Gate.java

package dmg.util ;

import static org.dcache.util.MathUtils.addWithInfinity;
import static org.dcache.util.MathUtils.subWithInfinity;

public class Gate {
   private boolean _isOpen = true ;
   public Gate(){}
   public Gate( boolean isOpen ){
      _isOpen = isOpen ;
   }

   public synchronized boolean await(long millis) throws InterruptedException
   {
       long deadline = addWithInfinity(System.currentTimeMillis(), millis);
       while (!_isOpen && deadline > System.currentTimeMillis()) {
           wait(subWithInfinity(deadline, System.currentTimeMillis()));
       }
       return _isOpen;
   }

   public synchronized Object check(){
      while( true ){
         if( _isOpen ) {
             return this;
         }
         try{ wait() ; }catch( Exception ee ){}
      }

   }

   public synchronized boolean isOpen() {
       return _isOpen;
   }

   public synchronized void open(){
     _isOpen = true ;
     notifyAll() ;
   }
   public synchronized void close(){
     _isOpen = false ;
     notifyAll() ;
   }

}