initial commit.

ExpiringMemoryStore inherits from Store, not from MemoryStore
(hopefully that's alright)

MIT-LICENSE

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+Copyright (c) 2008 [Matthew Rudy Jacobs]
+
+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.

README

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+ExpiringMemoryStore
+===================
+
+Expiring MemoryStore is a modification to the default Rails MemoryStore which adds the :expires_in functionality that is so useful with Memcache.
+Although this increases the memory overhead slightly,
+it ensures that caches can be expired easily, without restarting your webserver.
+
+Just add;
+  config.cache_store = :expiring_memory_store
+to your environment.rb.
+
+Example
+=======
+
+  >> Rails.cache.write('are you there?', :im_still_here, :expires_in => 30)
+  => :im_still_here
+
+  >> Rails.cache.read('are you there?')
+  => :im_still_here
+
+wait 30 seconds
+
+  >> Rails.cache.read('are you there?')
+  => nil
+
+WICKED!!!
+
+Copyright (c) 2008 [Matthew Rudy Jacobs], released under the MIT license

Rakefile

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+require 'rake'
+require 'rake/testtask'
+require 'rake/rdoctask'
+
+desc 'Default: run unit tests.'
+task :default => :test
+
+desc 'Test the expiring_memory_store plugin.'
+Rake::TestTask.new(:test) do |t|
+  t.libs << 'lib'
+  t.pattern = 'test/**/*_test.rb'
+  t.verbose = true
+end
+
+desc 'Generate documentation for the expiring_memory_store plugin.'
+Rake::RDocTask.new(:rdoc) do |rdoc|
+  rdoc.rdoc_dir = 'rdoc'
+  rdoc.title    = 'ExpiringMemoryStore'
+  rdoc.options << '--line-numbers' << '--inline-source'
+  rdoc.rdoc_files.include('README')
+  rdoc.rdoc_files.include('lib/**/*.rb')
+end

init.rb

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+require 'active_support/cache/expiring_memory_store'

lib/active_support/cache/expiring_memory_store.rb

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+require 'activesupport'
+module ActiveSupport
+  module Cache
+    # Like MemoryStore, but caches are expired after the period specified in the :expires_in option.
+    class ExpiringMemoryStore < Store
+      def initialize
+        @data = {}
+      end
+
+      def read(name, options = nil)
+        super
+        value, expiry = @data[name]
+        if expiry && expiry < Time.now
+          delete(name)
+          return nil
+        end
+        return value
+      end
+
+      def write(name, value, options = nil)
+        super
+        @data[name] = [value.freeze, expires_at(options)].freeze
+        return value
+      end
+
+      def delete(name, options = nil)
+        super
+        @data.delete(name)
+      end
+
+      def delete_matched(matcher, options = nil)
+        super
+        @data.delete_if { |k,v| k =~ matcher }
+      end
+
+      def exist?(name,options = nil)
+        super
+        @data.has_key?(name)
+      end
+
+      def clear
+        @data.clear
+      end
+
+      private
+
+        def expires_at(options)
+          if expires_in = options && options[:expires_in]
+            return expires_in.from_now if expires_in != 0
+          end
+          return nil
+        end
+    end
+  end
+end

