Motivation
AbstractReferenceCounted and AbstractReferenceCountedByteBuf contain
duplicate logic for managing the volatile refcount in an optimized and
consistent manner, which increased in complexity in #8583. It's possible
to extract this into a common helper class now that all access is via an
AtomicIntegerFieldUpdater.
Modifications
- Move duplicate logic into a shared ReferenceCountUpdater class
- Incorporate some additional simplification for the most common single
increment/decrement cases (fewer checks/operations)
Result
Less code duplication, better encapsulation of the "non-trivial"
internal volatile refcount manipulation