*     href="https://github.com/google/guava#guava-google-core-libraries-for-java">flavor</a>)
   */
  @GwtIncompatible
  @J2ktIncompatible
  @CanIgnoreReturnValue
  @SuppressWarnings("Java7ApiChecker") // guava-android can rely on library desugaring now.
  @IgnoreJRERequirement // TODO: b/288085449 - Remove this once we use library-desugaring scents.
  @Beta // TODO: b/288085449 - Remove @Beta after we're sure that Java 8 APIs are safe for Android

    // NOTE: if timeout < 0, remainingNanos will be < 0 and we will fall into the while(true) loop
    // at the bottom and throw a timeoutexception.
    final long timeoutNanos = unit.toNanos(timeout); // we rely on the implicit null check on unit.
    long remainingNanos = timeoutNanos;
    if (Thread.interrupted()) {
      throw new InterruptedException();
    }
    Object localValue = value;

     * works well for hash tables since the bin lists tend to be short. (The average length is less
     * than two.)
     *
     * Read operations can thus proceed without locking, but rely on selected uses of volatiles to
     * ensure that completed write operations performed by other threads are noticed. For most
     * purposes, the "count" field, tracking the number of elements, serves as that volatile

     * the timeout arbitrarily inaccurate, given a queue that is slow to drain).
     */
    long deadline = System.nanoTime() + unit.toNanos(timeout);
    int added = 0;
    while (added < numElements) {
      // we could rely solely on #poll, but #drainTo might be more efficient when there are multiple
      // elements already available (e.g. LinkedBlockingQueue#drainTo locks only once)
      added += q.drainTo(buffer, numElements - added);

import java.util.concurrent.atomic.AtomicLong;
import javax.annotation.CheckForNull;

/**
 * A map containing {@code long} values that can be atomically updated. While writes to a
 * traditional {@code Map} rely on {@code put(K, V)}, the typical mechanism for writing to this map
 * is {@code addAndGet(K, long)}, which adds a {@code long} to the value currently associated with