Process/Coroutine Package in Java

Godmar Back

University of Utah, Dec 1995

sim package:

process.java, scheduler.java

queues package:

Queue, PriorityQueue
(for historic reasons, all methods of this class are capitalized)

random package:

rand, erand, and urand

This is a straightforward port of the process.c/coroutine.c library that uses Cthreads. A few points to note:

- all type checks have been removed as Java throws an exception in this case.

- I got rid of rlink because I hated it. There is no limit on the number of queues a process can be in. Similarly, there is no need for carrier objects as they are internally provided by the Queue class.

- Some functions have been removed as they don't fit in the Java model: terminate_and_delete(), for instance.
Other functions have been omitted as there is no need for them anymore. For instance, process::enqueue_proc(q) is simply q.Enqueue(process)

- In general, functions and variables previously global such as clock or current or activate() have become static members of the scheduler class.

- there is no distinction between coroutines and processes anymore

- processes are implemented using Java threads, which interact in a coroutine fashion. This is implemented using condition variables. See Object.wait()

- Examples:
CPU scheduler with test 1, 2, and 3
resource, a mutex implemented for processes with a test
sieve, an coroutine-based implementation of Erasthotenes' sieve.
carwash, a simulation of a car wash system.
powers, computing powers of n using DSS.
Condition variables with a test,