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
}
}
static VALUE
rb_condvar_initialize(VALUE self)
{
struct rb_condvar *cv = condvar_ptr(self);
list_head_init(&cv->waitq);
return self;
} Creates a new condition variable instance.
static VALUE
rb_condvar_broadcast(VALUE self)
{
struct rb_condvar *cv = condvar_ptr(self);
wakeup_all(&cv->waitq);
return self;
} Wakes up all threads waiting for this lock.
static VALUE
rb_condvar_signal(VALUE self)
{
struct rb_condvar *cv = condvar_ptr(self);
wakeup_one(&cv->waitq);
return self;
} Wakes up the first thread in line waiting for this lock.
static VALUE
rb_condvar_wait(int argc, VALUE *argv, VALUE self)
{
rb_execution_context_t *ec = GET_EC();
struct rb_condvar *cv = condvar_ptr(self);
struct sleep_call args;
rb_scan_args(argc, argv, "11", &args.mutex, &args.timeout);
COROUTINE_STACK_LOCAL(struct sync_waiter, w);
w->self = args.mutex;
w->th = ec->thread_ptr;
w->fiber = ec->fiber_ptr;
list_add_tail(&cv->waitq, &w->node);
rb_ensure(do_sleep, (VALUE)&args, delete_from_waitq, (VALUE)w);
return self;
} 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.
Ruby Core © 1993–2020 Yukihiro Matsumoto
Licensed under the Ruby License.
Ruby Standard Library © contributors
Licensed under their own licenses.