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# core.sync.mutex

The mutex module provides a primitive for maintaining mutually exclusive access.
License:
Boost License 1.0
Authors:
Sean Kelly

Source core/sync/mutex.d

class `Mutex`: object.Object.Monitor;
  This class represents a general purpose, recursive mutex.
  Implemented using pthread_mutex on Posix and CRITICAL_SECTION on Windows.
  Examples:

      import core.thread : Thread;

      class Resource
      {
          Mutex mtx;
          int cargo;

          this() shared @safe nothrow
          {
              mtx = new shared Mutex();
              cargo = 42;
          }

          void useResource() shared @safe nothrow @nogc
          {
              mtx.lock_nothrow();
              (cast() cargo) += 1;
              mtx.unlock_nothrow();
          }
      }

      shared Resource res = new shared Resource();

      auto otherThread = new Thread(
      {
          foreach (i; 0 .. 10000)
              res.useResource();
      }).start();

      foreach (i; 0 .. 10000)
          res.useResource();

      otherThread.join();

      assert (res.cargo == 20042);

  nothrow @nogc @trusted this();
  shared nothrow @nogc @trusted this();
    Initializes a mutex object.
  nothrow @nogc @trusted this(Object `obj`);
  shared nothrow @nogc @trusted this(Object `obj`);
    Initializes a mutex object and sets it as the monitor for `obj`.

    In `obj` must not already have a monitor.

  @trusted void `lock`();
  shared @trusted void `lock`();
  final nothrow @nogc @trusted void `lock_nothrow`(this Q)()
  if (is(Q == Mutex) || is(Q == shared(Mutex)));
    If this lock is not already held by the caller, the lock is acquired, then the internal counter is incremented by one.

    Note Mutex.`lock` does not throw, but a class derived from Mutex can throw. Use `lock_nothrow` in nothrow @nogc code.

  @trusted void `unlock`();
  shared @trusted void `unlock`();
  final nothrow @nogc @trusted void `unlock_nothrow`(this Q)()
  if (is(Q == Mutex) || is(Q == shared(Mutex)));
    Decrements the internal lock count by one. If this brings the count to zero, the lock is released.

    Note Mutex.`unlock` does not throw, but a class derived from Mutex can throw. Use `unlock_nothrow` in nothrow @nogc code.

  @trusted bool `tryLock`();
  shared @trusted bool `tryLock`();
  final nothrow @nogc @trusted bool `tryLock_nothrow`(this Q)()
  if (is(Q == Mutex) || is(Q == shared(Mutex)));
    If the lock is held by another caller, the method returns. Otherwise, the lock is acquired if it is not already held, and then the internal counter is incremented by one.
    Returns:
    true if the lock was acquired and false if not.

    Note Mutex.`tryLock` does not throw, but a class derived from Mutex can throw. Use `tryLock_nothrow` in nothrow @nogc code.

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