2 files changed, 354 insertions, 0 deletions
diff --git a/activerecord/test/cases/connection_adapters/connection_handler_test.rb b/activerecord/test/cases/connection_adapters/connection_handler_test.rb
index 5e3447efde..51d0cc3d12 100644
--- a/activerecord/test/cases/connection_adapters/connection_handler_test.rb
+++ b/activerecord/test/cases/connection_adapters/connection_handler_test.rb
@@ -170,6 +170,11 @@ module ActiveRecord
         ActiveRecord::Base.configurations = config
         ActiveRecord::Base.configurations.configs_for.each do |db_config|
           assert_instance_of ActiveRecord::DatabaseConfigurations::HashConfig, db_config
+          assert_instance_of String, db_config.env_name
+          assert_instance_of String, db_config.spec_name
+          db_config.config.keys.each do |key|
+            assert_instance_of String, key
+          end
         end
       ensure
         ActiveRecord::Base.configurations = @prev_configs
diff --git a/activerecord/test/cases/connection_adapters/connection_handlers_multi_db_test.rb b/activerecord/test/cases/connection_adapters/connection_handlers_multi_db_test.rb
new file mode 100644
index 0000000000..865aacc1b5
--- /dev/null
+++ b/activerecord/test/cases/connection_adapters/connection_handlers_multi_db_test.rb
@@ -0,0 +1,349 @@
+# frozen_string_literal: true
+
+require "cases/helper"
+require "models/person"
+
+module ActiveRecord
+  module ConnectionAdapters
+    class ConnectionHandlersMultiDbTest < ActiveRecord::TestCase
+      self.use_transactional_tests = false
+
+      fixtures :people
+
+      def setup
+        @handlers = { writing: ConnectionHandler.new, reading: ConnectionHandler.new }
+        @rw_handler = @handlers[:writing]
+        @ro_handler = @handlers[:reading]
+        @spec_name = "primary"
+        @rw_pool = @handlers[:writing].establish_connection(ActiveRecord::Base.configurations["arunit"])
+        @ro_pool = @handlers[:reading].establish_connection(ActiveRecord::Base.configurations["arunit"])
+      end
+
+      def teardown
+        ActiveRecord::Base.connection_handlers = { writing: ActiveRecord::Base.default_connection_handler }
+      end
+
+      class MultiConnectionTestModel < ActiveRecord::Base
+      end
+
+      def test_multiple_connection_handlers_works_in_a_threaded_environment
+        tf_writing = Tempfile.open "test_writing"
+        tf_reading = Tempfile.open "test_reading"
+
+        MultiConnectionTestModel.connects_to database: { writing: { database: tf_writing.path, adapter: "sqlite3" }, reading: { database: tf_reading.path, adapter: "sqlite3" } }
+
+        MultiConnectionTestModel.connection.execute("CREATE TABLE `test_1` (connection_role VARCHAR (255))")
+        MultiConnectionTestModel.connection.execute("INSERT INTO test_1 VALUES ('writing')")
+
+        ActiveRecord::Base.connected_to(role: :reading) do
+          MultiConnectionTestModel.connection.execute("CREATE TABLE `test_1` (connection_role VARCHAR (255))")
+          MultiConnectionTestModel.connection.execute("INSERT INTO test_1 VALUES ('reading')")
+        end
+
+        read_latch = Concurrent::CountDownLatch.new
+        write_latch = Concurrent::CountDownLatch.new
+
+        MultiConnectionTestModel.connection
+
+        thread = Thread.new do
+          MultiConnectionTestModel.connection
+
+          write_latch.wait
+          assert_equal "writing", MultiConnectionTestModel.connection.select_value("SELECT connection_role from test_1")
+          read_latch.count_down
+        end
+
+        ActiveRecord::Base.connected_to(role: :reading) do
+          write_latch.count_down
+          assert_equal "reading", MultiConnectionTestModel.connection.select_value("SELECT connection_role from test_1")
+          read_latch.wait
+        end
+
+        thread.join
+      ensure
+        tf_reading.close
+        tf_reading.unlink
+        tf_writing.close
+        tf_writing.unlink
+      end
+
+      unless in_memory_db?
