session_base.hpp

/*
    Copyright (c) 2007-2016 Contributors as noted in the AUTHORS file

    This file is part of libzmq, the ZeroMQ core engine in C++.

    libzmq is free software; you can redistribute it and/or modify it under
    the terms of the GNU Lesser General Public License (LGPL) as published
    by the Free Software Foundation; either version 3 of the License, or
    (at your option) any later version.

    As a special exception, the Contributors give you permission to link
    this library with independent modules to produce an executable,
    regardless of the license terms of these independent modules, and to
    copy and distribute the resulting executable under terms of your choice,
    provided that you also meet, for each linked independent module, the
    terms and conditions of the license of that module. An independent
    module is a module which is not derived from or based on this library.
    If you modify this library, you must extend this exception to your
    version of the library.

    libzmq 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 <stdarg.h>

#include "own.hpp"
#include "io_object.hpp"
#include "pipe.hpp"
#include "socket_base.hpp"
#include "stream_engine.hpp"

namespace zmq
{
class io_thread_t;
struct i_engine;
struct address_t;

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 (zmq::io_thread_t *io_thread_,
                                   bool active_,
                                   zmq::socket_base_t *socket_,
                                   const options_t &options_,
                                   address_t *addr_);

    //  To be used once only, when creating the session.
    void attach_pipe (zmq::pipe_t *pipe_);

    //  Following functions are the interface exposed towards the engine.
    virtual void reset ();
    void flush ();
    void rollback ();
    void engine_error (zmq::stream_engine_t::error_reason_t reason_);

    //  i_pipe_events interface implementation.
    void read_activated (zmq::pipe_t *pipe_);
    void write_activated (zmq::pipe_t *pipe_);
    void hiccuped (zmq::pipe_t *pipe_);
    void pipe_terminated (zmq::pipe_t *pipe_);

    //  Delivers a message. Returns 0 if successful; -1 otherwise.
    //  The function takes ownership of the message.
    virtual int push_msg (msg_t *msg_);

    int zap_connect ();
    bool zap_enabled ();

    //  Fetches a message. Returns 0 if successful; -1 otherwise.
    //  The caller is responsible for freeing the message when no
    //  longer used.
    virtual int pull_msg (msg_t *msg_);

    //  Receives message from ZAP socket.
    //  Returns 0 on success; -1 otherwise.
    //  The caller is responsible for freeing the message.
    int read_zap_msg (msg_t *msg_);

    //  Sends message to ZAP socket.
    //  Returns 0 on success; -1 otherwise.
    //  The function takes ownership of the message.
    int write_zap_msg (msg_t *msg_);

    socket_base_t *get_socket ();
    const char *get_endpoint () const;

  protected:
    session_base_t (zmq::io_thread_t *io_thread_,
                    bool active_,
                    zmq::socket_base_t *socket_,
                    const options_t &options_,
                    address_t *addr_);
    virtual ~session_base_t ();

  private:
    void start_connecting (bool wait_);

    void reconnect ();

    //  Handlers for incoming commands.
    void process_plug ();
    void process_attach (zmq::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 ();

    //  If true, this session (re)connects to the peer. Otherwise, it's
    //  a transient session created by the listener.
    const bool _active;

    //  Pipe connecting the session to its socket.
    zmq::pipe_t *_pipe;

    //  Pipe used to exchange messages with ZAP socket.
    zmq::pipe_t *_zap_pipe;

    //  This set is added to with pipes we are disconnecting, but haven't yet completed
    std::set<pipe_t *> _terminating_pipes;

    //  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.
    zmq::i_engine *_engine;

    //  The socket the session belongs to.
    zmq::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.
    zmq::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.
    address_t *_addr;

    session_base_t (const session_base_t &);
    const session_base_t &operator= (const session_base_t &);
};
}

#endif