1 files changed, 69 insertions, 0 deletions
diff --git a/framework/src/onos/core/api/src/main/java/org/onosproject/store/service/AtomicValue.java b/framework/src/onos/core/api/src/main/java/org/onosproject/store/service/AtomicValue.java
new file mode 100644
index 00000000..dfa0fb3c
--- /dev/null
+++ b/framework/src/onos/core/api/src/main/java/org/onosproject/store/service/AtomicValue.java
@@ -0,0 +1,69 @@
+/*
+ * Copyright 2015 Open Networking Laboratory
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.store.service;
+
+/**
+ * Distributed version of java.util.concurrent.atomic.AtomicReference.
+ *
+ * @param <V> value type
+ */
+public interface AtomicValue<V> {
+
+    /**
+     * Atomically sets the value to the given updated value if the current value is equal to the expected value.
+     * <p>
+     * IMPORTANT: Equality is based on the equality of the serialized byte[] representations.
+     * <p>
+     * @param expect  the expected value
+     * @param update  the new value
+     * @return true if successful. false return indicates that the actual value was not equal to the expected value.
+     */
+    boolean compareAndSet(V expect, V update);
+
+    /**
+     * Gets the current value.
+     * @return current value
+     */
+    V get();
+
+    /**
+     * Atomically sets to the given value and returns the old value.
+     * @param value the new value
+     * @return previous value
+     */
+    V getAndSet(V value);
+
+    /**
+     * Sets to the given value.
+     * @param value new value
+     */
+    void set(V value);
+
+    /**
+     * Registers the specified listener to be notified whenever the atomic value is updated.
+     *
+     * @param listener listener to notify about events
+     */
+    void addListener(AtomicValueEventListener<V> listener);
+
+    /**
+     * Unregisters the specified listener such that it will no longer
+     * receive atomic value update notifications.
+     *
+     * @param listener listener to unregister
+     */
+    void removeListener(AtomicValueEventListener<V> listener);
+}