Coro::Signal - thread signals (binary semaphores)


 use Coro;

 my $sig = new Coro::Signal;

 $sig->wait; # wait for signal

 # ... some other "thread"



This module implements signals/binary semaphores/condition variables (basically all the same thing). You can wait for a signal to occur or send it, in which case it will wake up one waiter, or it can be broadcast, waking up all waiters.

It is recommended not to mix send and broadcast calls on the same Coro::Signal without some deep thinking: while it should work as documented, it can easily confuse you :->

You don't have to load Coro::Signal manually, it will be loaded automatically when you use Coro and call the new constructor.

$sig = new Coro::Signal;

Create a new signal.


Wait for the signal to occur (via either send or broadcast). Returns immediately if the signal has been sent before.

$sig->wait ($callback)

If you pass a callback argument to wait, it will not wait, but immediately return. The callback will be called under the same conditions as wait without arguments would continue the thrad.

The callback might wake up any number of threads, but is NOT allowed to block (switch to other threads).


Send the signal, waking up one waiting process or remember the signal if no process is waiting.


Send the signal, waking up all waiting process. If no process is waiting the signal is lost.


Return true when the signal is being awaited by some process.


   Marc A. Lehmann <>