spin_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_spin_mutex_H
#define __TBB_spin_mutex_H

#include <cstddef>
#include <new>
#include "aligned_space.h"
#include "tbb_stddef.h"
#include "tbb_machine.h"
#include "tbb_profiling.h"

namespace tbb {


class spin_mutex {
    unsigned char flag;

public:

    spin_mutex() : flag(0) {
#if TBB_USE_THREADING_TOOLS
        internal_construct();
#endif
    }

    class scoped_lock : internal::no_copy {
    private:
        spin_mutex* my_mutex; 

        internal::uintptr my_unlock_value;

        void __TBB_EXPORTED_METHOD internal_acquire( spin_mutex& m );

        bool __TBB_EXPORTED_METHOD internal_try_acquire( spin_mutex& m );

        void __TBB_EXPORTED_METHOD internal_release();

        friend class spin_mutex;

    public:
        scoped_lock() : my_mutex(NULL), my_unlock_value(0) {}

        scoped_lock( spin_mutex& m ) { 
#if TBB_USE_THREADING_TOOLS||TBB_USE_ASSERT
            my_mutex=NULL;
            internal_acquire(m);
#else
            my_unlock_value = __TBB_LockByte(m.flag);
            my_mutex=&m;
#endif /* TBB_USE_THREADING_TOOLS||TBB_USE_ASSERT*/
        }

        void acquire( spin_mutex& m ) {
#if TBB_USE_THREADING_TOOLS||TBB_USE_ASSERT
            internal_acquire(m);
#else
            my_unlock_value = __TBB_LockByte(m.flag);
            my_mutex = &m;
#endif /* TBB_USE_THREADING_TOOLS||TBB_USE_ASSERT*/
        }


        bool try_acquire( spin_mutex& m ) {
#if TBB_USE_THREADING_TOOLS||TBB_USE_ASSERT
            return internal_try_acquire(m);
#else
            bool result = __TBB_TryLockByte(m.flag);
            if( result ) {
                my_unlock_value = 0;
                my_mutex = &m;
            }
            return result;
#endif /* TBB_USE_THREADING_TOOLS||TBB_USE_ASSERT*/
        }

        void release() {
#if TBB_USE_THREADING_TOOLS||TBB_USE_ASSERT
            internal_release();
#else
            __TBB_store_with_release(my_mutex->flag, static_cast<unsigned char>(my_unlock_value));
            my_mutex = NULL;
#endif /* TBB_USE_THREADING_TOOLS||TBB_USE_ASSERT */
        }

        ~scoped_lock() {
            if( my_mutex ) {
#if TBB_USE_THREADING_TOOLS||TBB_USE_ASSERT
                internal_release();
#else
                __TBB_store_with_release(my_mutex->flag, static_cast<unsigned char>(my_unlock_value));
#endif /* TBB_USE_THREADING_TOOLS||TBB_USE_ASSERT */
            }
        }
    };

    void __TBB_EXPORTED_METHOD internal_construct();

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

    // ISO C++0x compatibility methods

    void lock() {
#if TBB_USE_THREADING_TOOLS
        aligned_space<scoped_lock,1> tmp;
        new(tmp.begin()) scoped_lock(*this);
#else
        __TBB_LockByte(flag);
#endif /* TBB_USE_THREADING_TOOLS*/
    }


    bool try_lock() {
#if TBB_USE_THREADING_TOOLS
        aligned_space<scoped_lock,1> tmp;
        return (new(tmp.begin()) scoped_lock)->internal_try_acquire(*this);
#else
        return __TBB_TryLockByte(flag);
#endif /* TBB_USE_THREADING_TOOLS*/
    }

    void unlock() {
#if TBB_USE_THREADING_TOOLS
        aligned_space<scoped_lock,1> tmp;
        scoped_lock& s = *tmp.begin();
        s.my_mutex = this;
        s.my_unlock_value = 0;
        s.internal_release();
#else
        __TBB_store_with_release(flag, 0);
#endif /* TBB_USE_THREADING_TOOLS */
    }

    friend class scoped_lock;
};

__TBB_DEFINE_PROFILING_SET_NAME(spin_mutex)

} // namespace tbb

#endif /* __TBB_spin_mutex_H */

---

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

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