Thread::Queue - thread-safe queues
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 enqueue
s 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)
the Thread manpage =cut
sub new { my $class
= shift; return bless [@_], $class; }
sub dequeue { use attrs
qw(locked
method); my $q = shift;
cond_wait $q
until @$q; return shift @$q; }
sub dequeue_nb { use attrs
qw(locked
method); my $q = shift; if
(@$q) { return shift @$q; } else { return undef; } }
sub enqueue { use attrs
qw(locked
method); my $q = shift;
push(@$q,
@_) and cond_broadcast $q; }
sub pending { use attrs
qw(locked
method); my $q = shift; return
scalar(@$q);
}
1;
If rather than formatting bugs, you encounter substantive content errors in these documents, such as mistakes in the explanations or code, please use the perlbug utility included with the Perl distribution.