Introducing Model.cache { ... } for the occasional query caching needs. ( fantastic to reduce the 200 SELECT * from accounts WHERE id=1 queries in your views )

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@6138 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

4 files changed, 136 insertions, 34 deletions

diff --git a/activerecord/CHANGELOG b/activerecord/CHANGELOG
index 741a546993..ba42776c7f 100644
--- a/activerecord/CHANGELOG
+++ b/activerecord/CHANGELOG
@@ -1,5 +1,8 @@
 *SVN*
 
+* Reworked David's query cache to be available as Model.cache {...}. For the duration of the block no select query should be run more then once. Any inserts/deletes/executes will flush the whole cache however [Tobias Luetke]
+  Task.cache { Task.find(1); Task.find(1) } #=> 1 query
+  
 * When dealing with SQLite3, use the table_info pragma helper, so that the bindings can do some translation for when sqlite3 breaks incompatibly between point releases. [Jamis Buck]
 
 * Oracle: fix lob and text default handling.  #7344 [gfriedrich, Michael Schoen]
diff --git a/activerecord/lib/active_record/query_cache.rb b/activerecord/lib/active_record/query_cache.rb
index e79b3e05a7..415b25e096 100644
--- a/activerecord/lib/active_record/query_cache.rb
+++ b/activerecord/lib/active_record/query_cache.rb
@@ -6,7 +6,7 @@ module ActiveRecord
     end
 
     def clear_query_cache
-      @query_cache = {}
+      @query_cache.clear
     end
 
     def select_all(sql, name = nil)
@@ -16,14 +16,27 @@ module ActiveRecord
     def select_one(sql, name = nil)
       @query_cache[sql] ||= @connection.select_one(sql, name)
     end
+    
+    def select_values(sql, name = nil)
+      (@query_cache[sql] ||= @connection.select_values(sql, name)).dup
+    end
+
+    def select_value(sql, name = nil)
+      @query_cache[sql] ||= @connection.select_value(sql, name)
+    end
+    
+    def execute(sql, name = nil)
+      clear_query_cache
+      @connection.execute(sql, name)
+    end    
 
     def columns(table_name, name = nil)
       @query_cache["SHOW FIELDS FROM #{table_name}"] ||= @connection.columns(table_name, name)
     end
 
-    def insert(sql, name = nil, pk = nil, id_value = nil)
+    def insert(sql, name = nil, pk = nil, id_value = nil, sequence_name = nil)
       clear_query_cache
-      @connection.insert(sql, name, pk, id_value)
+      @connection.insert(sql, name, pk, id_value, sequence_name)
     end
 
     def update(sql, name = nil)
@@ -41,24 +54,26 @@ module ActiveRecord
         @connection.send(method, *arguments, &proc)
       end
   end
-  
+    
   class Base
     # Set the connection for the class with caching on
     class << self
-      alias_method :connection_without_query_cache=, :connection=
-
-      def connection=(spec)
-        if spec.is_a?(ConnectionSpecification) and spec.config[:query_cache]
-          spec = QueryCache.new(self.send(spec.adapter_method, spec.config))
-        end
-        self.connection_without_query_cache = spec
+      alias_method :connection_without_query_cache, :connection
+      
+      def query_caches
+        (Thread.current[:query_cache] ||= {})
+      end
+            
+      def cache        
+        query_caches[self] = QueryCache.new(connection)
+        yield
+      ensure 
+        query_caches[self] = nil
+      end        
+      
+      def connection
+        query_caches[self] || connection_without_query_cache
       end
     end
-  end
-  
-  class AbstractAdapter #:nodoc:
-    # Stub method to be able to treat the connection the same whether the query cache has been turned on or not
-    def clear_query_cache
-    end
-  end
+  end  
 end
diff --git a/activerecord/test/abstract_unit.rb b/activerecord/test/abstract_unit.rb
index 3fd94afc00..5a15871279 100755
--- a/activerecord/test/abstract_unit.rb
+++ b/activerecord/test/abstract_unit.rb
@@ -36,16 +36,10 @@ class Test::Unit::TestCase #:nodoc:
   end
 
   def assert_queries(num = 1)
-    ActiveRecord::Base.connection.class.class_eval do
-      self.query_count = 0
-      alias_method :execute, :execute_with_query_counting
-    end
+    $query_count = 0
     yield
   ensure
-    ActiveRecord::Base.connection.class.class_eval do
-      alias_method :execute, :execute_without_query_counting
-    end
-    assert_equal num, ActiveRecord::Base.connection.query_count, "#{ActiveRecord::Base.connection.query_count} instead of #{num} queries were executed."
+    assert_equal num, $query_count, "#{$query_count} instead of #{num} queries were executed."
   end
 
   def assert_no_queries(&block)
@@ -60,16 +54,26 @@ def current_adapter?(*types)
   end
 end
 
