Refactor change: Moved all distributed primitive implementation classes into onos-core-primitives bundle

Change-Id: Icd5dbd4133cb2f21bd403bcd598e6012813e6bfd
diff --git a/core/api/src/main/java/org/onosproject/store/LogicalTimestamp.java b/core/api/src/main/java/org/onosproject/store/LogicalTimestamp.java
new file mode 100644
index 0000000..caeca64
--- /dev/null
+++ b/core/api/src/main/java/org/onosproject/store/LogicalTimestamp.java
@@ -0,0 +1,81 @@
+/*
+ * 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;
+
+import static com.google.common.base.Preconditions.checkArgument;
+
+import java.util.Objects;
+
+import com.google.common.base.MoreObjects;
+import com.google.common.collect.ComparisonChain;
+
+/**
+ * Timestamp based on logical sequence value.
+ * <p>
+ * LogicalTimestamps are ordered by their sequence values.
+ */
+public class LogicalTimestamp implements Timestamp {
+
+    private final long value;
+
+    public LogicalTimestamp(long value) {
+        this.value = value;
+    }
+
+    @Override
+    public int compareTo(Timestamp o) {
+        checkArgument(o instanceof LogicalTimestamp,
+                "Must be LogicalTimestamp", o);
+        LogicalTimestamp that = (LogicalTimestamp) o;
+
+        return ComparisonChain.start()
+                .compare(this.value, that.value)
+                .result();
+    }
+
+    @Override
+    public int hashCode() {
+        return Long.hashCode(value);
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj) {
+            return true;
+        }
+        if (!(obj instanceof LogicalTimestamp)) {
+            return false;
+        }
+        LogicalTimestamp that = (LogicalTimestamp) obj;
+        return Objects.equals(this.value, that.value);
+    }
+
+    @Override
+    public String toString() {
+        return MoreObjects.toStringHelper(getClass())
+                    .add("value", value)
+                    .toString();
+    }
+
+    /**
+     * Returns the sequence value.
+     *
+     * @return sequence value
+     */
+    public long value() {
+        return this.value;
+    }
+}