Make legacy_connection_handling a module instance variable

activerecord/lib/active_record.rb

@@ -169,6 +169,9 @@ module Tasks
   autoload :TestDatabases, "active_record/test_databases"
   autoload :TestFixtures, "active_record/fixtures"
 
+  singleton_class.attr_accessor :legacy_connection_handling
+  self.legacy_connection_handling = true
+
   def self.eager_load!
     super
     ActiveRecord::Locking.eager_load!

activerecord/lib/active_record/connection_adapters/abstract/connection_handler.rb

@@ -100,7 +100,7 @@ def prevent_writes=(prevent_writes) # :nodoc:
       # See +READ_QUERY+ for the queries that are blocked by this
       # method.
       def while_preventing_writes(enabled = true)
-        unless ActiveRecord::Base.legacy_connection_handling
+        unless ActiveRecord.legacy_connection_handling
           raise NotImplementedError, "`while_preventing_writes` is only available on the connection_handler with legacy_connection_handling"
         end
 
@@ -143,7 +143,7 @@ def establish_connection(config, owner_name: Base, role: ActiveRecord::Base.curr
           payload[:config] = db_config.configuration_hash
         end
 
-        if ActiveRecord::Base.legacy_connection_handling
+        if ActiveRecord.legacy_connection_handling
           owner_to_pool_manager[pool_config.connection_specification_name] ||= LegacyPoolManager.new
         else
           owner_to_pool_manager[pool_config.connection_specification_name] ||= PoolManager.new

activerecord/lib/active_record/connection_adapters/abstract_adapter.rb

@@ -140,7 +140,7 @@ def use_metadata_table?
       # will return true based on +current_preventing_writes+.
       def preventing_writes?
         return true if replica?
-        return ActiveRecord::Base.connection_handler.prevent_writes if ActiveRecord::Base.legacy_connection_handling
+        return ActiveRecord::Base.connection_handler.prevent_writes if ActiveRecord.legacy_connection_handling
         return false if connection_klass.nil?
 
         connection_klass.current_preventing_writes

activerecord/lib/active_record/connection_handling.rb

@@ -135,7 +135,7 @@ def connects_to(database: {}, shards: {})
     #     Dog.first # finds first Dog record stored on the shard one replica
     #   end
     def connected_to(role: nil, shard: nil, prevent_writes: false, &blk)
-      if legacy_connection_handling
+      if ActiveRecord.legacy_connection_handling
         if self != Base
           raise NotImplementedError, "`connected_to` can only be called on ActiveRecord::Base with legacy connection handling."
         end
@@ -176,7 +176,7 @@ def connected_to(role: nil, shard: nil, prevent_writes: false, &blk)
     def connected_to_many(*classes, role:, shard: nil, prevent_writes: false)
       classes = classes.flatten
 
-      if legacy_connection_handling
+      if ActiveRecord.legacy_connection_handling
         raise NotImplementedError, "connected_to_many is not available with legacy connection handling"
       end
 
@@ -200,7 +200,7 @@ def connected_to_many(*classes, role:, shard: nil, prevent_writes: false)
     # It is not recommended to use this method in a request since it
     # does not yield to a block like +connected_to+.
     def connecting_to(role: default_role, shard: default_shard, prevent_writes: false)
-      if legacy_connection_handling
+      if ActiveRecord.legacy_connection_handling
         raise NotImplementedError, "`connecting_to` is not available with `legacy_connection_handling`."
       end
 
@@ -221,7 +221,7 @@ def connecting_to(role: default_role, shard: default_shard, prevent_writes: fals
     # See +READ_QUERY+ for the queries that are blocked by this
     # method.
     def while_preventing_writes(enabled = true, &block)
-      if legacy_connection_handling
+      if ActiveRecord.legacy_connection_handling
         connection_handler.while_preventing_writes(enabled, &block)
       else
         connected_to(role: current_role, prevent_writes: enabled, &block)
@@ -239,7 +239,7 @@ def connected_to?(role:, shard: ActiveRecord::Base.default_shard)
     end
 
     def lookup_connection_handler(handler_key) # :nodoc:
-      if ActiveRecord::Base.legacy_connection_handling
+      if ActiveRecord.legacy_connection_handling
         handler_key ||= ActiveRecord::Base.writing_role
         connection_handlers[handler_key] ||= ActiveRecord::ConnectionAdapters::ConnectionHandler.new
       else
@@ -249,7 +249,7 @@ def lookup_connection_handler(handler_key) # :nodoc:
 
