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-rw-r--r--actionpack/lib/abstract_controller/caching/fragments.rb1
-rw-r--r--actionpack/lib/action_controller/metal/helpers.rb2
-rw-r--r--actionpack/lib/action_dispatch/middleware/debug_view.rb4
-rw-r--r--actionview/lib/action_view/base.rb51
-rw-r--r--actionview/lib/action_view/template/handlers/erb/erubi.rb2
-rw-r--r--actionview/test/abstract_unit.rb4
-rw-r--r--actionview/test/actionpack/controller/view_paths_test.rb4
-rw-r--r--actionview/test/activerecord/multifetch_cache_test.rb2
-rw-r--r--actionview/test/template/capture_helper_test.rb2
-rw-r--r--actionview/test/template/compiled_templates_test.rb4
-rw-r--r--actionview/test/template/render_test.rb2
-rw-r--r--actionview/test/template/streaming_render_test.rb2
-rw-r--r--actionview/test/template/test_case_test.rb2
-rw-r--r--actionview/test/template/translation_helper_test.rb2
-rw-r--r--activerecord/CHANGELOG.md33
-rw-r--r--activerecord/lib/active_record.rb7
-rw-r--r--activerecord/lib/active_record/core.rb1
-rw-r--r--activerecord/lib/active_record/database_configurations.rb4
-rw-r--r--activerecord/lib/active_record/database_configurations/url_config.rb13
-rw-r--r--activerecord/lib/active_record/middleware/database_selector.rb74
-rw-r--r--activerecord/lib/active_record/middleware/database_selector/resolver.rb88
-rw-r--r--activerecord/lib/active_record/middleware/database_selector/resolver/session.rb45
-rw-r--r--activerecord/lib/active_record/railtie.rb8
-rw-r--r--activerecord/test/cases/connection_adapters/merge_and_resolve_default_url_config_test.rb8
-rw-r--r--activerecord/test/cases/database_selector_test.rb77
-rw-r--r--activerecord/test/models/topic.rb8
-rw-r--r--guides/rails_guides/generator.rb4
-rw-r--r--railties/lib/rails/generators/actions.rb6
-rw-r--r--railties/lib/rails/generators/rails/app/templates/config/environments/production.rb.tt20
-rw-r--r--railties/test/generators/actions_test.rb6
30 files changed, 444 insertions, 42 deletions
diff --git a/actionpack/lib/abstract_controller/caching/fragments.rb b/actionpack/lib/abstract_controller/caching/fragments.rb
index 4e454adc5f..18677ddd18 100644
--- a/actionpack/lib/abstract_controller/caching/fragments.rb
+++ b/actionpack/lib/abstract_controller/caching/fragments.rb
@@ -28,7 +28,6 @@ module AbstractController
self.fragment_cache_keys = []
if respond_to?(:helper_method)
- helper_method :fragment_cache_key
helper_method :combined_fragment_cache_key
end
end
diff --git a/actionpack/lib/action_controller/metal/helpers.rb b/actionpack/lib/action_controller/metal/helpers.rb
