Added distributed transaction support through a two phase commit protocol
Change-Id: I85d64234a24823fee8b3c2ea830abbb6867dad38
diff --git a/core/store/dist/src/main/java/org/onosproject/store/consistent/impl/Result.java b/core/store/dist/src/main/java/org/onosproject/store/consistent/impl/Result.java
new file mode 100644
index 0000000..548174a
--- /dev/null
+++ b/core/store/dist/src/main/java/org/onosproject/store/consistent/impl/Result.java
@@ -0,0 +1,91 @@
+/*
+ * 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.consistent.impl;
+
+/**
+ * Result of a database update operation.
+ *
+ * @param <V> return value type
+ */
+public final class Result<V> {
+
+ public enum Status {
+ /**
+ * Indicates a successful update.
+ */
+ OK,
+
+ /**
+ * Indicates a failure due to underlying state being locked by another transaction.
+ */
+ LOCKED
+ }
+
+ private final Status status;
+ private final V value;
+
+ /**
+ * Creates a new Result instance with the specified value with status set to Status.OK.
+ *
+ * @param <V> result value type
+ * @param value result value
+ * @return Result instance
+ */
+ public static <V> Result<V> ok(V value) {
+ return new Result<>(value, Status.OK);
+ }
+
+ /**
+ * Creates a new Result instance with status set to Status.LOCKED.
+ *
+ * @param <V> result value type
+ * @return Result instance
+ */
+ public static <V> Result<V> locked() {
+ return new Result<>(null, Status.LOCKED);
+ }
+
+ private Result(V value, Status status) {
+ this.value = value;
+ this.status = status;
+ }
+
+ /**
+ * Returns true if this result indicates a successful execution i.e status is Status.OK.
+ *
+ * @return true if successful, false otherwise
+ */
+ public boolean success() {
+ return status == Status.OK;
+ }
+
+ /**
+ * Returns the status of database update operation.
+ * @return database update status
+ */
+ public Status status() {
+ return status;
+ }
+
+ /**
+ * Returns the return value for the update.
+ * @return value returned by database update. If the status is another
+ * other than Status.OK, this returns a null
+ */
+ public V value() {
+ return value;
+ }
+}
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