Class: God::DriverEventQueue

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

Overview

The DriverEventQueue is a simple queue that holds TimedEvent instances in order to maintain the schedule of upcoming events.

Instance Method Summary collapse

Constructor Details

#initialize ⇒ DriverEventQueue

Initialize a DriverEventQueue.



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# File 'lib/god/driver.rb', line 92

def initialize
  @shutdown = false
  @events = []
  @monitor = Monitor.new
  @resource = @monitor.new_cond
end

Instance Method Details

#clear ⇒ Object

Clear the queue.

Returns nothing.



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# File 'lib/god/driver.rb', line 151

def clear
  @events.clear
end

#empty? ⇒ Boolean

Returns true if the queue is empty, false if not.

Returns:

  • (Boolean) 


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# File 'lib/god/driver.rb', line 144

def empty?
  @events.empty?
end

#length ⇒ Object Also known as: size

Returns the Integer length of the queue.



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# File 'lib/god/driver.rb', line 156

def length
  @events.length
end

#pop ⇒ Object

Wait until the queue has something due, pop it off the queue, and return it.

Returns the popped event.



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# File 'lib/god/driver.rb', line 113

def pop
  @monitor.synchronize do
    if @events.empty?
      raise ThreadError, 'queue empty' if @shutdown

      @resource.wait
    else
      delay = @events.first.at - Time.now
      @resource.wait(delay) if delay > 0
    end

    @events.shift
  end
end

#push(event) ⇒ Object

Add an event to the queue, wake any waiters if what we added needs to happen sooner than the next pending event.

Returns nothing.



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# File 'lib/god/driver.rb', line 132

def push(event)
  @monitor.synchronize do
    @events << event
    @events.sort!

    # If we've sorted the events and found the one we're adding is at
    # the front, it will likely need to run before the next due date.
    @resource.signal if @events.first == event
  end
end

#shutdown ⇒ Object

Wake any sleeping threads after setting the sentinel.

Returns nothing.



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# File 'lib/god/driver.rb', line 102

def shutdown
  @shutdown = true
  @monitor.synchronize do
    @resource.broadcast
  end
end