com.renren.dp.xlog.util.RemoteExceptionHandler.java Source code

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Here is the source code for com.renren.dp.xlog.util.RemoteExceptionHandler.java

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/**
 * Copyright 2007 The Apache Software Foundation
 *
 * 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 com.renren.dp.xlog.util;

import java.io.IOException;
import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;

import org.apache.hadoop.ipc.RemoteException;

/**
 * An immutable class which contains a static method for handling
 * org.apache.hadoop.ipc.RemoteException exceptions.
 */
public class RemoteExceptionHandler {
    /* Not instantiable */
    private RemoteExceptionHandler() {
        super();
    }

    /**
     * Examine passed Throwable.  See if its carrying a RemoteException. If so,
     * run {@link #decodeRemoteException(RemoteException)} on it.  Otherwise,
     * pass back <code>t</code> unaltered.
     * @param t Throwable to examine.
     * @return Decoded RemoteException carried by <code>t</code> or
     * <code>t</code> unaltered.
     */
    public static Throwable checkThrowable(final Throwable t) {
        Throwable result = t;
        if (t instanceof RemoteException) {
            try {
                result = RemoteExceptionHandler.decodeRemoteException((RemoteException) t);
            } catch (Throwable tt) {
                result = tt;
            }
        }
        return result;
    }

    /**
     * Examine passed IOException.  See if its carrying a RemoteException. If so,
     * run {@link #decodeRemoteException(RemoteException)} on it.  Otherwise,
     * pass back <code>e</code> unaltered.
     * @param e Exception to examine.
     * @return Decoded RemoteException carried by <code>e</code> or
     * <code>e</code> unaltered.
     */
    public static IOException checkIOException(final IOException e) {
        Throwable t = checkThrowable(e);
        return t instanceof IOException ? (IOException) t : new IOException(t);
    }

    /**
     * Converts org.apache.hadoop.ipc.RemoteException into original exception,
     * if possible. If the original exception is an Error or a RuntimeException,
     * throws the original exception.
     *
     * @param re original exception
     * @return decoded RemoteException if it is an instance of or a subclass of
     *         IOException, or the original RemoteException if it cannot be decoded.
     *
     * @throws IOException indicating a server error ocurred if the decoded
     *         exception is not an IOException. The decoded exception is set as
     *         the cause.
     * @deprecated Use {@link RemoteException#unwrapRemoteException()} instead.
     * In fact we should look into deprecating this whole class - St.Ack 2010929
     */
    public static IOException decodeRemoteException(final RemoteException re) throws IOException {
        IOException i = re;

        try {
            Class<?> c = Class.forName(re.getClassName());

            Class<?>[] parameterTypes = { String.class };
            Constructor<?> ctor = c.getConstructor(parameterTypes);

            Object[] arguments = { re.getMessage() };
            Throwable t = (Throwable) ctor.newInstance(arguments);

            if (t instanceof IOException) {
                i = (IOException) t;

            } else {
                i = new IOException("server error");
                i.initCause(t);
                throw i;
            }

        } catch (ClassNotFoundException x) {
            // continue
        } catch (NoSuchMethodException x) {
            // continue
        } catch (IllegalAccessException x) {
            // continue
        } catch (InvocationTargetException x) {
            // continue
        } catch (InstantiationException x) {
            // continue
        }
        return i;
    }
}