ReadWriteLock

For this homework, you will create a conditional read write lock and a thread safe indexed set using that lock.

Hints

Below are some hints that may help with this homework assignment:

• There are some differences between the IndexedSet version presented in lecture and the one provided here. You will have to determine if those differences change which methods should or shouldn't be overridden!

• The Javadoc comments for the SimpleReadWriteLock are written to give clues on the conditions the code should use for the wait() or notifyAll() calls.

• The lecture notes discuss a simple read write lock, but the one you must create is more complicated. In addition to tracking the number of readers and writers, it must track the active writer as well.

  This includes setting the active writer when a thread acquires the write lock and unsetting the active writer when the lock is fully released. The active writer can acquire additional read or write locks as long as it is the active writer.

  Leave this part for the end, after you have a simple read write lock already working.

• If your code is timing out, the best way to debug is to use logging. You need to figure out where your code is getting stuck, and debug from there.

• If your code inconsistently passes tests, there is a multithreading problem somewhere (it just doesn't always pop up when you run due to the nondeterminism of multithreading code). Logging can help debug these cases.

• The thread-safe lock tests are not comprehensive! They will catch a few places locks are not used properly, but not necessarily everywhere.

These hints are optional. There may be multiple approaches to solving this homework.

Instructions

Use the "Tasks" view in Eclipse to find the TODO comments for what need to be implemented and the "Javadoc" view to see additional details.

The tests are provided in the src/test/ directory; do not modify any of the files in that directory. Check the run details on GitHub Actions for how many points each test group is worth.

See the Homework Guides for additional details on homework requirements and submission.