     # Clears the query cache for all connections associated with the current thread.
     def clear_query_caches_for_current_thread
-      if ActiveRecord::Base.legacy_connection_handling
+      if ActiveRecord.legacy_connection_handling
         ActiveRecord::Base.connection_handlers.each_value do |handler|
           clear_on_handler(handler)
         end
@@ -358,7 +358,7 @@ def with_handler(handler_key, &blk)
       def with_role_and_shard(role, shard, prevent_writes)
         prevent_writes = true if role == reading_role
 
-        if ActiveRecord::Base.legacy_connection_handling
+        if ActiveRecord.legacy_connection_handling
           with_handler(role.to_sym) do
             connection_handler.while_preventing_writes(prevent_writes) do
               self.connected_to_stack << { shard: shard, klasses: [self] }

activerecord/lib/active_record/core.rb

@@ -164,8 +164,6 @@ def self.configurations
 
       class_attribute :default_shard, instance_writer: false
 
-      mattr_accessor :legacy_connection_handling, instance_writer: false, default: true
-
       mattr_accessor :application_record_class, instance_accessor: false, default: nil
 
       # Sets the async_query_executor for an application. By default the thread pool executor
@@ -225,7 +223,7 @@ def self.connection_handler=(handler)
       end
 
       def self.connection_handlers
-        if legacy_connection_handling
+        if ActiveRecord.legacy_connection_handling
         else
           raise NotImplementedError, "The new connection handling does not support accessing multiple connection handlers."
         end
@@ -234,7 +232,7 @@ def self.connection_handlers
       end
 
       def self.connection_handlers=(handlers)
-        if legacy_connection_handling
+        if ActiveRecord.legacy_connection_handling
           ActiveSupport::Deprecation.warn(<<~MSG)
             Using legacy connection handling is deprecated. Please set
             `legacy_connection_handling` to `false` in your application.
@@ -270,7 +268,7 @@ def self.asynchronous_queries_tracker # :nodoc:
       #     ActiveRecord::Base.current_role #=> :reading
       #   end
       def self.current_role
-        if ActiveRecord::Base.legacy_connection_handling
+        if ActiveRecord.legacy_connection_handling
           connection_handlers.key(connection_handler) || default_role
         else
           connected_to_stack.reverse_each do |hash|
@@ -311,7 +309,7 @@ def self.current_shard
       #     ActiveRecord::Base.current_preventing_writes #=> false
       #   end
       def self.current_preventing_writes
-        if legacy_connection_handling
+        if ActiveRecord.legacy_connection_handling
           connection_handler.prevent_writes
         else
           connected_to_stack.reverse_each do |hash|

activerecord/lib/active_record/query_cache.rb

@@ -28,7 +28,7 @@ def uncached(&block)
     def self.run
       pools = []
 
-      if ActiveRecord::Base.legacy_connection_handling
+      if ActiveRecord.legacy_connection_handling
         ActiveRecord::Base.connection_handlers.each do |key, handler|
           pools.concat(handler.connection_pool_list.reject { |p| p.query_cache_enabled }.each { |p| p.enable_query_cache! })
         end
@@ -42,7 +42,7 @@ def self.run
     def self.complete(pools)
       pools.each { |pool| pool.disable_query_cache! }
 
-      if ActiveRecord::Base.legacy_connection_handling
+      if ActiveRecord.legacy_connection_handling
         ActiveRecord::Base.connection_handlers.each do |_, handler|
           handler.connection_pool_list.each do |pool|
             pool.release_connection if pool.active_connection? && !pool.connection.transaction_open?

activerecord/lib/active_record/railtie.rb

@@ -200,11 +200,22 @@ class Railtie < Rails::Railtie # :nodoc:
     end
 
     initializer "active_record.set_configs" do |app|
-      ActiveSupport.on_load(:active_record) do
-        configs = app.config.active_record
+      configs = app.config.active_record
 
+      configs.each do |k, v|
+        next if k == :encryption
+        setter = "#{k}="
+        if ActiveRecord.respond_to?(setter)
+          ActiveRecord.send(setter, v)
+        end
+      end
+
+      ActiveSupport.on_load(:active_record) do
         configs.each do |k, v|
-          send "#{k}=", v if k != :encryption
+          next if k == :encryption
+          setter = "#{k}="
+          next if ActiveRecord.respond_to?(setter)
+          send(setter, v)
         end
       end
     end
@@ -213,7 +224,7 @@ class Railtie < Rails::Railtie # :nodoc:
     # and then establishes the connection.
     initializer "active_record.initialize_database" do
       ActiveSupport.on_load(:active_record) do
-        if ActiveRecord::Base.legacy_connection_handling
+        if ActiveRecord.legacy_connection_handling
           self.connection_handlers = { writing_role => ActiveRecord::Base.default_connection_handler }
         end
         self.configurations = Rails.application.config.database_configuration

