Class: SizedQueue

Inherits:
Queue
  • Object
show all
Defined in:
lib/thread.rb,
thread.c,
thread.c

Overview

This class represents queues of specified size capacity. The push operation may be blocked if the capacity is full.

See Queue for an example of how a SizedQueue works.

Instance Method Summary collapse

Methods inherited from Queue

#clear, #empty?, #length, #marshal_dump, #marshal_load

Constructor Details

#max=(size) ⇒ Object

Sets the maximum size of the queue.



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# File 'lib/thread.rb', line 374

def initialize(max)
  raise ArgumentError, "queue size must be positive" unless max > 0
  @max = max
  @queue_wait = []
  @queue_wait.taint		# enable tainted comunication
  super()
end

Instance Method Details

#max ⇒ Object

Returns the maximum size of the queue.



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# File 'lib/thread.rb', line 385

def max
  @max
end

#max=(size) ⇒ Object

Sets the maximum size of the queue.



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# File 'lib/thread.rb', line 392

def max=(max)
  Thread.critical = true
  if max <= @max
    @max = max
    Thread.critical = false
  else
    diff = max - @max
    @max = max
    Thread.critical = false
    diff.times do
	begin
 t = @queue_wait.shift
 t.run if t
	rescue ThreadError
 retry
	end
    end
  end
  max
end

#num_waiting ⇒ Object

Returns the number of threads waiting on the queue.



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# File 'lib/thread.rb', line 473

def num_waiting
  @waiting.size + @queue_wait.size
end

#pop(*args) ⇒ Object Also known as: shift, deq

call_seq: pop(non_block=false)

Retrieves data from the queue. If the queue is empty, the calling thread is suspended until data is pushed onto the queue. If non_block is true, the thread isn’t suspended, and an exception is raised.



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# File 'lib/thread.rb', line 440

def pop(*args)
  retval = super
  Thread.critical = true
  if @que.length < @max
    begin
	t = @queue_wait.shift
	t.wakeup if t
    rescue ThreadError
	retry
    ensure
	Thread.critical = false
    end
    begin
	t.run if t
    rescue ThreadError
    end
  end
  retval
end

#push(obj) ⇒ Object Also known as: <<, enq

Pushes obj to the queue.



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# File 'lib/thread.rb', line 417

def push(obj)
  Thread.critical = true
  while @que.length >= @max
    @queue_wait.push Thread.current
    Thread.stop
    Thread.critical = true
  end
  super
end