diff options
| -rw-r--r-- | activerecord/CHANGELOG.md | 36 | ||||
| -rw-r--r-- | activerecord/lib/active_record/connection_handling.rb | 97 | ||||
| -rw-r--r-- | activerecord/lib/active_record/core.rb | 3 | ||||
| -rw-r--r-- | activerecord/test/cases/connection_adapters/connection_handlers_multi_db_test.rb | 193 |
4 files changed, 328 insertions, 1 deletions
diff --git a/activerecord/CHANGELOG.md b/activerecord/CHANGELOG.md index 6397bc361a..00f4ee1aaa 100644 --- a/activerecord/CHANGELOG.md +++ b/activerecord/CHANGELOG.md @@ -1,3 +1,39 @@ +* Add basic API for connection switching to support multiple databases. + + 1) Adds a `connects_to` method for models to connect to multiple databases. Example: + + ``` + class AnimalsModel < ApplicationRecord + self.abstract_class = true + + connects_to database: { writing: :animals_primary, reading: :animals_replica } + end + + class Dog < AnimalsModel + # connected to both the animals_primary db for writing and the animals_replica for reading + end + ``` + + 2) Adds a `connected_to` block method for switching connection roles or connecting to + a database that the model didn't connect to. Connecting to the database in this block is + useful when you have another defined connection, for example `slow_replica` that you don't + want to connect to by default but need in the console, or a specific code block. + + ``` + ActiveRecord::Base.connected_to(role: :reading) do + Dog.first # finds dog from replica connected to AnimalsBase + Book.first # doesn't have a reading connection, will raise an error + end + ``` + + ``` + ActiveRecord::Base.connected_to(database: :slow_replica) do + SlowReplicaModel.first # if the db config has a slow_replica configuration this will be used to do the lookup, otherwise this will throw an exception + end + ``` + + *Eileen M. Uchitelle* + * Enum raises on invalid definition values When defining a Hash enum it can be easy to use [] instead of {}. This diff --git a/activerecord/lib/active_record/connection_handling.rb b/activerecord/lib/active_record/connection_handling.rb index 18114f9e1c..5141271db9 100644 --- a/activerecord/lib/active_record/connection_handling.rb +++ b/activerecord/lib/active_record/connection_handling.rb @@ -47,6 +47,92 @@ module ActiveRecord # The exceptions AdapterNotSpecified, AdapterNotFound and +ArgumentError+ # may be returned on an error. def establish_connection(config_or_env = nil) + config_hash = resolve_config_for_connection(config_or_env) + connection_handler.establish_connection(config_hash) + end + + # Connects a model to the databases specified. The +database+ keyword + # takes a hash consisting of a +role+ and a +database_key+. + # + # This will create a connection handler for switching between connections, + # look up the config hash using the +database_key+ and finally + # establishes a connection to that config. + # + # class AnimalsModel < ApplicationRecord + # self.abstract_class = true + # + # connects_to database: { writing: :primary, reading: :primary_replica } + # end + # + # Returns an array of established connections. + def connects_to(database: {}) + connections = [] + + database.each do |role, database_key| + config_hash = resolve_config_for_connection(database_key) + handler = lookup_connection_handler(role.to_sym) + + connections << handler.establish_connection(config_hash) + end + + connections + end + + # Connects to a database or role (ex writing, reading, or another + # custom role) for the duration of the block. + # + # If a role is passed, Active Record will look up the connection + # based on the requested role: + # + # ActiveRecord::Base.connected_to(role: :writing) do + # Dog.create! # creates dog using dog connection + # end + # + # ActiveRecord::Base.connected_to(role: :reading) do + # Dog.create! # throws exception because we're on a replica + # end + # + # ActiveRecord::Base.connected_to(role: :unknown_ode) do + # # raises exception due to non-existent role + # end + # + # For cases where you may want to connect to a database outside of the model, + # you can use +connected_to+ with a +database+ argument. The +database+ argument + # expects a symbol that corresponds to the database key in your config. + # + # This will connect to a new database for the queries inside the block. + # + # ActiveRecord::Base.connected_to(database: :animals_slow_replica) do + # Dog.run_a_long_query # runs a long query while connected to the +animals_slow_replica+ + # end + def connected_to(database: nil, role: nil, &blk) + if database && role + raise ArgumentError, "connected_to can only accept a database or role argument, but not both arguments." + elsif database + config_hash = resolve_config_for_connection(database) + handler = lookup_connection_handler(database.to_sym) + + with_handler(database.to_sym) do + handler.establish_connection(config_hash) + return yield + end + elsif role + with_handler(role.to_sym, &blk) + else + raise ArgumentError, "must provide a `database` or a `role`." + end + end + + def lookup_connection_handler(handler_key) # :nodoc: + connection_handlers[handler_key] ||= ActiveRecord::ConnectionAdapters::ConnectionHandler.new + end + + def with_handler(handler_key, &blk) # :nodoc: + handler = lookup_connection_handler(handler_key) + swap_connection_handler(handler, &blk) + end + + def resolve_config_for_connection(config_or_env) # :nodoc: raise "Anonymous class is not allowed." unless name config_or_env ||= DEFAULT_ENV.call.to_sym @@ -57,7 +143,7 @@ module ActiveRecord config_hash = resolver.resolve(config_or_env, pool_name).symbolize_keys config_hash[:name] = pool_name - connection_handler.establish_connection(config_hash) + config_hash end # Returns the connection currently associated with the class. This can @@ -118,5 +204,14 @@ module ActiveRecord delegate :clear_active_connections!, :clear_reloadable_connections!, :clear_all_connections!, :flush_idle_connections!, to: :connection_handler + + private + + def swap_connection_handler(handler, &blk) # :nodoc: + old_handler, ActiveRecord::Base.connection_handler = ActiveRecord::Base.connection_handler, handler + yield + ensure + ActiveRecord::Base.connection_handler = old_handler + end end end diff --git a/activerecord/lib/active_record/core.rb b/activerecord/lib/active_record/core.rb index 392602bc0f..b53681ee20 100644 --- a/activerecord/lib/active_record/core.rb +++ b/activerecord/lib/active_record/core.rb @@ -124,6 +124,8 @@ module ActiveRecord mattr_accessor :belongs_to_required_by_default, instance_accessor: false + mattr_accessor :connection_handlers, instance_accessor: false, default: {} + class_attribute :default_connection_handler, instance_writer: false self.filter_attributes = [] @@ -137,6 +139,7 @@ module ActiveRecord end self.default_connection_handler = ConnectionAdapters::ConnectionHandler.new + self.connection_handlers = { writing: ActiveRecord::Base.default_connection_handler } end module ClassMethods 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..d4e8cbee81 --- /dev/null +++ b/activerecord/test/cases/connection_adapters/connection_handlers_multi_db_test.rb @@ -0,0 +1,193 @@ +# 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] + 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 + 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] + 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 + 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 + end + end +end |