/** {@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 void addAttributeListener(GridTaskSessionAttributeListener lsnr, boolean rewind) {
    A.notNull(lsnr, "lsnr");

    Map<Object, Object> attrs = null;

    List<GridTaskSessionAttributeListener> lsnrs;

    synchronized (mux) {
      lsnrs = new ArrayList<GridTaskSessionAttributeListener>(this.lsnrs.size());

      lsnrs.addAll(this.lsnrs);

      lsnrs.add(lsnr);

      lsnrs = Collections.unmodifiableList(lsnrs);

      this.lsnrs = lsnrs;

      if (rewind) attrs = new HashMap<Object, Object>(this.attrs);
    }

    if (rewind) {
      for (Map.Entry<Object, Object> entry : attrs.entrySet()) {
        for (GridTaskSessionAttributeListener l : lsnrs) {
          l.onAttributeSet(entry.getKey(), entry.getValue());
        }
      }
    }
  }
  /** {@inheritDoc} */
  @Override
  public boolean waitForAttribute(Object key, Object val, long timeout)
      throws InterruptedException {
    A.notNull(key, "key");

    if (timeout == 0) timeout = Long.MAX_VALUE;

    long now = System.currentTimeMillis();

    // Prevent overflow.
    long end = now + timeout < 0 ? Long.MAX_VALUE : now + timeout;

    // Don't wait longer than session timeout.
    if (end > endTime) end = endTime;

    synchronized (mux) {
      boolean isFound = false;

      while (!closed && !(isFound = isAttributeSet(key, val)) && now < end) {
        mux.wait(end - now);

        now = System.currentTimeMillis();
      }

      if (closed) throw new InterruptedException("Session was closed: " + this);

      return isFound;
    }
  }
  /**
   * Creates JEXL predicate with given parameters.
   *
   * @param exprStr JEXL boolean expression. Note that non-boolean return value will evaluate this
   *     predicate to {@code false}.
   * @param var1 Name of the 1st bound variable in JEXL expression.
   * @param var2 Name of the 2nd bound variable in JEXL expression.
   */
  public GridJexlPredicate2(String exprStr, String var1, String var2) {
    A.notNull(exprStr, "exprStr", var1, "var1", var2, "var2");

    this.exprStr = exprStr;
    this.var1 = var1;
    this.var2 = var2;
  }
  /**
   * Sets JEXL context variable value and returns {@code this}.
   *
   * @param var Name of the variable in JEXL context (new or existing).
   * @param val Value to be set or overridden in JEXL context.
   * @return This predicate so that this call can be chained.
   */
  public GridJexlPredicate2<T1, T2> with(String var, @Nullable Object val) {
    A.notNull(var, "var");

    map.put(var, val);

    return this;
  }
  /**
   * @param keys Keys.
   * @return If near entries for given keys are locked.
   */
  public boolean isAllLockedNearOnly(Iterable<? extends K> keys) {
    A.notNull(keys, "keys");

    for (K key : keys) if (!isLockedNearOnly(key)) return false;

    return true;
  }
  /** {@inheritDoc} */
  @Override
  public boolean waitForAttributes(Map<?, ?> attrs, long timeout) throws InterruptedException {
    A.notNull(attrs, "attrs");

    if (attrs.isEmpty()) {
      return true;
    }

    if (timeout == 0) timeout = Long.MAX_VALUE;

    long now = System.currentTimeMillis();

    // Prevent overflow.
    long end = now + timeout < 0 ? Long.MAX_VALUE : now + timeout;

    // Don't wait longer than session timeout.
    if (end > endTime) end = endTime;

    synchronized (mux) {
      boolean isFound = false;

      while (!closed
          && !(isFound = this.attrs.entrySet().containsAll(attrs.entrySet()))
          && now < end) {
        mux.wait(end - now);

        now = System.currentTimeMillis();
      }

      if (closed) throw new InterruptedException("Session was closed: " + this);

      return isFound;
    }
  }
  /** {@inheritDoc} */
  @Override
  public Map<?, ?> waitForAttributes(Collection<?> keys, long timeout) throws InterruptedException {
    A.notNull(keys, "keys");

    if (keys.isEmpty()) return Collections.emptyMap();

    if (timeout == 0) timeout = Long.MAX_VALUE;

    long now = System.currentTimeMillis();

    // Prevent overflow.
    long end = now + timeout < 0 ? Long.MAX_VALUE : now + timeout;

    // Don't wait longer than session timeout.
    if (end > endTime) end = endTime;

    synchronized (mux) {
      while (!closed && !attrs.keySet().containsAll(keys) && now < end) {
        mux.wait(end - now);

        now = System.currentTimeMillis();
      }

      if (closed) throw new InterruptedException("Session was closed: " + this);

