Use ActiveSupport::WeakHash for MRI, JRuby prefers Weakling.

1 files changed, 46 insertions, 0 deletions

diff --git a/activesupport/lib/active_support/weak_hash.rb b/activesupport/lib/active_support/weak_hash.rb
new file mode 100644
index 0000000000..c6bf098074
--- /dev/null
+++ b/activesupport/lib/active_support/weak_hash.rb
@@ -0,0 +1,46 @@
+module ActiveSupport
+  class WeakHash
+    def initialize(cache = Hash.new)
+      @cache = cache
+      @key_map = {}
+      @rev_cache = Hash.new{|h,k| h[k] = {}}
+      @reclaim_value = lambda do |value_id|
+        if value = @rev_cache.delete(value_id)
+          value.each_key{|key| @cache.delete key}
+        end
+      end
+    end
+
+    def [](key)
+      value_id = @cache[key]
+      value_id && ObjectSpace._id2ref(value_id)
+    rescue RangeError
+      nil
+    end
+
+    def []=(key, value)
+      key2 = case key
+             when Fixnum, Symbol, true, false, nil
+               key
+             else
+               key.dup
+             end
+
+      @rev_cache[value.object_id][key2] = true
+      @cache[key2] = value.object_id
+      @key_map[key.object_id] = key2
+
+      ObjectSpace.define_finalizer(value, @reclaim_value)
+    end
+
+    def clear
+      @cache.clear
+    end
+
+    def delete(key)
+      @cache.delete(key)
+    end
+  end
+end
+
+ActiveSupport::WeakHash = ::Weakling::WeakHash if defined?(RUBY_ENGINE) && RUBY_ENGINE == 'jruby'