Class: Collective::Idler

Inherits:
Object
  • Object
show all
Extended by:
Utilities
Defined in:
lib/collective/idler.rb

Overview

Idler wraps some other callable (a proc or object which responds to #call) The callable should return a falsy value when it did nothing, or a truthy value when it did something. The idler will sleep when there is nothing to do.

Defined Under Namespace

Modules: Utilities

Constant Summary collapse

MIN_SLEEP = 
0.125
MAX_SLEEP = 
1.0

Instance Attribute Summary collapse

Instance Method Summary collapse

Methods included from Utilities

wait_until

Constructor Details

#initialize(callable = nil, options = {}, &callable_block) ⇒ Idler

Returns a new instance of Idler.



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# File 'lib/collective/idler.rb', line 19

def initialize( callable = nil, options = {}, &callable_block )
  @callable = callable || callable_block
  raise unless @callable.respond_to?(:call)

  @max_sleep = options[:max_sleep] || MAX_SLEEP
  raise if @max_sleep <= 0

  @min_sleep = options[:min_sleep] || MIN_SLEEP
  raise if @min_sleep <= 0
  raise if @max_sleep < @min_sleep

  @sleep     = nil
end

Instance Attribute Details

#sleep ⇒ Object (readonly)

Returns the value of attribute sleep.



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# File 'lib/collective/idler.rb', line 17

def sleep
  @sleep
end

Instance Method Details

#call(*args, &block) ⇒ Object 



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# File 'lib/collective/idler.rb', line 33

def call( *args, &block )
  
  result = call_with_wakefulness( @callable, *args, &block )

  if result then
    wake
  else
    sleep_more
  end

  return result
end

#call_with_wakefulness(callable, *args, &block) ⇒ Object 



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# File 'lib/collective/idler.rb', line 46

def call_with_wakefulness( callable, *args, &block )
  begin
    callable.call(*args,&block)
  rescue Exception                          # when errors occur,
    @sleep = @min_sleep                     # reduce sleeping almost all the way (but not to 0)
    raise                                   # do not consume any exceptions
  end
end

#sleep_more ⇒ Object 



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# File 'lib/collective/idler.rb', line 55

def sleep_more
  if @sleep then
    @sleep = [ @sleep * 2, @max_sleep ].min
  else
    @sleep = @min_sleep
  end
  Kernel.sleep(@sleep) if @sleep          # Interrupt will propogate through sleep().
end

#wake ⇒ Object 



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# File 'lib/collective/idler.rb', line 64

def wake
  @sleep = nil
end