From: headius@...
Date: 2015-12-19T15:29:27+00:00
Subject: [ruby-core:72387] [Ruby trunk - Bug #11822] Semantics of Queue#pop after close are wrong

Issue #11822 has been updated by Charles Nutter.


Clarifying my statements above:

"So we should bump this to to Ruby 2.4 to address the inability to check for closed? and pop at the same time, as in Go."

I mean we should discuss further API improvements like Queue#pop! or pop? for Ruby 2.4.

"This can go forward in 2.3."

I mean current #close, #closed?, #push, and #pop changes can go forward as they are implemented on trunk today.

----------------------------------------
Bug #11822: Semantics of Queue#pop after close are wrong
https://bugs.ruby-lang.org/issues/11822#change-55676

* Author: Charles Nutter
* Status: Open
* Priority: Normal
* Assignee: Koichi Sasada
* ruby -v: 
* Backport: 2.0.0: UNKNOWN, 2.1: UNKNOWN, 2.2: UNKNOWN
----------------------------------------
Current test/ruby/thread/test_queue.rb test_close has the following assertion that seems wrong to me:

```ruby
  def test_close
    [->{Queue.new}, ->{SizedQueue.new 3}].each do |qcreate|
      q = qcreate.call
      assert_equal false, q.closed?
      q << :something
      assert_equal q, q.close
      assert q.closed?
      assert_raise_with_message(ClosedQueueError, /closed/){q << :nothing}
      assert_equal q.pop, :something  # <<< THIS ONE
      assert_nil q.pop
      assert_nil q.pop
      # non-blocking
      assert_raise_with_message(ThreadError, /queue empty/){q.pop(non_block=true)}
    end
  end
```

Once a queue is closed, I don't think it should ever return a result anymore. The queue should be cleared and pop should always return nil.

In r52691, ko1 states that "deq'ing on closed queue returns nil, always." This test does not match that behavior.



-- 
https://bugs.ruby-lang.org/