[Summary view] [Print] [Text view]

   1  package Thread::Queue;
   2  
   3  use threads::shared;
   4  use strict;
   5  
   6  our $VERSION = '2.00';
   7  
   8  =head1 NAME
   9  
  10  Thread::Queue - thread-safe queues
  11  
  12  =head1 SYNOPSIS
  13  
  14      use Thread::Queue;
  15      my $q = new Thread::Queue;
  16      $q->enqueue("foo", "bar");
  17      my $foo = $q->dequeue;    # The "bar" is still in the queue.
  18      my $foo = $q->dequeue_nb; # returns "bar", or undef if the queue was empty
  19      my $left = $q->pending;   # returns the number of items still in the queue
  20  
  21  =head1 DESCRIPTION
  22  
  23  A queue, as implemented by C<Thread::Queue> is a thread-safe 
  24  data structure much like a list.  Any number of threads can safely 
  25  add elements to the end of the list, or remove elements from the head 
  26  of the list. (Queues don't permit adding or removing elements from 
  27  the middle of the list).
  28  
  29  =head1 FUNCTIONS AND METHODS
  30  
  31  =over 8
  32  
  33  =item new
  34  
  35  The C<new> function creates a new empty queue.
  36  
  37  =item enqueue LIST
  38  
  39  The C<enqueue> method adds a list of scalars on to the end of the queue.
  40  The queue will grow as needed to accommodate the list.
  41  
  42  =item dequeue
  43  
  44  The C<dequeue> method removes a scalar from the head of the queue and
  45  returns it. If the queue is currently empty, C<dequeue> will block the
  46  thread until another thread C<enqueue>s a scalar.
  47  
  48  =item dequeue_nb
  49  
  50  The C<dequeue_nb> method, like the C<dequeue> method, removes a scalar from
  51  the head of the queue and returns it. Unlike C<dequeue>, though,
  52  C<dequeue_nb> won't block if the queue is empty, instead returning
  53  C<undef>.
  54  
  55  =item pending
  56  
  57  The C<pending> method returns the number of items still in the queue.
  58  
  59  =back
  60  
  61  =head1 SEE ALSO
  62  
  63  L<threads>, L<threads::shared>
  64  
  65  =cut
  66  
  67  sub new {
  68      my $class = shift;
  69      my @q : shared = @_;
  70      return bless \@q, $class;
  71  }
  72  
  73  sub dequeue  {
  74      my $q = shift;
  75      lock(@$q);
  76      cond_wait @$q until @$q;
  77      cond_signal @$q if @$q > 1;
  78      return shift @$q;
  79  }
  80  
  81  sub dequeue_nb {
  82      my $q = shift;
  83      lock(@$q);
  84      return shift @$q;
  85  }
  86  
  87  sub enqueue {
  88      my $q = shift;
  89      lock(@$q);
  90      push @$q, @_  and cond_signal @$q;
  91  }
  92  
  93  sub pending  {
  94      my $q = shift;
  95      lock(@$q);
  96      return scalar(@$q);
  97  }
  98  
  99  1;
 100  
 101