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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.client;</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 java.io.UncheckedIOException;</span> |
| <span class="source-line-no">023</span><span id="line-23">import java.util.ArrayList;</span> |
| <span class="source-line-no">024</span><span id="line-24">import java.util.Iterator;</span> |
| <span class="source-line-no">025</span><span id="line-25">import java.util.List;</span> |
| <span class="source-line-no">026</span><span id="line-26">import org.apache.hadoop.hbase.client.metrics.ScanMetrics;</span> |
| <span class="source-line-no">027</span><span id="line-27">import org.apache.yetus.audience.InterfaceAudience;</span> |
| <span class="source-line-no">028</span><span id="line-28"></span> |
| <span class="source-line-no">029</span><span id="line-29">/**</span> |
| <span class="source-line-no">030</span><span id="line-30"> * Interface for client-side scanning. Go to {@link Table} to obtain instances.</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.Public</span> |
| <span class="source-line-no">033</span><span id="line-33">public interface ResultScanner extends Closeable, Iterable<Result> {</span> |
| <span class="source-line-no">034</span><span id="line-34"></span> |
| <span class="source-line-no">035</span><span id="line-35"> @Override</span> |
| <span class="source-line-no">036</span><span id="line-36"> default Iterator<Result> iterator() {</span> |
| <span class="source-line-no">037</span><span id="line-37"> return new Iterator<Result>() {</span> |
| <span class="source-line-no">038</span><span id="line-38"> // The next RowResult, possibly pre-read</span> |
| <span class="source-line-no">039</span><span id="line-39"> Result next = null;</span> |
| <span class="source-line-no">040</span><span id="line-40"></span> |
| <span class="source-line-no">041</span><span id="line-41"> // return true if there is another item pending, false if there isn't.</span> |
| <span class="source-line-no">042</span><span id="line-42"> // this method is where the actual advancing takes place, but you need</span> |
| <span class="source-line-no">043</span><span id="line-43"> // to call next() to consume it. hasNext() will only advance if there</span> |
| <span class="source-line-no">044</span><span id="line-44"> // isn't a pending next().</span> |
| <span class="source-line-no">045</span><span id="line-45"> @Override</span> |
| <span class="source-line-no">046</span><span id="line-46"> public boolean hasNext() {</span> |
| <span class="source-line-no">047</span><span id="line-47"> if (next != null) {</span> |
| <span class="source-line-no">048</span><span id="line-48"> return true;</span> |
| <span class="source-line-no">049</span><span id="line-49"> }</span> |
| <span class="source-line-no">050</span><span id="line-50"> try {</span> |
| <span class="source-line-no">051</span><span id="line-51"> return (next = ResultScanner.this.next()) != null;</span> |
| <span class="source-line-no">052</span><span id="line-52"> } catch (IOException e) {</span> |
| <span class="source-line-no">053</span><span id="line-53"> throw new UncheckedIOException(e);</span> |
| <span class="source-line-no">054</span><span id="line-54"> }</span> |
| <span class="source-line-no">055</span><span id="line-55"> }</span> |
| <span class="source-line-no">056</span><span id="line-56"></span> |
| <span class="source-line-no">057</span><span id="line-57"> // get the pending next item and advance the iterator. returns null if</span> |
| <span class="source-line-no">058</span><span id="line-58"> // there is no next item.</span> |
| <span class="source-line-no">059</span><span id="line-59"> @Override</span> |
| <span class="source-line-no">060</span><span id="line-60"> public Result next() {</span> |
| <span class="source-line-no">061</span><span id="line-61"> // since hasNext() does the real advancing, we call this to determine</span> |
| <span class="source-line-no">062</span><span id="line-62"> // if there is a next before proceeding.</span> |
| <span class="source-line-no">063</span><span id="line-63"> if (!hasNext()) {</span> |
| <span class="source-line-no">064</span><span id="line-64"> return null;</span> |
| <span class="source-line-no">065</span><span id="line-65"> }</span> |
| <span class="source-line-no">066</span><span id="line-66"></span> |
| <span class="source-line-no">067</span><span id="line-67"> // if we get to here, then hasNext() has given us an item to return.</span> |
| <span class="source-line-no">068</span><span id="line-68"> // we want to return the item and then null out the next pointer, so</span> |
| <span class="source-line-no">069</span><span id="line-69"> // we use a temporary variable.</span> |
