NAME

SYNOPSIS

 use Coro;

 $sig = new Coro::SemaphoreSet [initial value];

 $sig->down ("semaphoreid"); # wait for signal

 # ... some other "thread"

 $sig->up ("semaphoreid");

DESCRIPTION

This is useful if you want to allow parallel tasks to run in parallel but not on the same problem. Just use a SemaphoreSet and lock on the problem identifier.

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

new [initial count]

Creates a new semaphore set with the given initial lock count for each individual semaphore. See Coro::Semaphore.

$semset->down ($id)

Decrement the counter, therefore "locking" the named semaphore. This method waits until the semaphore is available if the counter is zero.

$semset->up ($id)

Unlock the semaphore again. If the semaphore reaches the default count for this set and has no waiters, the space allocated for it will be freed.

$semset->try ($id)

Try to "down" the semaphore. Returns true when this was possible, otherwise return false and leave the semaphore unchanged.

$semset->count ($id)

Return the current semaphore count for the specified semaphore.

$semset->waiters ($id)

Returns the number (in scalar context) or list (in list context) of waiters waiting on the specified semaphore.

$semset->wait ($id)

Same as Coro::Semaphore::wait on the specified semaphore.

$guard = $semset->guard ($id)

This method calls "down" and then creates a guard object. When the guard object is destroyed it automatically calls "up".

$semaphore = $semset->sem ($id)

This SemaphoreSet version is based on Coro::Semaphore's. This function creates (if necessary) the underlying Coro::Semaphore object and returns it. You may legally call any Coro::Semaphore method on it, but note that calling "$semset->up" can invalidate the returned semaphore.

AUTHOR/SUPPORT/CONTACT

   Marc A. Lehmann <schmorp@schmorp.de>
   http://software.schmorp.de/pkg/Coro.html