Text::MicroMason::Cache::File - Basic Cache with File-Based Expiration

Text-MicroMason documentation Contained in the Text-MicroMason distribution.

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NAME

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Text::MicroMason::Cache::File - Basic Cache with File-Based Expiration

DESCRIPTION

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This simple cache class expects the keys provided to it to be file pathnames, and considers the cached value to have expired if the corresponding file is changed.

It does not perform the following functions: cache size limiting, or deep copying of complex values.

Public Methods

new()
  $cache = Text::MicroMason::Cache::File->new();
get()
  $value = $cache->get( $filename );

Retrieves the value associated with this key, or undef if there is no value.

set()
  $cache->set( $filename, $value );

Stores the provided value in association with this key.

clear()
  $cache->clear();

Removes all data from the cache.

SEE ALSO

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For uses of this cache class, see Text::MicroMason::CompileCache.

Additional cache classes are available in the Text::MicroMason::Cache:: namespace, or select other caching modules on CPAN that support the interface described in Cache::Cache.

For distribution, installation, support, copyright and license information, see Text::MicroMason::Docs::ReadMe.

Text-MicroMason documentation Contained in the Text-MicroMason distribution. 
package Text::MicroMason::Cache::File;
@ISA = 'Text::MicroMason::Cache::Simple';

use strict;

# Array field names
use constant LAST_CHECK => 0;
use constant AGE        => 1;
use constant VALUE      => 2;

######################################################################

sub get { 
    my ( $self, $file ) = @_;
    my $entry = $self->SUPER::get( $file ) 
        or return;
    unless (ref($entry) eq 'ARRAY' and @$entry == 3 ) {
        Carp::croak("MicroMason: cache '$self' data corrupted; " . 
                    "value for '$file' should not be '$entry'");
    }
    
    my $time = time();
    if ( $entry->[LAST_CHECK] < $time ) { # don't check more than once per second
        my $current_age = -M $file;
        if ( $entry->[AGE] > $current_age ) {
            @$entry = ( 0, 0, undef ); # file has changed; cache invalid
            return;
        } else {
            $entry->[LAST_CHECK] = $time;
        }
    }
    return $entry->[VALUE];
}

sub set { 
    my ($self, $file, $sub) = @_;
    $self->SUPER::set( $file => [ time(), -M $file, $sub ] ); 
    return $sub; 
}

######################################################################

1;

__END__

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