Remove `@connection` in `StatementPool`

`@connection` in `StatementPool` is only used for PG adapter.
No need for abstract `StatementPool` class.

4 files changed, 6 insertions, 8 deletions

diff --git a/activerecord/lib/active_record/connection_adapters/mysql_adapter.rb b/activerecord/lib/active_record/connection_adapters/mysql_adapter.rb
index e4fcff8814..3622f80037 100644
--- a/activerecord/lib/active_record/connection_adapters/mysql_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/mysql_adapter.rb
@@ -80,8 +80,7 @@ module ActiveRecord
 
       def initialize(connection, logger, connection_options, config)
         super
-        @statements = StatementPool.new(@connection,
-                                        self.class.type_cast_config_to_integer(config.fetch(:statement_limit) { 1000 }))
+        @statements = StatementPool.new(self.class.type_cast_config_to_integer(config.fetch(:statement_limit) { 1000 }))
         @client_encoding = nil
         connect
       end
diff --git a/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb b/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb
index 27291bd2ea..9de79a614c 100644
--- a/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb
@@ -211,7 +211,8 @@ module ActiveRecord
 
       class StatementPool < ConnectionAdapters::StatementPool
         def initialize(connection, max)
-          super
+          super(max)
+          @connection = connection
           @counter = 0
         end
 
diff --git a/activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb b/activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb
index 24fc67938d..8721578331 100644
--- a/activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb
@@ -81,8 +81,7 @@ module ActiveRecord
         super(connection, logger)
 
         @active     = nil
-        @statements = StatementPool.new(@connection,
-                                        self.class.type_cast_config_to_integer(config.fetch(:statement_limit) { 1000 }))
+        @statements = StatementPool.new(self.class.type_cast_config_to_integer(config.fetch(:statement_limit) { 1000 }))
         @config = config
 
         @visitor = Arel::Visitors::SQLite.new self
diff --git a/activerecord/lib/active_record/connection_adapters/statement_pool.rb b/activerecord/lib/active_record/connection_adapters/statement_pool.rb
index 82e9ef3d3d..57463dd749 100644
--- a/activerecord/lib/active_record/connection_adapters/statement_pool.rb
+++ b/activerecord/lib/active_record/connection_adapters/statement_pool.rb
@@ -3,10 +3,9 @@ module ActiveRecord
     class StatementPool
       include Enumerable
 
-      def initialize(connection, max = 1000)
+      def initialize(max = 1000)
         @cache = Hash.new { |h,pid| h[pid] = {} }
-        @connection = connection
-        @max        = max
+        @max = max
       end
 
       def each(&block)