internal package Foswiki::Contrib::CacheContrib
Interface to the caching services. This consists of two parts:
- basic caching: cache computational results for a short period of time for faster access
- a caching user agent: fetch external resources and cache them
Both of these requirements happen so often in Foswiki plugins that they have been provided as
a basic service to be accessed by third party plugins. For instance, ImagePlugin caches
image geometries as analysing and extracting this information from pictures can be quite expensive.
NumberPlugin fetches exchange rates of currencies from an external provider and caches them locally.
FeedPlugin fetches RSS and Atom feeds and caches them locally when rerendering them on a Foswiki page.
SolrPlugin serializes binary document formats while indexing their content with interim results cached
locally to speed up reindexing those documents.
getUserAgent($namespace) -> $ua
returns a singleton caching user agent compatible to CPAN:LWP::UserAgent
(defaults to "UserAgent") parameter defines the cache section used for this agent.
getCache($namespace, $expire) -> $cache
returns a CHI cache object
for the given namespace.
my $cache = Foswiki::Contrib::CacheContrib::getCache("ImagePlugin");
getExternalResource($url, ...) -> $response
Fetch an external resource using the caching UserAgent. This is equivalent
with just adding caching.
It basically is compatible with
my $response = Foswiki::Contrib::CacheContrib::getExternalResource($url);
throw Error::Simple("http error fetching $url: ".$response->code." - ".$response->status_line)
my $content = $response->decoded_content();
clears the cache for the given namespace
purges expired entries of the cache for the given namespace