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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.coprocessor;</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.IOException;</span>
<span class="source-line-no">021</span><span id="line-21">import org.apache.hadoop.hbase.HBaseInterfaceAudience;</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">import org.apache.yetus.audience.InterfaceStability;</span>
<span class="source-line-no">024</span><span id="line-24"></span>
<span class="source-line-no">025</span><span id="line-25">import org.apache.hbase.thirdparty.com.google.protobuf.Message;</span>
<span class="source-line-no">026</span><span id="line-26">import org.apache.hbase.thirdparty.com.google.protobuf.Service;</span>
<span class="source-line-no">027</span><span id="line-27"></span>
<span class="source-line-no">028</span><span id="line-28">/**</span>
<span class="source-line-no">029</span><span id="line-29"> * Coprocessors implement this interface to observe and mediate endpoint invocations on a region.</span>
<span class="source-line-no">030</span><span id="line-30"> * &lt;br&gt;</span>
<span class="source-line-no">031</span><span id="line-31"> * &lt;br&gt;</span>
<span class="source-line-no">032</span><span id="line-32"> * &lt;h3&gt;Exception Handling&lt;/h3&gt; For all functions, exception handling is done as follows:</span>
<span class="source-line-no">033</span><span id="line-33"> * &lt;ul&gt;</span>
<span class="source-line-no">034</span><span id="line-34"> * &lt;li&gt;Exceptions of type {@link IOException} are reported back to client.&lt;/li&gt;</span>
<span class="source-line-no">035</span><span id="line-35"> * &lt;li&gt;For any other kind of exception:</span>
<span class="source-line-no">036</span><span id="line-36"> * &lt;ul&gt;</span>
<span class="source-line-no">037</span><span id="line-37"> * &lt;li&gt;If the configuration {@link CoprocessorHost#ABORT_ON_ERROR_KEY} is set to true, then the</span>
<span class="source-line-no">038</span><span id="line-38"> * server aborts.&lt;/li&gt;</span>
<span class="source-line-no">039</span><span id="line-39"> * &lt;li&gt;Otherwise, coprocessor is removed from the server and</span>
<span class="source-line-no">040</span><span id="line-40"> * {@link org.apache.hadoop.hbase.DoNotRetryIOException} is returned to the client.&lt;/li&gt;</span>
<span class="source-line-no">041</span><span id="line-41"> * &lt;/ul&gt;</span>
<span class="source-line-no">042</span><span id="line-42"> * &lt;/li&gt;</span>
<span class="source-line-no">043</span><span id="line-43"> * &lt;/ul&gt;</span>
<span class="source-line-no">044</span><span id="line-44"> */</span>
<span class="source-line-no">045</span><span id="line-45">@InterfaceAudience.LimitedPrivate(HBaseInterfaceAudience.COPROC)</span>
<span class="source-line-no">046</span><span id="line-46">@InterfaceStability.Evolving</span>
<span class="source-line-no">047</span><span id="line-47">public interface EndpointObserver {</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"> * Called before an Endpoint service method is invoked. The request message can be altered by</span>
<span class="source-line-no">051</span><span id="line-51"> * returning a new instance. Throwing an exception will abort the invocation. Calling</span>
<span class="source-line-no">052</span><span id="line-52"> * {@link org.apache.hadoop.hbase.coprocessor.ObserverContext#bypass()} has no effect in this</span>
<span class="source-line-no">053</span><span id="line-53"> * hook.</span>
<span class="source-line-no">054</span><span id="line-54"> * @param ctx the environment provided by the region server</span>
<span class="source-line-no">055</span><span id="line-55"> * @param service the endpoint service</span>
<span class="source-line-no">056</span><span id="line-56"> * @param request Request message expected by given {@code Service}'s method (by the name</span>
<span class="source-line-no">057</span><span id="line-57"> * {@code methodName}).</span>
<span class="source-line-no">058</span><span id="line-58"> * @param methodName the invoked service method</span>
<span class="source-line-no">059</span><span id="line-59"> * @return the possibly modified message</span>
<span class="source-line-no">060</span><span id="line-60"> */</span>
<span class="source-line-no">061</span><span id="line-61"> default Message preEndpointInvocation(ObserverContext&lt;RegionCoprocessorEnvironment&gt; ctx,</span>
<span class="source-line-no">062</span><span id="line-62"> Service service, String methodName, Message request) throws IOException {</span>
<span class="source-line-no">063</span><span id="line-63"> return request;</span>
<span class="source-line-no">064</span><span id="line-64"> }</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"> * Called after an Endpoint service method is invoked. The response message can be altered using</span>
<span class="source-line-no">068</span><span id="line-68"> * the builder.</span>
<span class="source-line-no">069</span><span id="line-69"> * @param ctx the environment provided by the region server</span>
<span class="source-line-no">070</span><span id="line-70"> * @param service the endpoint service</span>
<span class="source-line-no">071</span><span id="line-71"> * @param methodName the invoked service method</span>
<span class="source-line-no">072</span><span id="line-72"> * @param request Request message expected by given {@code Service}'s method (by the name</span>
<span class="source-line-no">073</span><span id="line-73"> * {@code methodName}).</span>
<span class="source-line-no">074</span><span id="line-74"> * @param responseBuilder Builder for final response to the client, with original response from</span>
<span class="source-line-no">075</span><span id="line-75"> * Service's method merged into it.</span>
<span class="source-line-no">076</span><span id="line-76"> */</span>
<span class="source-line-no">077</span><span id="line-77"> default void postEndpointInvocation(ObserverContext&lt;RegionCoprocessorEnvironment&gt; ctx,</span>
<span class="source-line-no">078</span><span id="line-78"> Service service, String methodName, Message request, Message.Builder responseBuilder)</span>
<span class="source-line-no">079</span><span id="line-79"> throws IOException {</span>
<span class="source-line-no">080</span><span id="line-80"> }</span>
<span class="source-line-no">081</span><span id="line-81">}</span>
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