NAME¶
Poet::Cache -- Poet caching with CHI
SYNOPSIS¶
# In a conf file...
cache:
defaults:
driver: Memcached
servers: ["10.0.0.15:11211", "10.0.0.15:11212"]
# In a script...
use Poet::Script qw($cache);
# In a module...
use Poet qw($cache);
# In a component...
my $cache = $m->cache;
# For an arbitrary namespace...
my $cache = Poet::Cache->new(namespace => 'Some::Namespace')
# then...
my $customer = $cache->get($name);
if ( !defined $customer ) {
$customer = get_customer_from_db($name);
$cache->set( $name, $customer, "10 minutes" );
}
my $customer2 = $cache->compute($name2, "10 minutes", sub {
get_customer_from_db($name2)
});
DESCRIPTION¶
Poet::Cache is a subclass of CHI. CHI provides a unified caching API over a
variety of storage backends, such as memory, plain files, memory mapped files,
memcached, and DBI.
Each package and Mason component uses its own CHI namespace so that caches
remain separate.
CONFIGURATION¶
The Poet configuration entry 'cache', if any, will be passed to Poet::Cache->
config(). This can go in any Poet conf file, e.g. "local.cfg"
or "global/cache.cfg".
Here's a simple configuration that caches everything to files under
"data/cache". This is also the default if no configuration is
present.
cache:
defaults:
driver: File
root_dir: ${root}/data/cache
Here's a more involved configuration that defines several "storage
types" and assigns each namespace a storage type.
cache:
defaults:
expires_variance: 0.2
storage:
file:
driver: File
root_dir: ${root}/data/cache
memcached:
driver: Memcached
servers: ["10.0.0.15:11211", "10.0.0.15:11212"]
compress_threshold: 4096
namespace:
/some/component: { storage: file, expires_in: 5min }
/some/other/component: { storage: memcached, expires_in: 1h }
Some::Library: { storage: memcached, expires_in: 10min }
Given the configuration above, and the code
package Some::Library;
use Poet qw($cache);
this $cache will be created with properties
driver: Memcached
servers: ["10.0.0.15:11211", "10.0.0.15:11212"]
compress_threshold: 4096
expires_in: 10min
USAGE¶
Obtaining cache handle¶
- •
- In a script (namespace will be 'main'):
use Poet::Script qw($cache);
- •
- In a module "MyApp::Foo" (namespace will be 'MyApp::Foo'):
use Poet qw($cache);
- •
- In a component "/foo/bar" (namespace will be '/foo/bar'):
my $cache = $m->cache;
- •
- Manually for an arbitrary namespace:
my $cache = Poet::Cache->new(namespace => 'Some::Namespace');
# or
my $cache = MyApp::Cache->new(category => 'Some::Namespace');
Using cache handle¶
my $customer = $cache->get($name);
if ( !defined $customer ) {
$customer = get_customer_from_db($name);
$cache->set( $name, $customer, "10 minutes" );
}
my $customer2 = $cache->compute($name2, "10 minutes", sub {
get_customer_from_db($name2)
});
See CHI and Mason::Plugin::Cache for more details.
MODIFIABLE METHODS¶
These methods are not intended to be called externally, but may be useful to
override or modify with method modifiers in subclasses.
- initialize_caching
- Called once when the Poet environment is initialized. By default, calls
"__PACKAGE__->config" with the configuration entry
'cache'.
SEE ALSO¶
Poet
AUTHOR¶
Jonathan Swartz <swartz@pobox.com>
COPYRIGHT AND LICENSE¶
This software is copyright (c) 2012 by Jonathan Swartz.
This is free software; you can redistribute it and/or modify it under the same
terms as the Perl 5 programming language system itself.