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
Methods
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Class Public methods
new()

Creates a new queue instance.

static VALUE
rb_queue_initialize(VALUE self)
{
    RSTRUCT_SET(self, QUEUE_QUE, ary_buf_new());
    RSTRUCT_SET(self, QUEUE_WAITERS, ary_buf_new());
    return self;
}
Instance Public methods
<<(p1)

Alias for push.

Alias for: push
clear()

Removes all objects from the queue.

static VALUE
rb_queue_clear(VALUE self)
{
    rb_ary_clear(GET_QUEUE_QUE(self));
    return self;
}
close

Closes the queue. A closed queue cannot be re-opened.

After the call to close completes, the following are true:

  • closed? will return true

  • close will be ignored.

  • calling enq/push/<< will return nil.

  • when empty? is false, calling deq/pop/shift will return an object from the queue as usual.

ClosedQueueError is inherited from StopIteration, so that you can break loop block.

Example:

    q = Queue.new
    Thread.new{
      while e = q.deq # wait for nil to break loop
        # ...
      end
    }
    q.close
static VALUE
rb_queue_close(VALUE self)
{
    return queue_do_close(self, FALSE);
}
closed?

Returns true if the queue is closed.

static VALUE
rb_queue_closed_p(VALUE self)
{
    return queue_closed_p(self) ? Qtrue : Qfalse;
}
deq(*args)

Alias for push.

Alias for: pop
empty?

Returns true if the queue is empty.

static VALUE
rb_queue_empty_p(VALUE self)
{
    return queue_length(self) == 0 ? Qtrue : Qfalse;
}
enq(p1)
Alias for: push
length
size

Returns the length of the queue.

Also aliased as: size
static VALUE
rb_queue_length(VALUE self)
{
    unsigned long len = queue_length(self);
    return ULONG2NUM(len);
}
num_waiting()

Returns the number of threads waiting on the queue.

static VALUE
rb_queue_num_waiting(VALUE self)
{
    unsigned long len = queue_num_waiting(self);
    return ULONG2NUM(len);
}
pop(non_block=false)
deq(non_block=false)
shift(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.

Also aliased as: deq, shift
static VALUE
rb_queue_pop(int argc, VALUE *argv, VALUE self)
{
    int should_block = queue_pop_should_block(argc, argv);
    return queue_do_pop(self, should_block);
}
push(object)
enq(object)
<<(object)

Pushes the given object to the queue.

Also aliased as: enq, <<
static VALUE
rb_queue_push(VALUE self, VALUE obj)
{
    return queue_do_push(self, obj);
}
shift(*args)

Alias for pop.

Alias for: pop
size()

Alias for pop.

Alias for: length