test/expiring_memory_store_test.rb

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+require 'rubygems'
+require 'test/unit'
+require 'mocha'
+require File.dirname(__FILE__) + '/../init'
+
+class CacheStoreTest < Test::Unit::TestCase
+  def setup
+    @cache = ActiveSupport::Cache.lookup_store(:expiring_memory_store)
+  end
+
+  def test_fetch_without_cache_miss
+    @cache.stubs(:read).with('foo', {}).returns('bar')
+    @cache.expects(:write).never
+    assert_equal 'bar', @cache.fetch('foo') { 'baz' }
+  end
+
+  def test_fetch_with_cache_miss
+    @cache.stubs(:read).with('foo', {}).returns(nil)
+    @cache.expects(:write).with('foo', 'baz', {})
+    assert_equal 'baz', @cache.fetch('foo') { 'baz' }
+  end
+
+  def test_fetch_with_forced_cache_miss
+    @cache.expects(:read).never
+    @cache.expects(:write).with('foo', 'bar', :force => true)
+    @cache.fetch('foo', :force => true) { 'bar' }
+  end
+end
+
+# Tests the base functionality that should be identical across all cache stores.
+module CacheStoreBehavior
+  def test_should_read_and_write_strings
+    @cache.write('foo', 'bar')
+    assert_equal 'bar', @cache.read('foo')
+  end
+
+  def test_should_read_and_write_hash
+    @cache.write('foo', {:a => "b"})
+    assert_equal({:a => "b"}, @cache.read('foo'))
+  end
+
+  def test_should_read_and_write_nil
+    @cache.write('foo', nil)
+    assert_equal nil, @cache.read('foo')
+  end
+
+  def test_fetch_without_cache_miss
+    @cache.write('foo', 'bar')
+    assert_equal 'bar', @cache.fetch('foo') { 'baz' }
+  end
+
+  def test_fetch_with_cache_miss
+    assert_equal 'baz', @cache.fetch('foo') { 'baz' }
+  end
+
+  def test_fetch_with_forced_cache_miss
+    @cache.fetch('foo', :force => true) { 'bar' }
+  end
+
+  def test_increment
+    @cache.write('foo', 1, :raw => true)
+    assert_equal 1, @cache.read('foo', :raw => true).to_i
+    assert_equal 2, @cache.increment('foo')
+    assert_equal 2, @cache.read('foo', :raw => true).to_i
+    assert_equal 3, @cache.increment('foo')
+    assert_equal 3, @cache.read('foo', :raw => true).to_i
+  end
+
+  def test_decrement
+    @cache.write('foo', 3, :raw => true)
+    assert_equal 3, @cache.read('foo', :raw => true).to_i
+    assert_equal 2, @cache.decrement('foo')
+    assert_equal 2, @cache.read('foo', :raw => true).to_i
+    assert_equal 1, @cache.decrement('foo')
+    assert_equal 1, @cache.read('foo', :raw => true).to_i
+  end
+end
+
+class ExpiringMemoryStoreTest < Test::Unit::TestCase
+  def setup
+    @cache = ActiveSupport::Cache.lookup_store(:expiring_memory_store)
+  end
+
+  include CacheStoreBehavior
+
+  def test_store_objects_should_be_immutable
+    @cache.write('foo', 'bar')
+    assert_raise(ActiveSupport::FrozenObjectError) { @cache.read('foo').gsub!(/.*/, 'baz') }
+    assert_equal 'bar', @cache.read('foo')
+  end
+
+  def test_by_default_values_should_not_expire
+    time_now = Time.now
+    Time.stubs(:now).returns(time_now)
+
+    @cache.write('foo', 'bar')
+    assert_equal 'bar', @cache.read('foo')
+
+    Time.stubs(:now).returns(time_now + 5.years )
+    assert_equal 'bar', @cache.read('foo')
+  end
+
+  def test_values_should_expire_is_param_is_set
+    time_now = Time.now
+    Time.stubs(:now).returns(time_now)
+
+    @cache.write('foo', 'bar', :expires_in => 1.year)
+    assert_equal 'bar', @cache.read('foo')
+
+    Time.stubs(:now).returns(time_now + 5.years )
+    assert_equal nil, @cache.read('foo')
+  end
+
+  def test_values_should_expire_when_the_param_tells_it_to
+    time_now = Time.now
+    Time.stubs(:now).returns(time_now)
+
+    @cache.write('foo', 'bar', :expires_in => 1.year)
+    assert_equal 'bar', @cache.read('foo')
+
+    Time.stubs(:now).returns(time_now + 1.year - 1 )
+    assert_equal 'bar', @cache.read('foo')
+
+    Time.stubs(:now).returns(time_now + 1.year + 1 )
+    assert_equal nil, @cache.read('foo')
+  end
+end