fix for 100% cpu bug during dht selection

see also: http://www.yacy-forum.de/viewtopic.php?p=34068#34068

git-svn-id: https://svn.berlios.de/svnroot/repos/yacy/trunk@3570 6c8d7289-2bf4-0310-a012-ef5d649a1542

source/de/anomic/kelondro/kelondroRotateIterator.java

@@ -47,6 +47,9 @@ public class kelondroRotateIterator implements kelondroCloneableIterator {
     }
     
     public Object next() {
+    	// attention: this iterator has no termination - on purpose.
+    	// it must be taken care that a calling method has a termination predicate different
+    	// from the hasNext() method
         if (!(a.hasNext())) {
             a = (kelondroCloneableIterator) clone.clone(modifier);
         }

source/de/anomic/plasma/plasmaWordIndex.java

@@ -496,14 +496,18 @@ public final class plasmaWordIndex implements indexRI {
         Iterator i = wordContainers(startHash, ram, rot);
         if (ram) count = Math.min(dhtOutCache.size(), count);
         indexContainer container;
+        // this loop does not terminate using the i.hasNex() predicate when rot == true
+        // because then the underlying iterator is a rotating iterator without termination
+        // in this case a termination must be ensured with a counter
+        // It must also be ensured that the counter is in/decreased every loop
         while ((count > 0) && (i.hasNext())) {
             container = (indexContainer) i.next();
             if ((container != null) && (container.size() > 0)) {
                 containers.add(container);
-                count--;
             }
+            count--; // decrease counter even if the container was null or empty to ensure termination
         }
-        return containers;
+        return containers; // this may return less containers as demanded
     }
 
     public kelondroCloneableIterator wordContainers(String startHash, boolean ram, boolean rot) {