package Koha::Cache;
# Copyright 2009 Chris Cormack and The Koha Dev Team
+# Parts copyright 2012-2013 C & P Bibliography Services
#
# This file is part of Koha.
#
=head1 SYNOPSIS
- use Koha::Cache (cache_type => $cache_type, %params );
+ use Koha::Cache;
+ my $cache = Koha::Cache->new({cache_type => $cache_type, %params});
=head1 DESCRIPTION
-Base class for Koha::Cache::X. Subclasses need to provide the following methods
-
-B<_cache_handle ($params_hr)> - cache handle creator
-
-B<set_in_cache ($key, $value, $expiry)>
-
-B<get_from_cache ($key)>
-
-B<clear_from_cache ($key)>
-
-B<flush_all ()>
+Koha caching routines. This class provides two interfaces for cache access.
+The first, traditional interface provides the following functions:
=head1 FUNCTIONS
use strict;
use warnings;
use Carp;
+use Module::Load::Conditional qw(can_load);
+use Koha::Cache::Object;
use base qw(Class::Accessor);
-use Koha::Cache::Memcached;
+__PACKAGE__->mk_ro_accessors(
+ qw( cache memcached_cache fastmmap_cache memory_cache ));
+
+=head2 new
-__PACKAGE__->mk_ro_accessors( qw( cache ) );
+Create a new Koha::Cache object. This is required for all cache-related functionality.
+
+=cut
sub new {
- my $class = shift;
- my $param = shift;
- my $cache_type = $ENV{CACHING_SYSTEM} || $param->{cache_type} || 'memcached';
- my $subclass = __PACKAGE__."::".ucfirst($cache_type);
- my $cache = $subclass->_cache_handle($param)
- or croak "Cannot create cache handle for '$cache_type'";
- return bless $class->SUPER::new({cache => $cache}), $subclass;
+ my ( $class, $self ) = @_;
+ $self->{'default_type'} =
+ $self->{cache_type}
+ || $ENV{CACHING_SYSTEM}
+ || 'memcached';
+
+ $ENV{DEBUG} && carp "Default caching system: $self->{'default_type'}";
+
+ $self->{'timeout'} ||= 0;
+ $self->{'namespace'} ||= $ENV{MEMCACHED_NAMESPACE} || 'koha';
+
+ if ( can_load( modules => { 'Cache::Memcached::Fast' => undef } ) ) {
+ _initialize_memcached($self);
+ if ( $self->{'default_type'} eq 'memcached'
+ && defined( $self->{'memcached_cache'} ) )
+ {
+ $self->{'cache'} = $self->{'memcached_cache'};
+ }
+ }
+
+ if ( can_load( modules => { 'Cache::FastMmap' => undef } ) ) {
+ _initialize_fastmmap($self);
+ if ( $self->{'default_type'} eq 'fastmmap'
+ && defined( $self->{'fastmmap_cache'} ) )
+ {
+ $self->{'cache'} = $self->{'fastmmap_cache'};
+ }
+ }
+
+ if ( can_load( modules => { 'Cache::Memory' => undef } ) ) {
+ _initialize_memory($self);
+ if ( $self->{'default_type'} eq 'memory'
+ && defined( $self->{'memory_cache'} ) )
+ {
+ $self->{'cache'} = $self->{'memory_cache'};
+ }
+ }
+
+# NOTE: The following five lines could be uncommented if we wanted to
+# fall back to any functioning cache. Commented out since this would
+# represent a change in behavior.
