| /* |
| * 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 |
| * limitations under the License. |
| */ |
| package org.apache.calcite.avatica.remote; |
| |
| import org.apache.calcite.avatica.AvaticaSeverity; |
| import org.apache.calcite.avatica.NoSuchConnectionException; |
| import org.apache.calcite.avatica.remote.Service.ErrorResponse; |
| import org.apache.calcite.avatica.remote.Service.Request; |
| import org.apache.calcite.avatica.remote.Service.Response; |
| import org.apache.calcite.avatica.remote.Service.RpcMetadataResponse; |
| |
| import java.io.IOException; |
| |
| /** |
| * Abstract base class for {@link Handler}s to extend to inherit functionality common across |
| * serialization strategies. |
| * |
| * @param <T> The format Requests/Responses are serialized as. |
| */ |
| public abstract class AbstractHandler<T> implements Handler<T> { |
| private static final String NULL_EXCEPTION_MESSAGE = "(null exception message)"; |
| protected final Service service; |
| private RpcMetadataResponse metadata = null; |
| |
| public AbstractHandler(Service service) { |
| this.service = service; |
| } |
| |
| abstract Request decode(T serializedRequest) throws IOException; |
| |
| /** |
| * Serialize the given {@link Response} per the concrete {@link Handler} implementation. |
| * |
| * @param response The {@link Response} to serialize. |
| * @return A serialized representation of the {@link Response}. |
| */ |
| abstract T encode(Response response) throws IOException; |
| |
| /** |
| * Unwrap Avatica-specific context about a given exception. |
| * |
| * @param e A caught exception throw by Avatica implementation. |
| * @return An {@link ErrorResponse}. |
| */ |
| ErrorResponse unwrapException(Exception e) { |
| // By default, we know nothing extra. |
| int errorCode = ErrorResponse.UNKNOWN_ERROR_CODE; |
| String sqlState = ErrorResponse.UNKNOWN_SQL_STATE; |
| AvaticaSeverity severity = AvaticaSeverity.UNKNOWN; |
| String errorMsg = null; |
| |
| // Extract the contextual information if we have it. We may not. |
| if (e instanceof AvaticaRuntimeException) { |
| AvaticaRuntimeException rte = (AvaticaRuntimeException) e; |
| errorCode = rte.getErrorCode(); |
| sqlState = rte.getSqlState(); |
| severity = rte.getSeverity(); |
| errorMsg = rte.getErrorMessage(); |
| } else if (e instanceof NoSuchConnectionException) { |
| errorCode = ErrorResponse.MISSING_CONNECTION_ERROR_CODE; |
| severity = AvaticaSeverity.ERROR; |
| errorMsg = e.getMessage(); |
| } else { |
| // Try to construct a meaningful error message when the server impl doesn't provide one. |
| errorMsg = getCausalChain(e); |
| } |
| |
| return new ErrorResponse(e, errorMsg, errorCode, sqlState, severity, metadata); |
| } |
| |
| /** |
| * Compute a response for the given request, handling errors generated by that computation. |
| * |
| * @param serializedRequest The caller's request. |
| * @return A {@link Response} with additional context about that response. |
| */ |
| public HandlerResponse<T> apply(T serializedRequest) { |
| try { |
| final Service.Request request = decode(serializedRequest); |
| final Service.Response response = request.accept(service); |
| return new HandlerResponse<>(encode(response), HTTP_OK); |
| } catch (Exception e) { |
| return convertToErrorResponse(e); |
| } |
| } |
| |
| /** |
| * Attempts to convert an Exception to an ErrorResponse. If there is an issue in serialization, |
| * a RuntimeException is thrown instead (wrapping the original exception if necessary). |
| * |
| * @param e The exception to convert. |
| * @return A HandlerResponse instance. |
| */ |
| public HandlerResponse<T> convertToErrorResponse(Exception e) { |
| return createErrorResponse(e, HTTP_INTERNAL_SERVER_ERROR); |
| } |
| |
| /** |
| * Attempts to convert an Exception to an ErrorResponse with an HTTP status code of {@code 401}. |
| */ |
| public HandlerResponse<T> unauthenticatedErrorResponse(Exception e) { |
| return createErrorResponse(e, HTTP_UNAUTHENTICATED); |
| } |
| |
| /** |
| * Attempts to convert an Exception to an ErrorResponse with an HTTP stauts code of {@code 403}. |
| */ |
| public HandlerResponse<T> unauthorizedErrorResponse(Exception e) { |
| return createErrorResponse(e, HTTP_UNAUTHORIZED); |
| } |
| |
| private HandlerResponse<T> createErrorResponse(Exception e, int statusCode) { |
| ErrorResponse errorResp = unwrapException(e); |
| try { |
| return new HandlerResponse<>(encode(errorResp), statusCode); |
| } catch (IOException e1) { |
| // TODO provide a canned ErrorResponse |
| |
| // If we can't serialize the error message, we can't give a meaningful error to caller. |
| // Just try to not unnecessarily create more exceptions. |
| if (e instanceof RuntimeException) { |
| throw (RuntimeException) e; |
| } |
| throw new RuntimeException(e); |
| } |
| } |
| |
| /** |
| * Constructs a message for the summary of an Exception. |
| * |
| * @param e The Exception to summarize. |
| * @return A summary message for the Exception. |
| */ |
| private String getCausalChain(Exception e) { |
| StringBuilder sb = new StringBuilder(16); |
| Throwable curr = e; |
| // Could use Guava, but that would increase dependency set unnecessarily. |
| while (null != curr) { |
| if (sb.length() > 0) { |
| sb.append(" -> "); |
| } |
| String message = curr.getMessage(); |
| sb.append(curr.getClass().getSimpleName()).append(": "); |
| sb.append(null == message ? NULL_EXCEPTION_MESSAGE : message); |
| curr = curr.getCause(); |
| } |
| if (sb.length() == 0) { |
| // Catch the case where we have no error message. |
| return "Unknown error message"; |
| } |
| return sb.toString(); |
| } |
| |
| @Override public void setRpcMetadata(RpcMetadataResponse metadata) { |
| this.metadata = metadata; |
| } |
| } |
| |
| // End AbstractHandler.java |