// GWT's ConcurrentHashMap is a wrapper around HashMap, but it rejects null keys, which matches
    // the behaviour of the non-GWT implementation of newConcurrentHashSet().
    // On the other hand HashSet might be better for code size if apps aren't
    // already using Collections.newSetFromMap and ConcurrentHashMap.
    return Collections.newSetFromMap(new ConcurrentHashMap<E, Boolean>());
  }

  private final OkHttpClient client;
  private final Set<HttpUrl> fetchedUrls = Collections.synchronizedSet(new LinkedHashSet<>());
  private final BlockingQueue<HttpUrl> queue;
  private final ConcurrentHashMap<String, AtomicInteger> hostnames = new ConcurrentHashMap<>();
  private final int hostLimit;

  public Crawler(OkHttpClient client, int queueLimit, int hostLimit) {
    this.client = client;
    this.queue = new LinkedBlockingQueue<>(queueLimit);

    /**
     * Creates and returns a new instance of {@link ConcurrentHashMap}.
     *
     * @param <K> the key type of {@link ConcurrentHashMap}
     * @param <V> the value type of {@link ConcurrentHashMap}
     * @return a new instance of {@link ConcurrentHashMap}
     * @see ConcurrentHashMap#ConcurrentHashMap()
     */
    public static <K, V> ConcurrentHashMap<K, V> newConcurrentHashMap() {
        return new ConcurrentHashMap<>();

   * what to do with <a
   * href="https://github.com/openjdk/jdk/blob/c25c4896ad9ef031e3cddec493aef66ff87c48a7/src/java.base/share/classes/java/util/concurrent/ConcurrentHashMap.java#L4830">{@code
   * ConcurrentHashMap} support for {@code entrySet().add()}</a>.
   */
  @J2ktIncompatible
  @GwtIncompatible // reflection
  public static Method getAddUnsupportedNotPresentMethod() {

   * what to do with <a
   * href="https://github.com/openjdk/jdk/blob/c25c4896ad9ef031e3cddec493aef66ff87c48a7/src/java.base/share/classes/java/util/concurrent/ConcurrentHashMap.java#L4830">{@code
   * ConcurrentHashMap} support for {@code entrySet().add()}</a>.
   */
  @J2ktIncompatible
  @GwtIncompatible // reflection
  public static Method getAddUnsupportedNotPresentMethod() {

     * @param value the value to be added to the <code>Map</code>
     * @return a {@literal Maps} for constructing a {@link ConcurrentHashMap} with the specified key and value
     */
    public static <KEY, VALUE> Maps<KEY, VALUE> concurrentHashMap(final KEY key, final VALUE value) {
        return new Maps<>(new ConcurrentHashMap<KEY, VALUE>()).$(key, value);
    }

    /**

   * figure out what to do with <a
   * href="https://github.com/openjdk/jdk/blob/c25c4896ad9ef031e3cddec493aef66ff87c48a7/src/java.base/share/classes/java/util/concurrent/ConcurrentHashMap.java#L4830">{@code
   * ConcurrentHashMap} support for {@code entrySet().add()}</a>.
   */
  @J2ktIncompatible
  @GwtIncompatible // reflection
  public static Method getAddAllUnsupportedNonePresentMethod() {

    private static final Logger logger = LogManager.getLogger(ProcessHelper.class);

    /** Map of running processes indexed by session ID */
    protected final ConcurrentHashMap<String, JobProcess> runningProcessMap = new ConcurrentHashMap<>();

    /** Timeout in seconds for process destruction */
    protected int processDestroyTimeout = 10;

    /**
     * Default constructor for ProcessHelper.

import com.google.common.base.Function;
import com.google.common.testing.NullPointerTester;
import com.google.errorprone.annotations.CanIgnoreReturnValue;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.CountDownLatch;
import junit.framework.TestCase;
import org.jspecify.annotations.NullUnmarked;

/**
 * @author Charles Fry
 */
@GwtCompatible
@J2ktIncompatible // MapMaker

import com.google.common.base.Function;
import com.google.common.primitives.Ints;
import java.util.List;
import java.util.Random;
import java.util.concurrent.Callable;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import java.util.concurrent.ConcurrentSkipListMap;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;