Lightly - Ruby File Cache
Lightly is a file cache for performing heavy tasks, lightly.
Install
$ gem install lightly
Or with bundler:
gem 'lightly'
Usage
Lightly can be used both as an instance, and as a static class.
require 'lightly'
# Instance
cache = Lightly.new life: '3h'
response = cache.get 'key' do
# Heavy operation here
end
# Static
Lightly.life = '3h'
Lightly.get 'key' do
# Heavy operation here
end
The design intention is to provide both a globally available singleton
Lightly
object, as well as multiple caching instances, with different
settings - depending on the use case.
Note that the examples in this README are all using the instance syntax, but all methods are also available statically.
This is the basic usage pattern:
require 'lightly'
lightly = Lightly.new
content = lightly.get 'key' do
# Heavy operation here
entire_internet.download
end
This will look for a cached object with the given key and return it if it exists and not older than 1 hour. Otherwise, it will perform the operation inside the block, and save it to the cache object.
By default, the cached objects are stored in the ./cache
directory, and
expire after 60 minutes. The cache directory will be created as needed.
In addition, the provided key is hashed to its MD5 representation.
You can change these settings on initialization:
lightly = Lightly.new dir: 'tmp/my_cache', life: 7200, hash: false
Or later:
lightly = Lightly.new
lightly.dir = 'tmp/my_cache'
lightly.life = '1d'
lightly.hash = false
The life
property accepts any of these formats:
cache.life = 10 # 10 seconds
cache.life = '20s' # 20 seconds
cache.life = '10m' # 10 minutes
cache.life = '10h' # 10 hours
cache.life = '10d' # 10 days
To check if a key is cached, use the cached?
method:
lightly = Lightly.new
lightly.cached? 'example'
# => false
content = lightly.get 'example' do
open('http://example.com').read
end
lightly.cached? 'example'
# => true
You can enable/disable the cache at any time:
lightly = Lightly.new
lightly.disable
lightly.enabled?
# => false
content = lightly.get 'example' do
open('http://example.com').read
end
lightly.cached? 'example'
# => false
lightly.enable
content = lightly.get 'example' do
open('http://example.com').read
end
lightly.cached? 'example'
# => true
To flush the cache, call:
lightly = Lightly.new
lightly.flush
To clear the cache for a given key, call:
lightly = Lightly.new
lightly.clear 'example'
If your block returns false or nil, the data will not be cached:
result = cache.get 'test' do
false
end
puts cache.cached? 'test'
# => false
For a similar gem that provides caching specifically for HTTP downloads, see the WebCache gem