@GuardedBy("monitor")
    final IdentityHashMap<Service, Stopwatch> startupTimers = new IdentityHashMap<>();

    /**
     * These two booleans are used to mark the state as ready to start.
     *
     * <p>{@link #ready}: is set by {@link #markReady} to indicate that all listeners have been
     * correctly installed
     *
     * <p>{@link #transitioned}: is set by {@link #transitionService} to indicate that some

import java.nio.ByteBuffer;
import java.nio.ByteOrder;

/**
 * A convenience base class for implementors of {@code Hasher}; handles accumulating data until an
 * entire "chunk" (of implementation-dependent length) is ready to be hashed.
 *
 * @author Kevin Bourrillion
 * @author Dimitris Andreou
 */
// TODO(kevinb): this class still needs some design-and-document-for-inheritance love
@ElementTypesAreNonnullByDefault

      target.put(seq.charAt(pos++));
    }
    return charsToRead;
  }

  @Override
  public synchronized int read() throws IOException {
    checkOpen();
    requireNonNull(seq); // safe because of checkOpen
    return hasRemaining() ? seq.charAt(pos++) : -1;
  }

  @Override
  public synchronized int read(char[] cbuf, int off, int len) throws IOException {
    checkPositionIndexes(off, off + len, cbuf.length);
    checkOpen();

      target.put(seq.charAt(pos++));
    }
    return charsToRead;
  }

  @Override
  public synchronized int read() throws IOException {
    checkOpen();
    requireNonNull(seq); // safe because of checkOpen
    return hasRemaining() ? seq.charAt(pos++) : -1;
  }

  @Override
  public synchronized int read(char[] cbuf, int off, int len) throws IOException {
    checkPositionIndexes(off, off + len, cbuf.length);
    checkOpen();

    }
    this.functions = functions;
  }

  /**
   * Constructs a {@code HashCode} from the {@code Hasher} objects of the functions. Each of them
   * has consumed the entire input and they are ready to output a {@code HashCode}. The order of the
   * hashers are the same order as the functions given to the constructor.
   */
  // this could be cleaner if it passed HashCode[], but that would create yet another array...

  }

  public void testSimpleWithWait() {
    RateLimiter limiter = RateLimiter.create(5.0, stopwatch);
    limiter.acquire(); // R0.00
    stopwatch.sleepMillis(200); // U0.20, we are ready for the next request...
    limiter.acquire(); // R0.00, ...which is granted immediately
    limiter.acquire(); // R0.20
    assertEvents("R0.00", "U0.20", "R0.00", "R0.20");
  }

  }

  public void testSimpleWithWait() {
    RateLimiter limiter = RateLimiter.create(5.0, stopwatch);
    limiter.acquire(); // R0.00
    stopwatch.sleepMillis(200); // U0.20, we are ready for the next request...
    limiter.acquire(); // R0.00, ...which is granted immediately
    limiter.acquire(); // R0.20
    assertEvents("R0.00", "U0.20", "R0.00", "R0.20");
  }

Due to Guava's nature as a subset of Google's internal codebase which is
automatically synced to the public GitHub repository, we are unable to merge
pull requests directly into the master branch. Instead, once a pull request is
ready for merging, we'll make the appropriate changes in the internal codebase
and, when the change is synced out, give the pull request author credit for the
commit.

Contributor License Agreement
-----------------------------

 *   <li>It doesn't offer a way to wait for multiple events before taking action. For example, it
 *       doesn't offer a way to wait for multiple producers to all report that they're "ready," nor
 *       does it offer a way to batch multiple events from a single producer together.
 *   <li>It doesn't support backpressure and other features needed for resilience.
 *   <li>It doesn't provide much control of threading.

   * translates to "almost empty buffers", which can be filled immediately.
   *
   * On the other hand, past underutilization could mean that "the server responsible for handling
   * the request has become less ready for future requests", i.e. its caches become stale, and
   * requests become more likely to trigger expensive operations (a more extreme case of this