      Map<Object, Object> retVal = new HashMap<Object, Object>(keys.size());

      for (Object key : keys) retVal.put(key, attrs.get(key));

      return retVal;
    }
  }
  /** {@inheritDoc} */
  @SuppressWarnings("unchecked")
  @Override
  public <K, V> V waitForAttribute(K key, long timeout) throws InterruptedException {
    A.notNull(key, "key");

    if (timeout == 0) timeout = Long.MAX_VALUE;

    long now = System.currentTimeMillis();

    // Prevent overflow.
    long end = now + timeout < 0 ? Long.MAX_VALUE : now + timeout;

    // Don't wait longer than session timeout.
    if (end > endTime) end = endTime;

    synchronized (mux) {
      while (!closed && !attrs.containsKey(key) && now < end) {
        mux.wait(end - now);

        now = System.currentTimeMillis();
      }

      if (closed) throw new InterruptedException("Session was closed: " + this);

      return (V) attrs.get(key);
    }
  }
  /** {@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);
    }
  }
  /** {@inheritDoc} */
  @Override
  public void setAttribute(Object key, @Nullable Object val) {
    A.notNull(key, "key");

    synchronized (attrs) {
      attrs.put(key, val);
    }
  }
  /** {@inheritDoc} */
  @Override
  public void setAttributes(Map<?, ?> attrs) {
    A.notNull(attrs, "attrs");

    synchronized (this.attrs) {
      this.attrs.putAll(attrs);
    }
  }
  /** {@inheritDoc} */
  @SuppressWarnings("unchecked")
  @Override
  public <K, V> V getAttribute(K key) {
    A.notNull(key, "key");

    synchronized (attrs) {
      return (V) attrs.get(key);
    }
  }
  /** {@inheritDoc} */
  @Override
  public boolean removeCheckpoint(String key) throws GridException {
    A.notNull(key, "key");

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

    return ctx.checkpoint().removeCheckpoint(this, key);
  }
  /** {@inheritDoc} */
  @Override
  public GridJobSibling getJobSibling(GridUuid jobId) throws GridException {
    A.notNull(jobId, "jobId");

    Collection<GridJobSibling> tmp = getJobSiblings();

    for (GridJobSibling sibling : tmp) if (sibling.getJobId().equals(jobId)) return sibling;

    return null;
  }
  /** {@inheritDoc} */
  @SuppressWarnings("unchecked")
  @Override
  public <T> T loadCheckpoint(String key) throws GridException {
    A.notNull(key, "key");

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

    return (T) ctx.checkpoint().loadCheckpoint(this, key);
  }
  /**
   * 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 boolean removeAttributeListener(GridTaskSessionAttributeListener lsnr) {
    A.notNull(lsnr, "lsnr");

    synchronized (mux) {
      List<GridTaskSessionAttributeListener> lsnrs =
          new ArrayList<GridTaskSessionAttributeListener>(this.lsnrs);

      boolean rmv = lsnrs.remove(lsnr);

      this.lsnrs = Collections.unmodifiableList(lsnrs);

      return rmv;
    }
  }
  /** {@inheritDoc} */
  @Override
  public void setAttributes(Map<?, ?> attrs) throws GridException {
    A.notNull(attrs, "attrs");

    if (attrs.isEmpty()) return;

    // Note that there is no mux notification in this block.
    // The reason is that we wait for ordered attributes to
    // come back from task prior to notification. The notification
    // will happen in 'setInternal(...)' method.
    synchronized (mux) {
      this.attrs.putAll(attrs);
    }

    if (isTaskNode()) ctx.task().setAttributes(this, attrs);
  }
  /** @param attrs Attributes to set. */
  public void setInternal(Map<?, ?> attrs) {
    A.notNull(attrs, "attrs");

    if (attrs.isEmpty()) return;

    List<GridTaskSessionAttributeListener> lsnrs;

    synchronized (mux) {
      this.attrs.putAll(attrs);

      lsnrs = this.lsnrs;

      mux.notifyAll();
    }

    for (Map.Entry<?, ?> entry : attrs.entrySet())
      for (GridTaskSessionAttributeListener lsnr : lsnrs)
        lsnr.onAttributeSet(entry.getKey(), entry.getValue());
  }
  /**
   * 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 void setAttribute(Object key, Object val) throws GridException {
    A.notNull(key, "key");

    setAttributes(Collections.singletonMap(key, val));
  }
  /** {@inheritDoc} */
  @Override
  public int countDown(int val) throws GridException {
    A.ensure(val > 0, "val should be positive");

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