public void decrement() {
    add(-1L);
  }

  /**
   * Returns the current sum. The returned value is NOT an atomic snapshot; invocation in
   * the absence of concurrent updates returns an accurate result, but concurrent updates that occur
   * while the sum is being calculated might not be incorporated.
   *
   * @return the sum
   */
  @Override
  public long sum() {
    long sum = base;
    Cell[] as = cells;

        return executor.schedule(this, schedule.delay, schedule.unit);
      }
    }

    /**
     * Contains the most recently submitted {@code Future}, which may be cancelled or updated,
     * always under a lock.
     */
    private static final class SupplantableFuture implements Cancellable {
      private final ReentrantLock lock;

      @GuardedBy("lock")

      checkNotDone();
      mac.update(b);
    }

    @Override
    protected void update(byte[] b, int off, int len) {
      checkNotDone();
      mac.update(b, off, len);
    }

    @Override
    protected void update(ByteBuffer bytes) {
      checkNotDone();
      checkNotNull(bytes);
      mac.update(bytes);
    }

    private void checkNotDone() {

    // Memoized get also retains the value.
    assertEquals(6, getDoneFromTimeoutOverload(transformedFuture).intValue());

    // Unsurprisingly, recomposing the future will return an updated value.
    assertEquals(8, getDone(transform(immediateFuture, adder, directExecutor())).intValue());

    // Repeating, with the timeout version
    assertEquals(
        8,

      entries[srcIndex] = 0;

      // also need to update whoever's "next" pointer was pointing to the last entry place
      int tableIndex = smearedHash(object) & mask;
      int next = CompactHashing.tableGet(table, tableIndex);
      int srcNext = srcIndex + 1;
      if (next == srcNext) {
        // we need to update the root pointer
        CompactHashing.tableSet(table, tableIndex, dstIndex + 1);

  /** Updates this hasher with the given byte. */
  protected abstract void update(byte b);

  /** Updates this hasher with the given bytes. */
  protected void update(byte[] b) {
    update(b, 0, b.length);
  }

  /** Updates this hasher with {@code len} bytes starting at {@code off} in the given buffer. */
  protected void update(byte[] b, int off, int len) {

    }

    @Override
    void compareAndSetSeenExceptions(
        AggregateFutureState<?> state, @CheckForNull Set<Throwable> expect, Set<Throwable> update) {
      seenExceptionsUpdater.compareAndSet(state, expect, update);
    }

    @Override
    int decrementAndGetRemainingCount(AggregateFutureState<?> state) {
      return remainingCountUpdater.decrementAndGet(state);
    }
  }

      Providers.setProviderList(providers);
    }
  }

  public void testMultipleUpdates() throws Exception {
    Mac mac = Mac.getInstance("HmacSHA1");
    mac.init(SHA1_KEY);
    mac.update("hello".getBytes(UTF_8));
    mac.update("world".getBytes(UTF_8));

    assertEquals(
        HashCode.fromBytes(mac.doFinal()),
        Hashing.hmacSha1(SHA1_KEY)
            .newHasher()
            .putString("hello", UTF_8)

  @Override
  public synchronized void write(int b) throws IOException {
    update(1);
    out.write(b);
  }

  @Override
  public synchronized void write(byte[] b) throws IOException {
    write(b, 0, b.length);
  }

  @Override
  public synchronized void write(byte[] b, int off, int len) throws IOException {
    update(len);
    out.write(b, off, len);
  }

  @Override

 * views are modifiable.
 *
 * <p>This class is not threadsafe when any concurrent operations update the multimap. Concurrent
 * read operations will work correctly if the last write <i>happens-before</i> any reads. To allow
 * concurrent update operations, wrap your multimap with a call to {@link
 * Multimaps#synchronizedSetMultimap}.
 *