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Thread::Queue - thread-safe queues |
Thread::Queue - thread-safe queues
none
use Thread::Queue;
my $q = new Thread::Queue;
$q->enqueue("foo", "bar");
my $foo = $q->dequeue; # The "bar" is still in the queue.
my $foo = $q->dequeue_nb; # returns "bar", or undef if the queue was
# empty
my $left = $q->pending; # returns the number of items still in the queue
A queue, as implemented by Thread::Queue is a thread-safe data structure
much like a list. Any number of threads can safely add elements to the end
of the list, or remove elements from the head of the list. (Queues don't
permit adding or removing elements from the middle of the list)
new function creates a new empty queue.
enqueue method adds a list of scalars on to the end of the queue.
The queue will grow as needed to accomodate the list.
dequeue method removes a scalar from the head of the queue and
returns it. If the queue is currently empty, dequeue will block the
thread until another thread enqueues a scalar.
dequeue_nb method, like the dequeue method, removes a scalar from
the head of the queue and returns it. Unlike dequeue, though,
dequeue_nb won't block if the queue is empty, instead returning
undef.
pending method returns the number of items still in the queue. (If
there can be multiple readers on the queue it's best to lock the queue
before checking to make sure that it stays in a consistent state)
=cut
sub new { my $class = shift; return bless [@_], $class; }
sub dequeue : locked : method { my $q = shift; cond_wait $q until @$q; return shift @$q; }
sub dequeue_nb : locked : method { my $q = shift; if (@$q) { return shift @$q; } else { return undef; } }
sub enqueue : locked : method { my $q = shift; push(@$q, @_) and cond_broadcast $q; }
sub pending : locked : method { my $q = shift; return scalar(@$q); }
1;
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Thread::Queue - thread-safe queues |