*
   * <ol>
   *   <li>calls {@link ExecutorService#shutdown()}, disabling acceptance of new submitted tasks.
   *   <li>awaits executor service termination for half of the specified timeout.
   *   <li>if the timeout expires, it calls {@link ExecutorService#shutdownNow()}, cancelling
   *       pending tasks and interrupting running tasks.

   *
   * <p>Among the improvements that this method and {@code LoadingCache.get(K)} both provide are:
   *
   * <ul>
   *   <li>{@linkplain LoadingCache#get(Object) awaiting the result of a pending load} rather than
   *       starting a redundant one
   *   <li>eliminating the error-prone caching boilerplate
   *   <li>tracking load {@linkplain #stats statistics}
   * </ul>
   *

 * that wrap {@link MessageDigest}s.
 *
 * <p>Parameters for the benchmark are:
 *
 * <ul>
 *   <li>size: The length of the byte array to hash.
 *   <li>algorithm: the algorithm to hash with (e.g. MD5, SHA1, etc.).
 *   <li>hashMethod: how to hash the data (using the Hashing API or the MessageDigest API).
 * </ul>
 *
 * @author Kurt Alfred Kluever
 */

 * Benchmarks (as of December 2011) show that:
 *
 * <ul>
 *   <li>for an unnested {@code lock()} and {@code unlock()}, a cycle detecting lock takes 38ns as
 *       opposed to the 24ns taken by a plain lock.
 *   <li>for nested locking, the cost increases with the depth of the nesting:
 *       <ul>
 *         <li>2 levels: average of 64ns per lock()/unlock()
 *         <li>3 levels: average of 77ns per lock()/unlock()

 * second invocation, so implementors have made various choices, including:
 *
 * <ul>
 *   <li>returning the same iterator again
 *   <li>throwing an exception of some kind
 *   <li>or the usual, <i>robust</i> behavior, which all known {@link Collection} implementations
 *       have, of returning a new, independent iterator
 * </ul>
 *

 *
 * <ul>
 *   <li>whether threads should be marked as {@linkplain Thread#setDaemon daemon} threads
 *   <li>a {@linkplain ThreadFactoryBuilder#setNameFormat naming format}
 *   <li>a {@linkplain Thread#setPriority thread priority}
 *   <li>an {@linkplain Thread#setUncaughtExceptionHandler uncaught exception handler}
 *   <li>a {@linkplain ThreadFactory#newThread backing thread factory}
 * </ul>
 *

   *
   * <ul>
   *   <li>If {@code exceptions} has a single exception and that exception is a {@link
   *       RuntimeException}, return it
   *   <li>If {@code exceptions} has a single exceptions and that exceptions is not a
   *       {@link RuntimeException}, return a simple {@code RuntimeException} that wraps it

/**
 * Benchmarks for comparing the various {@link HashCode#equals} methods.
 *
 * <p>Parameters for the benchmark are:
 *
 * <ul>
 *   <li>size: the length of the byte array to hash
 *   <li>whereToDiffer: where in the array the bytes should differ
 *   <li>equalsImpl: which implementation of array equality to use
 * </ul>
 *
 * <p><b>Important note:</b> the primary goal of this benchmark is to ensure that varying {@code

/**
 * Benchmarks for comparing the various {@link HashCode#equals} methods.
 *
 * <p>Parameters for the benchmark are:
 *
 * <ul>
 *   <li>size: the length of the byte array to hash
 *   <li>whereToDiffer: where in the array the bytes should differ
 *   <li>equalsImpl: which implementation of array equality to use
 * </ul>
 *
 * <p><b>Important note:</b> the primary goal of this benchmark is to ensure that varying {@code

 *
 * <p>Unpacking this definition:
 *
 * <ul>
 *   <li><b>block of data:</b> the input for a hash function is always, in concept, an ordered byte
 *       array. This hashing API accepts an arbitrary sequence of byte and multibyte values (via
 *       {@link Hasher}), but this is merely a convenience; these are always translated into raw
 *       byte sequences under the covers.