Deprecate reporting methods for silencing output as they aren't thread safe

[tommeier]

As per #13139, this is the deprecation warning methods for these thread unsafe methods.

[carlosantoniodasilva]

There are some test failures, and a lot of deprecations in our own test suite 😢. If I got it right, we would keep using that in our own tests, but deprecate as public API, right? So we'll have to cleanup the deprecations in our own tests somehow.

@tommeier mind taking a look at the failures? Maybe we would need to copy these to a test helper or something like that to use on our tests, and leave the public ones deprecated.

[tommeier]

Happy to do so @carlosantoniodasilva :) All the failures are just the additional output including deprecation warnings. Where would be a good spot for a test_helper? Considering that we'd want to use the methods in railties and active support (for example), is there a good shared spot?

[rafaelfranca]

Merged at 1fbb5c1...3121412

[bf4]

Is there going to be something to replace this? Some of this code is also duplicated elsewhere in the codebase without the deprecation. I'm not sure why e.g. railties/test/isolation_abstract_unit.rb implements it's own capture.

Also, wouldn't the below be thread-safe due to how it uses pipes and threads? (untested assertion). silencing would just be a matter of not returning the captured output.

    # From episode 029 of Ruby Tapas by Avdi
    # https://rubytapas.dpdcart.com/subscriber/post?id=88
    def capture_output(stream=STDOUT, &block)
      old_stdout = stream.clone
      pipe_r, pipe_w = IO.pipe
      pipe_r.sync    = true
      output         = ""
      reader = Thread.new do
        begin
          loop do
            output << pipe_r.readpartial(1024)
          end
        rescue EOFError
        end
      end
      stream.reopen(pipe_w)
      yield
    ensure
      stream.reopen(old_stdout)
      pipe_w.close
      reader.join
      pipe_r.close
      return output
    end

or e.g. https://github.com/rubygems/rubygems/blob/dd7ca9b2c321f7/lib/rubygems/util.rb#L74

  NULL_DEVICE = defined?(IO::NULL) ? IO::NULL : Gem.win_platform? ? 'NUL' : '/dev/null'

  def self.silent_system(null_device=NULL_DEVICE,&block)
    require 'thread'

    @silent_mutex ||= Mutex.new

    @silent_mutex.synchronize do
      begin
        stdout = STDOUT.dup
        stderr = STDERR.dup

        STDOUT.reopen null_device, 'w'
        STDERR.reopen null_device, 'w'

        return yield
      ensure
        STDOUT.reopen stdout
        STDERR.reopen stderr
        stdout.close
        stderr.close
      end
    end
  end

[rafaelfranca]

Is there going to be something to replace this?

No.

Some of this code is also duplicated elsewhere in the codebase without the deprecation.

Yes, it is duplicated because the framework still need these methods but we don't want to make them available for the users.

[bf4]

Thanks :)

[pboling]

@bf4 I have extracted the silence stream functionality into a standalone gem called silent_stream. Should ease the migration from Rails <= 4 to Rails >= 5 for some projects. Also can be used outside Rails.