1 files changed, 121 insertions, 0 deletions

diff --git a/framework/src/onos/core/store/dist/src/main/java/org/onosproject/store/consistent/impl/Result.java b/framework/src/onos/core/store/dist/src/main/java/org/onosproject/store/consistent/impl/Result.java
new file mode 100644
index 00000000..856f706d
--- /dev/null
+++ b/framework/src/onos/core/store/dist/src/main/java/org/onosproject/store/consistent/impl/Result.java
@@ -0,0 +1,121 @@
+/*
+ * 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;
+
+import static com.google.common.base.MoreObjects.toStringHelper;
+
+import java.util.Objects;
+
+/**
+ * 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;
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(value, status);
+    }
+
+    @SuppressWarnings("unchecked")
+    @Override
+    public boolean equals(Object other) {
+        if (!(other instanceof Result)) {
+            return false;
+        }
+        Result<V> that = (Result<V>) other;
+        return Objects.equals(this.value, that.value) &&
+               Objects.equals(this.status, that.status);
+    }
+
+    @Override
+    public String toString() {
+        return toStringHelper(this)
+                .add("status", status)
+                .add("value", value)
+                .toString();
+    }
+}
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