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.
#
-# Koha is free software; you can redistribute it and/or modify it under the
-# terms of the GNU General Public License as published by the Free Software
-# Foundation; either version 2 of the License, or (at your option) any later
-# version.
+# Koha is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
#
-# Koha is distributed in the hope that it will be useful, but WITHOUT ANY
-# WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
-# A PARTICULAR PURPOSE. See the GNU General Public License for more details.
+# Koha is distributed in the hope that it will be useful, but
+# WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
#
-# You should have received a copy of the GNU General Public License along
-# with Koha; if not, write to the Free Software Foundation, Inc.,
-# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+# You should have received a copy of the GNU General Public License
+# along with Koha; if not, see <http://www.gnu.org/licenses>.
=head1 NAME
=head1 SYNOPSIS
- use Koha::Cache (cache_type => $cache_type, %params );
+ use Koha::Cache;
+ my $cache = Koha::Cache->new({cache_type => $cache_type, %params});
-=head1 DESCRIPTION
-
-Base class for Koha::Cache::X. Subclasses must provide the following methods
-
-B<_cache_handle ($params_hr)> - cache handle creator
-
-Subclasses may override the following methods if they are not using a
-CHI-derived cache
+ # see also Koha::Caches->get_instance;
-B<set_in_cache ($key, $value, $expiry)>
-
-B<get_from_cache ($key)>
-
-B<clear_from_cache ($key)>
+=head1 DESCRIPTION
-B<flush_all ()>
+Koha caching routines. This class provides two interfaces for cache access.
+The first, traditional OO interface provides the following functions:
=head1 FUNCTIONS
use strict;
use warnings;
-use Carp;
-use Module::Load::Conditional qw(can_load);
-use Module::Load;
+use Carp qw( croak );
+use Module::Load::Conditional qw( can_load );
+use Sereal::Encoder;
+use Sereal::Decoder;
-my $have_chi = 0;
-
-BEGIN: {
- if ( can_load( modules => { CHI => undef } ) ) {
- $have_chi = 1;
- }
-}
+use C4::Context;
+use Koha::Cache::Object;
+use Koha::Config;
use base qw(Class::Accessor);
-__PACKAGE__->mk_ro_accessors(qw( cache ));
+__PACKAGE__->mk_ro_accessors(
+ qw( cache memcached_cache ));
+
+our %L1_cache;
+our $L1_encoder = Sereal::Encoder->new;
+our $L1_decoder = Sereal::Decoder->new;
+
+=head2 new
+
+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}
+ my ( $class, $self, $params ) = @_;
+ $self->{'default_type'} =
+ $self->{cache_type}
+ || $ENV{CACHING_SYSTEM} # DELME What about this?
|| 'memcached';
- my $subclass = __PACKAGE__ . "::" . ucfirst($cache_type);
- $param->{have_chi} = $have_chi;
- unless ( can_load( modules => { $subclass => undef } ) ) {
- $subclass = __PACKAGE__ . "::" . ucfirst('Null');
- load $subclass;
+
+ my $subnamespace = $params->{subnamespace} // '';
+
+ $self->{'timeout'} ||= 0;
+ # Should we continue to support MEMCACHED ENV vars?
+ $self->{'namespace'} ||= $ENV{MEMCACHED_NAMESPACE};
+ my @servers = split /,/, $ENV{MEMCACHED_SERVERS} || '';
+ $self->{namespace} ||= C4::Context->config('memcached_namespace') || 'koha';
+ @servers = split /,/, C4::Context->config('memcached_servers') // ''
+ unless @servers;
+ $self->{namespace} .= ":$subnamespace:";
+
+ if ( $self->{'default_type'} eq 'memcached'
+ && can_load( modules => { 'Cache::Memcached::Fast::Safe' => undef } )
+ && _initialize_memcached($self, @servers)
+ && defined( $self->{'memcached_cache'} ) )
+ {
+ $self->{'cache'} = $self->{'memcached_cache'};
}
- my $cache = $subclass->_cache_handle($param);
+
return
- bless $class->SUPER::new( { cache => $cache, have_chi => $have_chi } ),
- $subclass;
+ bless $self,
+ $class;
+}
+
+sub _initialize_memcached {
+ my ($self, @servers) = @_;
+
+ return unless @servers;
+
+ # Cache::Memcached::Fast::Safe doesn't allow a default expire time to be set
+ # so we force it on setting.
