SerializedSafeMemoizer.java

/**
 * Iteration 2: Serialized Naive Safe Memoizer
 * A thread-safe implementation of a memoizer that caches computed results.
 * This implementation synchronizes the entire compute method, ensuring thread safety
 * but potentially creating performance bottlenecks under high contention.
 */   
public class SerializedNaiveSafeMemoizer<A,V> implements Computable<A,V> {
    @GuardedBy("this") // documents that cache is protected by the intrinsic lock
    private final Map<A,V> cache = new HashMap<>();
    private final Computable<A,V> computable;

    public SerializedNaiveSafeMemoizer(Computable<A,V> computable) {
        this.computable = computable;
    }

    // Notice synchronized keyword here
    @Override
    public synchronized V compute(A arg) throws InterruptedException {
        V result = cache.get(arg);
        if (result == null) {
            result = computable.compute(arg);
            cache.put(arg, result);
        }
        return result;
    }

}