/** {@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 apply(@Nullable T1 t1, @Nullable T2 t2) {
    lazyCompile();

    if (expr != null) {
      JexlContext ctx = new MapContext();

      ctx.set(var1, t1);
      ctx.set(var2, t2);

      for (Map.Entry<String, Object> e : map.entrySet()) {
        ctx.set(e.getKey(), e.getValue());
      }

      try {
        Object obj = expr.evaluate(ctx);

        if (obj instanceof Boolean) {
          return (Boolean) obj;
        }
      } catch (Exception ex) {
        throw F.wrap(ex);
      }
    }

    return false;
  }
  /** @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());
  }