| <span class="source-line-no">070</span><span id="line-70"> Result temp = next;</span> |
| <span class="source-line-no">071</span><span id="line-71"> next = null;</span> |
| <span class="source-line-no">072</span><span id="line-72"> return temp;</span> |
| <span class="source-line-no">073</span><span id="line-73"> }</span> |
| <span class="source-line-no">074</span><span id="line-74"> };</span> |
| <span class="source-line-no">075</span><span id="line-75"> }</span> |
| <span class="source-line-no">076</span><span id="line-76"></span> |
| <span class="source-line-no">077</span><span id="line-77"> /**</span> |
| <span class="source-line-no">078</span><span id="line-78"> * Grab the next row's worth of values. The scanner will return a Result.</span> |
| <span class="source-line-no">079</span><span id="line-79"> * @return Result object if there is another row, null if the scanner is exhausted.</span> |
| <span class="source-line-no">080</span><span id="line-80"> * @throws IOException e</span> |
| <span class="source-line-no">081</span><span id="line-81"> */</span> |
| <span class="source-line-no">082</span><span id="line-82"> Result next() throws IOException;</span> |
| <span class="source-line-no">083</span><span id="line-83"></span> |
| <span class="source-line-no">084</span><span id="line-84"> /**</span> |
| <span class="source-line-no">085</span><span id="line-85"> * Get nbRows rows. How many RPCs are made is determined by the {@link Scan#setCaching(int)}</span> |
| <span class="source-line-no">086</span><span id="line-86"> * setting (or hbase.client.scanner.caching in hbase-site.xml).</span> |
| <span class="source-line-no">087</span><span id="line-87"> * @param nbRows number of rows to return</span> |
| <span class="source-line-no">088</span><span id="line-88"> * @return Between zero and nbRows rowResults. Scan is done if returned array is of zero-length</span> |
| <span class="source-line-no">089</span><span id="line-89"> * (We never return null).</span> |
| <span class="source-line-no">090</span><span id="line-90"> */</span> |
| <span class="source-line-no">091</span><span id="line-91"> default Result[] next(int nbRows) throws IOException {</span> |
| <span class="source-line-no">092</span><span id="line-92"> List<Result> resultSets = new ArrayList<>(nbRows);</span> |
| <span class="source-line-no">093</span><span id="line-93"> for (int i = 0; i < nbRows; i++) {</span> |
| <span class="source-line-no">094</span><span id="line-94"> Result next = next();</span> |
| <span class="source-line-no">095</span><span id="line-95"> if (next != null) {</span> |
| <span class="source-line-no">096</span><span id="line-96"> resultSets.add(next);</span> |
| <span class="source-line-no">097</span><span id="line-97"> } else {</span> |
| <span class="source-line-no">098</span><span id="line-98"> break;</span> |
| <span class="source-line-no">099</span><span id="line-99"> }</span> |
| <span class="source-line-no">100</span><span id="line-100"> }</span> |
| <span class="source-line-no">101</span><span id="line-101"> return resultSets.toArray(new Result[0]);</span> |
| <span class="source-line-no">102</span><span id="line-102"> }</span> |
| <span class="source-line-no">103</span><span id="line-103"></span> |
| <span class="source-line-no">104</span><span id="line-104"> /**</span> |
| <span class="source-line-no">105</span><span id="line-105"> * Closes the scanner and releases any resources it has allocated</span> |
| <span class="source-line-no">106</span><span id="line-106"> */</span> |
| <span class="source-line-no">107</span><span id="line-107"> @Override</span> |
| <span class="source-line-no">108</span><span id="line-108"> void close();</span> |
| <span class="source-line-no">109</span><span id="line-109"></span> |
| <span class="source-line-no">110</span><span id="line-110"> /**</span> |
| <span class="source-line-no">111</span><span id="line-111"> * Allow the client to renew the scanner's lease on the server.</span> |
| <span class="source-line-no">112</span><span id="line-112"> * @return true if the lease was successfully renewed, false otherwise.</span> |
| <span class="source-line-no">113</span><span id="line-113"> */</span> |
| <span class="source-line-no">114</span><span id="line-114"> boolean renewLease();</span> |
| <span class="source-line-no">115</span><span id="line-115"></span> |
| <span class="source-line-no">116</span><span id="line-116"> /** Returns the scan metrics, or {@code null} if we do not enable metrics. */</span> |
| <span class="source-line-no">117</span><span id="line-117"> ScanMetrics getScanMetrics();</span> |
| <span class="source-line-no">118</span><span id="line-118">}</span> |
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| </pre> |
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