+ my $memcached = Cache::Memcached::Fast::Safe->new(
+ {
+ servers => \@servers,
+ compress_threshold => 10_000,
+ namespace => $self->{'namespace'},
+ utf8 => 1,
+ }
+ );
+
+ # Ensure we can actually talk to the memcached server
+ my $ismemcached = $memcached->set('ismemcached','1');
+ unless ($ismemcached) {
+ warn "\nConnection to the memcached servers '@servers' failed. Are the unix socket permissions set properly? Is the host reachable?\nIf you ignore this warning, you will face performance issues\n";
+ return $self;
+ }
+ $self->{'memcached_cache'} = $memcached;
+ return $self;
}
+=head2 is_cache_active
+
+Routine that checks whether or not a default caching method is active on this
+object.
+
+=cut
+
sub is_cache_active {
- return $ENV{CACHING_SYSTEM} ? '1' : '';
+ my $self = shift;
+ return $self->{'cache'} ? 1 : 0;
}
+=head2 set_in_cache
+
+ $cache->set_in_cache($key, $value, [$options]);
+
+Save a value to the specified key in the cache. A hashref of options may be
+specified.
+
+The possible options are:
+
+=over
+
+=item expiry
+
+Expiry time of this cached entry in seconds.
+
+=item cache
+
+The cache object to use if you want to provide your own. It should be an
+instance of C<Cache::*> and follow the same interface as L<Cache::Memcache>.
+
+=back
+
+=cut
+
sub set_in_cache {
- my ( $self, $key, $value, $expiry ) = @_;
+ my ( $self, $key, $value, $options ) = @_;
+
+ my $unsafe = $options->{unsafe} || 0;
+
+ # the key mustn't contain whitespace (or control characters) for memcache
+ # but shouldn't be any harm in applying it globally.
+ $key =~ s/[\x00-\x20]/_/g;
+
+ my $cache = $options->{cache} || 'cache';
croak "No key" unless $key;
- $ENV{DEBUG} && warn "set_in_cache for $key";
- return unless $self->{cache};
- return unless $self->{have_chi};
+ return unless ( $self->{$cache} && ref( $self->{$cache} ) =~ m/^Cache::/ );
+ my $expiry = $options->{expiry};
+ $expiry //= $self->{timeout};
+ my $set_sub = $self->{ref($self->{$cache}) . "_set"};
+
+ my $flag = '-CF0'; # 0: scalar, 1: frozen data structure
+ if (ref($value)) {
+ # Set in L1 cache as a data structure
+ # We only save the frozen form: we do want to save $value in L1
+ # directly in order to protect it. And thawing now may not be
+ # needed, so improves performance.
+ $value = $L1_encoder->encode($value);
+ $L1_cache{$self->{namespace}}{$key}->{frozen} = $value;
+ $flag = '-CF1';
+ } else {
+ # Set in L1 cache as a scalar; exit if we are caching an undef
+ $L1_cache{$self->{namespace}}{$key} = $value;
+ return if !defined $value;
+ }
- if ( defined $expiry ) {
- return $self->{cache}->set( $key, $value, $expiry );
+ $value .= $flag;
+ # We consider an expiry of 0 to be infinite
+ if ( $expiry ) {
+ return $set_sub
+ ? $set_sub->( $key, $value, $expiry )
+ : $self->{$cache}->set( $key, $value, $expiry );
}
else {
- return $self->{cache}->set( $key, $value );
+ return $set_sub
+ ? $set_sub->( $key, $value )
+ : $self->{$cache}->set( $key, $value );
}
}
+=head2 get_from_cache
+
+ my $value = $cache->get_from_cache($key, [ $options ]);
+
+Retrieve the value stored under the specified key in the cache.
+
+The possible options are:
+
+=over
+
+=item unsafe
+
+If set, this will avoid performing a deep copy of the item. This
+means that it won't be safe if something later modifies the result of the
+function. It should be used with caution, and could save processing time
+in some situations where is safe to use it. Make sure you know what you are doing!
