Class: PeriodicScheduler

Inherits:
Object
  • Object
show all
Defined in:
lib/periodic-scheduler.rb

Defined Under Namespace

Classes: EmptyScheduleError, Event, MissedScheduleError, RealTimeToQuantizedSpaceProjection

Instance Method Summary collapse

Constructor Details

#initialize(quantum = 5.0, options = {}) ⇒ PeriodicScheduler

Returns a new instance of PeriodicScheduler.



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# File 'lib/periodic-scheduler.rb', line 82

def initialize(quantum = 5.0, options = {})
  time_source = (options[:time_source] or lambda {Time.now.to_f})
  wait_function = (options[:wait_function] or lambda{|t| sleep t})

  @quantized_space = RealTimeToQuantizedSpaceProjection.new(
    quantum,
    lambda {|v| v.ceil} # behave like sleep - never execute too early
  )
  @time_source = time_source
  @wait_function = wait_function

  @events = {}
end

Instance Method Details

#after(period, &callback) ⇒ Object 



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# File 'lib/periodic-scheduler.rb', line 96

def after(period, &callback)
	schedule_event Event.new(@quantized_space, real_now, period, false, &callback)
end

#empty? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/periodic-scheduler.rb', line 156

def empty?
@events.empty?
end

#every(period, &callback) ⇒ Object 



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# File 'lib/periodic-scheduler.rb', line 100

def every(period, &callback)
	schedule_event Event.new(@quantized_space, real_now, period, true, &callback)
end

#run ⇒ Object

Raises:



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# File 'lib/periodic-scheduler.rb', line 113

def run
earliest_quant = @events.keys.sort.first
raise EmptyScheduleError, "no events scheduled" unless earliest_quant

  wait_time = @quantized_space.revers_project(earliest_quant) - real_now
wait_time = 0 if wait_time < 0
  wait(wait_time)

objects = []

  qnow = quantized_now

# move quants to be run away to separate array
  quants = @events.keys.select{|k| k <= qnow}.sort.map{|q| @events.delete(q)}

# we have missed one or more scheduled quants
if quants.length > 1
    begin
      # we raise it so it has proper backtrace
      raise MissedScheduleError.new("missed schedule by #{-wait_time} seconds")
    rescue StandardError => error
		yield error if block_given?
    end
  end

# Call callback for every quant and reschedule if needed
  quants.each do |events|
	# get all events for quantum that are not stopped
    events.each do |e|
      begin
        objects << e.call
      rescue StandardError => error
			# Yield errors to block
			yield error if block_given?
      end
      e.reschedule(quantized_now) if e.keep? and not e.stopped?
    end
  end

# return collected callabck return objects
objects
end

#run!(&block) ⇒ Object 



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# File 'lib/periodic-scheduler.rb', line 104

def run!(&block)
  begin
    loop do
      run(&block)
    end
  rescue EmptyScheduleError
  end
end