001/* 002 * Licensed to the Apache Software Foundation (ASF) under one 003 * or more contributor license agreements. See the NOTICE file 004 * distributed with this work for additional information 005 * regarding copyright ownership. The ASF licenses this file 006 * to you under the Apache License, Version 2.0 (the 007 * "License"); you may not use this file except in compliance 008 * with the License. You may obtain a copy of the License at 009 * 010 * http://www.apache.org/licenses/LICENSE-2.0 011 * 012 * Unless required by applicable law or agreed to in writing, software 013 * distributed under the License is distributed on an "AS IS" BASIS, 014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 015 * See the License for the specific language governing permissions and 016 * limitations under the License. 017 */ 018package org.apache.hadoop.hbase.coprocessor; 019 020import com.google.protobuf.Message; 021import com.google.protobuf.Service; 022import java.io.IOException; 023import org.apache.hadoop.hbase.HBaseInterfaceAudience; 024import org.apache.yetus.audience.InterfaceAudience; 025import org.apache.yetus.audience.InterfaceStability; 026 027/** 028 * Coprocessors implement this interface to observe and mediate endpoint invocations on a region. 029 * <br> 030 * <br> 031 * <h3>Exception Handling</h3> For all functions, exception handling is done as follows: 032 * <ul> 033 * <li>Exceptions of type {@link IOException} are reported back to client.</li> 034 * <li>For any other kind of exception: 035 * <ul> 036 * <li>If the configuration {@link CoprocessorHost#ABORT_ON_ERROR_KEY} is set to true, then the 037 * server aborts.</li> 038 * <li>Otherwise, coprocessor is removed from the server and 039 * {@link org.apache.hadoop.hbase.DoNotRetryIOException} is returned to the client.</li> 040 * </ul> 041 * </li> 042 * </ul> 043 */ 044@InterfaceAudience.LimitedPrivate(HBaseInterfaceAudience.COPROC) 045@InterfaceStability.Evolving 046public interface EndpointObserver { 047 048 /** 049 * Called before an Endpoint service method is invoked. The request message can be altered by 050 * returning a new instance. Throwing an exception will abort the invocation. Calling 051 * {@link org.apache.hadoop.hbase.coprocessor.ObserverContext#bypass()} has no effect in this 052 * hook. 053 * @param ctx the environment provided by the region server 054 * @param service the endpoint service 055 * @param request Request message expected by given {@code Service}'s method (by the name 056 * {@code methodName}). 057 * @param methodName the invoked service method 058 * @return the possibly modified message 059 */ 060 default Message preEndpointInvocation(ObserverContext<RegionCoprocessorEnvironment> ctx, 061 Service service, String methodName, Message request) throws IOException { 062 return request; 063 } 064 065 /** 066 * Called after an Endpoint service method is invoked. The response message can be altered using 067 * the builder. 068 * @param ctx the environment provided by the region server 069 * @param service the endpoint service 070 * @param methodName the invoked service method 071 * @param request Request message expected by given {@code Service}'s method (by the name 072 * {@code methodName}). 073 * @param responseBuilder Builder for final response to the client, with original response from 074 * Service's method merged into it. 075 */ 076 default void postEndpointInvocation(ObserverContext<RegionCoprocessorEnvironment> ctx, 077 Service service, String methodName, Message request, Message.Builder responseBuilder) 078 throws IOException { 079 } 080}