GridCacheAlwaysEvictionPolicy.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.apache.ignite.internal.processors.cache;

import java.io.Externalizable;
import java.io.IOException;
import java.io.ObjectInput;
import java.io.ObjectOutput;
import org.apache.ignite.cache.eviction.EvictableEntry;
import org.apache.ignite.cache.eviction.EvictionPolicy;

/**
 * Cache eviction policy that expires every entry essentially keeping the cache empty.
 * This eviction policy can be used whenever one cache is used to front another
 * and its size should be kept at {@code 0}.
 */
public class GridCacheAlwaysEvictionPolicy<K, V> implements EvictionPolicy<K, V>, Externalizable {
    /** {@inheritDoc} */
    @Override public void onEntryAccessed(boolean rmv, EvictableEntry<K, V> entry) {
        if (!rmv && entry.isCached())
            entry.evict();
    }

    /** {@inheritDoc} */
    @Override public void writeExternal(ObjectOutput out) throws IOException {
        // No-op.
    }

    /** {@inheritDoc} */
    @Override public void readExternal(ObjectInput in) throws IOException, ClassNotFoundException {
        // No-op.
    }
}