Reader-writer lock allowing multiple concurrent readers or one exclusive writer.

Example

{ RwLock } :: import "std/sync/rwlock";

lock := RwLock.new();
// Multiple readers can hold the lock simultaneously
lock.read_lock();
// ... read shared data ...
lock.read_unlock();

// Only one writer at a time, blocks all readers
lock.write_lock();
// ... write shared data ...
lock.write_unlock();