+        def test_establish_connection_using_3_levels_config
+          previous_env, ENV["RAILS_ENV"] = ENV["RAILS_ENV"], "default_env"
+
+          config = {
+            "default_env" => {
+              "readonly" => { "adapter" => "sqlite3", "database" => "db/readonly.sqlite3" },
+              "primary"  => { "adapter" => "sqlite3", "database" => "db/primary.sqlite3" }
+            }
+          }
+          @prev_configs, ActiveRecord::Base.configurations = ActiveRecord::Base.configurations, config
+
+          ActiveRecord::Base.connects_to(database: { writing: :primary, reading: :readonly })
+
+          assert_not_nil pool = ActiveRecord::Base.connection_handlers[:writing].retrieve_connection_pool("primary")
+          assert_equal "db/primary.sqlite3", pool.spec.config[:database]
+
+          assert_not_nil pool = ActiveRecord::Base.connection_handlers[:reading].retrieve_connection_pool("primary")
+          assert_equal "db/readonly.sqlite3", pool.spec.config[:database]
+        ensure
+          ActiveRecord::Base.configurations = @prev_configs
+          ActiveRecord::Base.establish_connection(:arunit)
+          ENV["RAILS_ENV"] = previous_env
+        end
+
+        def test_switching_connections_via_handler
+          previous_env, ENV["RAILS_ENV"] = ENV["RAILS_ENV"], "default_env"
+
+          config = {
+            "default_env" => {
+              "readonly" => { "adapter" => "sqlite3", "database" => "db/readonly.sqlite3" },
+              "primary"  => { "adapter" => "sqlite3", "database" => "db/primary.sqlite3" }
+            }
+          }
+          @prev_configs, ActiveRecord::Base.configurations = ActiveRecord::Base.configurations, config
+
+          ActiveRecord::Base.connects_to(database: { writing: :primary, reading: :readonly })
+
+          ActiveRecord::Base.connected_to(role: :reading) do
+            @ro_handler = ActiveRecord::Base.connection_handler
+            assert_equal ActiveRecord::Base.connection_handler, ActiveRecord::Base.connection_handlers[:reading]
+            assert_equal :reading, ActiveRecord::Base.current_role
+            assert ActiveRecord::Base.connected_to?(role: :reading)
+            assert_not ActiveRecord::Base.connected_to?(role: :writing)
+          end
+
+          ActiveRecord::Base.connected_to(role: :writing) do
+            assert_equal ActiveRecord::Base.connection_handler, ActiveRecord::Base.connection_handlers[:writing]
+            assert_not_equal @ro_handler, ActiveRecord::Base.connection_handler
+            assert_equal :writing, ActiveRecord::Base.current_role
+            assert ActiveRecord::Base.connected_to?(role: :writing)
+            assert_not ActiveRecord::Base.connected_to?(role: :reading)
+          end
+        ensure
+          ActiveRecord::Base.configurations = @prev_configs
+          ActiveRecord::Base.establish_connection(:arunit)
+          ENV["RAILS_ENV"] = previous_env
+        end
+
+        def test_switching_connections_with_database_url
+          previous_env, ENV["RAILS_ENV"] = ENV["RAILS_ENV"], "default_env"
+          previous_url, ENV["DATABASE_URL"] = ENV["DATABASE_URL"], "postgres://localhost/foo"
+
+          ActiveRecord::Base.connected_to(database: { writing: "postgres://localhost/bar" }) do
+            assert_equal :writing, ActiveRecord::Base.current_role
+            assert ActiveRecord::Base.connected_to?(role: :writing)
+
+            handler = ActiveRecord::Base.connection_handler
+            assert_equal handler, ActiveRecord::Base.connection_handlers[:writing]
+
+            assert_not_nil pool = handler.retrieve_connection_pool("primary")
+            assert_equal({ adapter: "postgresql", database: "bar", host: "localhost" }, pool.spec.config)
+          end
+        ensure
+          ActiveRecord::Base.establish_connection(:arunit)
+          ENV["RAILS_ENV"] = previous_env
+          ENV["DATABASE_URL"] = previous_url
+        end
+
+        def test_switching_connections_with_database_config_hash
+          previous_env, ENV["RAILS_ENV"] = ENV["RAILS_ENV"], "default_env"
+          config = { adapter: "sqlite3", database: "db/readonly.sqlite3" }
+
+          ActiveRecord::Base.connected_to(database: { writing: config }) do
