Close indexes as they are removed from the IndexCollection

Change-Id: I71cf370be094ae1eba73b2dec9e0dfec3b9a5c09

gerrit-lucene/src/main/java/com/google/gerrit/lucene/LuceneIndexModule.java

@@ -109,7 +109,7 @@ public class LuceneIndexModule extends LifecycleModule {
 
     @Override
     public void stop() {
-      index.close();
+      // Do nothing; indexes are closed by IndexCollection.
     }
   }
 }

gerrit-lucene/src/main/java/com/google/gerrit/lucene/LuceneVersionManager.java

@@ -220,5 +220,6 @@ class LuceneVersionManager implements LifecycleListener {
 
   @Override
   public void stop() {
+    // Do nothing; indexes are closed on demand by IndexCollection.
   }
 }

gerrit-server/src/main/java/com/google/gerrit/server/index/IndexCollection.java

@@ -49,7 +49,10 @@ public class IndexCollection implements LifecycleListener {
   }
 
   public void setSearchIndex(ChangeIndex index) {
-    searchIndex.set(index);
+    ChangeIndex old = searchIndex.getAndSet(index);
+    if (old != null && old != index) {
+      old.close();
+    }
   }
 
   public Collection<ChangeIndex> getWriteIndexes() {
@@ -76,7 +79,11 @@ public class IndexCollection implements LifecycleListener {
       }
     }
     if (removeIndex >= 0) {
-      writeIndexes.remove(removeIndex);
+      try {
+        writeIndexes.get(removeIndex).close();
+      } finally {
+        writeIndexes.remove(removeIndex);
+      }
     }
   }