+#
+#unless (defined($self->{'cache'})) {
+# foreach my $cachemember (qw(memory_cache fastmmap_cache memcached_cache)) {
+# $self->{'cache'} = $self->{$cachemember} if (defined($self->{$cachemember}));
+# }
+#}
+
+ return
+ bless $self,
+ $class;
}
+sub _initialize_memcached {
+ my ($self) = @_;
+ my @servers =
+ split /,/, $self->{'cache_servers'}
+ ? $self->{'cache_servers'}
+ : $ENV{MEMCACHED_SERVERS};
+
+ $ENV{DEBUG}
+ && carp "Memcached server settings: "
+ . join( ', ', @servers )
+ . " with "
+ . $self->{'namespace'};
+ $self->{'memcached_cache'} = Cache::Memcached::Fast->new(
+ {
+ servers => \@servers,
+ compress_threshold => 10_000,
+ namespace => $self->{'namespace'},
+ }
+ );
+ return $self;
+}
+
+sub _initialize_fastmmap {
+ my ($self) = @_;
+
+ $self->{'fastmmap_cache'} = Cache::FastMmap->new(
+ 'share_file' => "/tmp/sharefile-koha-$self->{'namespace'}",
+ 'expire_time' => $self->{'timeout'},
+ 'unlink_on_exit' => 0,
+ );
+ return $self;
+}
+
+sub _initialize_memory {
+ my ($self) = @_;
+
+ $self->{'memory_cache'} = Cache::Memory->new(
+ 'namespace' => $self->{'namespace'},
+ 'default_expires' => $self->{'timeout'}
+ );
+ return $self;
+}
+
+=head2 is_cache_active
+
+Routine that checks whether or not a caching system has been selected. This is
+not an instance method.
+
+=cut
+
sub is_cache_active {
- return $ENV{CACHING_SYSTEM} ? '1' : '' ;
+ return $ENV{CACHING_SYSTEM} ? '1' : '';
+}
+
+=head2 set_in_cache
+
+ $cache->set_in_cache($key, $value, [$expiry]);
+
+Save a value to the specified key in the default cache, optionally with a
+particular expiry.
+
+=cut
+
+sub set_in_cache {
+ my ( $self, $key, $value, $expiry, $cache ) = @_;
+ $cache ||= 'cache';
+ croak "No key" unless $key;
+ $ENV{DEBUG} && carp "set_in_cache for $key";
+
+ return unless ( $self->{$cache} && ref( $self->{$cache} ) =~ m/^Cache::/ );
+ if ( defined $expiry ) {
+ if ( ref( $self->{$cache} ) eq 'Cache::Memory' ) {
+ $expiry = "$expiry sec";
+ }
+ return $self->{$cache}->set( $key, $value, $expiry );
+ }
+ else {
+ return $self->{$cache}->set( $key, $value );
+ }
+}
+
+=head2 get_from_cache
+
+ my $value = $cache->get_from_cache($key);
+
+Retrieve the value stored under the specified key in the default cache.
+
+=cut
+
+sub get_from_cache {
+ my ( $self, $key, $cache ) = @_;
+ $cache ||= 'cache';
+ croak "No key" unless $key;
+ $ENV{DEBUG} && carp "get_from_cache for $key";
+ return unless ( $self->{$cache} && ref( $self->{$cache} ) =~ m/^Cache::/ );
+ return $self->{$cache}->get($key);
+}
+
+=head2 clear_from_cache
+
+ $cache->clear_from_cache($key);
+
+Remove the value identified by the specified key from the default cache.
+
+=cut
+
+sub clear_from_cache {
+ my ( $self, $key, $cache ) = @_;
+ $cache ||= 'cache';
+ croak "No key" unless $key;
+ return unless ( $self->{$cache} && ref( $self->{$cache} ) =~ m/^Cache::/ );
+ return $self->{$cache}->delete($key)
+ if ( ref( $self->{$cache} ) eq 'Cache::Memcached::Fast' );
+ return $self->{$cache}->remove($key);
+}
+
+=head2 flush_all
+
+ $cache->flush_all();
+
+Clear the entire default cache.
+
+=cut
+
+sub flush_all {
+ my ( $self, $cache ) = shift;
+ $cache ||= 'cache';
+ return unless ( $self->{$cache} && ref( $self->{$cache} ) =~ m/^Cache::/ );
+ return $self->{$cache}->flush_all()
+ if ( ref( $self->{$cache} ) eq 'Cache::Memcached::Fast' );
+ return $self->{$cache}->clear();
+}
+
+=head1 TIED INTERFACE
+
+Koha::Cache also provides a tied interface which enables users to provide a
+constructor closure and (after creation) treat cached data like normal reference
+variables and rely on the cache Just Working and getting updated when it
+expires, etc.
