Lightly - Ruby File Cache

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Lightly is a file cache for performing heavy tasks, lightly.

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Install

$ gem install lightly

Or with bundler:

gem 'lightly'

Usage

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 = 7200 # seconds
lightly.hash = false

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

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For a similar gem that provides caching specifically for HTTP downloads, see the WebCache gem