- NAME
- SYNOPSIS
- DESCRIPTION
- FUNCTIONS AND METHODS
- SEE ALSO

# NAME

Thread::Queue - thread-safe queues

# SYNOPSIS

        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

# DESCRIPTION

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)

# FUNCTIONS AND METHODS

new

  The new function creates a new empty queue.

enqueue LIST

  The 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

  The 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

  The 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

  The 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)

# SEE ALSO

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;