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rails--rails/activesupport/lib/active_support/notifications.rb

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require 'thread'
module ActiveSupport
# Notifications provides an instrumentation API for Ruby. To instrument an action
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# in Ruby you just need to:
#
# ActiveSupport::Notifications.instrument(:render, :extra => :information) do
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# render :text => "Foo"
# end
#
# Those actions are consumed by listeners. A listener is anything that responds
# to push. You can even register an array:
#
# @listener = []
# ActiveSupport::Notifications.register @listener
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#
# ActiveSupport::Notifications.instrument(:render, :extra => :information) do
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# render :text => "Foo"
# end
#
# event #=> ActiveSupport::Notifications::Event
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# event.name #=> :render
# event.duration #=> 10 (in miliseconds)
# event.result #=> "Foo"
# event.payload #=> { :extra => :information }
#
# Notifications ships with a default listener implementation which puts events in
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# a stream and consume them in a Thread. This implementation is thread safe
# and is available at ActiveSupport::Notifications::Listener.
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#
module Notifications
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@stacked_events = Hash.new { |h,k| h[k] = [] }
@listeners = []
def self.instrument(name, payload=nil)
stack = @stacked_events[Thread.current.object_id]
event = Event.new(name, stack.last, payload)
stack << event
event.result = yield
event
ensure
event.finish!
stack.delete(event)
@listeners.each { |s| s.push(event) }
end
def self.register(listener)
@listeners << listener
end
def self.unregister(listener)
@listeners.delete(listener)
end
class Event
attr_reader :name, :time, :duration, :parent, :thread_id, :payload
attr_accessor :result
def initialize(name, parent=nil, payload=nil)
@name = name
@time = Time.now
@thread_id = Thread.current.object_id
@parent = parent
@payload = payload
end
def finish!
@duration = 1000 * (Time.now.to_f - @time.to_f)
end
end
class Listener
attr_reader :mutex, :signaler, :thread
def initialize
@mutex, @signaler = Mutex.new, ConditionVariable.new
@stream = []
@thread = Thread.new do
loop do
(event = @stream.shift) ? consume(event) : wait
end
end
end
def wait
@mutex.synchronize do
@signaler.wait(@mutex)
end
end
def push(event)
@mutex.synchronize do
@stream.push(event)
@signaler.broadcast
end
end
def consume(event)
raise NotImplementedError
end
end
end
end