ShutdownSignalException.java

// Copyright (c) 2007-Present Pivotal Software, Inc.  All rights reserved.
//
// This software, the RabbitMQ Java client library, is triple-licensed under the
// Mozilla Public License 1.1 ("MPL"), the GNU General Public License version 2
// ("GPL") and the Apache License version 2 ("ASL"). For the MPL, please see
// LICENSE-MPL-RabbitMQ. For the GPL, please see LICENSE-GPL2.  For the ASL,
// please see LICENSE-APACHE2.
//
// This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND,
// either express or implied. See the LICENSE file for specific language governing
// rights and limitations of this software.
//
// If you have any questions regarding licensing, please contact us at
// info@rabbitmq.com.

package com.rabbitmq.client;

import com.rabbitmq.utility.SensibleClone;

/**
 * Encapsulates a shutdown condition for a connection to an AMQP broker.
 * Depending on HardError when calling
 * {@link com.rabbitmq.client.ShutdownSignalException#getReference()} we will
 * either get a reference to the Connection or Channel instance that fired
 * this exception.
 */

public class ShutdownSignalException extends RuntimeException implements SensibleClone<ShutdownSignalException> {
    /** Default for non-checking. */
    private static final long serialVersionUID = 1L;

    /** True if the connection is shut down, or false if this signal refers to a channel */
    private final boolean _hardError;

    /**
     * True if this exception is caused by explicit application
     * action; false if it originated with the broker or as a result
     * of detectable non-deliberate application failure
     */
    private final boolean _initiatedByApplication;

    /** Possible explanation */
    private final Method _reason;

    /** Either Channel or Connection instance, depending on _hardError */
    private final Object _ref;

    /**
     * Construct a ShutdownSignalException from the arguments.
     * @param hardError the relevant hard error
     * @param initiatedByApplication if the shutdown was client-initiated
     * @param reason AMQP method describing the exception reason
     * @param ref Reference to Connection or Channel that fired the signal
     */
    public ShutdownSignalException(boolean hardError,
                                   boolean initiatedByApplication,
                                   Method reason, Object ref)
    {
        this(hardError, initiatedByApplication, reason, ref, "", null);
    }

    /**
     * Construct a ShutdownSignalException from the arguments.
     * @param hardError the relevant hard error
     * @param initiatedByApplication if the shutdown was client-initiated
     * @param reason AMQP method describing the exception reason
     * @param ref Reference to Connection or Channel that fired the signal
     * @param messagePrefix prefix to add to exception message
     */
    public ShutdownSignalException(boolean hardError,
                                   boolean initiatedByApplication,
                                   Method reason, Object ref, String messagePrefix, Throwable cause)
    {
        super(composeMessage(hardError, initiatedByApplication, reason, messagePrefix, cause));
        this._hardError = hardError;
        this._initiatedByApplication = initiatedByApplication;
        this._reason = reason;
        // Depending on hardError what we got is either Connection or Channel reference
        this._ref = ref;
    }

    private static String composeMessage(boolean hardError, boolean initiatedByApplication,
                                         Method reason, String messagePrefix, Throwable cause) {
        final String connectionOrChannel = hardError ? "connection" : "channel";
        final String appInitiated = "clean " + connectionOrChannel + " shutdown";
        final String nonAppInitiated = connectionOrChannel + " error";
        final String explanation = initiatedByApplication ? appInitiated : nonAppInitiated;

        StringBuilder result = new StringBuilder(messagePrefix).append(explanation);
        if(reason != null) {
            result.append("; protocol method: ").append(reason);
        }
        if(cause != null) {
            result.append("; cause: ").append(cause);
        }
        return result.toString();
    }

    /** @return true if this signals a connection error, or false if a channel error */
    public boolean isHardError() { return _hardError; }

    /** @return true if this exception was caused by explicit application
     * action; false if it originated with the broker or as a result
     * of detectable non-deliberate application failure
     */
    public boolean isInitiatedByApplication() { return _initiatedByApplication; }

    /** @return the reason, if any */
    public Method getReason() { return _reason; }

    /** @return Reference to Connection or Channel object that fired the signal **/
    public Object getReference() { return _ref; }

    @Override
    public ShutdownSignalException sensibleClone() {
        try {
            return (ShutdownSignalException)super.clone();
        } catch (CloneNotSupportedException e) {
            // You've got to be kidding me
            throw new Error(e);
        }
    }
}