Added destroy() method to DistributedPrimitive interface
Implement replace method in ConsistentMap
Using Versioned#valueOrNull in place of Versioned#valueOrElse where appropriate

Change-Id: Ief3f3547d589d35f5c821a1c47035f91078e8316
diff --git a/core/api/src/main/java/org/onosproject/cluster/DefaultPartition.java b/core/api/src/main/java/org/onosproject/cluster/DefaultPartition.java
index 5832608..07a5d71 100644
--- a/core/api/src/main/java/org/onosproject/cluster/DefaultPartition.java
+++ b/core/api/src/main/java/org/onosproject/cluster/DefaultPartition.java
@@ -42,6 +42,11 @@
         this.members = ImmutableSet.copyOf(members);
     }
 
+    public DefaultPartition(Partition other) {
+        this.id = checkNotNull(other.getId());
+        this.members = ImmutableSet.copyOf(other.getMembers());
+    }
+
     @Override
     public PartitionId getId() {
         return this.id;
diff --git a/core/api/src/main/java/org/onosproject/store/service/AsyncConsistentMap.java b/core/api/src/main/java/org/onosproject/store/service/AsyncConsistentMap.java
index d83c553..2bec77a 100644
--- a/core/api/src/main/java/org/onosproject/store/service/AsyncConsistentMap.java
+++ b/core/api/src/main/java/org/onosproject/store/service/AsyncConsistentMap.java
@@ -37,12 +37,12 @@
  * a temporary disruption in network connectivity between participating nodes
  * or due to a node being temporarily down.
  * </p><p>
- * All values stored in this map are versioned and the API supports optimistic
- * concurrency by allowing conditional updates that take into consideration
- * the version or value that was previously read.
+ * All values stored in this map are {@link Versioned versioned} and the API
+ * supports optimistic concurrency by allowing conditional updates that take into
+ * consideration the version or value that was previously read.
  * </p><p>
  * This map does not allow null values. All methods can throw a ConsistentMapException
- * (which extends RuntimeException) to indicate failures.
+ * (which extends {@code RuntimeException}) to indicate failures.
  * <p>
  * All methods of this interface return a {@link CompletableFuture future} immediately
  * after a successful invocation. The operation itself is executed asynchronous and
@@ -56,6 +56,11 @@
         return DistributedPrimitive.Type.CONSISTENT_MAP;
     }
 
+    @Override
+    default CompletableFuture<Void> destroy() {
+        return clear();
+    }
+
     /**
      * Returns the number of entries in the map.
      *
diff --git a/core/api/src/main/java/org/onosproject/store/service/ConsistentMap.java b/core/api/src/main/java/org/onosproject/store/service/ConsistentMap.java
index 19f8954..805c995 100644
--- a/core/api/src/main/java/org/onosproject/store/service/ConsistentMap.java
+++ b/core/api/src/main/java/org/onosproject/store/service/ConsistentMap.java
@@ -25,24 +25,11 @@
 import java.util.function.Predicate;
 
 /**
- * A distributed, strongly consistent key-value map.
- * <p>
- * This map offers strong read-after-update (where update == create/update/delete)
- * consistency. All operations to the map are serialized and applied in a consistent
- * manner.
- * <p>
- * The stronger consistency comes at the expense of availability in
- * the event of a network partition. A network partition can be either due to
- * a temporary disruption in network connectivity between participating nodes
- * or due to a node being temporarily down.
- * </p><p>
- * All values stored in this map are versioned and the API supports optimistic
- * concurrency by allowing conditional updates that take into consideration
- * the version or value that was previously read.
- * </p><p>
- * This map does not allow null values. All methods can throw a ConsistentMapException
- * (which extends RuntimeException) to indicate failures.
+ * {@code ConsistentMap} provides the same functionality as {@link AsyncConsistentMap} with
+ * the only difference that all its methods block until the corresponding operation completes.
  *
+ * @param <K> type of key
+ * @param <V> type of value
  */
 public interface ConsistentMap<K, V> extends DistributedPrimitive {
 
diff --git a/core/api/src/main/java/org/onosproject/store/service/DistributedPrimitive.java b/core/api/src/main/java/org/onosproject/store/service/DistributedPrimitive.java
index 6a6c09e..ed2e9c9 100644
--- a/core/api/src/main/java/org/onosproject/store/service/DistributedPrimitive.java
+++ b/core/api/src/main/java/org/onosproject/store/service/DistributedPrimitive.java
@@ -15,6 +15,8 @@
  */
 package org.onosproject.store.service;
 
+import java.util.concurrent.CompletableFuture;
+
 import org.onosproject.core.ApplicationId;
 
 /**
@@ -76,4 +78,15 @@
     default ApplicationId applicationId() {
         return null;
     }
+
+    /**
+     * Purges state associated with this primitive.
+     * <p>
+     * Implementations can override and provide appropriate clean up logic for purging
+     * any state state associated with the primitive. Whether modifications made within the
+     * destroy method have local or global visibility is left unspecified.
+     */
+    default CompletableFuture<Void> destroy() {
+        return CompletableFuture.completedFuture(null);
+    }
 }
diff --git a/core/api/src/main/java/org/onosproject/store/service/EventuallyConsistentMap.java b/core/api/src/main/java/org/onosproject/store/service/EventuallyConsistentMap.java
index 2369619..5399422 100644
--- a/core/api/src/main/java/org/onosproject/store/service/EventuallyConsistentMap.java
+++ b/core/api/src/main/java/org/onosproject/store/service/EventuallyConsistentMap.java
@@ -201,12 +201,4 @@
      * @param listener listener to deregister for events
      */
     void removeListener(EventuallyConsistentMapListener<K, V> listener);
-
-    /**
-     * Shuts down the map and breaks communication between different instances.
-     * This allows the map objects to be cleaned up and garbage collected.
-     * Calls to any methods on the map subsequent to calling destroy() will
-     * throw a {@link java.lang.RuntimeException}.
-     */
-    void destroy();
 }
diff --git a/core/api/src/main/java/org/onosproject/store/service/Synchronous.java b/core/api/src/main/java/org/onosproject/store/service/Synchronous.java
index be65382..d938e48 100644
--- a/core/api/src/main/java/org/onosproject/store/service/Synchronous.java
+++ b/core/api/src/main/java/org/onosproject/store/service/Synchronous.java
@@ -15,6 +15,8 @@
  */
 package org.onosproject.store.service;
 
+import java.util.concurrent.CompletableFuture;
+
 /**
  * DistributedPrimitive that is a synchronous (blocking) version of
  * another.
@@ -38,4 +40,9 @@
     public Type type() {
         return primitive.type();
     }
+
+    @Override
+    public CompletableFuture<Void> destroy() {
+        return primitive.destroy();
+    }
 }