.. SPDX-FileCopyrightText: 2021 Intel Corporation .. .. SPDX-License-Identifier: CC-BY-4.0

===== mutex

[mutex.mutex]

A mutex is a class that models :doc:Mutex requirement <../named_requirements/mutexes/mutex> using an adaptive approach, it guarantees that the thread that cannot acquire the lock spins before blocking. The mutex class satisfies all of the mutex requirements described in the [thread.mutex.requirements] section of the ISO C++ standard. The mutex class is not fair or recursive.

.. code:: cpp

// Defined in header <oneapi/tbb/mutex.h>

namespace oneapi {
    namespace tbb {
        class mutex {
        public:
            mutex() noexcept;
            ~mutex();

            mutex(const mutex&) = delete;
            mutex& operator=(const mutex&) = delete;

            class scoped_lock;

            void lock();
            bool try_lock();
            void unlock();

            static constexpr bool is_rw_mutex = false;
            static constexpr bool is_recursive_mutex = false;
            static constexpr bool is_fair_mutex = false;
        };
    }
}

Member classes

.. namespace:: oneapi::tbb::mutex

.. cpp:class:: scoped_lock

The corresponding ``scoped_lock`` class. See :doc:`Mutex requirement <../named_requirements/mutexes/mutex>`.

Member functions

.. cpp:function:: mutex()

Constructs a ``mutex`` with the unlocked state.

.. cpp:function:: ~mutex()

Destroys an unlocked ``mutex``.

.. cpp:function:: void lock()

Acquires a lock. It uses an adaptive logic for waiting, thus it is blocked after a certain time of busy waiting.

.. cpp:function:: bool try_lock()

Tries to acquire a lock (non-blocking). Returns **true** if succeeded; **false** otherwise.

.. cpp:function:: void unlock()

Releases the lock held by a current thread.