activerecord/lib/active_record/test_fixtures.rb

@@ -193,7 +193,7 @@ def enlist_fixture_connections
       # need to share a connection pool so that the reading connection
       # can see data in the open transaction on the writing connection.
       def setup_shared_connection_pool
-        if ActiveRecord::Base.legacy_connection_handling
+        if ActiveRecord.legacy_connection_handling
           writing_handler = ActiveRecord::Base.connection_handlers[ActiveRecord::Base.writing_role]
 
           ActiveRecord::Base.connection_handlers.values.each do |handler|
@@ -236,7 +236,7 @@ def setup_shared_connection_pool
       end
 
       def teardown_shared_connection_pool
-        if ActiveRecord::Base.legacy_connection_handling
+        if ActiveRecord.legacy_connection_handling
           @legacy_saved_pool_configs.each_pair do |handler, names|
             names.each_pair do |name, shards|
               shards.each_pair do |shard_name, pool_config|

activerecord/test/cases/adapter_prevent_writes_test.rb

@@ -127,16 +127,16 @@ def test_errors_when_an_insert_query_prefixed_by_a_double_dash_comment_containin
 
   class AdapterPreventWritesLegacyTest < ActiveRecord::TestCase
     def setup
-      @old_value = ActiveRecord::Base.legacy_connection_handling
-      ActiveRecord::Base.legacy_connection_handling = true
+      @old_value = ActiveRecord.legacy_connection_handling
+      ActiveRecord.legacy_connection_handling = true
 
       @connection = ActiveRecord::Base.connection
       @connection_handler = ActiveRecord::Base.connection_handler
     end
 
     def teardown
       clean_up_legacy_connection_handlers
-      ActiveRecord::Base.legacy_connection_handling = @old_value
+      ActiveRecord.legacy_connection_handling = @old_value
     end
 
     def test_preventing_writes_predicate_legacy

activerecord/test/cases/adapters/mysql2/mysql2_adapter_prevent_writes_test.rb

@@ -105,15 +105,15 @@ class Mysql2AdapterPreventWritesLegacyTest < ActiveRecord::Mysql2TestCase
   include DdlHelper
 
   def setup
-    @old_value = ActiveRecord::Base.legacy_connection_handling
-    ActiveRecord::Base.legacy_connection_handling = true
+    @old_value = ActiveRecord.legacy_connection_handling
+    ActiveRecord.legacy_connection_handling = true
 
     @conn = ActiveRecord::Base.connection
     @connection_handler = ActiveRecord::Base.connection_handler
   end
 
   def teardown
-    ActiveRecord::Base.legacy_connection_handling = @old_value
+    ActiveRecord.legacy_connection_handling = @old_value
   end
 
   def test_errors_when_an_insert_query_is_called_while_preventing_writes

activerecord/test/cases/adapters/postgresql/postgresql_adapter_prevent_writes_test.rb

@@ -106,15 +106,15 @@ class PostgreSQLAdapterPreventWritesLegacyTest < ActiveRecord::PostgreSQLTestCas
       include ConnectionHelper
 
       def setup
-        @old_value = ActiveRecord::Base.legacy_connection_handling
-        ActiveRecord::Base.legacy_connection_handling = true
+        @old_value = ActiveRecord.legacy_connection_handling
+        ActiveRecord.legacy_connection_handling = true
 
         @connection = ActiveRecord::Base.connection
         @connection_handler = ActiveRecord::Base.connection_handler
       end
 
       def teardown
-        ActiveRecord::Base.legacy_connection_handling = @old_value
+        ActiveRecord.legacy_connection_handling = @old_value
       end
 
       def test_errors_when_an_insert_query_is_called_while_preventing_writes

activerecord/test/cases/adapters/sqlite3/sqlite3_adapter_prevent_writes_test.rb

@@ -95,16 +95,16 @@ class SQLite3AdapterPreventWritesLegacyTest < ActiveRecord::SQLite3TestCase
       self.use_transactional_tests = false
 
       def setup
-        @old_value = ActiveRecord::Base.legacy_connection_handling
-        ActiveRecord::Base.legacy_connection_handling = true
+        @old_value = ActiveRecord.legacy_connection_handling
+        ActiveRecord.legacy_connection_handling = true
 
