Adding Key class for intents

Change-Id: Ib6e586bcc938e062de0b1d6c92e3b885334a4769

+/*
+ * 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.net.intent;
+
+import com.google.common.hash.HashFunction;
+import com.google.common.hash.Hashing;
+import org.onosproject.core.ApplicationId;
+
+import java.nio.charset.StandardCharsets;
+import java.util.Objects;
+
+/**
+ * Key class for Intents.
+ */
+// TODO maybe pull this up to utils
+// TODO need to make this classes kryo serializable
+public class Key {
+
+    private final long hash;
+    private static final HashFunction HASH_FN = Hashing.md5();
+
+    private Key(long hash) {
+        this.hash = hash;
+    }
+
+    public long hash() {
+        return hash;
+    }
+
+    public static Key of(String key, ApplicationId appId) {
+        return new StringKey(key, appId);
+    }
+
+    public static Key of(long key, ApplicationId appId) {
+        return new LongKey(key, appId);
+    }
+
+    private final static class StringKey extends Key {
+
+        private final ApplicationId appId;
+        private final String key;
+
+        private StringKey(String key, ApplicationId appId) {
+            super(HASH_FN.newHasher()
+                          .putShort(appId.id())
+                          .putString(key, StandardCharsets.UTF_8)
+                          .hash().asLong());
+            this.key = key;
+            this.appId = appId;
+        }
+
+        @Override
+        public String toString() {
+            return key;
+        }
+
+        @Override
+        public int hashCode() {
+            return Objects.hash(key);
+        }
+
+        @Override
+        public boolean equals(Object obj) {
+            if (this == obj) {
+                return true;
+            }
+            if (obj == null || getClass() != obj.getClass()) {
+                return false;
+            }
+            final StringKey other = (StringKey) obj;
+            return this.hash() == other.hash() &&
+                    Objects.equals(this.appId, other.appId) &&
+                    Objects.equals(this.key, other.key);
+        }
+    }
+
+    private final static class LongKey extends Key {
+
+        private final ApplicationId appId;
+        private static long key;
+
+        private LongKey(long key, ApplicationId appId) {
+            super(HASH_FN.newHasher()
+                          .putShort(appId.id())
+                          .putLong(key)
+                          .hash().asLong());
+            this.key = key;
+            this.appId = appId;
+        }
+
+        @Override
+        public String toString() {
+            return Long.toString(key);
+        }
+
+        @Override
+        public int hashCode() {
+            return Objects.hash(key);
+        }
+
+        @Override
+        public boolean equals(Object obj) {
+            if (this == obj) {
+                return true;
+            }
+            if (obj == null || getClass() != obj.getClass()) {
+                return false;
+            }
+            final LongKey other = (LongKey) obj;
+            return Objects.equals(this.appId, other.appId) &&
+                    this.key == other.key;
+        }
+
+    }
+}
+
+