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require 'timeout'

class Thread

# Thread::Queue is thread safe a FIFO queue. It provdies a way to synchronize

# communication between threads. This queue does not block when items are

# removed (see Thread::Queue#remove)

#

# This queue does not allow nil elements.

class Queue

class NoSuchElementError < StandardError

end

include Enumerable

#

# Creates a new queue.

#

def initialize

@que = []

@que.taint # enable tainted communication

self.taint

@mutex = Mutex.new

end

def each(&block)

@que.each(&block)

end

#

# Adds +obj+ to the head of the queue.

#

# Raises an ArgumentError if +obj+ is nil.

#

def add(obj)

raise(ArgumentError, 'nil is not allowed in this queue') if obj.nil?

@mutex.synchronize { @que.push obj }

self

end

alias :push :add

alias :<< :add

def offer(obj, timeout = nil)

add obj

end

# Retrieves data from the queue head, and removes it.

#

# Raises a NoSuchElementError if the queue is empty.

def remove

@mutex.synchronize {

raise NoSuchElementError if empty?

@que.shift

}

end

alias :pop :remove

alias :shift :remove

alias :deq :remove

# Retrieves data from the queue head, and removes it.

#

# Returns nil if this queue is empty.

def poll

@mutex.synchronize {

if empty?

nil

else

@que.shift

end

}

end

# Retrieves data from the queue head, but does not removes it.

#

# Returns nil if the queue is empty

def peek

@mutex.synchronize { @que.first }

end

alias :first :peek

# Retrieves data from the queue head, but does not removes it.

#

# Raises NoSuchElementError if the queue is empty.

def element

@mutex.synchronize {

if empty?

raise NoSuchElementError

else

@que.first

end

}

end

#

# Returns +true+ if the queue is empty.

#

def empty?

@que.empty?

end

#

# Removes all objects from the queue.

#

def clear

@que.clear

end

#

# Returns the length of the queue.

#

def length

@que.length

end

alias :size :length

end

# Thread::Queue is thread safe a FIFO queue. It provdies a way to synchronize

# communication between threads.

#

# This queue does not allow nil elements.

class BlockingQueue < Queue

def initialize

@waiting = []

@waiting.taint

super

end

# Retrieves data from the queue head, and removes it.

#

# If the queue is empty, remove will block until there is something

# in the queue.

def take

@mutex.synchronize {

while true

if @que.empty?

# @waiting.include? check is necessary for avoiding a race against

# Thread.wakeup [Bug 5195]

@waiting.push Thread.current unless @waiting.include?(Thread.current)

@mutex.sleep

else

return @que.shift

end

end

}

end

alias :pop :take

alias :shift :take

alias :deq :take

# Adds +obj+ to the head of the queue.

#

# Raises an ArgumentError if +obj+ is nil.

#

def add(obj)

raise ArgumentError if obj.nil?

@mutex.synchronize {

@que.push obj

begin

t = @waiting.shift

t.wakeup if t

rescue ThreadError

retry

end

}

self

end

alias :push :add

alias :<< :add

# Retrieves data from the queue head, and removes it.

#

# Blocks for +timeout+ seconds if the queue is empty, and returns nil if

# the timeout expires.

def poll(timeout = nil)

return super() unless timeout

begin

Timeout.timeout(timeout) do

take

end

rescue TimeoutError

nil

end

end

end

end

require 'minitest/autorun'

require 'thread/queue'

class Thread

class TestCase < MiniTest::Unit::TestCase

class Latch

def initialize

@mutex = Mutex.new

@cond = ConditionVariable.new

end

def release

@mutex.synchronize { @cond.broadcast }

end

def await

@mutex.synchronize { @cond.wait @mutex }

end

end

attr_reader :queue

POISON = Object.new

def grind(num_threads, num_objects, num_iterations, klass, *args)

from_workers = klass.new(*args)

to_workers = klass.new(*args)

to_consumers = num_threads.times.map {

Thread.new {

while object = to_workers.pop

break if object == POISON

from_workers.push object

end

}

}

from_consumer = Thread.new {

num_iterations.times {

num_objects.times { from_workers.pop }

}

}

num_iterations.times {

num_objects.times { to_workers.push 99 }

}

num_threads.times { to_workers.push POISON }

to_consumers.each { |t| t.join }

from_consumer.join

assert_equal 0, from_workers.size

assert_equal 0, to_workers.size

end

def non_block_grind(num_threads, num_objects, num_iterations, klass, *args)

from_workers = klass.new(*args)

to_workers = klass.new(*args)

