Class: AsyncEmitter

Inherits:
Object
  • Object
show all
Defined in:
lib/async_emitter.rb

Overview

The AsyncEmitter class provides a mechanism for asyncronous communication in Ruby programs. Each instantiation provides notification of events registered using any object that is valid as a Hash key. Multiple events can be registered for each key and listeners can be registered for one or many events. Listeners for a key event can be released.

Where more then one listener is registered for an event they are notified in the order they are recieved.

Example

emitter = AsyncEmitter.new
emitter.on :error, lambda { |e| puts "Error: #{e}" }
emitter.on :data, lambda { |data| puts "Data: #{data}" }

begin
    data = get_data_from_somewhere
    emitter.emit :data, data
rescue Exception => e
    emitter.emit :error, e
end

Author:

  • Greg Martin

Instance Method Summary collapse

Constructor Details

#initialize ⇒ AsyncEmitter

Returns a new instance of AsyncEmitter.



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# File 'lib/async_emitter.rb', line 30

def initialize
	@emissions = {}
end

Instance Method Details

#emit(token, data) ⇒ Object

Send notification of an event

#####################################################################

Parameters:

  • token (Object) —

    the Hash key representing the event

  • data (Object) —

    argument to be passed to the events procedure



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# File 'lib/async_emitter.rb', line 87

def emit (token, data)
	@emissions[token][:semaphore] ||= Mutex.new
	@emissions[token][:cv] ||= ConditionVariable.new 
	@emissions[token][:data] ||= []

	@emissions[token][:semaphore].synchronize do
		@emissions[token][:data].push data
		@emissions[token][:cv].signal
	end

end

#on(token, p, once_only = false) ⇒ Object

Register for notification

######################################################################

Parameters:

  • token (Object) —

    any valid Hash key representing the event

  • p (Proc) —

    a procedure to be called on notification

  • once_only (Boolean) (defaults to: false) —

    defualts to false, if true the notification is removed after being fired once



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# File 'lib/async_emitter.rb', line 42

def on (token, p, once_only=false)
	@emissions[token] ||= {}
	@emissions[token][:p] ||= []
	@emissions[token][:data] ||= []
	@emissions[token][:semaphore] ||= Mutex.new
	@emissions[token][:cv] ||= ConditionVariable.new 
	
	@emissions[token][:p].push Hash[:p => p, :o => once_only]

	@emissions[token][:thread] ||= Thread.new do
		
		@emissions[token][:active] = true
		
		while @emissions[token][:active]
			@emissions[token][:semaphore].synchronize do
				self.post_data_for token
				@emissions[token][:cv].wait @emissions[token][:semaphore]
				if @emissions[token][:active]
					self.post_data_for token
				end
			end
		end

	end

end

#once(token, p) ⇒ Object

Register for single notification - convenience and self documenting method for: on token, proc, true

######################################################################

Parameters:

  • token (Object) —

    any valid Hash key representing the event

  • p (Proc) —

    a procedure to be called on notification



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# File 'lib/async_emitter.rb', line 76

def once (token, p)
	self.on token, p, true
end

#release(token) ⇒ Object

Remove notification for an event

Parameters:

  • token (Object) —

    Hash key representing the event



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# File 'lib/async_emitter.rb', line 105

def release (token)
	@emissions[token][:active] = false
	Thread.kill @emissions[token][:thread]
end

#release_all ⇒ Object

Remove all notifications



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# File 'lib/async_emitter.rb', line 113

def release_all 
	@emissions.each do |key, value|
		value[:active] = false
		Thread.kill value[:thread]
	end
end