1 files changed, 71 insertions, 0 deletions

diff --git a/framework/src/onos/core/store/dist/src/main/java/org/onosproject/store/consistent/impl/AsyncCachingConsistentMap.java b/framework/src/onos/core/store/dist/src/main/java/org/onosproject/store/consistent/impl/AsyncCachingConsistentMap.java
new file mode 100644
index 00000000..7e575b01
--- /dev/null
+++ b/framework/src/onos/core/store/dist/src/main/java/org/onosproject/store/consistent/impl/AsyncCachingConsistentMap.java
@@ -0,0 +1,71 @@
+/*
+ * 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 java.util.concurrent.CompletableFuture;
+
+import org.onosproject.core.ApplicationId;
+import org.onosproject.store.service.Serializer;
+import org.onosproject.store.service.Versioned;
+
+import com.google.common.cache.CacheBuilder;
+import com.google.common.cache.CacheLoader;
+import com.google.common.cache.LoadingCache;
+
+/**
+ * Extension of DefaultAsyncConsistentMap that provides a weaker read consistency
+ * guarantee in return for better read performance.
+ *
+ * @param <K> key type
+ * @param <V> value type
+ */
+public class AsyncCachingConsistentMap<K, V> extends DefaultAsyncConsistentMap<K, V> {
+
+    private final LoadingCache<K, CompletableFuture<Versioned<V>>> cache =
+            CacheBuilder.newBuilder()
+                        .maximumSize(10000) // TODO: make configurable
+                        .build(new CacheLoader<K, CompletableFuture<Versioned<V>>>() {
+                            @Override
+                            public CompletableFuture<Versioned<V>> load(K key)
+                                    throws Exception {
+                                return AsyncCachingConsistentMap.super.get(key);
+                            }
+                        });
+
+    public AsyncCachingConsistentMap(String name,
+            ApplicationId applicationId,
+            Database database,
+            Serializer serializer,
+            boolean readOnly,
+            boolean purgeOnUninstall,
+            boolean meteringEnabled) {
+        super(name, applicationId, database, serializer, readOnly, purgeOnUninstall, meteringEnabled);
+        addListener(event -> cache.invalidate(event.key()));
+    }
+
+    @Override
+    public CompletableFuture<Versioned<V>> get(K key) {
+        CompletableFuture<Versioned<V>> cachedValue = cache.getIfPresent(key);
+        if (cachedValue != null) {
+            if (cachedValue.isCompletedExceptionally()) {
+                cache.invalidate(key);
+            } else {
+                return cachedValue;
+            }
+        }
+        return cache.getUnchecked(key);
+    }
+}
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