ConcurrentMementoSupplier Java

ConcurrentMementoSupplier.java

package pl.athlan.common.concurrent;

import java.util.function.Supplier;

import javax.annotation.concurrent.ThreadSafe;

/**
 * Thread-safe implementation of {@link MementoSupplier}.
 *
 * @param <T>
 */
@ThreadSafe
class ConcurrentMementoSupplier<T> implements MementoSupplier<T> {

    private final Supplier<T> delegate;
    private final ThreadLocal<T> lastSuppliedValue = new ThreadLocal<>();

    ConcurrentMementoSupplier(final Supplier<T> delegate) {
        this.delegate = delegate;
    }

    @Override
    public T get() {
        T value = delegate.get();
        lastSuppliedValue.set(value);
        return value;
    }

    @Override
    public T getLastSuppliedValue() {
        return lastSuppliedValue.get();
    }
}