SemaphoreSet(3) User Contributed Perl Documentation SemaphoreSet(3)NAMECoro::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/
perl v5.14.2 2011-11-11 SemaphoreSet(3)
