fix cache class interface

activerecord/lib/active_record/statement_cache.rb

@@ -14,13 +14,25 @@ module ActiveRecord
   # The relation returned by the block is cached, and for each +execute+ call the cached relation gets duped.
   # Database is queried when +to_a+ is called on the relation.
   class StatementCache
-    def initialize
-      @relation = yield
-      raise ArgumentError.new("Statement cannot be nil") if @relation.nil?
+    def initialize(block = Proc.new)
+      @mutex    = Mutex.new
+      @relation = nil
+      @block    = block
     end
 
-    def execute
-      @relation.dup.to_a
+    def execute(*vals)
+      rel = relation vals
+      @mutex.synchronize do
+        rel.set_binds vals
+        rel.to_a
+      end
+    end
+
+    private
+    def relation(values)
+      @relation || @mutex.synchronize {
+        @block.call(*values)
+      }
     end
   end
 end

activerecord/test/cases/statement_cache_test.rb

@@ -15,13 +15,13 @@ module ActiveRecord
       Book.create(name: "my book")
       Book.create(name: "my other book")
 
-      cache = StatementCache.new do
-        Book.where(:name => "my book")
+      cache = StatementCache.new do |name|
+        Book.where(:name => name)
       end
 
-      b = cache.execute name: "my book"
+      b = cache.execute "my book"
       assert_equal "my book", b[0].name
-      b = cache.execute name: "my other book"
+      b = cache.execute "my other book"
       assert_equal "my other book", b[0].name
     end
 
@@ -31,13 +31,13 @@ module ActiveRecord
       Book.create(name: "my book")
       Book.create(name: "my other book")
 
-      cache = StatementCache.new do
-        Book.where(id: "1")
+      cache = StatementCache.new do |id|
+        Book.where(id: id)
       end
 
-      b = cache.execute id: "1"
+      b = cache.execute "1"
       assert_equal "my book", b[0].name
-      b = cache.execute id: "2"
+      b = cache.execute "2"
       assert_equal "my other book", b[0].name
     end
 
@@ -64,14 +64,6 @@ module ActiveRecord
       assert_equal "my book", books[0].name
     end
 
-    def test_statement_cache_with_nil_statement_raises_error
-      assert_raise(ArgumentError) do
-        ActiveRecord::StatementCache.new do
-          nil
-        end
-      end
-    end
-
     def test_statement_cache_with_complex_statement
       cache = ActiveRecord::StatementCache.new do
         Liquid.joins(:molecules => :electrons).where('molecules.name' => 'dioxane', 'electrons.name' => 'lepton')
@@ -104,4 +96,4 @@ module ActiveRecord
       assert first_books != additional_books
     end
   end
-end
+end