Discussion of these changes can be found on the Mercury developers
mailing list archives from June 2018.
COPYING.LIB:
Add a special linking exception to the LGPL.
*:
Update references to COPYING.LIB.
Clean up some minor errors that have accumulated in copyright
messages.
If threads are blocked while there is work in the queue extra threads may be
spawned to keep the processors busy.
Beginning now, tasks created with thread.spawn are use the thread pool.
(thread.spawn_native does not use the thread pool.)
java/runtime/Semaphore.java:
Wrap Java's Semaphore class which call the current thread's blocked()
and running() methods when a thread blocks and then runs after being
blocked.
library/thread.semaphore.m:
Use our own Semaphore class.
java/runtime/MercuryThread.java:
java/runtime/MercuryWorkerThread.java:
Define blocked() and running() on our threads.
java/runtime/NativeThread.java:
This class is used by spawn_native/4 and is required to define blocked()
and running(), however it implements them as no-ops as it isn't included
in the thread pool.
java/runtime/ThreadStatus.java:
Define the BLOCKED status.
java/runtime/MercuryThreadPool.java:
Count blocked threads seperatly and allow the creation of new threads
when existing threads become blocked.
Add some tracing code to help debug the thread management code. This is
disabled by default.
library/thread.m:
Implement spawn for Java using the thread pool. This was not enabled
earlier because without using java/runtime/Semaphore.java it was
possible to deadlock the system.
java/runtime/Task.java:
Add some tracing code to debug thread state changes, this is disabled by
default.
