package org.apidesign.reentrant;

 import java.util.Collection;

 import java.util.concurrent.atomic.AtomicInteger;

 public class CriticalSectionReentrantForLoop<T extends Comparable<T>> implements CriticalSection<T> {

     private volatile T pilot;

     private AtomicInteger cnt = new AtomicInteger();

     public void assignPilot(T pilot) {

         this.pilot = pilot;

     }

     // BEGIN: reentrant.merge.for

     public int sumBigger(Collection<T> args) {

         T pilotCopy = this.pilot;

         for (;;) {

             int previous = cnt.get();

             int own = doCriticalSection(args, pilotCopy);

             // if there was no parallel or reentrant change, 

             // apply and return. Otherwise try once more.

             if (cnt.compareAndSet(previous, own + previous)) {

                 return own;

             }

         }

     }

     // END: reentrant.merge.for

     private int doCriticalSection(Collection<T> args, T pilotCopy) {

         int own = 0;

         for (T cmp : args) {

             if (pilotCopy.compareTo(cmp) < 0) {

                 own++;

             }

         }

         return own;

     }

     public int getCount() {

         return cnt.get();

     }

 }