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Class: EventMachine::TickLoop

Relationships & Source Files
Inherits: Object
Defined in: lib/em/tick_loop.rb

Overview

A TickLoop is useful when one needs to distribute amounts of work throughout ticks in order to maintain response times. It is also useful for simple repeated checks and metrics.

Examples:

# Here we run through an array one item per tick until it is empty, 
# printing each element.
# When the array is empty, we return :stop from the callback, and the
# loop will terminate.
# When the loop terminates, the on_stop callbacks will be called.  
EM.run do
  array = (1..100).to_a

  tickloop = EM.tick_loop do
    if array.empty?
      :stop
    else
      puts array.shift
    end
  end

  tickloop.on_stop { EM.stop }
end

Class Method Summary

Instance Attribute Summary

Instance Method Summary

  • #on_stop(*a, &b)

    Arguments: A callback (EM::Callback) to call once on the next stop (or immediately if already stopped).

  • #start

    Start the tick loop, will raise argument error if the loop is already running.

  • #stop

    Stop the tick loop immediately, and call it's on_stop callbacks.

  • #schedule private

Constructor Details

.new(*a, &b) ⇒ TickLoop

Arguments: A callback (EM::Callback) to call each tick. If the call returns :stop then the loop will be stopped. Any other value is ignored.

[ GitHub ] 

  


# File 'lib/em/tick_loop.rb', line 35



def initialize(*a, &b)
  @work = EM::Callback(*a, &b)
  @stops = []
  @stopped = true
end


  







Instance Attribute Details



  

    #stopped?  ⇒ Boolean  (readonly)
  



  

    
Query if the loop is stopped.


  





  


  [ GitHub ]


  

  


# File 'lib/em/tick_loop.rb', line 60



def stopped?
  @stopped
end


  







Instance Method Details



  

    #on_stop(*a, &b)  
  



  

    
Arguments: A callback (EM::Callback) to call once on the next stop (or
immediately if already stopped).


  



  [ GitHub ]


  

  


# File 'lib/em/tick_loop.rb', line 43



def on_stop(*a, &b)
  if @stopped
    EM::Callback(*a, &b).call
  else
    @stops << EM::Callback(*a, &b)
  end
end


  








  

    #schedule   (private)
  

  [ GitHub ]


  

  


# File 'lib/em/tick_loop.rb', line 73



def schedule
  EM.next_tick do
    next if @stopped
    if @work.call == :stop
      stop
    else
      schedule
    end
  end
  self
end


  








  

    #start  
  



  

    
Start the tick loop, will raise argument error if the loop is already
running.


  





  
Raises:


    
  
  • 
    (ArgumentError)
  
    • 





  [ GitHub ]


  

  


# File 'lib/em/tick_loop.rb', line 66



def start
  raise ArgumentError, "double start" unless @stopped
  @stopped = false
  schedule
end


  








  

    #stop  
  



  

    
Stop the tick loop immediately, and call it's on_stop callbacks.


  



  [ GitHub ]


  

  


# File 'lib/em/tick_loop.rb', line 52



def stop
  @stopped = true
  until @stops.empty?
    @stops.shift.call
  end
end