/**
   * Set local batch size for this sequences.
   *
   * @param size Sequence batch size. Must be more then 0.
   */
  @Override
  public void batchSize(int size) {
    A.ensure(size > 0, " Batch size can't be less then 0: " + size);

    lock.lock();

    try {
      batchSize = size;
    } finally {
      lock.unlock();
    }
  }
  /** {@inheritDoc} */
  @Override
  public void saveCheckpoint(
      String key, Object state, GridTaskSessionScope scope, long timeout, boolean overwrite)
      throws GridException {
    A.notNull(key, "key");
    A.ensure(timeout >= 0, "timeout >= 0");

    synchronized (mux) {
      if (closed) throw new GridException("Failed to save checkpoint (session closed): " + this);
    }

    ctx.checkpoint().storeCheckpoint(this, key, state, scope, timeout, overwrite);
  }
  /** {@inheritDoc} */
  @Override
  public R get(long timeout, TimeUnit unit) throws GridException {
    A.ensure(timeout >= 0, "timeout cannot be negative: " + timeout);
    A.notNull(unit, "unit");

    checkValid();

    try {
      long now = System.currentTimeMillis();

      long end = timeout == 0 ? Long.MAX_VALUE : now + MILLISECONDS.convert(timeout, unit);

      // Account for overflow.
      if (end < 0) end = Long.MAX_VALUE;

      synchronized (mux) {
        while (!done && !cancelled && now < end) {
          mux.wait(end - now);

          if (!done) now = System.currentTimeMillis();
        }

        if (done) {
          if (err != null) throw U.cast(err);

          return res;
        }

        if (cancelled) throw new GridFutureCancelledException("Future was cancelled: " + this);

        throw new GridFutureTimeoutException(
            "Timeout was reached before computation completed [duration="
                + duration()
                + "ms, timeout="
                + unit.toMillis(timeout)
                + "ms]");
      }
    } catch (InterruptedException e) {
      throw new GridInterruptedException(
          "Got interrupted while waiting for future to complete [duration="
              + duration()
              + "ms, timeout="
              + unit.toMillis(timeout)
              + "ms]",
          e);
    }
  }
  /**
   * Asynchronous sequence update operation. Will add given amount to the sequence value.
   *
   * @param l Increment amount.
   * @param updateCall Cache call that will update sequence reservation count in accordance with l.
   * @param updated If {@code true}, will return sequence value after update, otherwise will return
   *     sequence value prior to update.
   * @return Future indicating sequence value.
   * @throws GridException If update failed.
   */
  private GridFuture<Long> internalUpdateAsync(
      long l, @Nullable Callable<Long> updateCall, boolean updated) throws GridException {
    checkRemoved();

    A.ensure(l > 0, " Parameter mustn't be less then 1: " + l);

    lock.lock();

    try {
      // If reserved range isn't exhausted.
      if (locVal + l <= upBound) {
        long curVal = locVal;

        locVal += l;

        return new GridFinishedFuture<Long>(ctx.kernalContext(), updated ? locVal : curVal);
      }
    } finally {
      lock.unlock();
    }

    if (updateCall == null) updateCall = internalUpdate(l, updated);

    while (true) {
      if (updateGuard.compareAndSet(false, true)) {
        try {
          // This call must be outside lock.
          return ctx.closures().callLocalSafe(updateCall, true);
        } finally {
          lock.lock();

          try {
            updateGuard.set(false);

            cond.signalAll();
          } finally {
            lock.unlock();
          }
        }
      } else {
        lock.lock();

        try {
          while (locVal >= upBound && updateGuard.get()) {
            try {
              cond.await(500, MILLISECONDS);
            } catch (InterruptedException e) {
              throw new GridInterruptedException(e);
            }
          }

          checkRemoved();

          // If reserved range isn't exhausted.
          if (locVal + l <= upBound) {
            long curVal = locVal;

            locVal += l;

            return new GridFinishedFuture<Long>(ctx.kernalContext(), updated ? locVal : curVal);
          }
        } finally {
          lock.unlock();
        }
      }
    }
  }
  /** {@inheritDoc} */
  @Override
  public GridFuture<Long> getAndAddAsync(long l) throws GridException {
    A.ensure(l > 0, " Parameter mustn't be less then 1: " + l);

    return internalUpdateAsync(l, null, false);
  }
  /** {@inheritDoc} */
  @Override
  public long addAndGet(long l) throws GridException {
    A.ensure(l > 0, " Parameter mustn't be less then 1: " + l);

    return internalUpdate(l, null, true);
  }
  /** {@inheritDoc} */
  @Override
  public int countDown(int val) throws GridException {
    A.ensure(val > 0, "val should be positive");

    return CU.outTx(new CountDownCallable(val), ctx);
  }