diff options
Diffstat (limited to 'activerecord/lib/active_record')
10 files changed, 234 insertions, 27 deletions
diff --git a/activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb b/activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb index 28d37881b6..16344b160d 100644 --- a/activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb +++ b/activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb @@ -1,7 +1,5 @@ # frozen_string_literal: true -require "active_support/deprecation" - module ActiveRecord module ConnectionAdapters #:nodoc: # Abstract representation of an index definition on a table. Instances of @@ -259,8 +257,6 @@ module ActiveRecord include ColumnMethods attr_reader :name, :temporary, :if_not_exists, :options, :as, :comment, :indexes, :foreign_keys - attr_writer :indexes - deprecate :indexes= def initialize( conn, diff --git a/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb b/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb index d1ff32df3f..9a7d7285f2 100644 --- a/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb +++ b/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb @@ -77,9 +77,6 @@ module ActiveRecord SIMPLE_INT = /\A\d+\z/ - attr_writer :visitor - deprecate :visitor= - attr_accessor :pool attr_reader :schema_cache, :visitor, :owner, :logger, :lock, :prepared_statements, :prevent_writes alias :in_use? :owner diff --git a/activerecord/lib/active_record/core.rb b/activerecord/lib/active_record/core.rb index 369d63e40a..519acd7605 100644 --- a/activerecord/lib/active_record/core.rb +++ b/activerecord/lib/active_record/core.rb @@ -101,6 +101,7 @@ module ActiveRecord # environment where dumping schema is rarely needed. mattr_accessor :dump_schema_after_migration, instance_writer: false, default: true + mattr_accessor :database_selector, instance_writer: false ## # :singleton-method: # Specifies which database schemas to dump when calling db:structure:dump. diff --git a/activerecord/lib/active_record/database_configurations.rb b/activerecord/lib/active_record/database_configurations.rb index 11aed6c002..73adf66684 100644 --- a/activerecord/lib/active_record/database_configurations.rb +++ b/activerecord/lib/active_record/database_configurations.rb @@ -134,9 +134,11 @@ module ActiveRecord end def build_db_config_from_hash(env_name, spec_name, config) - if url = config["url"] + if config.has_key?("url") + url = config["url"] config_without_url = config.dup config_without_url.delete "url" + ActiveRecord::DatabaseConfigurations::UrlConfig.new(env_name, spec_name, url, config_without_url) elsif config["database"] || (config.size == 1 && config.values.all? { |v| v.is_a? String }) ActiveRecord::DatabaseConfigurations::HashConfig.new(env_name, spec_name, config) diff --git a/activerecord/lib/active_record/database_configurations/url_config.rb b/activerecord/lib/active_record/database_configurations/url_config.rb index 81917fc4c1..8e8aa69478 100644 --- a/activerecord/lib/active_record/database_configurations/url_config.rb +++ b/activerecord/lib/active_record/database_configurations/url_config.rb @@ -56,12 +56,17 @@ module ActiveRecord end private - def build_config(original_config, url) - if /^jdbc:/.match?(url) - hash = { "url" => url } + + def build_url_hash(url) + if url.nil? || /^jdbc:/.match?(url) + { "url" => url } else - hash = ActiveRecord::ConnectionAdapters::ConnectionSpecification::ConnectionUrlResolver.new(url).to_hash + ActiveRecord::ConnectionAdapters::ConnectionSpecification::ConnectionUrlResolver.new(url).to_hash end + end + + def build_config(original_config, url) + hash = build_url_hash(url) if original_config[env_name] original_config[env_name].merge(hash) diff --git a/activerecord/lib/active_record/middleware/database_selector.rb b/activerecord/lib/active_record/middleware/database_selector.rb new file mode 100644 index 0000000000..adcfca4f8d --- /dev/null +++ b/activerecord/lib/active_record/middleware/database_selector.rb @@ -0,0 +1,74 @@ +# frozen_string_literal: true + +require "active_record/middleware/database_selector/resolver" + +module ActiveRecord + module Middleware + # The DatabaseSelector Middleware provides a framework for automatically + # swapping from the primary to the replica database connection. Rails + # provides a basic framework to determine when to swap and allows for + # applications to write custom strategy classes to override the default + # behavior. + # + # The resolver class defines when the application should switch (i.e. read + # from the primary if a write occurred less than 2 seconds ago) and an + # operations class that sets a value that helps the resolver class decide + # when to switch. + # + # Rails default middleware uses the request's session to set a timestamp + # that informs the application when to read from a primary or read from a + # replica. + # + # To use the DatabaseSelector in your application with default settings add + # the following options to your environment config: + # + # config.active_record.database_selector = { delay: 2.seconds } + # config.active_record.database_resolver = ActiveRecord::Middleware::DatabaseSelector::Resolver + # config.active_record.database_operations = ActiveRecord::Middleware::DatabaseSelector::Resolver::Session + # + # New applications will include these lines commented out in the production.rb. + # + # The default behavior can be changed by setting the config options to a + # custom class: + # + # config.active_record.database_selector = { delay: 2.seconds } + # config.active_record.database_resolver = MyResolver + # config.active_record.database_operations = MyResolver::MySession + class DatabaseSelector + def initialize(app, resolver_klass = Resolver, operations_klass = Resolver::Session) + @app = app + @resolver_klass = resolver_klass + @operations_klass = operations_klass + end + + attr_reader :resolver_klass, :operations_klass + + # Middleware that determines which database connection to use in a multiple + # database application. + def call(env) + request = ActionDispatch::Request.new(env) + + select_database(request) do + @app.call(env) + end + end + + private + + def select_database(request, &blk) + operations = operations_klass.build(request) + database_resolver = resolver_klass.call(operations) + + if reading_request?(request) + database_resolver.read(&blk) + else + database_resolver.write(&blk) + end + end + + def reading_request?(request) + request.get? || request.head? + end + end + end +end diff --git a/activerecord/lib/active_record/middleware/database_selector/resolver.rb b/activerecord/lib/active_record/middleware/database_selector/resolver.rb new file mode 100644 index 0000000000..acdb9b3238 --- /dev/null +++ b/activerecord/lib/active_record/middleware/database_selector/resolver.rb @@ -0,0 +1,89 @@ +# frozen_string_literal: true + +require "active_record/middleware/database_selector/resolver/session" + +module ActiveRecord + module Middleware + class DatabaseSelector + # The Resolver class is used by the DatabaseSelector middleware to + # determine which database the request should use. + # + # To change the behavior of the Resolver class in your application, + # create a custom resolver class that inherits from + # DatabaseSelector::Resolver and implements the methods that need to + # be changed. + # + # By default the Resolver class will send read traffic to the replica + # if it's been 2 seconds since the last write. + class Resolver # :nodoc: + SEND_TO_REPLICA_DELAY = 2.seconds + + def self.call(resolver) + new(resolver) + end + + def initialize(resolver) + @resolver = resolver + @instrumenter = ActiveSupport::Notifications.instrumenter + end + + attr_reader :resolver, :instrumenter + + def read(&blk) + if read_from_primary? + read_from_primary(&blk) + else + read_from_replica(&blk) + end + end + + def write(&blk) + write_to_primary(&blk) + end + + private + + def read_from_primary(&blk) + ActiveRecord::Base.connection.while_preventing_writes do + ActiveRecord::Base.connected_to(role: :writing) do + instrumenter.instrument("database_selector.active_record.read_from_primary") do + yield + end + end + end + end + + def read_from_replica(&blk) + ActiveRecord::Base.connected_to(role: :reading) do + instrumenter.instrument("database_selector.active_record.read_from_replica") do + yield + end + end + end + + def write_to_primary(&blk) + ActiveRecord::Base.connected_to(role: :writing) do + instrumenter.instrument("database_selector.active_record.wrote_to_primary") do + yield + ensure + resolver.update_last_write_timestamp + end + end + end + + def read_from_primary? + !time_since_last_write_ok? + end + + def send_to_replica_delay + (ActiveRecord::Base.database_selector && ActiveRecord::Base.database_selector[:delay]) || + SEND_TO_REPLICA_DELAY + end + + def time_since_last_write_ok? + Time.now - resolver.last_write_timestamp >= send_to_replica_delay + end + end + end + end +end diff --git a/activerecord/lib/active_record/middleware/database_selector/resolver/session.rb b/activerecord/lib/active_record/middleware/database_selector/resolver/session.rb new file mode 100644 index 0000000000..33e0af5ee4 --- /dev/null +++ b/activerecord/lib/active_record/middleware/database_selector/resolver/session.rb @@ -0,0 +1,45 @@ +# frozen_string_literal: true + +module ActiveRecord + module Middleware + class DatabaseSelector + class Resolver + # The session class is used by the DatabaseSelector::Resolver to save + # timestamps of the last write in the session. + # + # The last_write is used to determine whether it's safe to read + # from the replica or the request needs to be sent to the primary. + class Session # :nodoc: + def self.build(request) + new(request.session) + end + + # Converts time to a timestamp that represents milliseconds since + # epoch. + def self.convert_time_to_timestamp(time) + time.to_i * 1000 + time.usec / 1000 + end + + # Converts milliseconds since epoch timestamp into a time object. + def self.convert_timestamp_to_time(timestamp) + timestamp ? Time.at(timestamp / 1000, (timestamp % 1000) * 1000) : Time.at(0) + end + + def initialize(session) + @session = session + end + + attr_reader :session + + def last_write_timestamp + self.class.convert_timestamp_to_time(session[:last_write]) + end + + def update_last_write_timestamp + session[:last_write] = self.class.convert_time_to_timestamp(Time.now) + end + end + end + end + end +end diff --git a/activerecord/lib/active_record/railtie.rb b/activerecord/lib/active_record/railtie.rb index 6346a95d57..a981fa97d9 100644 --- a/activerecord/lib/active_record/railtie.rb +++ b/activerecord/lib/active_record/railtie.rb @@ -88,6 +88,14 @@ module ActiveRecord end end + initializer "active_record.database_selector" do + if config.active_record.database_selector + resolver = config.active_record.delete(:database_resolver) + operations = config.active_record.delete(:database_operations) + config.app_middleware.use ActiveRecord::Middleware::DatabaseSelector, resolver, operations + end + end + initializer "Check for cache versioning support" do config.after_initialize do |app| ActiveSupport.on_load(:active_record) do diff --git a/activerecord/lib/active_record/reflection.rb b/activerecord/lib/active_record/reflection.rb index b2110f727c..6d2f75a3ae 100644 --- a/activerecord/lib/active_record/reflection.rb +++ b/activerecord/lib/active_record/reflection.rb @@ -612,21 +612,9 @@ module ActiveRecord # returns either +nil+ or the inverse association name that it finds. def automatic_inverse_of - return unless can_find_inverse_of_automatically?(self) + if can_find_inverse_of_automatically?(self) + inverse_name = ActiveSupport::Inflector.underscore(options[:as] || active_record.name.demodulize).to_sym - inverse_name_candidates = - if options[:as] - [options[:as]] - else - active_record_name = active_record.name.demodulize - [active_record_name, ActiveSupport::Inflector.pluralize(active_record_name)] - end - - inverse_name_candidates.map! do |candidate| - ActiveSupport::Inflector.underscore(candidate).to_sym - end - - inverse_name_candidates.detect do |inverse_name| begin reflection = klass._reflect_on_association(inverse_name) rescue NameError @@ -635,7 +623,9 @@ module ActiveRecord reflection = false end - valid_inverse_reflection?(reflection) + if valid_inverse_reflection?(reflection) + return inverse_name + end end end |