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90d6237762
This is a regression for #36184. And also, add new `monotonic` argument to the last of the method signature rather than the first.
280 lines
10 KiB
Ruby
280 lines
10 KiB
Ruby
# frozen_string_literal: true
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require "active_support/notifications/instrumenter"
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require "active_support/notifications/fanout"
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require "active_support/per_thread_registry"
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module ActiveSupport
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# = Notifications
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#
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# <tt>ActiveSupport::Notifications</tt> provides an instrumentation API for
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# Ruby.
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#
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# == Instrumenters
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#
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# To instrument an event you just need to do:
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#
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# ActiveSupport::Notifications.instrument('render', extra: :information) do
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# render plain: 'Foo'
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# end
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#
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# That first executes the block and then notifies all subscribers once done.
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#
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# In the example above +render+ is the name of the event, and the rest is called
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# the _payload_. The payload is a mechanism that allows instrumenters to pass
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# extra information to subscribers. Payloads consist of a hash whose contents
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# are arbitrary and generally depend on the event.
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#
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# == Subscribers
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#
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# You can consume those events and the information they provide by registering
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# a subscriber.
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#
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# ActiveSupport::Notifications.subscribe('render') do |name, start, finish, id, payload|
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# name # => String, name of the event (such as 'render' from above)
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# start # => Time, when the instrumented block started execution
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# finish # => Time, when the instrumented block ended execution
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# id # => String, unique ID for the instrumenter that fired the event
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# payload # => Hash, the payload
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# end
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#
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# Here, the +start+ and +finish+ values represent wall-clock time. If you are
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# concerned about accuracy, you can register a monotonic subscriber.
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#
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# ActiveSupport::Notifications.monotonic_subscribe('render') do |name, start, finish, id, payload|
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# name # => String, name of the event (such as 'render' from above)
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# start # => Monotonic time, when the instrumented block started execution
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# finish # => Monotonic time, when the instrumented block ended execution
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# id # => String, unique ID for the instrumenter that fired the event
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# payload # => Hash, the payload
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# end
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#
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# The +start+ and +finish+ values above represent monotonic time.
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#
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# For instance, let's store all "render" events in an array:
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#
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# events = []
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#
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# ActiveSupport::Notifications.subscribe('render') do |*args|
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# events << ActiveSupport::Notifications::Event.new(*args)
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# end
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#
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# That code returns right away, you are just subscribing to "render" events.
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# The block is saved and will be called whenever someone instruments "render":
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#
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# ActiveSupport::Notifications.instrument('render', extra: :information) do
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# render plain: 'Foo'
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# end
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#
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# event = events.first
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# event.name # => "render"
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# event.duration # => 10 (in milliseconds)
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# event.payload # => { extra: :information }
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#
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# The block in the <tt>subscribe</tt> call gets the name of the event, start
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# timestamp, end timestamp, a string with a unique identifier for that event's instrumenter
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# (something like "535801666f04d0298cd6"), and a hash with the payload, in
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# that order.
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#
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# If an exception happens during that particular instrumentation the payload will
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# have a key <tt>:exception</tt> with an array of two elements as value: a string with
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# the name of the exception class, and the exception message.
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# The <tt>:exception_object</tt> key of the payload will have the exception
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# itself as the value:
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#
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# event.payload[:exception] # => ["ArgumentError", "Invalid value"]
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# event.payload[:exception_object] # => #<ArgumentError: Invalid value>
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#
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# As the earlier example depicts, the class <tt>ActiveSupport::Notifications::Event</tt>
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# is able to take the arguments as they come and provide an object-oriented
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# interface to that data.
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#
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# It is also possible to pass an object which responds to <tt>call</tt> method
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# as the second parameter to the <tt>subscribe</tt> method instead of a block:
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#
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# module ActionController
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# class PageRequest
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# def call(name, started, finished, unique_id, payload)
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# Rails.logger.debug ['notification:', name, started, finished, unique_id, payload].join(' ')
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# end
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# end
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# end
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#
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# ActiveSupport::Notifications.subscribe('process_action.action_controller', ActionController::PageRequest.new)
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#
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# resulting in the following output within the logs including a hash with the payload:
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#
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# notification: process_action.action_controller 2012-04-13 01:08:35 +0300 2012-04-13 01:08:35 +0300 af358ed7fab884532ec7 {
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# controller: "Devise::SessionsController",
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# action: "new",
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# params: {"action"=>"new", "controller"=>"devise/sessions"},
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# format: :html,
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# method: "GET",
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# path: "/login/sign_in",
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# status: 200,
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# view_runtime: 279.3080806732178,
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# db_runtime: 40.053
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# }
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#
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# You can also subscribe to all events whose name matches a certain regexp:
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#
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# ActiveSupport::Notifications.subscribe(/render/) do |*args|
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# ...
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# end
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#
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# and even pass no argument to <tt>subscribe</tt>, in which case you are subscribing
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# to all events.