index 0faaac1ce4..f1fb7ab0f7 100644
--- a/actionpack/lib/action_controller/metal/helpers.rb
+++ b/actionpack/lib/action_controller/metal/helpers.rb
@@ -75,7 +75,7 @@ module ActionController
# Provides a proxy to access helper methods from outside the view.
def helpers
@helper_proxy ||= begin
- proxy = ActionView::Base.new
+ proxy = ActionView::Base.empty
proxy.config = config.inheritable_copy
proxy.extend(_helpers)
end
diff --git a/actionpack/lib/action_dispatch/middleware/debug_view.rb b/actionpack/lib/action_dispatch/middleware/debug_view.rb
index ac12dc13a1..5a7010a1c2 100644
--- a/actionpack/lib/action_dispatch/middleware/debug_view.rb
+++ b/actionpack/lib/action_dispatch/middleware/debug_view.rb
@@ -10,7 +10,9 @@ module ActionDispatch
RESCUES_TEMPLATE_PATH = File.expand_path("templates", __dir__)
def initialize(assigns)
- super([RESCUES_TEMPLATE_PATH], assigns)
+ paths = [RESCUES_TEMPLATE_PATH]
+ renderer = ActionView::Renderer.new ActionView::LookupContext.new(paths)
+ super(renderer, assigns)
end
def debug_params(params)
diff --git a/actionview/lib/action_view/base.rb b/actionview/lib/action_view/base.rb
index 6cb342a0a9..fe9f3f9503 100644
--- a/actionview/lib/action_view/base.rb
+++ b/actionview/lib/action_view/base.rb
@@ -3,6 +3,7 @@
require "active_support/core_ext/module/attr_internal"
require "active_support/core_ext/module/attribute_accessors"
require "active_support/ordered_options"
+require "active_support/deprecation"
require "action_view/log_subscriber"
require "action_view/helpers"
require "action_view/context"
@@ -187,7 +188,7 @@ module ActionView #:nodoc:
end
end
- attr_accessor :view_renderer
+ attr_reader :view_renderer
attr_internal :config, :assigns
delegate :lookup_context, to: :view_renderer
@@ -197,17 +198,49 @@ module ActionView #:nodoc:
@_assigns = new_assigns.each { |key, value| instance_variable_set("@#{key}", value) }
end
- def initialize(context = nil, assigns = {}, controller = nil, formats = nil) #:nodoc:
+ # :stopdoc:
+
+ def self.build_renderer(context, controller, formats)
+ lookup_context = context.is_a?(ActionView::LookupContext) ?
+ context : ActionView::LookupContext.new(context)
+ lookup_context.formats = formats if formats
+ lookup_context.prefixes = controller._prefixes if controller
+ ActionView::Renderer.new(lookup_context)
+ end
+
+ def self.empty
+ with_view_paths([])
+ end
+
+ def self.with_view_paths(view_paths, assigns = {}, controller = nil)
+ with_context ActionView::LookupContext.new(view_paths), assigns, controller
+ end
+
+ def self.with_context(context, assigns = {}, controller = nil)
+ new ActionView::Renderer.new(context), assigns, controller
+ end
+
+ NULL = Object.new
+
+ # :startdoc:
+
+ def initialize(renderer, assigns = {}, controller = nil, formats = NULL) #:nodoc:
@_config = ActiveSupport::InheritableOptions.new
- if context.is_a?(ActionView::Renderer)
- @view_renderer = context
+ unless formats == NULL
+ ActiveSupport::Deprecation.warn <<~eowarn
+ Passing formats to ActionView::Base.new is deprecated
+ eowarn
+ end
+
+ if renderer.is_a?(ActionView::Renderer)
+ @view_renderer = renderer
else
- lookup_context = context.is_a?(ActionView::LookupContext) ?
- context : ActionView::LookupContext.new(context)
- lookup_context.formats = formats if formats
- lookup_context.prefixes = controller._prefixes if controller
- @view_renderer = ActionView::Renderer.new(lookup_context)
+ ActiveSupport::Deprecation.warn <<~eowarn
+ ActionView::Base instances should be constructed with a view renderer,
+ assigments, and a controller.
+ eowarn
+ @view_renderer = self.class.build_renderer(renderer, controller, formats)
end
@cache_hit = {}
diff --git a/actionview/lib/action_view/template/handlers/erb/erubi.rb b/actionview/lib/action_view/template/handlers/erb/erubi.rb
index e155bae89d..15ca202024 100644
--- a/actionview/lib/action_view/template/handlers/erb/erubi.rb
+++ b/actionview/lib/action_view/template/handlers/erb/erubi.rb
@@ -26,7 +26,7 @@ module ActionView
view = Class.new(ActionView::Base) {
include action_view_erb_handler_context._routes.url_helpers
class_eval("define_method(:_template) { |local_assigns, output_buffer| #{src} }", @filename || "(erubi)", 0)
- }.new(action_view_erb_handler_context)
+ }.with_context(action_view_erb_handler_context)
view.run(:_template, {}, ActionView::OutputBuffer.new)
end
diff --git a/actionview/test/abstract_unit.rb b/actionview/test/abstract_unit.rb