to_latch = Latch.new

from_latch = Latch.new

to_consumers = num_threads.times.map {

Thread.new {

to_latch.await

while object = to_workers.pop

break if object == POISON

from_workers.push object

end

}

}

from_consumer = Thread.new {

from_latch.await

num_iterations.times {

num_objects.times { from_workers.pop }

}

}

num_iterations.times {

num_objects.times { to_workers.push 99 }

}

num_threads.times { to_workers.push POISON }

Thread.pass until to_consumers.all? { |c| c.status == "sleep" }

Thread.pass until from_consumer.status == "sleep"

to_latch.release

to_consumers.each { |t| t.join }

from_latch.release

from_consumer.join

assert_equal 0, from_workers.size

assert_equal 0, to_workers.size

end

end

end

require 'helper'

class Thread

class TestBlockingQueue < TestCase

attr_reader :queue

def setup

@queue = Thread::BlockingQueue.new

super

end

def test_add_returns_self

assert_equal queue, queue.add(1)

end

def test_queue

grind(5, 1000, 15, Thread::BlockingQueue)

end

def test_offer

assert queue.offer(1)

assert_equal 1, queue.length

end

def test_clear

10.times { |i| queue << i }

assert_equal 10, queue.length

queue.clear

assert_equal 0, queue.length

assert queue.empty?

end

def test_enumerable

10.times { |i| queue << i }

assert_equal 10.times.map { |i| i }, queue.to_a

list = []

queue.map { |x| list << x }

assert_equal 10.times.map { |i| i }, list

assert_equal 10.times.map { |i| i }, queue.to_a

refute_equal queue.to_a.object_id, queue.to_a.object_id

end

def test_add

queue.add "foo"

assert_equal "foo", queue.take

assert queue.empty?

end

def test_add_nil

assert_raises(ArgumentError) do

queue.add nil

end

end

def test_remove_empty

assert queue.empty?

t = Thread.new { queue.take }

queue << 1

assert_equal 1, t.join.value

end

def test_poll

queue.add "foo"

assert_equal "foo", queue.poll

end

def test_poll_empty

assert_nil queue.poll

end

def test_poll_timeout

assert_nil queue.poll(1)

t = Thread.new { queue.poll(10) }

queue << "foo"

assert_equal "foo", t.join.value

end

def test_peek

queue.add "foo"

assert_equal "foo", queue.peek

assert_equal "foo", queue.take

end

def test_first

queue.add "foo"

assert_equal "foo", queue.first

assert_equal "foo", queue.remove

end

def test_peek_empty

assert queue.empty?

assert_nil queue.peek

end

def test_element

queue.add "foo"

assert_equal "foo", queue.element

assert_equal "foo", queue.take

end

def test_element_empty

assert queue.empty?

assert_raises(Queue::NoSuchElementError) do

queue.element

end

end

end

end

require 'helper'

class Thread

class TestQueue < TestCase

alias :grind :non_block_grind

def setup

super

@queue = Thread::Queue.new

end

def test_queue

grind(5, 1000, 15, Thread::Queue)

end

def test_add_returns_self

assert_equal queue, queue.add(1)

end

def test_offer

assert queue.offer(1)

end

def test_clear

10.times { |i| queue << i }

assert_equal 10, queue.length

queue.clear

assert_equal 0, queue.length

assert queue.empty?

end

def test_enumerable

10.times { |i| queue << i }

assert_equal 10.times.map { |i| i }, queue.to_a

list = []

queue.map { |x| list << x }

assert_equal 10.times.map { |i| i }, list

assert_equal 10.times.map { |i| i }, queue.to_a

refute_equal queue.to_a.object_id, queue.to_a.object_id

end

def test_add

queue.add "foo"

assert_equal "foo", queue.remove

assert queue.empty?

end

def test_add_nil

assert_raises(ArgumentError) do

queue.add nil

end

end

def test_remove_empty

assert queue.empty?

assert_raises(Queue::NoSuchElementError) do

queue.remove

end

end

def test_poll

queue.add "foo"

assert_equal "foo", queue.poll

end

def test_poll_empty

assert_nil queue.poll

end

def test_peek

queue.add "foo"

assert_equal "foo", queue.peek

assert_equal "foo", queue.remove

end

def test_first

queue.add "foo"

assert_equal "foo", queue.first

assert_equal "foo", queue.remove

end

def test_peek_empty

assert queue.empty?

assert_nil queue.peek

end

def test_element

queue.add "foo"

assert_equal "foo", queue.element

assert_equal "foo", queue.remove

end

def test_element_empty

assert queue.empty?

assert_raises(Queue::NoSuchElementError) do

queue.element

end

end

def test_offer_optionally_takes_timeout

assert queue.empty?

queue.offer 0, 10

assert_equal 1, queue.length

end

end

end