Elizabeth Mattijsen > Thread-Queue-Any-1.14 > Thread::Queue::Any

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Module Version: 1.14   Source  

NAME ^

Thread::Queue::Any - thread-safe queues for any data-structure

SYNOPSIS ^

    use Thread::Queue::Any;
    my $q= Thread::Queue::Any->new;
    $q->enqueue("foo", ["bar"], {"zoo"});
    my ( $foo, $bar, $zoo )= $q->dequeue;
    my ( $foo, $bar, $zoo )= $q->dequeue_dontwait;
    my ( $iffoo, $ifbar, $ifzoo)= $q->dequeue_keep;
    my $left= $q->pending;

    # specify class with "freeze" and "thaw" methods
    use Thread::Queue::Any serializer => 'Storable';

    # specify custom freeze and thaw subroutines
    use Thread::Queue::Any freeze => \&solid, thaw => \&liquid;

    # thaw hook for subclasses
    package Thread::Queue::Any::Foo;
    @ISA= 'Thread::Queue::Any';
    my $THAW= __PACKAGE__->THAW;

VERSION ^

This documentation describes version 1.14.

DESCRIPTION ^

                    *** A note of CAUTION ***

 This module only functions if threading has been enabled when building
 Perl, or if the "forks" module has been installed on an unthreaded Perl.

                    *************************

A queue, as implemented by Thread::Queue::Any is a thread-safe data structure that inherits from Thread::Queue. But unlike the standard Thread::Queue, you can pass (a reference to) any data structure to the queue.

Apart from the fact that the parameters to enqueue are considered to be a set that needs to be enqueued together and that dequeue returns all of the parameters that were enqueued together, this module is a drop-in replacement for Thread::Queue in every other aspect.

Any number of threads can safely add elements to the end of the list, or remove elements from the head of the list.

CLASS METHODS ^

new

 $queue= Thread::Queue::Any->new;

The new function creates a new empty queue.

THAW

 $THAW= $subclass->THAW;

Return the code reference for de-serializing enqueued data. Intended to be used by subclasses only, such as Thread::Queue::Any::Monitored.

OBJECT METHODS ^

enqueue LIST

 $queue->enqueue( 'string', $scalar, [], {} );

The enqueue method adds a reference to all the specified parameters on to the end of the queue. The queue will grow as needed.

dequeue

 ( $string, $scalar, $listref, $hashref )= $queue->dequeue;

 $string= $queue->dequeue;          # first only in scalar context

The dequeue method removes a reference from the head of the queue, dereferences it and returns the resulting values. If the queue is currently empty, dequeue will block the thread until another thread enqueues.

If called in scalar context, only the first value will be returned. This is only recommended if enqueue is always only called with one parameter.

dequeue_dontwait

 ( $string, $scalar, $listref, $hashref )= $queue->dequeue_dontwait;

 $string= $queue->dequeue_dontwait; # first only in scalar context

The dequeue_dontwait method, like the dequeue method, removes a reference from the head of the queue, dereferences it and returns the resulting values. Unlike dequeue, though, dequeue_dontwait won't wait if the queue is empty, instead returning an empty list if the queue is empty.

For compatibility with Thread::Queue, the name "dequeue_nb" is available as a synonym for this method.

If called in scalar context, only the first value will be returned. This is only recommended if enqueue is always only called with one parameter.

dequeue_keep

 ( $string, $scalar, $listref, $hashref )= $queue->dequeue_keep;

 $string= $queue->dequeue_keep;     # first only in scalar context

The dequeue_keep method, like the dequeue_dontwait method, takes a reference from the head of the queue, dereferences it and returns the resulting values. Unlike dequeue_dontwait, though, the dequeue_keep won't remove the set from the queue. It can therefore be used to test if the next set to be returned from the queue with dequeue or dequeue_dontwait will have a specific value.

If called in scalar context, only the first value will be returned. This is only recommended if enqueue is always only called with one parameter.

pending

 $pending= $queue->pending;

The pending method returns the number of items still in the queue.

USING ANOTHER SERIALIZER ^

Passing unshared values between threads is accomplished by serializing the specified values when enqueuing and de-serializing the queued value on equeuing. This allows for great flexibility at the expense of more CPU usage. It also limits what can be passed, as e.g. code references can not be serialized with the default serializer and therefore not be passed.

By default, the Storable module is used to serialize data. If you want to use a different serializer, you can specify this when you load this module with the serializer parameter:

 use Thread::Queue::Any serializer => 'Thread::Serialize';

The value of the parameter is the name of the class that will provide a freeze and thaw subroutine. It will be automatically loaded if specified.

If you happen to have subroutines in another module with a different name, you can also specify the freeze and thaw parameter with a code reference of the subroutine to be called. So the above example could also be specified as:

 use Thread::Serialize;
 use Thread::Queue::Any
   freeze => \&Thread::Serialize::freeze,
   thaw   => \&Thread::Serialize::thaw,
 ;

REQUIRED MODULES ^

 Test::More (0.88)
 Thread::Queue (any)

INSTALLATION ^

This distribution contains two versions of the code: one maintenance version for versions of perl < 5.014 (known as 'maint'), and the version currently in development (known as 'blead'). The standard build for your perl version is:

 perl Makefile.PL
 make
 make test
 make install

This will try to test and install the "blead" version of the code. If the Perl version does not support the "blead" version, then the running of the Makefile.PL will *fail*. In such a case, one can force the installing of the "maint" version of the code by doing:

 perl Makefile.PL maint

Alternately, if you want automatic selection behavior, you can set the AUTO_SELECT_MAINT_OR_BLEAD environment variable to a true value. On Unix-like systems like so:

 AUTO_SELECT_MAINT_OR_BLEAD=1 perl Makefile.PL

If your perl does not support the "blead" version of the code, then it will automatically install the "maint" version of the code.

Please note that any additional parameters will simply be passed on to the underlying Makefile.PL processing.

AUTHOR ^

Elizabeth Mattijsen, <liz@dijkmat.nl>.

Please report bugs to <perlbugs@dijkmat.nl>.

COPYRIGHT ^

Copyright (c) 2002, 2003, 2007, 2012 Elizabeth Mattijsen <liz@dijkmat.nl>. All rights reserved. This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

SEE ALSO ^

threads, threads::shared, Thread::Queue, Storable.

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