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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.util.Optional;</span> |
| <span class="source-line-no">021</span><span id="line-21">import org.apache.yetus.audience.InterfaceAudience;</span> |
| <span class="source-line-no">022</span><span id="line-22"></span> |
| <span class="source-line-no">023</span><span id="line-23">/**</span> |
| <span class="source-line-no">024</span><span id="line-24"> * This is the low level API for asynchronous scan.</span> |
| <span class="source-line-no">025</span><span id="line-25"> * <p></span> |
| <span class="source-line-no">026</span><span id="line-26"> * All results that match the given scan object will be passed to this class by calling</span> |
| <span class="source-line-no">027</span><span id="line-27"> * {@link #onNext(Result[], ScanController)}. {@link #onComplete()} means the scan is finished, and</span> |
| <span class="source-line-no">028</span><span id="line-28"> * {@link #onError(Throwable)} means we hit an unrecoverable error and the scan is terminated.</span> |
| <span class="source-line-no">029</span><span id="line-29"> * {@link #onHeartbeat(ScanController)} means the RS is still working but we can not get a valid</span> |
| <span class="source-line-no">030</span><span id="line-30"> * result to call {@link #onNext(Result[], ScanController)}. This is usually because the matched</span> |
| <span class="source-line-no">031</span><span id="line-31"> * results are too sparse, for example, a filter which almost filters out everything is specified.</span> |
| <span class="source-line-no">032</span><span id="line-32"> * <p></span> |
| <span class="source-line-no">033</span><span id="line-33"> * Notice that, all the methods here will be called directly in the thread which we send request to</span> |
| <span class="source-line-no">034</span><span id="line-34"> * HBase service. So if you want the asynchronous scanner fetch data from HBase in background while</span> |
| <span class="source-line-no">035</span><span id="line-35"> * you process the returned data, you need to move the processing work to another thread to make the</span> |
| <span class="source-line-no">036</span><span id="line-36"> * {@link #onNext(Result[], ScanController)} call return immediately. And please do NOT do any time</span> |
| <span class="source-line-no">037</span><span id="line-37"> * consuming tasks in these methods unless you know what you are doing.</span> |
| <span class="source-line-no">038</span><span id="line-38"> * @since 2.0.0</span> |
| <span class="source-line-no">039</span><span id="line-39"> */</span> |
| <span class="source-line-no">040</span><span id="line-40">@InterfaceAudience.Public</span> |
| <span class="source-line-no">041</span><span id="line-41">public interface AdvancedScanResultConsumer extends ScanResultConsumerBase {</span> |
| <span class="source-line-no">042</span><span id="line-42"></span> |
| <span class="source-line-no">043</span><span id="line-43"> /**</span> |
| <span class="source-line-no">044</span><span id="line-44"> * Used to resume a scan.</span> |
| <span class="source-line-no">045</span><span id="line-45"> */</span> |
| <span class="source-line-no">046</span><span id="line-46"> @InterfaceAudience.Public</span> |
| <span class="source-line-no">047</span><span id="line-47"> interface ScanResumer {</span> |
| <span class="source-line-no">048</span><span id="line-48"></span> |
| <span class="source-line-no">049</span><span id="line-49"> /**</span> |
| <span class="source-line-no">050</span><span id="line-50"> * Resume the scan. You are free to call it multiple time but only the first call will take</span> |
| <span class="source-line-no">051</span><span id="line-51"> * effect.</span> |
| <span class="source-line-no">052</span><span id="line-52"> */</span> |
| <span class="source-line-no">053</span><span id="line-53"> void resume();</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"> * Used to suspend or stop a scan, or get a scan cursor if available.</span> |
| <span class="source-line-no">058</span><span id="line-58"> * <p></span> |
| <span class="source-line-no">059</span><span id="line-59"> * Notice that, you should only call the {@link #suspend()} or {@link #terminate()} inside onNext</span> |
| <span class="source-line-no">060</span><span id="line-60"> * or onHeartbeat method. A IllegalStateException will be thrown if you call them at other places.</span> |
| <span class="source-line-no">061</span><span id="line-61"> * <p></span> |
| <span class="source-line-no">062</span><span id="line-62"> * You can only call one of the {@link #suspend()} and {@link #terminate()} methods(of course you</span> |
| <span class="source-line-no">063</span><span id="line-63"> * are free to not call them both), and the methods are not reentrant. An IllegalStateException</span> |
| <span class="source-line-no">064</span><span id="line-64"> * will be thrown if you have already called one of the methods.</span> |
| <span class="source-line-no">065</span><span id="line-65"> */</span> |
| <span class="source-line-no">066</span><span id="line-66"> @InterfaceAudience.Public</span> |
| <span class="source-line-no">067</span><span id="line-67"> interface ScanController {</span> |
| <span class="source-line-no">068</span><span id="line-68"></span> |
| <span class="source-line-no">069</span><span id="line-69"> /**</span> |
| <span class="source-line-no">070</span><span id="line-70"> * Suspend the scan.</span> |
| <span class="source-line-no">071</span><span id="line-71"> * <p></span> |
