+        //  To be used once only, when creating the session.
+        void attach_pipe (class pipe_t *pipe_);
+
+        //  Following functions are the interface exposed towards the engine.
+        bool read (msg_t *msg_);
+        bool write (msg_t *msg_);
+        void flush ();
+        void detach ();
+
+        //  i_pipe_events interface implementation.
+        void read_activated (class pipe_t *pipe_);
+        void write_activated (class pipe_t *pipe_);
+        void hiccuped (class pipe_t *pipe_);
+        void terminated (class pipe_t *pipe_);
+
+    protected:
+
+        session_base_t (class io_thread_t *io_thread_, bool connect_,
+            class socket_base_t *socket_, const options_t &options_,
+            const char *protocol_, const char *address_);
+        ~session_base_t ();
+
+    private:
+
+        void start_connecting (bool wait_);
+
+        void detached ();
+
+        //  Handlers for incoming commands.
+        void process_plug ();
+        void process_attach (struct i_engine *engine_);
+        void process_term (int linger_);
+
+        //  i_poll_events handlers.
+        void timer_event (int id_);
+
+        //  Remove any half processed messages. Flush unflushed messages.
+        //  Call this function when engine disconnect to get rid of leftovers.
+        void clean_pipes ();
+
+        //  Call this function to move on with the delayed process_term.
+        void proceed_with_term ();
+
+        //  If true, this session (re)connects to the peer. Otherwise, it's
+        //  a transient session created by the listener.
+        bool connect;
+
+        //  Pipe connecting the session to its socket.
+        class pipe_t *pipe;
+
+        //  This flag is true if the remainder of the message being processed
+        //  is still in the in pipe.
+        bool incomplete_in;
+
+        //  True if termination have been suspended to push the pending
+        //  messages to the network.
+        bool pending;
+
+        //  The protocol I/O engine connected to the session.
+        struct i_engine *engine;
+
+        //  The socket the session belongs to.
+        class socket_base_t *socket;
+
+        //  I/O thread the session is living in. It will be used to plug in
+        //  the engines into the same thread.
+        class io_thread_t *io_thread;
+
+        //  ID of the linger timer
+        enum {linger_timer_id = 0x20};
+
+        //  True is linger timer is running.
+        bool has_linger_timer;
+
+        //  Protocol and address to use when connecting.
+        std::string protocol;
+        std::string address;
+
+        session_base_t (const session_base_t&);
+        const session_base_t &operator = (const session_base_t&);
+    };
+
+}
+
+#endif