Expand description
SharedRWLock - cross-process reader-writer lock with writer
priority.
Multiple concurrent readers OR exactly one writer. When a writer is waiting, new readers block to prevent writer starvation.
§State encoding
ONE AtomicU64 packed:
- bit 63: writer active (1 if a writer holds the lock)
- bits 32-62: writers waiting count (31 bits)
- bits 0-31: reader count (32 bits)
All transitions are single CAS so observers never see torn state.