Add constructor for configuration of CacheSize

Change-Id: Ifdac489d87ad1b1ab23e43f05980f9cf0e5b834e

@@ -13,7 +13,6 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-
 package org.onosproject.store.primitives.impl;
 
 import java.util.concurrent.CompletableFuture;
@@ -40,10 +39,11 @@ import com.google.common.cache.LoadingCache;
  * @param <V> value type
  */
 public class CachingAsyncConsistentMap<K, V> extends DelegatingAsyncConsistentMap<K, V> {
+    private int maxCacheSize = 10000;
 
     private final LoadingCache<K, CompletableFuture<Versioned<V>>> cache =
             CacheBuilder.newBuilder()
-                        .maximumSize(10000) // TODO: make configurable
+                    .maximumSize(maxCacheSize)
                     .build(new CacheLoader<K, CompletableFuture<Versioned<V>>>() {
                         @Override
                         public CompletableFuture<Versioned<V>> load(K key)
@@ -54,11 +54,28 @@ public class CachingAsyncConsistentMap<K, V> extends DelegatingAsyncConsistentMa
 
     private final MapEventListener<K, V> cacheInvalidator = event -> cache.invalidate(event.key());
 
+    /**
+     * Default constructor.
+     *
+     * @param backingMap a distributed, strongly consistent map for backing
+     */
     public CachingAsyncConsistentMap(AsyncConsistentMap<K, V> backingMap) {
         super(backingMap);
         super.addListener(cacheInvalidator);
     }
 
+    /**
+     * Constructor to configure cache size of LoadingCache.
+     *
+     * @param backingMap a distributed, strongly consistent map for backing
+     * @param cacheSize the maximum size of the cache
+     */
+    public CachingAsyncConsistentMap(AsyncConsistentMap<K, V> backingMap, int cacheSize) {
+        super(backingMap);
+        super.addListener(cacheInvalidator);
+        maxCacheSize = cacheSize;
+    }
+
     @Override
     public CompletableFuture<Void> destroy() {
         return super.destroy().thenCompose(v -> removeListener(cacheInvalidator));