         @conn = ActiveRecord::Base.connection
 
         @connection_handler = ActiveRecord::Base.connection_handler
       end
 
       def teardown
-        ActiveRecord::Base.legacy_connection_handling = @old_value
+        ActiveRecord.legacy_connection_handling = @old_value
       end
 
       def test_errors_when_an_insert_query_is_called_while_preventing_writes

activerecord/test/cases/base_prevent_writes_test.rb

@@ -97,15 +97,15 @@ class BasePreventWritesTest < ActiveRecord::TestCase
 
   class BasePreventWritesLegacyTest < ActiveRecord::TestCase
     def setup
-      @old_value = ActiveRecord::Base.legacy_connection_handling
-      ActiveRecord::Base.legacy_connection_handling = true
+      @old_value = ActiveRecord.legacy_connection_handling
+      ActiveRecord.legacy_connection_handling = true
       ActiveRecord::Base.establish_connection :arunit
       ARUnit2Model.establish_connection :arunit2
     end
 
     def teardown
       clean_up_legacy_connection_handlers
-      ActiveRecord::Base.legacy_connection_handling = @old_value
+      ActiveRecord.legacy_connection_handling = @old_value
     end
 
     if !in_memory_db?

activerecord/test/cases/base_test.rb

@@ -1682,8 +1682,8 @@ def test_protected_environments_are_stored_as_an_array_of_string
   end
 
   test "cannot call connected_to on subclasses of ActiveRecord::Base with legacy connection handling" do
-    old_value = ActiveRecord::Base.legacy_connection_handling
-    ActiveRecord::Base.legacy_connection_handling = true
+    old_value = ActiveRecord.legacy_connection_handling
+    ActiveRecord.legacy_connection_handling = true
 
     error = assert_raises(NotImplementedError) do
       Bird.connected_to(role: :reading) { }
@@ -1692,7 +1692,7 @@ def test_protected_environments_are_stored_as_an_array_of_string
     assert_equal "`connected_to` can only be called on ActiveRecord::Base with legacy connection handling.", error.message
   ensure
     clean_up_legacy_connection_handlers
-    ActiveRecord::Base.legacy_connection_handling = old_value
+    ActiveRecord.legacy_connection_handling = old_value
   end
 
   test "cannot call connected_to with role and shard on non-abstract classes" do
@@ -1744,25 +1744,25 @@ def test_protected_environments_are_stored_as_an_array_of_string
   end
 
   test "#connecting_to doesn't work with legacy connection handling" do
-    old_value = ActiveRecord::Base.legacy_connection_handling
-    ActiveRecord::Base.legacy_connection_handling = true
+    old_value = ActiveRecord.legacy_connection_handling
+    ActiveRecord.legacy_connection_handling = true
 
     assert_raises NotImplementedError do
       SecondAbstractClass.connecting_to(role: :writing, prevent_writes: true)
     end
   ensure
-    ActiveRecord::Base.legacy_connection_handling = old_value
+    ActiveRecord.legacy_connection_handling = old_value
   end
 
   test "#connected_to_many doesn't work with legacy connection handling" do
-    old_value = ActiveRecord::Base.legacy_connection_handling
-    ActiveRecord::Base.legacy_connection_handling = true
+    old_value = ActiveRecord.legacy_connection_handling
+    ActiveRecord.legacy_connection_handling = true
 
     assert_raises NotImplementedError do
       ActiveRecord::Base.connected_to_many([SecondAbstractClass], role: :writing)
     end
   ensure
-    ActiveRecord::Base.legacy_connection_handling = old_value
+    ActiveRecord.legacy_connection_handling = old_value
   end
 
   test "#connected_to_many cannot be called on anything but ActiveRecord::Base" do

activerecord/test/cases/connection_adapters/legacy_connection_handlers_multi_db_test.rb

@@ -11,8 +11,8 @@ class LegacyConnectionHandlersMultiDbTest < ActiveRecord::TestCase
       fixtures :people
 
       def setup
-        @old_value = ActiveRecord::Base.legacy_connection_handling
-        ActiveRecord::Base.legacy_connection_handling = true
+        @old_value = ActiveRecord.legacy_connection_handling
+        ActiveRecord.legacy_connection_handling = true
         assert_deprecated do
           ActiveRecord::Base.connection_handlers = { writing: ActiveRecord::Base.default_connection_handler }
         end
@@ -29,7 +29,7 @@ def setup
 
       def teardown
         clean_up_legacy_connection_handlers
-        ActiveRecord::Base.legacy_connection_handling = @old_value
+        ActiveRecord.legacy_connection_handling = @old_value
       end
 
       class SecondaryBase < ActiveRecord::Base