state.h

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/***************************************************************************
 * include/stxxl/bits/common/state.h
 *
 * Part of the STXXL. See http://stxxl.sourceforge.net
 *
 * Copyright (C) 2002 Roman Dementiev <[email protected]>
 * Copyright (C) 2008 Andreas Beckmann <[email protected]>
 * Copyright (C) 2013 Timo Bingmann <[email protected]>
 *
 * Distributed under the Boost Software License, Version 1.0.
 * (See accompanying file LICENSE_1_0.txt or copy at
 * http://www.boost.org/LICENSE_1_0.txt)
 **************************************************************************/

#ifndef STXXL_COMMON_STATE_HEADER
#define STXXL_COMMON_STATE_HEADER

#include <stxxl/bits/noncopyable.h>
#include <stxxl/bits/common/mutex.h>
#include <stxxl/bits/common/condition_variable.h>


STXXL_BEGIN_NAMESPACE

template <typename ValueType = int>
class state : private noncopyable
{
 typedef ValueType value_type;

 //! mutex for condition variable
 mutex m_mutex;

 //! condition variable
 condition_variable m_cond;

 //! current state
 value_type m_state;

public:
 state(const value_type& s)
 : m_state(s)
 { }

 void set_to(const value_type& new_state)
 {
 scoped_mutex_lock lock(m_mutex);
 m_state = new_state;
 lock.unlock();
 m_cond.notify_all();
 }

 void wait_for(const value_type& needed_state)
 {
 scoped_mutex_lock lock(m_mutex);
 while (needed_state != m_state)
 m_cond.wait(lock);
 }

 value_type operator () ()
 {
 scoped_mutex_lock lock(m_mutex);
 return m_state;
 }
};

STXXL_END_NAMESPACE

#endif // !STXXL_COMMON_STATE_HEADER