class 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:

require 'thread'

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 Instance Methods

broadcast click to toggle source

Wakes up all threads waiting for this condition.

static VALUE
rb_condvar_broadcast(VALUE self)
{
    ConditionVariable *condvar;

    Data_Get_Struct(self, ConditionVariable, condvar);
  
    thread_exclusive(wake_all, (VALUE)&condvar->waiting);
    rb_thread_schedule();

    return self;
}
marshal_dump() click to toggle source
static VALUE
dummy_dump(VALUE self)
{
    return rb_str_new2("");
}
marshal_load(p1) click to toggle source

for marshalling mutexes and condvars

static VALUE
dummy_load(VALUE self, VALUE string)
{
    return Qnil;
}
signal click to toggle source

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

static VALUE
rb_condvar_signal(VALUE self)
{
    ConditionVariable *condvar;
    Data_Get_Struct(self, ConditionVariable, condvar);
    signal_condvar(condvar);
    return self;
}
wait click to toggle source

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

static VALUE
rb_condvar_wait(VALUE self, VALUE mutex_v)
{
    ConditionVariable *condvar;
    Data_Get_Struct(self, ConditionVariable, condvar);

    if (CLASS_OF(mutex_v) != rb_cMutex) {
        /* interoperate with legacy mutex */
        legacy_wait_args args;
        args.condvar = condvar;
        args.mutex = mutex_v;
        rb_iterate(legacy_exclusive_unlock, mutex_v, legacy_wait, (VALUE)&args);
    } else {
        Mutex *mutex;
        Data_Get_Struct(mutex_v, Mutex, mutex);
        wait_condvar(condvar, mutex);
    }

    return self;
}