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1   /*
2    * Licensed to the Apache Software Foundation (ASF) under one
3    * or more contributor license agreements.  See the NOTICE file
4    * distributed with this work for additional information
5    * regarding copyright ownership.  The ASF licenses this file
6    * to you under the Apache License, Version 2.0 (the
7    * "License"); you may not use this file except in compliance
8    * with the License.  You may obtain a copy of the License at
9    *
10   *   http://www.apache.org/licenses/LICENSE-2.0
11   *
12   * Unless required by applicable law or agreed to in writing, software
13   * distributed under the License is distributed on an "AS IS" BASIS,
14   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15   * See the License for the specific language governing permissions and
16   * limitations under the License.
17   */
18  package org.apache.omid.transaction;
19  
20  import com.google.common.base.Optional;
21  
22  import java.io.IOException;
23  
24  /**
25   * An behavior that needs to be implemented by transaction managers 
26   * to try to locate the possible commit timestamp for a cell. It
27   * allows to the transaction managers implementing this interface to
28   * search the commit timestamp in a local cache of their own or in 
29   * their particular shadow cells implementation.
30   */
31  public interface CommitTimestampLocator {
32  
33      Optional<Long> readCommitTimestampFromCache(long startTimestamp);
34  
35      Optional<Long> readCommitTimestampFromShadowCell(long startTimestamp) throws IOException;
36  
37  }