1 /** 2 * Copyright 2011 The Apache Software Foundation 3 * 4 * Licensed to the Apache Software Foundation (ASF) under one 5 * or more contributor license agreements. See the NOTICE file 6 * distributed with this work for additional information 7 * regarding copyright ownership. The ASF licenses this file 8 * to you under the Apache License, Version 2.0 (the 9 * "License"); you may not use this file except in compliance 10 * with the License. You may obtain a copy of the License at 11 * 12 * http://www.apache.org/licenses/LICENSE-2.0 13 * 14 * Unless required by applicable law or agreed to in writing, software 15 * distributed under the License is distributed on an "AS IS" BASIS, 16 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 17 * See the License for the specific language governing permissions and 18 * limitations under the License. 19 */ 20 package org.apache.hadoop.hbase.ipc; 21 22 import java.io.IOException; 23 24 /** 25 * A call whose response can be delayed by the server. 26 */ 27 public interface Delayable { 28 /** 29 * Signal that the call response should be delayed, thus freeing the RPC 30 * server to handle different requests. 31 * 32 * @param delayReturnValue Controls whether the return value of the call 33 * should be set when ending the delay or right away. There are cases when 34 * the return value can be set right away, even if the call is delayed. 35 */ 36 public void startDelay(boolean delayReturnValue); 37 38 /** 39 * @return is the call delayed? 40 */ 41 public boolean isDelayed(); 42 43 /** 44 * @return is the return value delayed? 45 */ 46 public boolean isReturnValueDelayed(); 47 48 /** 49 * Signal that the RPC server is now allowed to send the response. 50 * @param result The value to return to the caller. If the corresponding 51 * delay response specified that the return value should 52 * not be delayed, this parameter must be null. 53 * @throws IOException 54 */ 55 public void endDelay(Object result) throws IOException; 56 57 /** 58 * Signal the end of a delayed RPC, without specifying the return value. Use 59 * this only if the return value was not delayed 60 * @throws IOException 61 */ 62 public void endDelay() throws IOException; 63 64 /** 65 * End the call, throwing and exception to the caller. This works regardless 66 * of the return value being delayed. 67 * @param t Object to throw to the client. 68 * @throws IOException 69 */ 70 public void endDelayThrowing(Throwable t) throws IOException; 71 }