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/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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
 *
 * http://www.apache.org/licenses/LICENSE-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
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package org.apache.hadoop.hbase.ipc;

import java.io.IOException;

import org.apache.hadoop.hbase.classification.InterfaceAudience;
import org.apache.hadoop.util.StringUtils;

import com.google.protobuf.RpcCallback;
import com.google.protobuf.RpcController;
import org.apache.hadoop.util.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<MyResponse> 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); * } * *

*/ @InterfaceAudience.Private public class ServerRpcController implements RpcController { /** * The exception thrown within * {@link com.google.protobuf.Service#callMethod( * Descriptors.MethodDescriptor, RpcController, Message, RpcCallback)}, * if any. */ // TODO: 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 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; } /** * Throws an IOException back out if one is currently stored. */ public void checkFailed() throws IOException { if (failedOnException()) { throw getFailedOn(); } } }