scope evalJava_prep2.

// flag is per thread, cache is per program (in-memory cache of JavaX source -> loaded Class)
static new ThreadLocal<Bool> #useCacheInThread;
static volatile bool #useCache;

// cached main classes, used only when you enable it
static Map<S, O> #cache = synchronizedMRUCache(100);

static O evalJava_prep2(S main) {
  bool _useCache = useCache || isTrue(useCacheInThread!);
  if (_useCache) {
    O obj = cache.get(main);
    if (obj != null) ret obj;
  }
  O obj = veryQuickJava(main);
  if (_useCache)
    cache.put(main, obj);
  makeDependent(obj);
  setOpt(obj, "getProgramName_cache", "User Code");
  ret obj;
}

end scope

Began life as a copy of #1011860