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## Class interprocess_upgradable_mutex

boost::interprocess::interprocess_upgradable_mutex

## Synopsis

    // In header: <boost/interprocess/sync/interprocess_upgradable_mutex.hpp>

    class interprocess_upgradable_mutex {
    public:

      // private member functions
      interprocess_upgradable_mutex(const interprocess_upgradable_mutex &);
      interprocess_upgradable_mutex &
      operator=(const interprocess_upgradable_mutex &);

      // public member functions
      interprocess_upgradable_mutex();
      ~interprocess_upgradable_mutex();
      void lock();
      bool try_lock();
      template<typename TimePoint> bool timed_lock(const TimePoint &);
      template<typename TimePoint> bool try_lock_until(const TimePoint &);
      template<typename Duration> bool try_lock_for(const Duration &);
      void unlock();
      void lock_sharable();
      void lock_shared();
      bool try_lock_sharable();
      bool try_lock_shared();
      template<typename TimePoint> bool timed_lock_sharable(const TimePoint &);
      template<typename TimePoint> bool try_lock_shared_until(const TimePoint &);
      template<typename Duration> bool try_lock_shared_for(const Duration &);
      void unlock_sharable();
      void unlock_shared();
      void lock_upgradable();
      bool try_lock_upgradable();
      template<typename TimePoint> bool timed_lock_upgradable(const TimePoint &);
      void unlock_upgradable();
      void unlock_and_lock_upgradable();
      void unlock_and_lock_sharable();
      void unlock_upgradable_and_lock_sharable();
      void unlock_upgradable_and_lock();
      bool try_unlock_upgradable_and_lock();
      template<typename TimePoint>
        bool timed_unlock_upgradable_and_lock(const TimePoint &);
      bool try_unlock_sharable_and_lock();
      bool try_unlock_sharable_and_lock_upgradable();
    };

## Description

Wraps a interprocess_upgradable_mutex that can be placed in shared memory and can be shared between processes. Allows timed lock tries

### `interprocess_upgradable_mutex` private member functions

1.     interprocess_upgradable_mutex(const interprocess_upgradable_mutex &);

2.     interprocess_upgradable_mutex &
       operator=(const interprocess_upgradable_mutex &);

### `interprocess_upgradable_mutex` public member functions

1.     interprocess_upgradable_mutex();

   Constructs the upgradable lock. Throws interprocess_exception on error.

2.     ~interprocess_upgradable_mutex();

   Destroys the upgradable lock. Does not throw.

3.     void lock();

   Requires: The calling thread does not own the mutex.

   Effects: The calling thread tries to obtain exclusive ownership of the mutex, and if another thread has exclusive, sharable or upgradable ownership of the mutex, it waits until it can obtain the ownership. Throws: interprocess_exception on error.

   Note: A program may deadlock if the thread that has ownership calls this function. If the implementation can detect the deadlock, an exception could be thrown.

4.     bool try_lock();

   Requires: The calling thread does not own the mutex.

   Effects: The calling thread tries to acquire exclusive ownership of the mutex without waiting. If no other thread has exclusive, sharable or upgradable ownership of the mutex this succeeds. Returns: If it can acquire exclusive ownership immediately returns true. If it has to wait, returns false. Throws: interprocess_exception on error.

   Note: A program may deadlock if the thread that has ownership calls this function. If the implementation can detect the deadlock, an exception could be thrown.

5.     template<typename TimePoint> bool timed_lock(const TimePoint & abs_time);

   Requires: The calling thread does not own the mutex.

   Effects: The calling thread tries to acquire exclusive ownership of the mutex waiting if necessary until no other thread has exclusive, sharable or upgradable ownership of the mutex or abs_time is reached. Returns: If acquires exclusive ownership, returns true. Otherwise returns false. Throws: interprocess_exception on error.

   Note: A program may deadlock if the thread that has ownership calls this function. If the implementation can detect the deadlock, an exception could be thrown.

6.     template<typename TimePoint> bool try_lock_until(const TimePoint & abs_time);

   Same as `timed_lock`, but this function is modeled after the standard library interface.

7.     template<typename Duration> bool try_lock_for(const Duration & dur);

   Same as `timed_lock`, but this function is modeled after the standard library interface.

8.     void unlock();

   Precondition: The thread must have exclusive ownership of the mutex. Effects: The calling thread releases the exclusive ownership of the mutex. Throws: An exception derived from interprocess_exception on error.

9.     void lock_sharable();

   Requires: The calling thread does not own the mutex.

   Effects: The calling thread tries to obtain sharable ownership of the mutex, and if another thread has exclusive ownership of the mutex, waits until it can obtain the ownership. Throws: interprocess_exception on error.

   Note: A program may deadlock if the thread that has ownership calls this function. If the implementation can detect the deadlock, an exception could be thrown.

10.     void lock_shared();

    Same as `lock_sharable` but with a std-compatible interface

11.     bool try_lock_sharable();

    Requires: The calling thread does not own the mutex.

    Effects: The calling thread tries to acquire sharable ownership of the mutex without waiting. If no other thread has exclusive ownership of the mutex this succeeds. Returns: If it can acquire sharable ownership immediately returns true. If it has to wait, returns false. Throws: interprocess_exception on error.

    Note: A program may deadlock if the thread that has ownership calls this function. If the implementation can detect the deadlock, an exception could be thrown.

12.     bool try_lock_shared();

    Same as `try_lock_sharable` but with a std-compatible interface

13.     template<typename TimePoint>
          bool timed_lock_sharable(const TimePoint & abs_time);

    Requires: The calling thread does not own the mutex.

