package ex2;

import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.atomic.LongAdder;

public final class Profiler {

    // not concurrent on purpose, since the value of the map is computed with a pure function
    // on the map key, and thus we don't care if the value is overwritten as a result of a
    // race condition
    private static final Map<Class<?>, Boolean> isThread = new HashMap<>();

    private static final LongAdder reads = new LongAdder();

    private static final LongAdder writes = new LongAdder();

    static {
        Runtime.getRuntime().addShutdownHook(new Thread(() -> {
                System.out.printf("Instance field read access: %d\nInstance field write access: %d\n",
                        reads.longValue(),
                        writes.longValue());
        }));
    }

    private Profiler() {
    }

    public static boolean isThread(final Class<?> clazz) {
        return isThread.computeIfAbsent(clazz, Thread.class::isAssignableFrom);
    }

    public static void increment(long readCount, long writeCount) {
        reads.add(readCount);
        writes.add(writeCount);
    }

}