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#
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# == Temporary Subscriptions
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#
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# Sometimes you do not want to subscribe to an event for the entire life of
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# the application. There are two ways to unsubscribe.
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#
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# WARNING: The instrumentation framework is designed for long-running subscribers,
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# use this feature sparingly because it wipes some internal caches and that has
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# a negative impact on performance.
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#
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# === Subscribe While a Block Runs
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#
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# You can subscribe to some event temporarily while some block runs. For
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# example, in
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#
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# callback = lambda {|*args| ... }
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# ActiveSupport::Notifications.subscribed(callback, "sql.active_record") do
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# ...
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# end
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#
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# the callback will be called for all "sql.active_record" events instrumented
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# during the execution of the block. The callback is unsubscribed automatically
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# after that.
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#
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# To record +started+ and +finished+ values with monotonic time,
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# specify the optional <tt>:monotonic</tt> option to the
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# <tt>subscribed</tt> method. The <tt>:monotonic</tt> option is set
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# to +false+ by default.
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#
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# callback = lambda {|name, started, finished, unique_id, payload| ... }
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# ActiveSupport::Notifications.subscribed(callback, "sql.active_record", monotonic: true) do
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# ...
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# end
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#
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# === Manual Unsubscription
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#
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# The +subscribe+ method returns a subscriber object:
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#
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# subscriber = ActiveSupport::Notifications.subscribe("render") do |*args|
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# ...
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# end
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#
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# To prevent that block from being called anymore, just unsubscribe passing
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# that reference:
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#
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# ActiveSupport::Notifications.unsubscribe(subscriber)
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#
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# You can also unsubscribe by passing the name of the subscriber object. Note
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# that this will unsubscribe all subscriptions with the given name:
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#
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# ActiveSupport::Notifications.unsubscribe("render")
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#
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# Subscribers using a regexp or other pattern-matching object will remain subscribed
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# to all events that match their original pattern, unless those events match a string
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# passed to `unsubscribe`:
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#
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# subscriber = ActiveSupport::Notifications.subscribe(/render/) { }
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# ActiveSupport::Notifications.unsubscribe('render_template.action_view')
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# subscriber.matches?('render_template.action_view') # => false
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# subscriber.matches?('render_partial.action_view') # => true
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#
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# == Default Queue
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#
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# Notifications ships with a queue implementation that consumes and publishes events
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# to all log subscribers. You can use any queue implementation you want.
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#
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module Notifications
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class << self
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attr_accessor :notifier
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def publish(name, *args)
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notifier.publish(name, *args)
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end
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def instrument(name, payload = {})
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if notifier.listening?(name)
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instrumenter.instrument(name, payload) { yield payload if block_given? }
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else
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yield payload if block_given?
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end
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end
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# Subscribe to a given event name with the passed +block+.
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#
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# You can subscribe to events by passing a String to match exact event
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# names, or by passing a Regexp to match all events that match a pattern.
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#
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# ActiveSupport::Notifications.subscribe(/render/) do |*args|
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# @event = ActiveSupport::Notifications::Event.new(*args)
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# end
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#
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# The +block+ will receive five parameters with information about the event:
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#
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# ActiveSupport::Notifications.subscribe('render') do |name, start, finish, id, payload|
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# name # => String, name of the event (such as 'render' from above)
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# start # => Time, when the instrumented block started execution
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# finish # => Time, when the instrumented block ended execution
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# id # => String, unique ID for the instrumenter that fired the event
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# payload # => Hash, the payload
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# end
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#
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# If the block passed to the method only takes one parameter,
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# it will yield an event object to the block:
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#
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# ActiveSupport::Notifications.subscribe(/render/) do |event|
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# @event = event
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# end
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def subscribe(pattern = nil, callback = nil, &block)
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notifier.subscribe(pattern, callback, monotonic: false, &block)
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end
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def monotonic_subscribe(pattern = nil, callback = nil, &block)
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notifier.subscribe(pattern, callback, monotonic: true, &block)
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end
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def subscribed(callback, pattern = nil, monotonic: false, &block)
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subscriber = notifier.subscribe(pattern, callback, monotonic: monotonic)
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yield
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ensure
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unsubscribe(subscriber)
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end
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def unsubscribe(subscriber_or_name)
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notifier.unsubscribe(subscriber_or_name)
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end
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def instrumenter
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InstrumentationRegistry.instance.instrumenter_for(notifier)
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end
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end
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# This class is a registry which holds all of the +Instrumenter+ objects
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# in a particular thread local. To access the +Instrumenter+ object for a
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# particular +notifier+, you can call the following method:
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#
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# InstrumentationRegistry.instrumenter_for(notifier)
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#
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# The instrumenters for multiple notifiers are held in a single instance of
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# this class.
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class InstrumentationRegistry # :nodoc:
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extend ActiveSupport::PerThreadRegistry
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def initialize
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@registry = {}
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end
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def instrumenter_for(notifier)
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@registry[notifier] ||= Instrumenter.new(notifier)
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end
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end
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self.notifier = Fanout.new
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end
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end
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