+            assert_equal :writing, ActiveRecord::Base.current_role
+            assert ActiveRecord::Base.connected_to?(role: :writing)
+
+            handler = ActiveRecord::Base.connection_handler
+            assert_equal handler, ActiveRecord::Base.connection_handlers[:writing]
+
+            assert_not_nil pool = handler.retrieve_connection_pool("primary")
+            assert_equal(config, pool.spec.config)
+          end
+        ensure
+          ActiveRecord::Base.establish_connection(:arunit)
+          ENV["RAILS_ENV"] = previous_env
+        end
+
+        def test_switching_connections_with_database_and_role_raises
+          error = assert_raises(ArgumentError) do
+            ActiveRecord::Base.connected_to(database: :readonly, role: :writing) { }
+          end
+          assert_equal "connected_to can only accept a `database` or a `role` argument, but not both arguments.", error.message
+        end
+
+        def test_switching_connections_without_database_and_role_raises
+          error = assert_raises(ArgumentError) do
+            ActiveRecord::Base.connected_to { }
+          end
+          assert_equal "must provide a `database` or a `role`.", error.message
+        end
+
+        def test_switching_connections_with_database_symbol
+          previous_env, ENV["RAILS_ENV"] = ENV["RAILS_ENV"], "default_env"
+
+          config = {
+            "default_env" => {
+              "readonly" => { adapter: "sqlite3", database: "db/readonly.sqlite3" },
+              "primary"  => { adapter: "sqlite3", database: "db/primary.sqlite3" }
+            }
+          }
+          @prev_configs, ActiveRecord::Base.configurations = ActiveRecord::Base.configurations, config
+
+          ActiveRecord::Base.connected_to(database: :readonly) do
+            assert_equal :readonly, ActiveRecord::Base.current_role
+            assert ActiveRecord::Base.connected_to?(role: :readonly)
+
+            handler = ActiveRecord::Base.connection_handler
+            assert_equal handler, ActiveRecord::Base.connection_handlers[:readonly]
+
+            assert_not_nil pool = handler.retrieve_connection_pool("primary")
+            assert_equal(config["default_env"]["readonly"], pool.spec.config)
+          end
+        ensure
+          ActiveRecord::Base.configurations = @prev_configs
+          ActiveRecord::Base.establish_connection(:arunit)
+          ENV["RAILS_ENV"] = previous_env
+        end
+
+        def test_connects_to_with_single_configuration
+          config = {
+            "development" => { "adapter" => "sqlite3", "database" => "db/primary.sqlite3" },
+          }
+          @prev_configs, ActiveRecord::Base.configurations = ActiveRecord::Base.configurations, config
+
+          ActiveRecord::Base.connects_to database: { writing: :development }
+
+          assert_equal 1, ActiveRecord::Base.connection_handlers.size
+          assert_equal ActiveRecord::Base.connection_handler, ActiveRecord::Base.connection_handlers[:writing]
+          assert_equal :writing, ActiveRecord::Base.current_role
+          assert ActiveRecord::Base.connected_to?(role: :writing)
+        ensure
+          ActiveRecord::Base.configurations = @prev_configs
+          ActiveRecord::Base.establish_connection(:arunit)
+        end
+
+        def test_connects_to_using_top_level_key_in_two_level_config
+          config = {
+            "development" => { "adapter" => "sqlite3", "database" => "db/primary.sqlite3" },
+            "development_readonly" => { "adapter" => "sqlite3", "database" => "db/readonly.sqlite3" }
+          }
+          @prev_configs, ActiveRecord::Base.configurations = ActiveRecord::Base.configurations, config
+
+          ActiveRecord::Base.connects_to database: { writing: :development, reading: :development_readonly }
+
+          assert_not_nil pool = ActiveRecord::Base.connection_handlers[:reading].retrieve_connection_pool("primary")
+          assert_equal "db/readonly.sqlite3", pool.spec.config[:database]
+        ensure
+          ActiveRecord::Base.configurations = @prev_configs
+          ActiveRecord::Base.establish_connection(:arunit)
+        end
+
+        def test_connects_to_returns_array_of_established_connections
