Reader-writer locks
A reader-writer lock is a synchronization construct that allows multiple threads to read shared data concurrently, while ensuring exclusive access for a thread that needs to write. It supports two types of locking:
- Read lock: Multiple threads can acquire the read lock simultaneously, as long as no thread holds the write lock.
- Write lock: Only one thread can hold the write lock at a time, and no other thread (reader or writer) may hold the lock concurrently.
Reader-writer locks typically expose two distinct interfaces — one for acquiring and releasing the read lock, and one for the write lock — with internal coordination to ensure mutual exclusion between readers and writers when necessary.