Cache::SharedMemoryCache - extends the MemoryCache.

Cache-Cache documentation Contained in the Cache-Cache distribution.

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NAME

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Cache::SharedMemoryCache -- extends the MemoryCache.

DESCRIPTION

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The SharedMemoryCache extends the MemoryCache class and binds the data store to shared memory so that separate process can use the same cache.

The official recommendation is now to use FileCache instead of SharedMemoryCache. The reasons for this include:

1) FileCache provides equal or better performance in all cases that we've been able to test. This is due to all modern OS's ability to buffer and cache file system accesses very well.

2) FileCache has no real limits on cached object size or the number of cached objects, whereas the SharedMemoryCache has limits, and rather low ones at that.

3) FileCache works well on every OS, whereas the SharedMemoryCache works only on systems that support IPC::ShareLite. And IPC::ShareLite is an impressive effort -- but think about how hard it is to get shared memory working properly on *one* system. Now imagine writing a wrapper around shared memory for many operating systems.

SYNOPSIS

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  use Cache::SharedMemoryCache;

  my %cache_options_= ( 'namespace' => 'MyNamespace',
			'default_expires_in' => 600 );

  my $shared_memory_cache = 
    new Cache::SharedMemoryCache( \%cache_options ) or
      croak( "Couldn't instantiate SharedMemoryCache" );

METHODS

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See Cache::Cache for the API documentation.

OPTIONS

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See Cache::Cache for the standard options.

PROPERTIES

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See Cache::Cache for the default properties.

SEE ALSO

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Cache::Cache, Cache::MemoryCache

AUTHOR

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Original author: DeWitt Clinton <dewitt@unto.net>

Last author: $Author: dclinton $

Copyright (C) 2001-2003 DeWitt Clinton

Cache-Cache documentation Contained in the Cache-Cache distribution. 
######################################################################
# $Id: SharedMemoryCache.pm,v 1.24 2004/04/24 15:46:47 dclinton Exp $
# Copyright (C) 2001-2003 DeWitt Clinton  All Rights Reserved
#
# Software distributed under the License is distributed on an "AS
# IS" basis, WITHOUT WARRANTY OF ANY KIND, either expressed or
# implied. See the License for the specific language governing
# rights and limitations under the License.
######################################################################


package Cache::SharedMemoryCache;


use strict;
use vars qw( @ISA );
use Cache::Cache;
use Cache::MemoryCache;
use Cache::CacheUtils qw( Assert_Defined Static_Params );
use Cache::SharedMemoryBackend;
use Error;


@ISA = qw ( Cache::MemoryCache );


sub Clear
{
  foreach my $namespace ( _Namespaces( ) )
  {
    _Get_Backend( )->delete_namespace( $namespace );
  }
}


sub Purge
{
  foreach my $namespace ( _Namespaces( ) )
  {
    _Get_Cache( $namespace )->purge( );
  }
}


sub Size
{
  my $size = 0;

  foreach my $namespace ( _Namespaces( ) )
  {
    $size += _Get_Cache( $namespace )->size( );
  }

  return $size;
}


sub _Namespaces
{
  return _Get_Backend( )->get_namespaces( );
}



sub _Get_Backend
{
  return new Cache::SharedMemoryBackend( );
}


sub _Get_Cache
{
  my ( $p_namespace ) = Static_Params( @_ );

  Assert_Defined( $p_namespace );

  return new Cache::SharedMemoryCache( { 'namespace' => $p_namespace } );
}


sub new
{
  my ( $self ) = _new( @_ );

  $self->_complete_initialization( );

  return $self;
}


sub _new
{
  my ( $proto, $p_options_hash_ref ) = @_;
  my $class = ref( $proto ) || $proto;
  my $self = $class->SUPER::_new( $p_options_hash_ref );
  $self->_set_backend( new Cache::SharedMemoryBackend( ) );
  return $self;
}


1;