Class: Mutex

Inherits:
Object show all
Defined in:
thread_sync.c,
thread_sync.c

Overview

Mutex implements a simple semaphore that can be used to coordinate access to shared data from multiple concurrent threads.

Example:

semaphore = Mutex.new

a = Thread.new {
  semaphore.synchronize {
    # access shared resource
  }
}

b = Thread.new {
  semaphore.synchronize {
    # access shared resource
  }
}

Instance Method Summary collapse

Constructor Details

#new ⇒ Object

Creates a new Mutex



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# File 'thread_sync.c', line 158

static VALUE
mutex_initialize(VALUE self)
{
    return self;
}

Instance Method Details

#lock ⇒ self

Attempts to grab the lock and waits if it isn’t available. Raises ThreadError if mutex was locked by the current thread.

Returns:

  • (self) 


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# File 'thread_sync.c', line 332

VALUE
rb_mutex_lock(VALUE self)
{
    return do_mutex_lock(self, 1);
}

#locked? ⇒ Boolean

Returns true if this lock is currently held by some thread.

Returns:

  • (Boolean) 


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# File 'thread_sync.c', line 176

VALUE
rb_mutex_locked_p(VALUE self)
{
    rb_mutex_t *mutex = mutex_ptr(self);

    return mutex->th ? Qtrue : Qfalse;
}

#owned? ⇒ Boolean

Returns true if this lock is currently held by current thread.

Returns:

  • (Boolean) 


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# File 'thread_sync.c', line 344

VALUE
rb_mutex_owned_p(VALUE self)
{
    rb_thread_t *th = GET_THREAD();
    rb_mutex_t *mutex = mutex_ptr(self);

    return mutex_owned_p(th, mutex);
}

#sleep(timeout = nil) ⇒ Numeric

Releases the lock and sleeps timeout seconds if it is given and non-nil or forever. Raises ThreadError if mutex wasn’t locked by the current thread.

When the thread is next woken up, it will attempt to reacquire the lock.

Note that this method can wakeup without explicit Thread#wakeup call. For example, receiving signal and so on.

Returns:



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# File 'thread_sync.c', line 504

static VALUE
mutex_sleep(int argc, VALUE *argv, VALUE self)
{
    VALUE timeout;

    timeout = rb_check_arity(argc, 0, 1) ? argv[0] : Qnil;
    return rb_mutex_sleep(self, timeout);
}

#synchronize { ... } ⇒ Object

Obtains a lock, runs the block, and releases the lock when the block completes. See the example under Mutex.

Yields:



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# File 'thread_sync.c', line 535

static VALUE
rb_mutex_synchronize_m(VALUE self)
{
    if (!rb_block_given_p()) {
	rb_raise(rb_eThreadError, "must be called with a block");
    }

    return rb_mutex_synchronize(self, rb_yield, Qundef);
}

#try_lock ⇒ Boolean

Attempts to obtain the lock and returns immediately. Returns true if the lock was granted.

Returns:

  • (Boolean) 


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# File 'thread_sync.c', line 202

VALUE
rb_mutex_trylock(VALUE self)
{
    rb_mutex_t *mutex = mutex_ptr(self);
    VALUE locked = Qfalse;

    if (mutex->th == 0) {
	rb_thread_t *th = GET_THREAD();
	mutex->th = th;
	locked = Qtrue;

	mutex_locked(th, self);
    }

    return locked;
}

#unlock ⇒ self

Releases the lock. Raises ThreadError if mutex wasn’t locked by the current thread.

Returns:

  • (self) 


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# File 'thread_sync.c', line 402

VALUE
rb_mutex_unlock(VALUE self)
{
    const char *err;
    rb_mutex_t *mutex = mutex_ptr(self);

    err = rb_mutex_unlock_th(mutex, GET_THREAD());
    if (err) rb_raise(rb_eThreadError, "%s", err);

    return self;
}