Abortable Reader-Writer Locks are No More Complex Than Abortable Mutex Locks

When a process attempts to acquire a mutex lock, it may be forced to wait if another process currently holds the lock. In certain applications, such as real-time operating systems and databases, indefinite waiting can cause a process to miss an important deadline. Hence, there has been research on designing abortable mutual exclusion locks, and fairly efficient algorithms of O(log n) RMR complexity have been discovered (n denotes the number of processes for which the algorithm is designed). The abort feature is just as important for a reader-writer lock as it is for a mutual exclusion lock, but to the best of our knowledge there are currently no abortable reader-writer locks that are starvation-free. We show the surprising result that any abortable, starvation-free mutual exclusion algorithm of RMR complexity t(n) can be transformed into an abortable, starvation-free reader-writer exclusion algorithm of RMR complexity O(t(n)). Thus, we obtain the first abortable, starvation-free reader-writer exclusion algorithm of O(log n) RMR complexity. Our results apply to the Cache-Coherent (CC) model of multiprocessors