| <span class="source-line-no">072</span><span id="line-72"> * This means we will stop fetching data in background, i.e., will not call onNext any more</span> |
| <span class="source-line-no">073</span><span id="line-73"> * before you resume the scan.</span> |
| <span class="source-line-no">074</span><span id="line-74"> * @return A resumer used to resume the scan later.</span> |
| <span class="source-line-no">075</span><span id="line-75"> */</span> |
| <span class="source-line-no">076</span><span id="line-76"> ScanResumer suspend();</span> |
| <span class="source-line-no">077</span><span id="line-77"></span> |
| <span class="source-line-no">078</span><span id="line-78"> /**</span> |
| <span class="source-line-no">079</span><span id="line-79"> * Terminate the scan.</span> |
| <span class="source-line-no">080</span><span id="line-80"> * <p></span> |
| <span class="source-line-no">081</span><span id="line-81"> * This is useful when you have got enough results and want to stop the scan in onNext method,</span> |
| <span class="source-line-no">082</span><span id="line-82"> * or you want to stop the scan in onHeartbeat method because it has spent too many time.</span> |
| <span class="source-line-no">083</span><span id="line-83"> */</span> |
| <span class="source-line-no">084</span><span id="line-84"> void terminate();</span> |
| <span class="source-line-no">085</span><span id="line-85"></span> |
| <span class="source-line-no">086</span><span id="line-86"> /**</span> |
| <span class="source-line-no">087</span><span id="line-87"> * Get the scan cursor if available.</span> |
| <span class="source-line-no">088</span><span id="line-88"> * @return The scan cursor.</span> |
| <span class="source-line-no">089</span><span id="line-89"> */</span> |
| <span class="source-line-no">090</span><span id="line-90"> Optional<Cursor> cursor();</span> |
| <span class="source-line-no">091</span><span id="line-91"> }</span> |
| <span class="source-line-no">092</span><span id="line-92"></span> |
| <span class="source-line-no">093</span><span id="line-93"> /**</span> |
| <span class="source-line-no">094</span><span id="line-94"> * Indicate that we have receive some data.</span> |
| <span class="source-line-no">095</span><span id="line-95"> * @param results the data fetched from HBase service.</span> |
| <span class="source-line-no">096</span><span id="line-96"> * @param controller used to suspend or terminate the scan. Notice that the {@code controller}</span> |
| <span class="source-line-no">097</span><span id="line-97"> * instance is only valid within scope of onNext method. You can only call its</span> |
| <span class="source-line-no">098</span><span id="line-98"> * method in onNext, do NOT store it and call it later outside onNext.</span> |
| <span class="source-line-no">099</span><span id="line-99"> */</span> |
| <span class="source-line-no">100</span><span id="line-100"> void onNext(Result[] results, ScanController controller);</span> |
| <span class="source-line-no">101</span><span id="line-101"></span> |
| <span class="source-line-no">102</span><span id="line-102"> /**</span> |
| <span class="source-line-no">103</span><span id="line-103"> * Indicate that there is a heartbeat message but we have not cumulated enough cells to call</span> |
| <span class="source-line-no">104</span><span id="line-104"> * {@link #onNext(Result[], ScanController)}.</span> |
| <span class="source-line-no">105</span><span id="line-105"> * <p></span> |
| <span class="source-line-no">106</span><span id="line-106"> * Note that this method will always be called when RS returns something to us but we do not have</span> |
| <span class="source-line-no">107</span><span id="line-107"> * enough cells to call {@link #onNext(Result[], ScanController)}. Sometimes it may not be a</span> |
| <span class="source-line-no">108</span><span id="line-108"> * 'heartbeat' message for RS, for example, we have a large row with many cells and size limit is</span> |
| <span class="source-line-no">109</span><span id="line-109"> * exceeded before sending all the cells for this row. For RS it does send some data to us and the</span> |
| <span class="source-line-no">110</span><span id="line-110"> * time limit has not been reached, but we can not return the data to client so here we call this</span> |
| <span class="source-line-no">111</span><span id="line-111"> * method to tell client we have already received something.</span> |
| <span class="source-line-no">112</span><span id="line-112"> * <p></span> |
| <span class="source-line-no">113</span><span id="line-113"> * This method give you a chance to terminate a slow scan operation.</span> |
| <span class="source-line-no">114</span><span id="line-114"> * @param controller used to suspend or terminate the scan. Notice that the {@code controller}</span> |
| <span class="source-line-no">115</span><span id="line-115"> * instance is only valid within the scope of onHeartbeat method. You can only</span> |
| <span class="source-line-no">116</span><span id="line-116"> * call its method in onHeartbeat, do NOT store it and call it later outside</span> |
| <span class="source-line-no">117</span><span id="line-117"> * onHeartbeat.</span> |
| <span class="source-line-no">118</span><span id="line-118"> */</span> |
| <span class="source-line-no">119</span><span id="line-119"> default void onHeartbeat(ScanController controller) {</span> |
| <span class="source-line-no">120</span><span id="line-120"> }</span> |
| <span class="source-line-no">121</span><span id="line-121">}</span> |
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| </pre> |
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