    Effects: The calling thread tries to acquire sharable ownership of the mutex waiting if necessary until no other thread has exclusive ownership of the mutex or abs_time is reached. Returns: If acquires sharable ownership, returns true. Otherwise returns false. Throws: interprocess_exception on error.

    Note: A program may deadlock if the thread that has ownership calls this function. If the implementation can detect the deadlock, an exception could be thrown.

14.     template<typename TimePoint>
          bool try_lock_shared_until(const TimePoint & abs_time);

    Same as `timed_lock_sharable`, but this function is modeled after the standard library interface.

15.     template<typename Duration> bool try_lock_shared_for(const Duration & dur);

    Same as `timed_lock_sharable`, but this function is modeled after the standard library interface.

16.     void unlock_sharable();

    Precondition: The thread must have sharable ownership of the mutex. Effects: The calling thread releases the sharable ownership of the mutex. Throws: An exception derived from interprocess_exception on error.

17.     void unlock_shared();

    Same as `unlock_sharable` but with a std-compatible interface

18.     void lock_upgradable();

    Requires: The calling thread does not own the mutex.

    Effects: The calling thread tries to obtain upgradable ownership of the mutex, and if another thread has exclusive or upgradable ownership of the mutex, waits until it can obtain the ownership. Throws: interprocess_exception on error.

    Note: A program may deadlock if the thread that has ownership calls this function. If the implementation can detect the deadlock, an exception could be thrown.

19.     bool try_lock_upgradable();

    Requires: The calling thread does not own the mutex.

    Effects: The calling thread tries to acquire upgradable ownership of the mutex without waiting. If no other thread has exclusive or upgradable ownership of the mutex this succeeds. Returns: If it can acquire upgradable ownership immediately returns true. If it has to wait, returns false. Throws: interprocess_exception on error.

    Note: A program may deadlock if the thread that has ownership calls this function. If the implementation can detect the deadlock, an exception could be thrown.

20.     template<typename TimePoint>
          bool timed_lock_upgradable(const TimePoint & abs_time);

    Requires: The calling thread does not own the mutex.

    Effects: The calling thread tries to acquire upgradable ownership of the mutex waiting if necessary until no other thread has exclusive or upgradable ownership of the mutex or abs_time is reached. Returns: If acquires upgradable ownership, returns true. Otherwise returns false. Throws: interprocess_exception on error.

    Note: A program may deadlock if the thread that has ownership calls this function. If the implementation can detect the deadlock, an exception could be thrown.

21.     void unlock_upgradable();

    Precondition: The thread must have upgradable ownership of the mutex. Effects: The calling thread releases the upgradable ownership of the mutex. Throws: An exception derived from interprocess_exception on error.

22.     void unlock_and_lock_upgradable();

    Precondition: The thread must have exclusive ownership of the mutex. Effects: The thread atomically releases exclusive ownership and acquires upgradable ownership. This operation is non-blocking. Throws: An exception derived from interprocess_exception on error.

23.     void unlock_and_lock_sharable();

    Precondition: The thread must have exclusive ownership of the mutex. Effects: The thread atomically releases exclusive ownership and acquires sharable ownership. This operation is non-blocking. Throws: An exception derived from interprocess_exception on error.

24.     void unlock_upgradable_and_lock_sharable();

    Precondition: The thread must have upgradable ownership of the mutex. Effects: The thread atomically releases upgradable ownership and acquires sharable ownership. This operation is non-blocking. Throws: An exception derived from interprocess_exception on error.

25.     void unlock_upgradable_and_lock();

    Precondition: The thread must have upgradable ownership of the mutex. Effects: The thread atomically releases upgradable ownership and acquires exclusive ownership. This operation will block until all threads with sharable ownership release their sharable lock. Throws: An exception derived from interprocess_exception on error.

26.     bool try_unlock_upgradable_and_lock();

    Precondition: The thread must have upgradable ownership of the mutex. Effects: The thread atomically releases upgradable ownership and tries to acquire exclusive ownership. This operation will fail if there are threads with sharable ownership, but it will maintain upgradable ownership. Returns: If acquires exclusive ownership, returns true. Otherwise returns false. Throws: An exception derived from interprocess_exception on error.

27.     template<typename TimePoint>
          bool timed_unlock_upgradable_and_lock(const TimePoint & abs_time);

    Precondition: The thread must have upgradable ownership of the mutex. Effects: The thread atomically releases upgradable ownership and tries to acquire exclusive ownership, waiting if necessary until abs_time. This operation will fail if there are threads with sharable ownership or timeout reaches, but it will maintain upgradable ownership. Returns: If acquires exclusive ownership, returns true. Otherwise returns false. Throws: An exception derived from interprocess_exception on error. *<zwj></zwj>/

28.     bool try_unlock_sharable_and_lock();

    Precondition: The thread must have sharable ownership of the mutex. Effects: The thread atomically releases sharable ownership and tries to acquire exclusive ownership. This operation will fail if there are threads with sharable or upgradable ownership, but it will maintain sharable ownership. Returns: If acquires exclusive ownership, returns true. Otherwise returns false. Throws: An exception derived from interprocess_exception on error.

29.     bool try_unlock_sharable_and_lock_upgradable();

    Precondition: The thread must have sharable ownership of the mutex. Effects: The thread atomically releases sharable ownership and tries to acquire upgradable ownership. This operation will fail if there are threads with sharable or upgradable ownership, but it will maintain sharable ownership. Returns: If acquires upgradable ownership, returns true. Otherwise returns false. Throws: An exception derived from interprocess_exception on error.