Merge pull request #10569 from vespa-engine/balder/more-efficient-trim

Removing elements from an array is very costly.

1 files changed, 6 insertions, 1 deletions

diff --git a/vespajlib/src/main/java/com/yahoo/collections/ListenableArrayList.java b/vespajlib/src/main/java/com/yahoo/collections/ListenableArrayList.java
index e3f73212170..44569471049 100644
--- a/vespajlib/src/main/java/com/yahoo/collections/ListenableArrayList.java
+++ b/vespajlib/src/main/java/com/yahoo/collections/ListenableArrayList.java
@@ -3,13 +3,13 @@ package com.yahoo.collections;
 
 import java.util.ArrayList;
 import java.util.Collection;
+import java.util.Collections;
 import java.util.List;
 
 /**
  * An array list which notifies listeners after one or more items are added
  *
  * @author bratseth
- * @since 5.1.17
  */
 @SuppressWarnings("serial")
 public class ListenableArrayList<ITEM> extends ArrayList<ITEM> {
@@ -56,6 +56,11 @@ public class ListenableArrayList<ITEM> extends ArrayList<ITEM> {
         return result;
     }
 
+    public List<Runnable> listeners() {
+        if (listeners == null) return Collections.emptyList();
+        return Collections.unmodifiableList(listeners);
+    }
+
     /**
      * Adds a listener which is invoked whenever elements are added to this.
      * This may not be invoked once for each added element.