class Queue

This class provides a way to synchronize communication between threads.

Example:

require 'thread'

queue = Queue.new

producer = Thread.new do
  5.times do |i|
    sleep rand(i) # simulate expense
    queue << i
    puts "#{i} produced"
  end
end

consumer = Thread.new do
  5.times do |i|
    value = queue.pop
    sleep rand(i/2) # simulate expense
    puts "consumed #{value}"
  end
end

consumer.join

Public Class Methods

new() click to toggle source

Creates a new queue.

# File lib/thread.rb, line 150
def initialize
  @que = []
  @que.taint          # enable tainted communication
  @num_waiting = 0
  self.taint
  @mutex = Mutex.new
  @cond = ConditionVariable.new
end

Public Instance Methods

<<(obj)

Alias of push

Alias for: push

clear() click to toggle source

Removes all objects from the queue.

# File lib/thread.rb, line 229
def clear
  @que.clear
end

deq(non_block=false)

Alias of pop

Alias for: pop

empty?() click to toggle source

Returns true if the queue is empty.

# File lib/thread.rb, line 222
def empty?
  @que.empty?
end

enq(obj)

Alias of push

Alias for: push

length() click to toggle source

Returns the length of the queue.

# File lib/thread.rb, line 236
def length
  @que.length
end

Also aliased as: size

num_waiting() click to toggle source

Returns the number of threads waiting on the queue.

# File lib/thread.rb, line 248
def num_waiting
  @num_waiting
end

pop(non_block=false) click to toggle source

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.

# File lib/thread.rb, line 186
def pop(non_block=false)
  Thread.handle_interrupt(StandardError => :on_blocking) do
    @mutex.synchronize do
      while true
        if @que.empty?
          if non_block
            raise ThreadError, "queue empty"
          else
            begin
              @num_waiting += 1
              @cond.wait @mutex
            ensure
              @num_waiting -= 1
            end
          end
        else
          return @que.shift
        end
      end
    end
  end
end

Also aliased as: shift, deq

push(obj) click to toggle source

Pushes obj to the queue.

# File lib/thread.rb, line 162
def push(obj)
  Thread.handle_interrupt(StandardError => :on_blocking) do
    @mutex.synchronize do
      @que.push obj
      @cond.signal
    end
  end
end

Also aliased as: <<, enq

shift(non_block=false)

Alias of pop

Alias for: pop

size()

Alias of length.

Alias for: length