// $Id$
//
// Copyright (C) 2007
// Fraunhofer Institute for Open Communication Systems (FOKUS)
// Competence Center NETwork research (NET), St. Augustin, GERMANY
//     Stefan Bund <g0dil@berlios.de>
//
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 2 of the License, or
// (at your option) any later version.
//
// This program 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 General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the
// Free Software Foundation, Inc.,
// 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.

/** \mainpage The SENF Scheduler Library

    The %Scheduler Library provides a single-threaded application event-loop multiplexing multiple
    event sources.

    \autotoc

    \section scheduler_scheduler The Scheduler

    The main interface is the senf::Scheduler class. This provides support for several types of
    events:
    \li File descriptors
    \li Timers
    \li UNIX signals

    \see senf::Scheduler


    \section scheduler_clockservice The ClockService

    To support precise event timing, the senf::ClockService class implements a reliable monotonous
    time source. It is based on the high precision POSIX clock and adds support for reliable
    conversion between an abstract clock type and absolute date/time

    \see senf::ClockService


    \section scheduler_helpers Miscellaneous helpers

    To ease the use of the Scheduler there are some additional helpers managing callbacks and
    registrations.

    \li senf::ReadHelper reads data from an arbitrary file descritor until a use specified condition
        is met (e.g. number of chars read or a specific character sequence is found in the input).
    \li senf::WriteHelper writes data to an arbitrary file descriptor until all provided data has
        been written.
    \li senf::SchedulerBinding is an RAII class which manages the registration of a file descriptor
        with the %scheduler.
    \li senf::SchedulerTimer is an RAII class which manages a timer registration.

    
    \section scheduler_i Implementation

    senf::Scheduler is only a wrapper around the real implementation. The real implementation is now
    based on a modular dispatcher architecture

    \see \ref scheduler_implementation
 */

/** \page scheduler_implementation The Scheduler Implementation

    The implentation architecture now is based on a set of dispatchers, one for each type of
    event.

    \autotoc

    \section scheduler_i_overview Overview

    The %scheduler utilizes the following components

    \li There is a dispatcher for each event type. This dispatcher manages the event specific
        registration and unregistration. The dispatcher is owns the event (and task) objects.
    
    \li Every registered event is represented by an event specific event class instance.

    \li The Dispatcher ultimately registeres with the senf::scheduler::FdManager. Since the
        event-loop is based on epoll() (it could easily be changed to be based on select() or
        poll()), all events must ultimately be represented by some type of file descriptor (not
        necessarily a \e different file descriptor for each event).

    \li The Dispatcher registeres all callbacks as tasks with the runner
        (senf::scheduler::FIFORunner).

    \li The senf::scheduler::FdManager uses senf::scheduler::detail::Poller to access the low-level epoll()
    API.

    All these classes are \e not singletons. They are all instantiatied by the senf::Scheduler
    singleton.


    \section scheduler_i_dispatchers Dispatchers
    
    There is one dispatcher for each event type

    \li senf::scheduler::FdDispatcher manages poll-able file descriptors. This does \e not include
        real files.
    \li senf::scheduler::FileDispatcher manages disk files
    \li senf::scheduler::TimerDispatcher manages timers
    \li senf::scheduler::SignalDispatcher manages UNIX signals

    At the moment, each dispatcher has a specific API and the integration into the main-loop is not
    standardized for performance reasons.

    The Dispatcher owns all relevant data, the other classese (senf::scheduler::FIFORunner,
    senf::scheduler::FdManager) only hold pointers to the data owned by the dispatcher.

    
    \section scheduler_i_mainloop The main loop

    The application mainloop is part of senf::Scheduler. It is constructed by calling the correct
    members of all these classes repeatedly in the correct order: 
    \li First dispatchers are set up
    \li then the senf::scheduler::FdManager is called to wait for an event
    \li After cleaning up the dispatchers,
    \li the senf::scheduler::FIFORunner is called to executed all now runnable tasks.
 */


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