index d71944e938..56d617309c 100644
--- a/actionview/test/abstract_unit.rb
+++ b/actionview/test/abstract_unit.rb
@@ -48,7 +48,7 @@ module RenderERBUtils
@view ||= begin
path = ActionView::FileSystemResolver.new(FIXTURE_LOAD_PATH)
view_paths = ActionView::PathSet.new([path])
- ActionView::Base.new(view_paths)
+ ActionView::Base.with_view_paths(view_paths)
end
end
@@ -61,7 +61,7 @@ module RenderERBUtils
ActionView::Template::Handlers::ERB,
{})
- template.render(ActionView::Base.new, {}).strip
+ template.render(ActionView::Base.empty, {}).strip
end
end
diff --git a/actionview/test/actionpack/controller/view_paths_test.rb b/actionview/test/actionpack/controller/view_paths_test.rb
index 7f3fe0fa08..c5238dd746 100644
--- a/actionview/test/actionpack/controller/view_paths_test.rb
+++ b/actionview/test/actionpack/controller/view_paths_test.rb
@@ -77,7 +77,7 @@ class ViewLoadPathsTest < ActionController::TestCase
end
def test_template_appends_view_path_correctly
- @controller.instance_variable_set :@template, ActionView::Base.new(TestController.view_paths, {}, @controller)
+ @controller.instance_variable_set :@template, ActionView::Base.with_view_paths(TestController.view_paths, {}, @controller)
class_view_paths = TestController.view_paths
@controller.append_view_path "foo"
@@ -89,7 +89,7 @@ class ViewLoadPathsTest < ActionController::TestCase
end
def test_template_prepends_view_path_correctly
- @controller.instance_variable_set :@template, ActionView::Base.new(TestController.view_paths, {}, @controller)
+ @controller.instance_variable_set :@template, ActionView::Base.with_view_paths(TestController.view_paths, {}, @controller)
class_view_paths = TestController.view_paths
@controller.prepend_view_path "baz"
diff --git a/actionview/test/activerecord/multifetch_cache_test.rb b/actionview/test/activerecord/multifetch_cache_test.rb
index 12be069e69..229b4e56d0 100644
--- a/actionview/test/activerecord/multifetch_cache_test.rb
+++ b/actionview/test/activerecord/multifetch_cache_test.rb
@@ -19,7 +19,7 @@ class MultifetchCacheTest < ActiveRecordTestCase
def combined_fragment_cache_key(key)
[ :views, key ]
end
- end.new(view_paths, {})
+ end.with_view_paths(view_paths, {})
end
def test_only_preloading_for_records_that_miss_the_cache
diff --git a/actionview/test/template/capture_helper_test.rb b/actionview/test/template/capture_helper_test.rb
index e172497c88..45070674ad 100644
--- a/actionview/test/template/capture_helper_test.rb
+++ b/actionview/test/template/capture_helper_test.rb
@@ -5,7 +5,7 @@ require "abstract_unit"
class CaptureHelperTest < ActionView::TestCase
def setup
super
- @av = ActionView::Base.new
+ @av = ActionView::Base.empty
@view_flow = ActionView::OutputFlow.new
end
diff --git a/actionview/test/template/compiled_templates_test.rb b/actionview/test/template/compiled_templates_test.rb
index 3cd6448e38..ded4786e62 100644
--- a/actionview/test/template/compiled_templates_test.rb
+++ b/actionview/test/template/compiled_templates_test.rb
@@ -72,13 +72,13 @@ class CompiledTemplatesTest < ActiveSupport::TestCase
def render_with_cache(*args)
view_paths = ActionController::Base.view_paths
- ActionView::Base.new(view_paths, {}).render(*args)
+ ActionView::Base.with_view_paths(view_paths, {}).render(*args)
end
def render_without_cache(*args)
path = ActionView::FileSystemResolver.new(FIXTURE_LOAD_PATH)
view_paths = ActionView::PathSet.new([path])
- ActionView::Base.new(view_paths, {}).render(*args)
+ ActionView::Base.with_view_paths(view_paths, {}).render(*args)
end
def modify_template(template, content)
diff --git a/actionview/test/template/render_test.rb b/actionview/test/template/render_test.rb
index afe68b7ff0..ab67423ea1 100644
--- a/actionview/test/template/render_test.rb
+++ b/actionview/test/template/render_test.rb
@@ -15,7 +15,7 @@ module RenderTestCases
def combined_fragment_cache_key(key)
[ :views, key ]
end
- end.new(paths, @assigns)
+ end.with_view_paths(paths, @assigns)
@controller_view = TestController.new.view_context
diff --git a/actionview/test/template/streaming_render_test.rb b/actionview/test/template/streaming_render_test.rb
index f196c42c4f..dda2095013 100644
--- a/actionview/test/template/streaming_render_test.rb
+++ b/actionview/test/template/streaming_render_test.rb
@@ -9,7 +9,7 @@ class SetupFiberedBase < ActiveSupport::TestCase
def setup
view_paths = ActionController::Base.view_paths
