/* Menes - C++ High-Level Utility Library
 * Copyright (C) 2003-2005  Jay Freeman (saurik)
*/

/*
 *        Redistribution and use in source and binary
 * forms, with or without modification, are permitted
 * provided that the following conditions are met:
 * 
 * 1. Redistributions of source code must retain the
 *    above copyright notice, this list of conditions
 *    and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the
 *    above copyright notice, this list of conditions
 *    and the following disclaimer in the documentation
 *    and/or other materials provided with the
 *    distribution.
 * 3. The name of the author may not be used to endorse
 *    or promote products derived from this software
 *    without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS''
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING,
 * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR
 * TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/

#ifndef MENES_MTA_LOCKS_HPP
#define MENES_MTA_LOCKS_HPP

#include "cxx/platform.hpp"

#ifdef MENES_PRAGMA_ONCE
#pragma once
#endif

#include "api/locks.hpp"
#include "ext/scopes.hpp"

namespace mta {

// XXX: what does this do?
class ThreadCondition {
  public:
    bool condition_;
    bool closed_;

    api::ThreadCondition::Mutex lock_;
    api::ThreadCondition cond_;

  public:
    explicit ThreadCondition(bool condition = false) :
        condition_(condition),
        closed_(false),
        cond_(lock_)
    {
    }

    bool Wait() {
        ext::ScopeLock<api::ThreadCondition::Mutex> guard(lock_);
        while (!closed_ && !condition_)
            cond_.Wait();
        condition_ = false;
        return closed_;
    }

    void Signal() {
        ext::ScopeLock<api::ThreadCondition::Mutex> guard(lock_);
        closed_ = true;
        cond_.Signal();
    }

    void Close() {
        ext::ScopeLock<api::ThreadCondition::Mutex> guard(lock_);
        closed_ = true;
        cond_.Broadcast();
    }
};

template <typename Value_>
class ConditionVariable :
    public ext::SmartPointer< Value_, Value_ *, ConditionVariable<Value_> >,
    public api::ThreadCondition::Mutex,
    public api::ThreadCondition
{
    friend _w32class ext::SmartPointer< Value_, Value_ *, ConditionVariable<Value_> >;

  private:
    // XXX: why is this mutable?!?
    mutable Value_ value_;

    _finline Value_ *GetSmartPointer_() const {
        return &value_;
    }

  public:
    ConditionVariable() :
        api::ThreadCondition(*static_cast<api::ThreadCondition::Mutex *>(this))
    {
    }

    ConditionVariable(const Value_ &value) :
        api::ThreadCondition(*static_cast<api::ThreadCondition::Mutex *>(this)),
        value_(value)
    {
    }
};

class ReaderWriterLock {
  private:
    mta::ConditionVariable<unsigned> active_;

  public:
    ReaderWriterLock() :
        active_(0)
    {
    }

    ~ReaderWriterLock() {
        _synchronized (active_)
            _assert(*active_ == 0);
    }

    void WriteLock() {
        active_.Lock();
        while (*active_ != 0)
            active_.Wait();
    }

    void WriteUnlock() {
        active_.Unlock();
    }

    void ReadLock() {
        _synchronized (active_)
            ++*active_;
    }

    void ReadUnlock() {
        _synchronized (active_) {
            --*active_;
            active_.Broadcast();
        }
    }
};

}

#endif//MENES_MTA_LOCKS_HPP