LUCENE-4459: Improve WeakIdentityMap.keyIterator() to remove GCed keys from backing map early instead of waiting for reap(). This makes test failures in TestWeakIdentityMap disappear, too.

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1394291 13f79535-47bb-0310-9956-ffa450edef68

lucene/CHANGES.txt

@@ -43,6 +43,11 @@ Optimizations
   into the skipdata. You need to reindex any indexes created with
   this experimental codec.  (Robert Muir)
 
+* LUCENE-4459: Improve WeakIdentityMap.keyIterator() to remove GCed keys
+  from backing map early instead of waiting for reap(). This makes test
+  failures in TestWeakIdentityMap disappear, too.
+  (Uwe Schindler, Mike McCandless, Robert Muir)
+
 Build
 
 * LUCENE-4451: Memory leak per unique thread caused by 

lucene/core/src/java/org/apache/lucene/util/WeakIdentityMap.java

@@ -133,14 +133,16 @@ public final class WeakIdentityMap<K,V> {
     
       @Override
       public boolean hasNext() {
-        return nextIsSet ? true : setNext();
+        return nextIsSet || setNext();
       }
       
       @Override @SuppressWarnings("unchecked")
       public K next() {
-        if (nextIsSet || setNext()) {
+        if (!hasNext()) {
-          try {
+          throw new NoSuchElementException();
+        }
         assert nextIsSet;
+        try {
           return (K) next;
         } finally {
            // release strong reference and invalidate current value:
@@ -148,8 +150,6 @@ public final class WeakIdentityMap<K,V> {
           next = null;
         }
       }
-        throw new NoSuchElementException();
-      }
       
       @Override
       public void remove() {
@@ -161,15 +161,16 @@ public final class WeakIdentityMap<K,V> {
         while (iterator.hasNext()) {
           next = iterator.next().get();
           if (next == null) {
-            // already garbage collected!
+            // the key was already GCed, we can remove it from backing map:
-            continue;
+            iterator.remove();
-          }
+          } else {
-          // unfold "null" special value
+            // unfold "null" special value:
             if (next == NULL) {
               next = null;
             }
             return nextIsSet = true;
           }
+        }
         return false;
       }
     };

lucene/core/src/test/org/apache/lucene/util/TestWeakIdentityMap.java

@@ -122,13 +122,16 @@ public class TestWeakIdentityMap extends LuceneTestCase {
     for (int i = 0; size > 0 && i < 10; i++) try {
       System.runFinalization();
       System.gc();
+      int newSize = map.size();
+      assertTrue("previousSize("+size+")>=newSize("+newSize+")", size >= newSize);
+      size = newSize;
       Thread.sleep(100L);
       c = 0;
       for (Iterator<String> it = map.keyIterator(); it.hasNext();) {
         assertNotNull(it.next());
         c++;
       }
-      final int newSize = map.size();
+      newSize = map.size();
       assertTrue("previousSize("+size+")>=iteratorSize("+c+")", size >= c);
       assertTrue("iteratorSize("+c+")>=newSize("+newSize+")", c >= newSize);
       size = newSize;
@@ -223,13 +226,16 @@ public class TestWeakIdentityMap extends LuceneTestCase {
     for (int i = 0; size > 0 && i < 10; i++) try {
       System.runFinalization();
       System.gc();
+      int newSize = map.size();
+      assertTrue("previousSize("+size+")>=newSize("+newSize+")", size >= newSize);
+      size = newSize;
       Thread.sleep(100L);
       int c = 0;
       for (Iterator<Object> it = map.keyIterator(); it.hasNext();) {
         assertNotNull(it.next());
         c++;
       }
-      final int newSize = map.size();
+      newSize = map.size();
       assertTrue("previousSize("+size+")>=iteratorSize("+c+")", size >= c);
       assertTrue("iteratorSize("+c+")>=newSize("+newSize+")", c >= newSize);
       size = newSize;