= tagged-cache

* http://github.com/antage/tagged-cache

== DESCRIPTION:

ActiveSupport cache adapter with tagged dependencies.

== SYNOPSIS:

=== RUBY EXAMPLE:

  require 'active_support'

  cache = ActiveSupport::Cache.lookup_store(:tagged_store,
    :tag_store => [:memory_store, :namespace => "tags"],
    :entity_store => [:memory_store, :namespace => "entities"]
  )

  # tags management
  cache.read_tag("tag1") # returns Fixnum
  cache.read_tags("tag1", "tag2") # returns Hash { "tag1" => tag1_version, "tag2" => tag2_version }
  cache.touch_tag("tag1") # increment tag1's version

  # reading and writing cache
  cache.write("cache key", value, :depends => ["tag1", "tag2"])
  cache.fetch("cache key", :depends => ["tag1", "tag2]) { value }

  # or

  cache.tagged_fetch("cache key") do |entry|
    entry.depends "tag1"
    entry << "tag2"
    entry.concat ["tag3", "tag4"]
    entry.concat "tag5", "tag6"
    value
  end

  # any object with method 'cache_tag' can be used as tag name
  class A
    attr_accessor :id

    def cache_tag
      "class/A/#{id}"
    end
  end

  cache.tagged_fetch("some cache path") do |entry|
    obj1 = A.new
    obj1.id = 1

    obj2 = A.new
    obj2.id = 2

    entry.depends obj1
    entry.depends obj2

    [obj1, obj2]
  end

=== RAILS EXAMPLE:

  # config/environments/production.rb:
  Rails3::Application.configure do
  ...
    config.cache_store = :tagged_store, { :tag_store => [:mem_cache_store, %w(localhost), { :namespace => "tags" }], :entity_store => [:mem_cache_store, %w(localhost), { :namespace => "entities" }] }
  ...
  end

  # app/controller/samples_controller.rb:
  class SamplesController < ApplicationController
    # specify :depends using lambda
    caches_action :show, :depends => lambda { |c|
      c.instance_eval do
        # @sample must respond to #cache_tag method
        [@sample]
      end
    }

    # specify :depends using method name
    caches_action :index, :depends => :index_tags

    def index
      @samples = Sample.all
    end

    def show
      @sample = Sample.find(params[:id])
    end

    private

    def index_tags
      # each element of @samples must respond to #cache_tag method
      @samples
    end
  end

== REQUIREMENTS:

* activesupport >= 3.0.0

== INSTALL:

* sudo gem install tagged-cache

== LICENSE:

(The MIT License)

Copyright (c) 2010 Anton Ageev

Permission is hereby granted, free of charge, to any person obtaining
a copy of this software and associated documentation files (the
'Software'), to deal in the Software without restriction, including
without limitation the rights to use, copy, modify, merge, publish,
distribute, sublicense, and/or sell copies of the Software, and to
permit persons to whom the Software is furnished to do so, subject to
the following conditions:

The above copyright notice and this permission notice shall be
included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.