369 lines
11 KiB
Ruby
369 lines
11 KiB
Ruby
module ActiveSupport
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remove_const :Notifications
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end
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module ActiveSupport
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module Notifications
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# Instrumentors are stored in a thread local.
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class Instrumenter
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attr_reader :id
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def initialize(notifier)
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@id = unique_id
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@notifier = notifier
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end
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# Instrument the given block by measuring the time taken to execute it
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# and publish it. Notice that events get sent even if an error occurs
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# in the passed-in block
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def instrument(name, payload={})
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@notifier.start(name, @id, payload)
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begin
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yield
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rescue Exception => e
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payload[:exception] = [e.class.name, e.message]
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raise e
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ensure
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@notifier.finish(name, @id, payload)
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end
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end
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private
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def unique_id
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SecureRandom.hex(10)
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end
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end
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class Event
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attr_reader :name, :time, :end, :transaction_id, :payload, :duration
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def initialize(name, start, ending, transaction_id, payload)
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@name = name
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@payload = payload.dup
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@time = start
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@transaction_id = transaction_id
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@end = ending
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@duration = 1000.0 * (@end - @time)
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end
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def parent_of?(event)
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start = (time - event.time) * 1000
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start <= 0 && (start + duration >= event.duration)
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end
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end
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end
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end
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module ActiveSupport
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module Notifications
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# This is a default queue implementation that ships with Notifications.
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# It just pushes events to all registered log subscribers.
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class Fanout
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def initialize
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@subscribers = []
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@listeners_for = {}
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end
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def subscribe(pattern = nil, block = Proc.new)
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subscriber = Subscribers.new pattern, block
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@subscribers << subscriber
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@listeners_for.clear
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subscriber
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end
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def unsubscribe(subscriber)
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@subscribers.reject! { |s| s.matches?(subscriber) }
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@listeners_for.clear
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end
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def start(name, id, payload)
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listeners_for(name).each { |s| s.start(name, id, payload) }
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end
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def finish(name, id, payload)
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listeners_for(name).each { |s| s.finish(name, id, payload) }
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end
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def publish(name, *args)
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listeners_for(name).each { |s| s.publish(name, *args) }
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end
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def listeners_for(name)
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@listeners_for[name] ||= @subscribers.select { |s| s.subscribed_to?(name) }
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end
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def listening?(name)
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listeners_for(name).any?
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end
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# This is a sync queue, so there is no waiting.
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def wait
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end
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module Subscribers # :nodoc:
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def self.new(pattern, listener)
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if listener.respond_to?(:call)
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subscriber = Timed.new pattern, listener
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else
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subscriber = Evented.new pattern, listener
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end
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unless pattern
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AllMessages.new(subscriber)
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else
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subscriber
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end
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end
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class Evented #:nodoc:
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def initialize(pattern, delegate)
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@pattern = pattern
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@delegate = delegate
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end
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def start(name, id, payload)
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@delegate.start name, id, payload
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end
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def finish(name, id, payload)
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@delegate.finish name, id, payload
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end
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def subscribed_to?(name)
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@pattern === name.to_s
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end
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def matches?(subscriber_or_name)
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self === subscriber_or_name ||
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@pattern && @pattern === subscriber_or_name
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end
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end
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class Timed < Evented
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def initialize(pattern, delegate)
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@timestack = Hash.new { |h,id|
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h[id] = Hash.new { |ids,name| ids[name] = [] }
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}
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super
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end
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def publish(name, *args)
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@delegate.call name, *args
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end
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def start(name, id, payload)
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@timestack[id][name].push Time.now
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end
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def finish(name, id, payload)
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started = @timestack[id][name].pop
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@delegate.call(name, started, Time.now, id, payload)
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end
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end
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class AllMessages # :nodoc:
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def initialize(delegate)
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@delegate = delegate
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end
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def start(name, id, payload)
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@delegate.start name, id, payload
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end
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def finish(name, id, payload)
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@delegate.finish name, id, payload
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end
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def publish(name, *args)
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@delegate.publish name, *args
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end
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def subscribed_to?(name)
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true
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end
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alias :matches? :===
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end
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end
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end
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end
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end
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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 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 text: "Foo"
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# end
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#
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# That executes the block first and 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. 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 will be called asynchronously whenever someone instruments "render":
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#
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# ActiveSupport::Notifications.instrument("render", extra: :information) do
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# render text: "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
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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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#
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# As the previous 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 as the second parameter passed to the
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# <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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# === 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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# == Default Queue
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#
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# Notifications ships with a queue implementation that consumes and publish events
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# to log subscribers in a thread. You can use any queue implementation you want.
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#
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module Notifications
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@instrumenters = Hash.new { |h,k| h[k] = notifier.listening?(k) }
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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 @instrumenters[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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def subscribe(*args, &block)
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notifier.subscribe(*args, &block).tap do
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@instrumenters.clear
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end
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end
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def subscribed(callback, *args, &block)
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subscriber = subscribe(*args, &callback)
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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(args)
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notifier.unsubscribe(args)
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@instrumenters.clear
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end
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def instrumenter
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Thread.current[:"instrumentation_#{notifier.object_id}"] ||= 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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