-ActiveRecord::Base.connection.class.class_eval do
-  cattr_accessor :query_count
+def uses_mocha(test_name)
+  require 'mocha'
+  require 'stubba'
+  yield
+rescue LoadError
+  $stderr.puts "Skipping #{test_name} tests. `gem install mocha` and try again."
+end
 
-  # Array of regexes of queries that are not counted against query_count
-  @@ignore_list = [/^SELECT currval/, /^SELECT CAST/, /^SELECT @@IDENTITY/]
+ActiveRecord::Base.connection.class.class_eval do  
+  
+  if not (const_get('IGNORED_SQL') rescue nil)    
+    IGNORED_SQL = [/^PRAGMA/, /^SELECT currval/, /^SELECT CAST/, /^SELECT @@IDENTITY/]
+
+    def execute_with_counting(sql, name = nil, &block)
+      $query_count ||= 0
+      $query_count  += 1 unless IGNORED_SQL.any? { |r| sql =~ r }
+      execute_without_counting(sql, name, &block)
+    end
 
-  alias_method :execute_without_query_counting, :execute
-  def execute_with_query_counting(sql, name = nil, &block)
-    self.query_count += 1 unless @@ignore_list.any? { |r| sql =~ r }
-    execute_without_query_counting(sql, name, &block)
+    alias_method_chain :execute, :counting
   end
 end
 
diff --git a/activerecord/test/query_cache_test.rb b/activerecord/test/query_cache_test.rb
new file mode 100644
index 0000000000..5326351483
--- /dev/null
+++ b/activerecord/test/query_cache_test.rb
@@ -0,0 +1,80 @@
+require 'abstract_unit'
+require 'fixtures/topic'
+require 'fixtures/reply'
+require 'fixtures/task'
+
+
+class QueryCacheTest < Test::Unit::TestCase
+  fixtures :tasks
+
+  
+  def test_find_queries
+    assert_queries(2) {  Task.find(1); Task.find(1) }        
+  end
+
+  def test_find_queries_with_cache
+    Task.cache do
+      assert_queries(1) {  Task.find(1); Task.find(1) }    
+    end
+  end
+  
+  def test_find_queries_with_cache
+    Task.cache do
+      assert_queries(1) {  Task.find(1); Task.find(1) }    
+    end
+  end
+
+  def test_cache_is_scoped_on_actual_class_only
+    Task.cache do
+      assert_queries(2) {  Topic.find(1); Topic.find(1) }    
+    end
+  end
+end
+
+uses_mocha('QueryCacheExpiryTest') do
+
+class QueryCacheExpiryTest < Test::Unit::TestCase
+  fixtures :tasks
+
+  def test_find
+    ActiveRecord::QueryCache.any_instance.expects(:clear_query_cache).times(0)
+    
+    Task.cache do 
+      Task.find(1)
+    end
+  end
+
+  def test_save
+    ActiveRecord::QueryCache.any_instance.expects(:clear_query_cache).times(1)
+    
+    Task.cache do 
+      Task.find(1).save
+    end
+  end
+
+  def test_destroy
+    ActiveRecord::QueryCache.any_instance.expects(:clear_query_cache).at_least_once
+    
+    Task.cache do 
+      Task.find(1).destroy
+    end
+  end
+
+  def test_create
+    ActiveRecord::QueryCache.any_instance.expects(:clear_query_cache).times(1)
+    
+    Task.cache do 
+      Task.create!
+    end
+  end
+
+  def test_new_save
+    ActiveRecord::QueryCache.any_instance.expects(:clear_query_cache).times(1)
+    
+    Task.cache do 
+      Task.new.save
+    end
+  end
+end
+
+end
\ No newline at end of file