Class: QueueWithTimeout

Inherits:
Object
  • Object
show all
Defined in:
lib/signalfx/signalflow/queue.rb

Overview

Borrowed from spin.atomicobject.com/2017/06/28/queue-pop-with-timeout-fixed/

Instance Method Summary collapse

Constructor Details

#initialize ⇒ QueueWithTimeout

Returns a new instance of QueueWithTimeout.



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# File 'lib/signalfx/signalflow/queue.rb', line 7

def initialize
  @mutex = Mutex.new
  @queue = []
  @received = ConditionVariable.new
end

Instance Method Details

#<<(x) ⇒ Object 



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# File 'lib/signalfx/signalflow/queue.rb', line 13

def <<(x)
  @mutex.synchronize do
    @queue << x
    @received.signal
  end
end

#pop(non_block = false) ⇒ Object 



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# File 'lib/signalfx/signalflow/queue.rb', line 20

def pop(non_block = false)
  pop_with_timeout(non_block ? 0 : nil)
end

#pop_with_timeout(timeout = nil) ⇒ Object 



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# File 'lib/signalfx/signalflow/queue.rb', line 24

def pop_with_timeout(timeout = nil)
  @mutex.synchronize do
    if timeout.nil?
      # wait indefinitely until there is an element in the queue
      while @queue.empty?
        @received.wait(@mutex)
      end
    elsif @queue.empty? && timeout != 0
      # wait for element or timeout
      timeout_time = timeout + Time.now.to_f
      while @queue.empty? && (remaining_time = timeout_time - Time.now.to_f) > 0
        @received.wait(@mutex, remaining_time)
      end
    end
    #if we're still empty after the timeout, raise exception
    raise ThreadError, "queue empty" if @queue.empty?
    @queue.shift
  end
end