NAME¶
Coro::SemaphoreSet - efficient set of counting semaphores
SYNOPSIS¶
use Coro;
$sig = new Coro::SemaphoreSet [initial value];
$sig->down ("semaphoreid"); # wait for signal
# ... some other "thread"
$sig->up ("semaphoreid");
DESCRIPTION¶
This module implements sets of counting semaphores (see Coro::Semaphore). It is
nothing more than a hash with normal semaphores as members, but is more
efficiently managed.
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 [inital 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¶
Marc Lehmann <schmorp@schmorp.de>
http://home.schmorp.de/