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hides the per thread registry instance, and caches singleton methods

Existing code was delegating to the instance with delegate
macro calls, or invoking the instance method to reach
the object and call its instance methods.

But the point is to have a clean class-level interface where
the thread local instance is hidden in the implementation.

References #11c6973.
References #10198.
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commit e5ef3abdd2336c34cd853a1f845f79b8b19fbb1b 1 parent 67bb49b
@fxn fxn authored
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6 activerecord/lib/active_record/scoping.rb
@@ -36,7 +36,7 @@ def populate_with_current_scope_attributes
# to get the current_scope for the +Board+ model, then you would use the
# following code:
#
- # registry = ActiveRecord::Scoping::ScopeRegistry.instance
+ # registry = ActiveRecord::Scoping::ScopeRegistry
# registry.set_value_for(:current_scope, "Board", some_new_scope)
#
# Now when you run:
@@ -52,10 +52,6 @@ def populate_with_current_scope_attributes
class ScopeRegistry # :nodoc:
extend ActiveSupport::PerThreadRegistry
- class << self
- delegate :value_for, :set_value_for, to: :instance
- end
-
VALID_SCOPE_TYPES = [:current_scope, :ignore_default_scope]
def initialize
View
4 activerecord/test/cases/base_test.rb
@@ -1377,9 +1377,9 @@ def test_current_scope_is_reset
UnloadablePost.send(:current_scope=, UnloadablePost.all)
UnloadablePost.unloadable
- assert_not_nil ActiveRecord::Scoping::ScopeRegistry.instance.value_for(:current_scope, "UnloadablePost")
+ assert_not_nil ActiveRecord::Scoping::ScopeRegistry.value_for(:current_scope, "UnloadablePost")
ActiveSupport::Dependencies.remove_unloadable_constants!
- assert_nil ActiveRecord::Scoping::ScopeRegistry.instance.value_for(:current_scope, "UnloadablePost")
+ assert_nil ActiveRecord::Scoping::ScopeRegistry.value_for(:current_scope, "UnloadablePost")
ensure
Object.class_eval{ remove_const :UnloadablePost } if defined?(UnloadablePost)
end
View
4 activesupport/lib/active_support/notifications.rb
@@ -193,10 +193,6 @@ def instrumenter
class InstrumentationRegistry # :nodoc:
extend ActiveSupport::PerThreadRegistry
- class << self
- delegate :instrumenter_for, to: :instance
- end
-
def initialize
@registry = {}
end
View
48 activesupport/lib/active_support/per_thread_registry.rb
@@ -1,7 +1,11 @@
module ActiveSupport
# This module is used to encapsulate access to thread local variables.
#
- # Given
+ # Instead of polluting the thread locals namespace:
+ #
+ # Thread.current[:connection_handler]
+ #
+ # you define a class that extends this module:
#
# module ActiveRecord
# class RuntimeRegistry
@@ -11,34 +15,40 @@ module ActiveSupport
# end
# end
#
- # <tt>ActiveRecord::RuntimeRegistry</tt> gets an +instance+ class method
- # that returns an instance of the class unique to the current thread. Thus,
- # instead of polluting +Thread.current+
- #
- # Thread.current[:connection_handler]
- #
- # you write
+ # and invoke the declared instance accessors as class methods. So
#
- # ActiveRecord::RuntimeRegistry.instance.connection_handler
+ # ActiveRecord::RuntimeRegistry.connection_handler = connection_handler
#
- # A +method_missing+ handler that proxies to the thread local instance is
- # installed in the extended class so the call above can be shortened to
+ # sets a connection handler local to the current thread, and
#
# ActiveRecord::RuntimeRegistry.connection_handler
#
- # The instance is stored as a thread local keyed by the name of the class,
- # that is the string "ActiveRecord::RuntimeRegistry" in the example above.
+ # returns a connection handler local to the current thread.
+ #
+ # This feature is accomplished by instantiating the class and storing the
+ # instance as a thread local keyed by the class name. In the example above
+ # a key "ActiveRecord::RuntimeRegistry" is stored in <tt>Thread.current</tt>.
+ # The class methods proxy to said thread local instance.
#
# If the class has an initializer, it must accept no arguments.
module PerThreadRegistry
- def instance
- Thread.current[self.name] ||= new
- end
-
protected
- def method_missing(*args, &block)
- instance.public_send(*args, &block)
+ def method_missing(name, *args, &block)
@frodsan
frodsan added a note

This method should be marked as :nodoc:, right?

@fxn Owner
fxn added a note

Yessir!

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+ # Caches the method definition as a singleton method of the receiver.
+ singleton_class.class_eval do
@frodsan
frodsan added a note

I'm not sure but this can be changed to +define_singleton_method+ :?

@fxn Owner
fxn added a note

Oh yes, didn't remember that one, would you change it?

@fxn Owner
fxn added a note

Much better!

@tenderlove Owner

This isn't thread safe. It will cause method redefinition warnings in concurrent systems (since there is no lock).

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+ define_method(name) do |*a, &b|
+ per_thread_registry_instance.public_send(name, *a, &b)
+ end
+ end
+
+ send(name, *args, &block)
+ end
+
+ private
+
+ def per_thread_registry_instance
+ Thread.current[name] ||= new
end
end
end
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