ConditionVariable

ConditionVariable objects augment class Mutex. Using condition variables, it is possible to suspend while in the middle of a critical section until a resource becomes available.

Example:

mutex = Mutex.new
resource = ConditionVariable.new
a = Thread.new {
 mutex.synchronize {
 # Thread 'a' now needs the resource
 resource.wait(mutex)
 # 'a' can now have the resource
 }
}
b = Thread.new {
 mutex.synchronize {
 # Thread 'b' has finished using the resource
 resource.signal
 }
}

Public Class Methods

new() click to toggle source

Creates a new condition variable instance.

 
 static VALUE
rb_condvar_initialize(VALUE self)
{
 struct rb_condvar *cv = condvar_ptr(self);;
 list_head_init(&cv->waitq);
 return self;
}

Public Instance Methods

broadcast() click to toggle source

Wakes up all threads waiting for this lock.

 
 static VALUE
rb_condvar_broadcast(VALUE self)
{
 struct rb_condvar *cv = condvar_ptr(self);
 wakeup_all(&cv->waitq);
 return self;
}

signal() click to toggle source

Wakes up the first thread in line waiting for this lock.

 
 static VALUE
rb_condvar_signal(VALUE self)
{
 struct rb_condvar *cv = condvar_ptr(self);
 wakeup_one(&cv->waitq);
 return self;
}

wait(mutex, timeout=nil) click to toggle source

Releases the lock held in mutex and waits; reacquires the lock on wakeup.

If timeout is given, this method returns after timeout seconds passed, even if no other thread doesn't signal.

 
 static VALUE
rb_condvar_wait(int argc, VALUE *argv, VALUE self)
{
 struct rb_condvar *cv = condvar_ptr(self);
 VALUE mutex, timeout;
 struct sleep_call args;
 struct sync_waiter w;
 rb_scan_args(argc, argv, "11", &mutex, &timeout);
 args.mutex = mutex;
 args.timeout = timeout;
 w.th = GET_THREAD();
 list_add_tail(&cv->waitq, &w.node);
 rb_ensure(do_sleep, (VALUE)&args, delete_from_waitq, (VALUE)&w);
 return self;
}