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1   /*
2    * ====================================================================
3    * Licensed to the Apache Software Foundation (ASF) under one
4    * or more contributor license agreements.  See the NOTICE file
5    * distributed with this work for additional information
6    * regarding copyright ownership.  The ASF licenses this file
7    * to you under the Apache License, Version 2.0 (the
8    * "License"); you may not use this file except in compliance
9    * with the License.  You may obtain a copy of the License at
10   *
11   *   http://www.apache.org/licenses/LICENSE-2.0
12   *
13   * Unless required by applicable law or agreed to in writing,
14   * software distributed under the License is distributed on an
15   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
16   * KIND, either express or implied.  See the License for the
17   * specific language governing permissions and limitations
18   * under the License.
19   * ====================================================================
20   *
21   * This software consists of voluntary contributions made by many
22   * individuals on behalf of the Apache Software Foundation.  For more
23   * information on the Apache Software Foundation, please see
24   * <http://www.apache.org/>.
25   *
26   */
27  package org.apache.http.impl.client.cache.memcached;
28  
29  import org.apache.http.client.cache.HttpCacheEntry;
30  
31  /**
32   * Creates {@link MemcachedCacheEntry} instances that can be used for
33   * serializing and deserializing {@link HttpCacheEntry} instances for
34   * storage in memcached.
35   */
36  public interface MemcachedCacheEntryFactory {
37  
38      /**
39       * Creates a new {@link MemcachedCacheEntry} for storing the
40       * given {@link HttpCacheEntry} under the given storage key. Since
41       * we are hashing storage keys into cache keys to accommodate
42       * limitations in memcached's key space, it is possible to have
43       * cache collisions. Therefore, we store the storage key along
44       * with the {@code HttpCacheEntry} so it can be compared
45       * on retrieval and thus detect collisions.
46       * @param storageKey storage key under which the entry will
47       *   be logically stored
48       * @param entry the cache entry to store
49       * @return a {@link MemcachedCacheEntry} ready to provide
50       *   a serialized representation
51       */
52      MemcachedCacheEntry getMemcachedCacheEntry(String storageKey, HttpCacheEntry entry);
53  
54      /**
55       * Creates an "unset" {@link MemcachedCacheEntry} ready to accept
56       * a serialized representation via {@link MemcachedCacheEntry#set(byte[])}
57       * and deserialize it into a storage key and a {@link HttpCacheEntry}.
58       * @return {@code MemcachedCacheEntry}
59       */
60      MemcachedCacheEntry getUnsetCacheEntry();
61  
62  }