001    /*
002     * Copyright (C) 2011 The Guava Authors
003     *
004     * Licensed under the Apache License, Version 2.0 (the "License");
005     * you may not use this file except in compliance with the License.
006     * You may obtain a copy of the License at
007     *
008     * http://www.apache.org/licenses/LICENSE-2.0
009     *
010     * Unless required by applicable law or agreed to in writing, software
011     * distributed under the License is distributed on an "AS IS" BASIS,
012     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013     * See the License for the specific language governing permissions and
014     * limitations under the License.
015     */
016    
017    package com.google.common.cache;
018    
019    import com.google.common.annotations.Beta;
020    
021    import java.util.Iterator;
022    import java.util.Map;
023    import java.util.concurrent.ConcurrentMap;
024    
025    /**
026     * The reason why a cached entry was removed.
027     *
028     * @author Charles Fry
029     * @since 10.0
030     */
031    @Beta
032    public enum RemovalCause {
033      /**
034       * The entry was manually removed by the user. This can result from the user invoking
035       * {@link Cache#invalidate}, {@link Cache#invalidateAll(Iterable)}, {@link Cache#invalidateAll()},
036       * {@link Map#remove}, {@link ConcurrentMap#remove}, or {@link Iterator#remove}.
037       */
038      EXPLICIT {
039        @Override
040        boolean wasEvicted() {
041          return false;
042        }
043      },
044    
045      /**
046       * The entry itself was not actually removed, but its value was replaced by the user. This can
047       * result from the user invoking {@link Cache#put}, {@link LoadingCache#refresh}, {@link Map#put},
048       * {@link Map#putAll}, {@link ConcurrentMap#replace(Object, Object)}, or
049       * {@link ConcurrentMap#replace(Object, Object, Object)}.
050       */
051      REPLACED {
052        @Override
053        boolean wasEvicted() {
054          return false;
055        }
056      },
057    
058      /**
059       * The entry was removed automatically because its key or value was garbage-collected. This
060       * can occur when using {@link CacheBuilder#weakKeys}, {@link CacheBuilder#weakValues}, or
061       * {@link CacheBuilder#softValues}.
062       */
063      COLLECTED {
064        @Override
065        boolean wasEvicted() {
066          return true;
067        }
068      },
069    
070      /**
071       * The entry's expiration timestamp has passed. This can occur when using
072       * {@link CacheBuilder#expireAfterWrite} or {@link CacheBuilder#expireAfterAccess}.
073       */
074      EXPIRED {
075        @Override
076        boolean wasEvicted() {
077          return true;
078        }
079      },
080    
081      /**
082       * The entry was evicted due to size constraints. This can occur when using
083       * {@link CacheBuilder#maximumSize} or {@link CacheBuilder#maximumWeight}.
084       */
085      SIZE {
086        @Override
087        boolean wasEvicted() {
088          return true;
089        }
090      };
091    
092      /**
093       * Returns {@code true} if there was an automatic removal due to eviction (the cause is neither
094       * {@link #EXPLICIT} nor {@link #REPLACED}).
095       */
096      abstract boolean wasEvicted();
097    }