(PECL ev >= 0.2.0)
EvWatcher::clear — Clear watcher pending status
   If the watcher is pending, this method clears its
   pending
   status and returns its
   revents
   bitset(as if its callback was invoked). If the watcher isn't pending
   it does nothing and returns
   0
   .
  
Sometimes it can be useful to "poll" a watcher instead of waiting for its callback to be invoked, which can be accomplished with this function.
Diese Funktion besitzt keine Parameter.
   In case if the watcher is pending, returns
   revents
   bitset as if the
   watcher callback
   had been invoked. Otherwise returns
   0
   .