@assigns = { secret: "in the sauce", name: nil }
- @view = ActionView::Base.new(view_paths, @assigns)
+ @view = ActionView::Base.with_view_paths(view_paths, @assigns)
@controller_view = TestController.new.view_context
end
diff --git a/actionview/test/template/test_case_test.rb b/actionview/test/template/test_case_test.rb
index 976b6bc77e..ab3ababba4 100644
--- a/actionview/test/template/test_case_test.rb
+++ b/actionview/test/template/test_case_test.rb
@@ -52,7 +52,7 @@ module ActionView
end
test "retrieve non existing config values" do
- assert_nil ActionView::Base.new.config.something_odd
+ assert_nil ActionView::Base.empty.config.something_odd
end
test "works without testing a helper module" do
diff --git a/actionview/test/template/translation_helper_test.rb b/actionview/test/template/translation_helper_test.rb
index e756348938..d04e68e182 100644
--- a/actionview/test/template/translation_helper_test.rb
+++ b/actionview/test/template/translation_helper_test.rb
@@ -36,7 +36,7 @@ class TranslationHelperTest < ActiveSupport::TestCase
}
}
)
- @view = ::ActionView::Base.new(ActionController::Base.view_paths, {})
+ @view = ::ActionView::Base.with_view_paths(ActionController::Base.view_paths, {})
end
teardown do
diff --git a/activerecord/CHANGELOG.md b/activerecord/CHANGELOG.md
index 67cf5881d3..654caafc92 100644
--- a/activerecord/CHANGELOG.md
+++ b/activerecord/CHANGELOG.md
@@ -1,3 +1,36 @@
+* Allow applications to automatically switch connections.
+
+ Adds a middleware and configuration options that can be used in your
+ application to automatically switch between the writing and reading
+ database connections.
+
+ `GET` and `HEAD` requests will read from the replica unless there was
+ a write in the last 2 seconds, otherwise they will read from the primary.
+ Non-get requests will always write to the primary. The middleware accepts
+ an argument for a Resolver class and a Operations class where you are able
+ to change how the auto-switcher works to be most beneficial for your
+ application.
+
+ To use the middleware in your application you can use the following
+ configuration options:
+
+ ```
+ 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
+ ```
+
+ To change the database selection strategy, pass a custom class to the
+ configuration options:
+
+ ```
+ config.active_record.database_selector = { delay: 10.seconds }
+ config.active_record.database_resolver = MyResolver
+ config.active_record.database_operations = MyResolver::MyCookies
+ ```
+
+ *Eileen M. Uchitelle*
+
* MySQL: Support `:size` option to change text and blob size.
*Ryuta Kamizono*
diff --git a/activerecord/lib/active_record.rb b/activerecord/lib/active_record.rb
index de94f9693f..7d66158f47 100644
--- a/activerecord/lib/active_record.rb
+++ b/activerecord/lib/active_record.rb
@@ -74,6 +74,7 @@ module ActiveRecord
autoload :Translation
autoload :Validations
autoload :SecureToken
+ autoload :DatabaseSelector, "active_record/middleware/database_selector"
eager_autoload do
autoload :ActiveRecordError, "active_record/errors"
@@ -153,6 +154,12 @@ module ActiveRecord
end
end
+ module Middleware
+ extend ActiveSupport::Autoload
+
+ autoload :DatabaseSelector, "active_record/middleware/database_selector"
+ end
+
module Tasks
extend ActiveSupport::Autoload
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..06529bc1c9
--- /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 mutliple
+ # 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..1c056e2156
--- /dev/null
+++ b/activerecord/lib/active_record/middleware/database_selector/resolver.rb
@@ -0,0 +1,88 @@
+# 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 inherts 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
+ resolver.update_last_write_timestamp
+ yield
+ 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/test/cases/connection_adapters/merge_and_resolve_default_url_config_test.rb b/activerecord/test/cases/connection_adapters/merge_and_resolve_default_url_config_test.rb
index 06c1c51724..225cccc62c 100644
--- a/activerecord/test/cases/connection_adapters/merge_and_resolve_default_url_config_test.rb
+++ b/activerecord/test/cases/connection_adapters/merge_and_resolve_default_url_config_test.rb
@@ -46,6 +46,14 @@ module ActiveRecord
assert_equal expected, actual
end
+ def test_resolver_with_nil_database_url_and_current_env
+ ENV["RAILS_ENV"] = "foo"
