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<pre><span class="source-line-no">001</span><span id="line-1">/*</span>
<span class="source-line-no">002</span><span id="line-2"> * Licensed to the Apache Software Foundation (ASF) under one</span>
<span class="source-line-no">003</span><span id="line-3"> * or more contributor license agreements. See the NOTICE file</span>
<span class="source-line-no">004</span><span id="line-4"> * distributed with this work for additional information</span>
<span class="source-line-no">005</span><span id="line-5"> * regarding copyright ownership. The ASF licenses this file</span>
<span class="source-line-no">006</span><span id="line-6"> * to you under the Apache License, Version 2.0 (the</span>
<span class="source-line-no">007</span><span id="line-7"> * "License"); you may not use this file except in compliance</span>
<span class="source-line-no">008</span><span id="line-8"> * with the License. You may obtain a copy of the License at</span>
<span class="source-line-no">009</span><span id="line-9"> *</span>
<span class="source-line-no">010</span><span id="line-10"> * http://www.apache.org/licenses/LICENSE-2.0</span>
<span class="source-line-no">011</span><span id="line-11"> *</span>
<span class="source-line-no">012</span><span id="line-12"> * Unless required by applicable law or agreed to in writing, software</span>
<span class="source-line-no">013</span><span id="line-13"> * distributed under the License is distributed on an "AS IS" BASIS,</span>
<span class="source-line-no">014</span><span id="line-14"> * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.</span>
<span class="source-line-no">015</span><span id="line-15"> * See the License for the specific language governing permissions and</span>
<span class="source-line-no">016</span><span id="line-16"> * limitations under the License.</span>
<span class="source-line-no">017</span><span id="line-17"> */</span>
<span class="source-line-no">018</span><span id="line-18">package org.apache.hadoop.hbase.wal;</span>
<span class="source-line-no">019</span><span id="line-19"></span>
<span class="source-line-no">020</span><span id="line-20">import java.io.Closeable;</span>
<span class="source-line-no">021</span><span id="line-21">import java.io.IOException;</span>
<span class="source-line-no">022</span><span id="line-22">import org.apache.yetus.audience.InterfaceAudience;</span>
<span class="source-line-no">023</span><span id="line-23"></span>
<span class="source-line-no">024</span><span id="line-24">/**</span>
<span class="source-line-no">025</span><span id="line-25"> * A one way WAL reader, without reset and seek support.</span>
<span class="source-line-no">026</span><span id="line-26"> * &lt;p/&gt;</span>
<span class="source-line-no">027</span><span id="line-27"> * In most cases you should use this interface to read WAL file, as the implementation is simple and</span>
<span class="source-line-no">028</span><span id="line-28"> * robust. For replication, where we want to tail the WAL file which is currently being written, you</span>
<span class="source-line-no">029</span><span id="line-29"> * should use {@link WALTailingReader} instead.</span>
<span class="source-line-no">030</span><span id="line-30"> * @see WALTailingReader</span>
<span class="source-line-no">031</span><span id="line-31"> */</span>
<span class="source-line-no">032</span><span id="line-32">@InterfaceAudience.Private</span>
<span class="source-line-no">033</span><span id="line-33">public interface WALStreamReader extends Closeable {</span>
<span class="source-line-no">034</span><span id="line-34"></span>
<span class="source-line-no">035</span><span id="line-35"> /**</span>
<span class="source-line-no">036</span><span id="line-36"> * Read the next entry in WAL.</span>
<span class="source-line-no">037</span><span id="line-37"> * &lt;p/&gt;</span>
<span class="source-line-no">038</span><span id="line-38"> * In most cases you should just use this method, especially when reading a closed wal file for</span>
<span class="source-line-no">039</span><span id="line-39"> * splitting or printing.</span>
<span class="source-line-no">040</span><span id="line-40"> */</span>
<span class="source-line-no">041</span><span id="line-41"> default WAL.Entry next() throws IOException {</span>
<span class="source-line-no">042</span><span id="line-42"> return next(null);</span>
<span class="source-line-no">043</span><span id="line-43"> }</span>
<span class="source-line-no">044</span><span id="line-44"></span>
<span class="source-line-no">045</span><span id="line-45"> /**</span>
<span class="source-line-no">046</span><span id="line-46"> * Read the next entry in WAL, use the given {@link WAL.Entry} if not {@code null} to hold the</span>
<span class="source-line-no">047</span><span id="line-47"> * data.</span>
<span class="source-line-no">048</span><span id="line-48"> * &lt;p/&gt;</span>
<span class="source-line-no">049</span><span id="line-49"> * Mainly used in MR.</span>
<span class="source-line-no">050</span><span id="line-50"> * @param reuse the entry to be used for reading, can be {@code null}</span>
<span class="source-line-no">051</span><span id="line-51"> */</span>
<span class="source-line-no">052</span><span id="line-52"> WAL.Entry next(WAL.Entry reuse) throws IOException;</span>
<span class="source-line-no">053</span><span id="line-53"></span>
<span class="source-line-no">054</span><span id="line-54"> /**</span>
<span class="source-line-no">055</span><span id="line-55"> * Get the current reading position.</span>
<span class="source-line-no">056</span><span id="line-56"> */</span>
<span class="source-line-no">057</span><span id="line-57"> long getPosition() throws IOException;</span>
<span class="source-line-no">058</span><span id="line-58"></span>
<span class="source-line-no">059</span><span id="line-59"> /**</span>
<span class="source-line-no">060</span><span id="line-60"> * Override to remove the 'throws IOException' as we are just a reader.</span>
<span class="source-line-no">061</span><span id="line-61"> */</span>
<span class="source-line-no">062</span><span id="line-62"> @Override</span>
<span class="source-line-no">063</span><span id="line-63"> void close();</span>
<span class="source-line-no">064</span><span id="line-64">}</span>
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