Merge "Bug 1781: Fix serialization of leafrefs"

[yangtools.git] / common / util / src / main / java / org / opendaylight / yangtools / util / ReadOnlyTrieMap.java

diff --git a/common/util/src/main/java/org/opendaylight/yangtools/util/ReadOnlyTrieMap.java b/common/util/src/main/java/org/opendaylight/yangtools/util/ReadOnlyTrieMap.java
index 88da121c8616f44aba44d633d9e599e1396fc5a4..0082ff3f5f782191e97c5de564601f4743b44757 100644 (file)
--- a/common/util/src/main/java/org/opendaylight/yangtools/util/ReadOnlyTrieMap.java
+++ b/common/util/src/main/java/org/opendaylight/yangtools/util/ReadOnlyTrieMap.java
@@ -7,14 +7,13 @@
  */
 package org.opendaylight.yangtools.util;
 
-import java.util.Map;
-
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
-
 import com.google.common.base.Preconditions;
 import com.google.common.collect.ForwardingMap;
 import com.romix.scala.collection.concurrent.TrieMap;
+import java.util.Map;
+import java.util.concurrent.atomic.AtomicReferenceFieldUpdater;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 /**
  * A read-only facade in front of a TrieMap. This is what we give out from
@@ -24,10 +23,13 @@ import com.romix.scala.collection.concurrent.TrieMap;
  * changes, we can cache it for future reference.
  */
 final class ReadOnlyTrieMap<K, V> extends ForwardingMap<K, V> {
+    @SuppressWarnings("rawtypes")
+    private static final AtomicReferenceFieldUpdater<ReadOnlyTrieMap, TrieMap> UPDATER =
+            AtomicReferenceFieldUpdater.newUpdater(ReadOnlyTrieMap.class, TrieMap.class, "readOnly");
     private static final Logger LOG = LoggerFactory.getLogger(ReadOnlyTrieMap.class);
     private final TrieMap<K, V> readWrite;
     private final int size;
-    private TrieMap<K, V> readOnly;
+    private volatile TrieMap<K, V> readOnly;
 
     ReadOnlyTrieMap(final TrieMap<K, V> map, final int size) {
         super();
@@ -43,15 +45,14 @@ final class ReadOnlyTrieMap<K, V> extends ForwardingMap<K, V> {
 
     @Override
     protected Map<K, V> delegate() {
-        if (readOnly == null) {
-            synchronized (this) {
-                if (readOnly == null) {
-                    readOnly = readWrite.readOnlySnapshot();
-                }
+        TrieMap<K, V> ret = readOnly;
+        if (ret == null) {
+            ret = readWrite.readOnlySnapshot();
+            if (!UPDATER.compareAndSet(this, null, ret)) {
+                ret = readOnly;
             }
         }
-
-        return readOnly;
+        return ret;
     }
 
     @Override