+ config = { "foo" => { "adapter" => "postgres", "url" => ENV["DATABASE_URL"] } }
+ actual = resolve_spec(:foo, config)
+ expected = { "adapter" => "postgres", "url" => nil, "name" => "foo" }
+ assert_equal expected, actual
+ end
+
def test_resolver_with_database_uri_and_current_env_symbol_key_and_rack_env
ENV["DATABASE_URL"] = "postgres://localhost/foo"
ENV["RACK_ENV"] = "foo"
diff --git a/activerecord/test/cases/database_selector_test.rb b/activerecord/test/cases/database_selector_test.rb
new file mode 100644
index 0000000000..f961fa754b
--- /dev/null
+++ b/activerecord/test/cases/database_selector_test.rb
@@ -0,0 +1,77 @@
+# frozen_string_literal: true
+
+require "cases/helper"
+require "models/person"
+require "action_dispatch"
+
+module ActiveRecord
+ class DatabaseSelectorTest < ActiveRecord::TestCase
+ setup do
+ @session_store = {}
+ @session = ActiveRecord::Middleware::DatabaseSelector::Resolver::Session.new(@session_store)
+ end
+
+ def test_empty_session
+ assert_equal Time.at(0), @session.last_write_timestamp
+ end
+
+ def test_writing_the_session_timestamps
+ assert @session.update_last_write_timestamp
+
+ session2 = ActiveRecord::Middleware::DatabaseSelector::Resolver::Session.new(@session_store)
+ assert_equal @session.last_write_timestamp, session2.last_write_timestamp
+ end
+
+ def test_writing_session_time_changes
+ assert @session.update_last_write_timestamp
+
+ before = @session.last_write_timestamp
+ sleep(0.1)
+
+ assert @session.update_last_write_timestamp
+ assert_not_equal before, @session.last_write_timestamp
+ end
+
+ def test_read_from_replicas
+ @session_store[:last_write] = ActiveRecord::Middleware::DatabaseSelector::Resolver::Session.convert_time_to_timestamp(Time.now - 5.seconds)
+
+ resolver = ActiveRecord::Middleware::DatabaseSelector::Resolver.new(@session)
+
+ called = false
+ resolver.read do
+ called = true
+ assert ActiveRecord::Base.connected_to?(role: :reading)
+ end
+ assert called
+ end
+
+ def test_read_from_primary
+ @session_store[:last_write] = ActiveRecord::Middleware::DatabaseSelector::Resolver::Session.convert_time_to_timestamp(Time.now)
+
+ resolver = ActiveRecord::Middleware::DatabaseSelector::Resolver.new(@session)
+
+ called = false
+ resolver.read do
+ called = true
+ assert ActiveRecord::Base.connected_to?(role: :writing)
+ end
+ assert called
+ end
+
+ def test_the_middleware_chooses_writing_role_with_POST_request
+ middleware = ActiveRecord::Middleware::DatabaseSelector.new(lambda { |env|
+ assert ActiveRecord::Base.connected_to?(role: :writing)
+ [200, {}, ["body"]]
+ })
+ assert_equal [200, {}, ["body"]], middleware.call("REQUEST_METHOD" => "POST")
+ end
+
+ def test_the_middleware_chooses_reading_role_with_GET_request
+ middleware = ActiveRecord::Middleware::DatabaseSelector.new(lambda { |env|
+ assert ActiveRecord::Base.connected_to?(role: :reading)
+ [200, {}, ["body"]]
+ })
+ assert_equal [200, {}, ["body"]], middleware.call("REQUEST_METHOD" => "GET")
+ end
+ end
+end
diff --git a/activerecord/test/models/topic.rb b/activerecord/test/models/topic.rb
index 03430154db..a6a47687a2 100644
--- a/activerecord/test/models/topic.rb
+++ b/activerecord/test/models/topic.rb
@@ -12,17 +12,9 @@ class Topic < ActiveRecord::Base
scope :scope_with_lambda, lambda { all }
- scope :by_private_lifo, -> { where(author_name: private_lifo) }
scope :by_lifo, -> { where(author_name: "lifo") }
scope :replied, -> { where "replies_count > 0" }
- class << self
- private
- def private_lifo
- "lifo"
- end
- end
-
scope "approved_as_string", -> { where(approved: true) }
scope :anonymous_extension, -> { } do
def one
diff --git a/guides/rails_guides/generator.rb b/guides/rails_guides/generator.rb
index fd33c3f8a7..b0ddb0e7e0 100644
--- a/guides/rails_guides/generator.rb
+++ b/guides/rails_guides/generator.rb
@@ -150,8 +150,8 @@ module RailsGuides
puts "Generating #{guide} as #{output_file}"
layout = @kindle ? "kindle/layout" : "layout"
- view = ActionView::Base.new(
- @source_dir,
+ view = ActionView::Base.with_view_paths(
+ [@source_dir],
edge: @edge,
version: @version,
mobi: "kindle/#{mobi}",
diff --git a/railties/lib/rails/generators/actions.rb b/railties/lib/rails/generators/actions.rb
index 3856a74a39..1a5f2ff203 100644
--- a/railties/lib/rails/generators/actions.rb
+++ b/railties/lib/rails/generators/actions.rb
@@ -222,6 +222,7 @@ module Rails
log :generate, what
options = args.extract_options!
