1 files changed, 69 insertions, 0 deletions
diff --git a/lib/puppet/util/cacher.rb b/lib/puppet/util/cacher.rb
new file mode 100644
index 000000000..7b352c72a
--- /dev/null
+++ b/lib/puppet/util/cacher.rb
@@ -0,0 +1,69 @@
+module Puppet::Util::Cacher
+    # Cause all cached values to be considered invalid.
+    def self.invalidate
+        @timestamp = Time.now
+    end
+
+    def self.valid?(timestamp)
+        unless defined?(@timestamp) and @timestamp
+            @timestamp = Time.now
+            return true
+        end
+        return timestamp >= @timestamp
+    end
+
+    def self.extended(other)
+        other.extend(InstanceMethods)
+    end
+
+    def self.included(other)
+        other.extend(ClassMethods)
+        other.send(:include, InstanceMethods)
+    end
+
+    module ClassMethods
+        private
+
+        def cached_attr(name, &block)
+            define_method(name) do
+                attr_cache(name, &block)
+            end
+        end
+    end
+
+    module InstanceMethods
+        private
+
+        def attr_cache(name, &block)
+            unless defined?(@cacher_caches) and @cacher_caches
+                @cacher_caches = Cache.new
+            end
+
+            @cacher_caches.value(name, &block)
+        end
+    end
+
+    class Cache
+        attr_accessor :caches, :timestamp
+
+        def initialize
+            @caches = {}
+        end
+
+        def value(name)
+            raise ArgumentError, "You must provide a block when using the cache" unless block_given?
+
+            if timestamp.nil? or ! Puppet::Util::Cacher.valid?(timestamp)
+                caches.clear
+                self.timestamp = Time.now
+            end
+
+            # Use 'include?' here rather than testing for truth, so we
+            # can cache false values.
+            unless caches.include?(name)
+                caches[name] = yield
+            end
+            caches[name]
+        end
+    end
+end