Adds a new top-level subscribe/unsubscribe which will ref/unref the
channel WeakReference to prevent subscriptions from getting garbage
collected.
PR-URL: https://github.com/nodejs/node/pull/42714
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Chengzhong Wu <legendecas@gmail.com>
Reviewed-By: Gerhard Stöbich <deb2001-github@yahoo.de>
Reviewed-By: Rafael Gonzaga <rafael.nunu@hotmail.com>
Reviewed-By: Vladimir de Turckheim <vlad2t@hotmail.com>
