queuing_rw_mutex.h

/*
    Copyright 2005-2009 Intel Corporation.  All Rights Reserved.

    The source code contained or described herein and all documents related
    to the source code ("Material") are owned by Intel Corporation or its
    suppliers or licensors.  Title to the Material remains with Intel
    Corporation or its suppliers and licensors.  The Material is protected
    by worldwide copyright laws and treaty provisions.  No part of the
    Material may be used, copied, reproduced, modified, published, uploaded,
    posted, transmitted, distributed, or disclosed in any way without
    Intel's prior express written permission.

    No license under any patent, copyright, trade secret or other
    intellectual property right is granted to or conferred upon you by
    disclosure or delivery of the Materials, either expressly, by
    implication, inducement, estoppel or otherwise.  Any license under such
    intellectual property rights must be express and approved by Intel in
    writing.
*/

#ifndef __TBB_queuing_rw_mutex_H
#define __TBB_queuing_rw_mutex_H

#include <cstring>
#include "atomic.h"
#include "tbb_profiling.h"

namespace tbb {


class queuing_rw_mutex {
public:
    queuing_rw_mutex() {
        q_tail = NULL;
#if TBB_USE_THREADING_TOOLS
        internal_construct();
#endif
    }

    ~queuing_rw_mutex() {
#if TBB_USE_ASSERT
        __TBB_ASSERT( !q_tail, "destruction of an acquired mutex");
#endif
    }

    class scoped_lock;
    friend class scoped_lock;


    class scoped_lock: internal::no_copy {
        void initialize() {
            mutex = NULL;
#if TBB_USE_ASSERT
            state = 0xFF; // Set to invalid state
            internal::poison_pointer(next);
            internal::poison_pointer(prev);
#endif /* TBB_USE_ASSERT */
        }
    public:

        scoped_lock() {initialize();}


        scoped_lock( queuing_rw_mutex& m, bool write=true ) {
            initialize();
            acquire(m,write);
        }

        ~scoped_lock() {
            if( mutex ) release();
        }

        void acquire( queuing_rw_mutex& m, bool write=true );

        bool try_acquire( queuing_rw_mutex& m, bool write=true );

        void release();


        bool upgrade_to_writer();

        bool downgrade_to_reader();

    private:
        queuing_rw_mutex* mutex;

        scoped_lock * prev, * next;

        typedef unsigned char state_t;

        atomic<state_t> state;


        unsigned char going;

        unsigned char internal_lock;

        void acquire_internal_lock();


        bool try_acquire_internal_lock();

        void release_internal_lock();

        void wait_for_release_of_internal_lock();

        void unblock_or_wait_on_internal_lock( uintptr_t );
    };

    void __TBB_EXPORTED_METHOD internal_construct();

    // Mutex traits
    static const bool is_rw_mutex = true;
    static const bool is_recursive_mutex = false;
    static const bool is_fair_mutex = true;

private:
    atomic<scoped_lock*> q_tail;

};

__TBB_DEFINE_PROFILING_SET_NAME(queuing_rw_mutex)

} // namespace tbb

#endif /* __TBB_queuing_rw_mutex_H */

---

Copyright © 2005-2009 Intel Corporation. All Rights Reserved.

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