+          config = {
+            "development" => { "adapter" => "sqlite3", "database" => "db/primary.sqlite3" },
+            "development_readonly" => { "adapter" => "sqlite3", "database" => "db/readonly.sqlite3" }
+          }
+          @prev_configs, ActiveRecord::Base.configurations = ActiveRecord::Base.configurations, config
+
+          result = ActiveRecord::Base.connects_to database: { writing: :development, reading: :development_readonly }
+
+          assert_equal(
+            [
+              ActiveRecord::Base.connection_handlers[:writing].retrieve_connection_pool("primary"),
+              ActiveRecord::Base.connection_handlers[:reading].retrieve_connection_pool("primary")
+            ],
+            result
+          )
+        ensure
+          ActiveRecord::Base.configurations = @prev_configs
+          ActiveRecord::Base.establish_connection(:arunit)
+        end
+      end
+
+      def test_connection_pools
+        assert_equal([@rw_pool], @handlers[:writing].connection_pools)
+        assert_equal([@ro_pool], @handlers[:reading].connection_pools)
+      end
+
+      def test_retrieve_connection
+        assert @rw_handler.retrieve_connection(@spec_name)
+        assert @ro_handler.retrieve_connection(@spec_name)
+      end
+
+      def test_active_connections?
+        assert_not_predicate @rw_handler, :active_connections?
+        assert_not_predicate @ro_handler, :active_connections?
+
+        assert @rw_handler.retrieve_connection(@spec_name)
+        assert @ro_handler.retrieve_connection(@spec_name)
+
+        assert_predicate @rw_handler, :active_connections?
+        assert_predicate @ro_handler, :active_connections?
+
+        @rw_handler.clear_active_connections!
+        assert_not_predicate @rw_handler, :active_connections?
+
+        @ro_handler.clear_active_connections!
+        assert_not_predicate @ro_handler, :active_connections?
+      end
+
+      def test_retrieve_connection_pool
+        assert_not_nil @rw_handler.retrieve_connection_pool(@spec_name)
+        assert_not_nil @ro_handler.retrieve_connection_pool(@spec_name)
+      end
+
+      def test_retrieve_connection_pool_with_invalid_id
+        assert_nil @rw_handler.retrieve_connection_pool("foo")
+        assert_nil @ro_handler.retrieve_connection_pool("foo")
+      end
+
+      def test_connection_handlers_are_per_thread_and_not_per_fiber
+        original_handlers = ActiveRecord::Base.connection_handlers
+
+        ActiveRecord::Base.connection_handlers = { writing: ActiveRecord::Base.default_connection_handler, reading: ActiveRecord::ConnectionAdapters::ConnectionHandler.new }
+
+        reading_handler = ActiveRecord::Base.connection_handlers[:reading]
+
+        reading = ActiveRecord::Base.with_handler(:reading) do
+          Person.connection_handler
+        end
+
+        assert_not_equal reading, ActiveRecord::Base.connection_handler
+        assert_equal reading, reading_handler
+      ensure
+        ActiveRecord::Base.connection_handlers = original_handlers
+      end
+
+      def test_connection_handlers_swapping_connections_in_fiber
+        original_handlers = ActiveRecord::Base.connection_handlers
+
+        ActiveRecord::Base.connection_handlers = { writing: ActiveRecord::Base.default_connection_handler, reading: ActiveRecord::ConnectionAdapters::ConnectionHandler.new }
+
+        reading_handler = ActiveRecord::Base.connection_handlers[:reading]
+
+        enum = Enumerator.new do |r|
+          r << ActiveRecord::Base.connection_handler
+        end
+
+        reading = ActiveRecord::Base.with_handler(:reading) do
+          enum.next
+        end
+
+        assert_equal reading, reading_handler
+      ensure
+        ActiveRecord::Base.connection_handlers = original_handlers
+      end
+
+      def test_calling_connected_to_on_a_non_existent_handler_raises
+        error = assert_raises ArgumentError do
+          ActiveRecord::Base.connected_to(role: :reading) do
+            yield
+          end
+        end
+
+        assert_equal "The reading role does not exist. Add it by establishing a connection with `connects_to` or use an existing role (writing).", error.message
+      end
+    end
+  end
+end