+
+=item cache
+
+The cache object to use if you want to provide your own. It should be an
+instance of C<Cache::*> and follow the same interface as L<Cache::Memcache>.
+
+=back
+
+=cut
+
sub get_from_cache {
- my ( $self, $key ) = @_;
+ my ( $self, $key, $options ) = @_;
+ my $cache = $options->{cache} || 'cache';
+ my $unsafe = $options->{unsafe} || 0;
+ $key =~ s/[\x00-\x20]/_/g;
croak "No key" unless $key;
- $ENV{DEBUG} && warn "get_from_cache for $key";
- return unless $self->{cache};
- return unless $self->{have_chi};
- return $self->{cache}->get($key);
+ return unless ( $self->{$cache} && ref( $self->{$cache} ) =~ m/^Cache::/ );
+
+ # Return L1 cache value if exists
+ if ( exists $L1_cache{$self->{namespace}}{$key} ) {
+ if (ref($L1_cache{$self->{namespace}}{$key})) {
+ if ($unsafe) {
+ # ONLY use thawed for unsafe calls !!!
+ $L1_cache{$self->{namespace}}{$key}->{thawed} ||= $L1_decoder->decode($L1_cache{$self->{namespace}}{$key}->{frozen});
+ return $L1_cache{$self->{namespace}}{$key}->{thawed};
+ } else {
+ return $L1_decoder->decode($L1_cache{$self->{namespace}}{$key}->{frozen});
+ }
+ } else {
+ # No need to thaw if it's a scalar
+ return $L1_cache{$self->{namespace}}{$key};
+ }
+ }
+
+ my $get_sub = $self->{ref($self->{$cache}) . "_get"};
+ my $L2_value = $get_sub ? $get_sub->($key) : $self->{$cache}->get($key);
+
+ return if ref($L2_value);
+ return unless (defined($L2_value) && length($L2_value) >= 4);
+
+ my $flag = substr($L2_value, -4, 4, '');
+ if ($flag eq '-CF0') {
+ # it's a scalar
+ $L1_cache{$self->{namespace}}{$key} = $L2_value;
+ return $L2_value;
+ } elsif ($flag eq '-CF1') {
+ # it's a frozen data structure
+ my $thawed;
+ eval { $thawed = $L1_decoder->decode($L2_value); };
+ return if $@;
+ $L1_cache{$self->{namespace}}{$key}->{frozen} = $L2_value;
+ # ONLY save thawed for unsafe calls !!!
+ $L1_cache{$self->{namespace}}{$key}->{thawed} = $thawed if $unsafe;
+ return $thawed;
+ }
+
+ # Unknown value / data type returned from L2 cache
+ return;
}
+=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 ) = @_;
+ my ( $self, $key, $cache ) = @_;
+ $key =~ s/[\x00-\x20]/_/g;
+ $cache ||= 'cache';
croak "No key" unless $key;
- return unless $self->{cache};
- return unless $self->{have_chi};
- return $self->{cache}->remove($key);
+ return unless ( $self->{$cache} && ref( $self->{$cache} ) =~ m/^Cache::/ );
+
+ # Clear from L1 cache
+ delete $L1_cache{$self->{namespace}}{$key};
+
+ return $self->{$cache}->delete($key)
+ if ( ref( $self->{$cache} ) =~ m'^Cache::Memcached' );
+ return $self->{$cache}->remove($key);
}
+=head2 flush_all
+
+ $cache->flush_all();
+
+Clear the entire default cache.
+
+=cut
+
sub flush_all {
- my $self = shift;
- return unless $self->{cache};
- return unless $self->{have_chi};
- return $self->{cache}->clear();
+ my ( $self, $cache ) = shift;
+ $cache ||= 'cache';
+ return unless ( $self->{$cache} && ref( $self->{$cache} ) =~ m/^Cache::/ );
+
+ $self->flush_L1_cache();
+
+ return $self->{$cache}->flush_all()
+ if ( ref( $self->{$cache} ) =~ m'^Cache::Memcached' );
+ return $self->{$cache}->clear();
+}
+
+sub flush_L1_cache {
+ my( $self ) = @_;
+ delete $L1_cache{$self->{namespace}};
+}
+
+=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 ( $args->{cache_type} and 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
projects / srvgit / blobdiff