spin_mutex.h

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/*
    Copyright (c) 2005-2019 Intel Corporation

    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
    You may obtain a copy of the License at

        http://www.apache.org/licenses/LICENSE-2.0

    Unless required by applicable law or agreed to in writing, software
    distributed under the License is distributed on an "AS IS" BASIS,
    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    See the License for the specific language governing permissions and
    limitations under the License.




*/

#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"
#include "internal/_mutex_padding.h"

namespace tbb {


class spin_mutex : internal::mutex_copy_deprecated_and_disabled {
    __TBB_atomic_flag 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;


        __TBB_Flag 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 ) : my_unlock_value(0) {
            internal::suppress_unused_warning(my_unlock_value);
#if TBB_USE_THREADING_TOOLS||TBB_USE_ASSERT
            my_mutex=NULL;
            internal_acquire(m);
#else
            my_mutex=&m;
            __TBB_LockByte(m.flag);
#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_mutex = &m;
            __TBB_LockByte(m.flag);
#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_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_UnlockByte(my_mutex->flag);
            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_UnlockByte(my_mutex->flag);
#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> 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> 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> tmp;
        scoped_lock& s = *tmp.begin();
        s.my_mutex = this;
        s.internal_release();
#else
        __TBB_UnlockByte(flag);
#endif /* TBB_USE_THREADING_TOOLS */
    }

    friend class scoped_lock;
}; // end of spin_mutex

__TBB_DEFINE_PROFILING_SET_NAME(spin_mutex)

} // namespace tbb

#if ( __TBB_x86_32 || __TBB_x86_64 )
#include "internal/_x86_eliding_mutex_impl.h"
#endif

namespace tbb {

#if ( __TBB_x86_32 || __TBB_x86_64 )
typedef interface7::internal::padded_mutex<interface7::internal::x86_eliding_mutex,false> speculative_spin_mutex;
#else
typedef interface7::internal::padded_mutex<spin_mutex,false> speculative_spin_mutex;
#endif
__TBB_DEFINE_PROFILING_SET_NAME(speculative_spin_mutex)

} // namespace tbb

#endif /* __TBB_spin_mutex_H */