+ options[:without_rails_env] = true
argument = args.flat_map(&:to_s).join(" ")
execute_command :rails, "generate #{what} #{argument}", options
@@ -284,14 +285,15 @@ module Rails
# based on the executor parameter provided.
def execute_command(executor, command, options = {}) # :doc:
log executor, command
- env = options[:env] || ENV["RAILS_ENV"] || "development"
+ env = options[:env] || ENV["RAILS_ENV"] || "development"
+ rails_env = " RAILS_ENV=#{env}" unless options[:without_rails_env]
sudo = options[:sudo] && !Gem.win_platform? ? "sudo " : ""
config = { verbose: false }
config[:capture] = options[:capture] if options[:capture]
config[:abort_on_failure] = options[:abort_on_failure] if options[:abort_on_failure]
- in_root { run("#{sudo}#{extify(executor)} #{command} RAILS_ENV=#{env}", config) }
+ in_root { run("#{sudo}#{extify(executor)} #{command}#{rails_env}", config) }
end
# Add an extension to the given name based on the platform.
diff --git a/railties/lib/rails/generators/rails/app/templates/config/environments/production.rb.tt b/railties/lib/rails/generators/rails/app/templates/config/environments/production.rb.tt
index 08befd9196..94f7dd0c79 100644
--- a/railties/lib/rails/generators/rails/app/templates/config/environments/production.rb.tt
+++ b/railties/lib/rails/generators/rails/app/templates/config/environments/production.rb.tt
@@ -98,4 +98,24 @@ Rails.application.configure do
# Do not dump schema after migrations.
config.active_record.dump_schema_after_migration = false
<%- end -%>
+
+ # Inserts middleware to perform automatic connection switching.
+ # The `database_selector` hash is used to pass options to the DatabaseSelector
+ # middleware. The `delay` is used to determine how long to wait after a write
+ # to send a subsequent read to the primary.
+ #
+ # The `database_resolver` class is used by the middleware to determine which
+ # database is appropriate to use based on the time delay.
+ #
+ # The `database_operations` class is used by the middleware to set timestamps
+ # for the last write to the primary. The resolver uses the operations class
+ # timestamps to determine how long to wait before reading from the replica.
+ #
+ # By default Rails will store a last write timestamp in the session. The
+ # DatabaseSelector middleware is designed as such you can define your own
+ # strategy for connection switching and pass that into the middleware through
+ # these configuration options.
+ # 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
end
diff --git a/railties/test/generators/actions_test.rb b/railties/test/generators/actions_test.rb
index 4932100ea2..44d4e92256 100644
--- a/railties/test/generators/actions_test.rb
+++ b/railties/test/generators/actions_test.rb
@@ -320,6 +320,12 @@ class ActionsTest < Rails::Generators::TestCase
assert_no_file "app/models/my_model.rb"
end
+ def test_generate_should_run_command_without_env
+ assert_called_with(generator, :run, ["rails generate model MyModel name:string", verbose: false]) do
+ action :generate, "model", "MyModel", "name:string"
+ end
+ end
+
def test_rake_should_run_rake_command_with_default_env
assert_called_with(generator, :run, ["rake log:clear RAILS_ENV=development", verbose: false]) do
with_rails_env nil do