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/*
* 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 {@link DefaultAsyncConsistentMap} that provides a weaker read consistency
* guarantee in return for better read performance.
* <p>
* For read/write operations that are local to a node this map implementation provides
* guarantees similar to a ConsistentMap. However for read/write operations executed
* across multiple nodes this implementation only provides eventual consistency.
*
* @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);
}
@Override
protected void beforeUpdate(K key) {
super.beforeUpdate(key);
cache.invalidate(key);
}
}
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