package Thread::Queue; use threads::shared; use strict; our $VERSION = '2.00'; =head1 NAME Thread::Queue - thread-safe queues =head1 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 =head1 DESCRIPTION A queue, as implemented by C 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). =head1 FUNCTIONS AND METHODS =over 8 =item new The C function creates a new empty queue. =item enqueue LIST The C method adds a list of scalars on to the end of the queue. The queue will grow as needed to accommodate the list. =item dequeue The C method removes a scalar from the head of the queue and returns it. If the queue is currently empty, C will block the thread until another thread Cs a scalar. =item dequeue_nb The C method, like the C method, removes a scalar from the head of the queue and returns it. Unlike C, though, C won't block if the queue is empty, instead returning C. =item pending The C method returns the number of items still in the queue. =back =head1 SEE ALSO L, L =cut sub new { my $class = shift; my @q : shared = @_; return bless \@q, $class; } sub dequeue { my $q = shift; lock(@$q); cond_wait @$q until @$q; cond_signal @$q if @$q > 1; return shift @$q; } sub dequeue_nb { my $q = shift; lock(@$q); return shift @$q; } sub enqueue { my $q = shift; lock(@$q); push @$q, @_ and cond_signal @$q; } sub pending { my $q = shift; lock(@$q); return scalar(@$q); } 1;