+
+ my $cache = Koha::Cache->new();
+ my $data = 'whatever';
+ my $scalar = Koha::Cache->create_scalar(
+ {
+ 'key' => 'whatever',
+ 'timeout' => 2,
+ 'constructor' => sub { return $data; },
+ }
+ );
+ print "$$scalar\n"; # Prints "whatever"
+ $data = 'somethingelse';
+ print "$$scalar\n"; # Prints "whatever" because it is cached
+ sleep 2; # Wait until the cache entry has expired
+ print "$$scalar\n"; # Prints "somethingelse"
+
+ my $hash = Koha::Cache->create_hash(
+ {
+ 'key' => 'whatever',
+ 'timeout' => 2,
+ 'constructor' => sub { return $data; },
+ }
+ );
+ print "$$variable\n"; # Prints "whatever"
+
+The gotcha with this interface, of course, is that the variable returned by
+create_scalar and create_hash is a I<reference> to a tied variable and not a
+tied variable itself.
+
+The tied variable is configured by means of a hashref passed in to the
+create_scalar and create_hash methods. The following parameters are supported:
+
+=over
+
+=item I<key>
+
+Required. The key to use for identifying the variable in the cache.
+
+=item I<constructor>
+
+Required. A closure (or reference to a function) that will return the value that
+needs to be stored in the cache.
+
+=item I<preload>
+
+Optional. A closure (or reference to a function) that gets run to initialize
+the cache when creating the tied variable.
+
+=item I<arguments>
+
+Optional. Array reference with the arguments that should be passed to the
+constructor function.
+
+=item I<timeout>
+
+Optional. The cache timeout in seconds for the variable. Defaults to 600
+(ten minutes).
+
+=item I<cache_type>
+
+Optional. Which type of cache to use for the variable. Defaults to whatever is
+set in the environment variable CACHING_SYSTEM. If set to 'null', disables
+caching for the tied variable.
+
+=item I<allowupdate>
+
+Optional. Boolean flag to allow the variable to be updated directly. When this
+is set and the variable is used as an l-value, the cache will be updated
+immediately with the new value. Using this is probably a bad idea on a
+multi-threaded system. When I<allowupdate> is not set to true, using the
+tied variable as an l-value will have no effect.
+
+=item I<destructor>
+
+Optional. A closure (or reference to a function) that should be called when the
+tied variable is destroyed.
+
+=item I<unset>
+
+Optional. Boolean flag to tell the object to remove the variable from the cache
+when it is destroyed or goes out of scope.
+
+=item I<inprocess>
+
+Optional. Boolean flag to tell the object not to refresh the variable from the
+cache every time the value is desired, but rather only when the I<local> copy
+of the variable is older than the timeout.
+
+=back
+
+=head2 create_scalar
+
+ my $scalar = Koha::Cache->create_scalar(\%params);
+
+Create scalar tied to the cache.
+
+=cut
+
+sub create_scalar {
+ my ( $self, $args ) = @_;
+
+ $self->_set_tied_defaults($args);
+
+ tie my $scalar, 'Koha::Cache::Object', $args;
+ return \$scalar;
+}
+
+sub create_hash {
+ my ( $self, $args ) = @_;
+
+ $self->_set_tied_defaults($args);
+
+ tie my %hash, 'Koha::Cache::Object', $args;
+ return \%hash;
+}
+
+sub _set_tied_defaults {
+ my ( $self, $args ) = @_;
+
+ $args->{'timeout'} = '600' unless defined( $args->{'timeout'} );
+ $args->{'inprocess'} = '0' unless defined( $args->{'inprocess'} );
+ unless ( lc( $args->{'cache_type'} ) eq 'null' ) {
+ $args->{'cache'} = $self;
+ $args->{'cache_type'} ||= $ENV{'CACHING_SYSTEM'};
+ }
+
+ return $args;
}
-=head2 EXPORT
+=head1 EXPORT
None by default.
=head1 SEE ALSO
-Koha::Cache::Memcached
+Koha::Cache::Object
=head1 AUTHOR
Chris Cormack, E<lt>chris@bigballofwax.co.nzE<gt>
Paul Poulain, E<lt>paul.poulain@biblibre.comE<gt>
+Jared Camins-Esakov, E<lt>jcamins@cpbibliography.comE<gt>
=cut
projects / koha.git / blobdiff