Speed up and simplify query caching.

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@7498 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

2 files changed, 117 insertions, 8 deletions

diff --git a/activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb b/activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb
index effb36faf1..4303d66451 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb
@@ -10,14 +10,15 @@ module ActiveRecord
       # Returns a record hash with the column names as keys and column values
       # as values.
       def select_one(sql, name = nil)
-        result = select(sql, name)
+        result = select_all(sql, name)
         result.first if result
       end
 
       # Returns a single value from a record
       def select_value(sql, name = nil)
-        result = select_one(sql, name)
-        result.nil? ? nil : result.values.first
+        if result = select_one(sql, name)
+          result.values.first
+        end
       end
 
       # Returns an array of the values of the first column in a select:
@@ -29,7 +30,9 @@ module ActiveRecord
 
       # Returns an array of arrays containing the field values.
       # Order is the same as that returned by #columns.
-      def select_rows(sql, name = nil) end
+      def select_rows(sql, name = nil)
+        raise NotImplementedError, "select_rows is an abstract method"
+      end
 
       # Executes the SQL statement in the context of this connection.
       def execute(sql, name = nil)
@@ -38,17 +41,17 @@ module ActiveRecord
 
       # Returns the last auto-generated ID from the affected table.
       def insert(sql, name = nil, pk = nil, id_value = nil, sequence_name = nil)
-        raise NotImplementedError, "insert is an abstract method"
+        insert_sql(sql, name, pk, id_value, sequence_name)
       end
 
       # Executes the update statement and returns the number of rows affected.
       def update(sql, name = nil)
-        execute(sql, name)
+        update_sql(sql, name)
       end
 
       # Executes the delete statement and returns the number of rows affected.
       def delete(sql, name = nil)
-        update(sql, name)
+        delete_sql(sql, name)
       end
 
       # Wrap a block in a transaction.  Returns result of block.
@@ -133,7 +136,7 @@ module ActiveRecord
       # Inserts the given fixture into the table. Overriden in adapters that require
       # something beyond a simple insert (eg. Oracle).
       def insert_fixture(fixture, table_name)
-        execute "INSERT INTO #{table_name} (#{fixture.key_list}) VALUES (#{fixture.value_list})", 'Fixture Insert'
+        insert "INSERT INTO #{table_name} (#{fixture.key_list}) VALUES (#{fixture.value_list})", 'Fixture Insert'
       end
 
       protected
@@ -142,6 +145,22 @@ module ActiveRecord
         def select(sql, name = nil)
           raise NotImplementedError, "select is an abstract method"
         end
+
+        # Returns the last auto-generated ID from the affected table.
+        def insert_sql(sql, name = nil, pk = nil, id_value = nil, sequence_name = nil)
+          execute(sql, name)
+          id_value
+        end
+
+        # Executes the update statement and returns the number of rows affected.
+        def update_sql(sql, name = nil)
+          execute(sql, name)
+        end
+
+        # Executes the delete statement and returns the number of rows affected.
+        def delete_sql(sql, name = nil)
+          update_sql(sql, name)
+        end
     end
   end
 end
diff --git a/activerecord/lib/active_record/connection_adapters/abstract/query_cache.rb b/activerecord/lib/active_record/connection_adapters/abstract/query_cache.rb
new file mode 100644
index 0000000000..42ff1d7d54
--- /dev/null
+++ b/activerecord/lib/active_record/connection_adapters/abstract/query_cache.rb
@@ -0,0 +1,90 @@
+module ActiveRecord
+  module ConnectionAdapters # :nodoc:
+    module QueryCache
+      class << self
+        def included(base)
+          base.class_eval do
+            attr_accessor :query_cache_enabled
+            alias_method_chain :columns, :query_cache
+            alias_method_chain :select_all, :query_cache
+          end
+
+          dirties_query_cache base, :insert, :update, :delete
+        end
+
+        def dirties_query_cache(base, *method_names)
+          method_names.each do |method_name|
+            base.class_eval <<-end_code, __FILE__, __LINE__
+              def #{method_name}_with_query_dirty(*args)
+                clear_query_cache if @query_cache_enabled
+                #{method_name}_without_query_dirty(*args)
+              end
+
+              alias_method_chain :#{method_name}, :query_dirty
+            end_code
+          end
+        end
+      end
+
+      # Enable the query cache within the block.
+      def cache
+        old, @query_cache_enabled = @query_cache_enabled, true
+        @query_cache ||= {}
+        yield
+      ensure
+        clear_query_cache
+        @query_cache_enabled = old
+      end
+
+      # Disable the query cache within the block.
+      def uncached
+        old, @query_cache_enabled = @query_cache_enabled, false
+        yield
+      ensure
+        @query_cache_enabled = old
+      end
+
+      def clear_query_cache
+        @query_cache.clear if @query_cache
+      end
+
+      def select_all_with_query_cache(*args)
+        if @query_cache_enabled
+          cache_sql(args.first) { select_all_without_query_cache(*args) }
+        else
+          select_all_without_query_cache(*args)
+        end
+      end
+
+      def columns_with_query_cache(*args)
+        if @query_cache_enabled
+          @query_cache["SHOW FIELDS FROM #{args.first}"] ||= columns_without_query_cache(*args)
+        else
+          columns_without_query_cache(*args)
+        end
+      end
+
+      private
+        def cache_sql(sql)
+          result =
+            if @query_cache.has_key?(sql)
+              log_info(sql, "CACHE", 0.0)
+              @query_cache[sql]
+            else
+              @query_cache[sql] = yield
+            end
+
+          case result
+          when Array
+            result.collect { |row| row.dup }
+          when nil, Fixnum, Float, true, false
+            result
+          else
+            result.dup
+          end
+        rescue TypeError
+          result
+        end
+    end
+  end
+end