I want to wrap ConcurrentSkipListSet to keep a fixed capacity of the latest (according to Comparator) values:
private int capacity = 100;
// using Integer just for an illustration
private ConcurrentSkipListSet<Integer> intSet = new ConcurrentSkipListSet<>();
Therefore, I implemented put() like this:
// This method should be atomic.
public void put(int value) {
intSet.add(value);
if (intSet.size() > capacity)
intSet.pollFirst();
}
However, this put() is not thread-safe.
Note: No other mutation methods. Of course, I need "read-only" methods like getLast() or getBefore(Integer value).
How to wrap ConcurrentSkipListSet to keep a fixed capacity of the latest values in a thread-safe way?
synchronized (set) {set.add(value);
if (set.size() > cap) {
set.pollFirst();
}
}