Thread::Queue - thread-safe queues

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

# NAME

Thread::Queue - thread-safe queues

# SUPPORTED PLATFORMS

none

# 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 `enqueue`s 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 : 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;

Thread::Queue - thread-safe queues