*
 * <pre>{@code
 * CacheLoader<Key, Graph> loader = CacheLoader.from(key -> createExpensiveGraph(key));
 * }</pre>
 *
 * @author Charles Fry
 * @since 10.0
 */
@GwtCompatible(emulated = true)
@ElementTypesAreNonnullByDefault
public abstract class CacheLoader<K, V> {
  /** Constructor for use by subclasses. */
  protected CacheLoader() {}

  /**

 * more simply:
 *
 * <pre>{@code
 * CacheLoader<Key, Graph> loader = CacheLoader.from(key -> createExpensiveGraph(key));
 * }</pre>
 *
 * @author Charles Fry
 * @since 10.0
 */
@GwtCompatible(emulated = true)
@ElementTypesAreNonnullByDefault
public abstract class CacheLoader<K, V> {
  /** Constructor for use by subclasses. */
  protected CacheLoader() {}

  /**

/**
 * Utility {@link CacheLoader} implementations intended for use in testing.
 *
 * @author mike nonemacher
 */
@GwtCompatible(emulated = true)
class TestingCacheLoaders {

  /**
   * Returns a {@link CacheLoader} that implements a naive {@link CacheLoader#loadAll}, delegating
   * {@link CacheLoader#load} calls to {@code loader}.
   */
  static <K, V> CacheLoader<K, V> bulkLoader(final CacheLoader<K, V> loader) {

      CacheBuilder<K, V> builder, CacheLoader<? super K, V> loader) {
    return new LocalLoadingCache<>(builder, loader);
  }

  private CacheBuilder<Object, Object> createCacheBuilder() {
    return CacheBuilder.newBuilder().recordStats();
  }

  // constructor tests

  public void testComputingFunction() {
    CacheLoader<Object, Object> loader =
        new CacheLoader<Object, Object>() {
          @Override

    // notification.

    final AtomicBoolean shouldWait = new AtomicBoolean(false);
    final CountDownLatch computingLatch = new CountDownLatch(1);
    CacheLoader<String, String> computingFunction =
        new CacheLoader<String, String>() {
          @Override
          public String load(String key) throws InterruptedException {
            if (shouldWait.get()) {
              computingLatch.await();

    assertEquals(2, stats.hitCount());
  }

  public void testReload() throws ExecutionException {
    final Object one = new Object();
    final Object two = new Object();
    CacheLoader<Object, Object> loader =
        new CacheLoader<Object, Object>() {
          @Override
          public Object load(Object key) {
            return one;
          }

          @Override

   *
   * <p>Caches loaded by a {@link CacheLoader} will issue a single request to {@link
   * CacheLoader#loadAll} for all keys which are not already present in the cache. All entries
   * returned by {@link CacheLoader#loadAll} will be stored in the cache, over-writing any
   * previously cached values. This method will throw an exception if {@link CacheLoader#loadAll}

/**
 * Utility {@link CacheLoader} implementations intended for use in testing.
 *
 * @author mike nonemacher
 */
@GwtCompatible(emulated = true)
class TestingCacheLoaders {

  /**
   * Returns a {@link CacheLoader} that implements a naive {@link CacheLoader#loadAll}, delegating
   * {@link CacheLoader#load} calls to {@code loader}.
   */
  static <K, V> CacheLoader<K, V> bulkLoader(final CacheLoader<K, V> loader) {

    assertEquals(2, stats.hitCount());
  }

  public void testReload() throws ExecutionException {
    final Object one = new Object();
    final Object two = new Object();
    CacheLoader<Object, Object> loader =
        new CacheLoader<Object, Object>() {
          @Override
          public Object load(Object key) {
            return one;
          }

          @Override

import static com.google.common.truth.Truth.assertThat;
import static java.util.concurrent.TimeUnit.SECONDS;
import static org.junit.Assert.assertThrows;

import com.google.common.cache.CacheLoader.InvalidCacheLoadException;
import com.google.common.cache.TestingRemovalListeners.QueuingRemovalListener;
import com.google.common.util.concurrent.UncheckedExecutionException;
import junit.framework.TestCase;

/**