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/*
 * Tencent is pleased to support the open source community by making Angel available.
 *
 * Copyright (C) 2017-2018 THL A29 Limited, a Tencent company. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in 
 * compliance with the License. You may obtain a copy of the License at
 *
 * https://opensource.org/licenses/Apache-2.0
 *
 * Unless required by applicable law or agreed to in writing, software distributed under the License
 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
 * or implied. See the License for the specific language governing permissions and limitations under
 * the License.
 *
 */


package com.tencent.angel.ipc;

import com.google.protobuf.RpcCallback;
import com.google.protobuf.RpcController;
import com.tencent.angel.utils.StringUtils;

import java.io.IOException;

/**
 * Used for server-side protobuf RPC service invocations. This handler allows invocation exceptions
 * to easily be passed through to the RPC server from coprocessor
 * {@link com.google.protobuf.Service} implementations.
 * 

*

* When implementing {@link com.google.protobuf.Service} defined methods, coprocessor endpoints can * use the following pattern to pass exceptions back to the RPC client: * public void myMethod(RpcController controller, MyRequest request, RpcCallback done) { * MyResponse response = null; * try { * // do processing * response = MyResponse.getDefaultInstance(); // or use a new builder to populate the response * } catch (IOException ioe) { * // pass exception back up * ResponseConverter.setControllerException(controller, ioe); * } * done.run(response); * } * *

*/ public class ServerRpcController implements RpcController { /** * The exception thrown within * {@link com.google.protobuf.Service#callMethod(com.google.protobuf.Descriptors.MethodDescriptor, com.google.protobuf.RpcController, com.google.protobuf.Message, com.google.protobuf.RpcCallback)} * , if any. */ // It would be good widen this to just Throwable, but IOException is what we // allow now private IOException serviceException; private String errorMessage; @Override public void reset() { serviceException = null; errorMessage = null; } @Override public boolean failed() { return (failedOnException() || errorMessage != null); } @Override public String errorText() { return errorMessage; } @Override public void startCancel() { // not implemented } @Override public void setFailed(String message) { errorMessage = message; } @Override public boolean isCanceled() { return false; } @Override public void notifyOnCancel(RpcCallback objectRpcCallback) { // not implemented } /** * Sets an exception to be communicated back to the {@link com.google.protobuf.Service} client. * * @param ioe the exception encountered during execution of the service method */ public void setFailedOn(IOException ioe) { serviceException = ioe; setFailed(StringUtils.stringifyException(ioe)); } /** * Returns any exception thrown during service method invocation, or {@code null} if no exception * was thrown. This can be used by clients to receive exceptions generated by RPC calls, even when * {@link com.google.protobuf.RpcCallback}s are used and no * {@link com.google.protobuf.ServiceException} is declared. */ public IOException getFailedOn() { return serviceException; } /** * Returns whether or not a server exception was generated in the prior RPC invocation. */ public boolean failedOnException() { return serviceException != null; } }