BUG-650: speed up ResolveDataChangeState.needsProcessing()

[controller.git] / opendaylight / md-sal / sal-inmemory-datastore / src / main / java / org / opendaylight / controller / md / sal / dom / store / impl / ResolveDataChangeState.java

diff --git a/opendaylight/md-sal/sal-inmemory-datastore/src/main/java/org/opendaylight/controller/md/sal/dom/store/impl/ResolveDataChangeState.java b/opendaylight/md-sal/sal-inmemory-datastore/src/main/java/org/opendaylight/controller/md/sal/dom/store/impl/ResolveDataChangeState.java
index d3c5a7cb70e8013734f64619b456e74ed18ee0e2..ea95030de3b82c758c478903448064d32fcdc10b 100644 (file)
--- a/opendaylight/md-sal/sal-inmemory-datastore/src/main/java/org/opendaylight/controller/md/sal/dom/store/impl/ResolveDataChangeState.java
+++ b/opendaylight/md-sal/sal-inmemory-datastore/src/main/java/org/opendaylight/controller/md/sal/dom/store/impl/ResolveDataChangeState.java
@@ -103,8 +103,19 @@ final class ResolveDataChangeState {
      * @return State handle
      */
     public ResolveDataChangeState child(final PathArgument childId) {
-        return new ResolveDataChangeState(nodeId.node(childId),
-            Iterables.concat(inheritedSub, subBuilders.values()),
+        /*
+         * We instantiate a concatenation only when needed, otherwise
+         * we reuse the collection. This speeds up Iterables.isEmpty()
+         * in needsProcessing().
+         */
+        final Iterable<Builder> sb;
+        if (subBuilders.isEmpty()) {
+            sb = inheritedSub;
+        } else {
+            sb = Iterables.concat(inheritedSub, subBuilders.values());
+        }
+
+        return new ResolveDataChangeState(nodeId.node(childId), sb,
             oneBuilders.values(), getListenerChildrenWildcarded(nodes, childId));
     }