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Efficient reliable UDP unicast, UDP multicast, and IPC transport protocol.
There is a newer version: 1.46.7
/*
 * Copyright 2014-2021 Real Logic Limited.
 *
 * 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://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 io.aeron.command;

import io.aeron.ErrorCode;
import org.agrona.*;

/**
 * Control message flyweight for any errors sent from driver to clients
 *  *   0                   1                   2                   3
 *   0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
 *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *  |              Offending Command Correlation ID                 |
 *  |                                                               |
 *  +---------------------------------------------------------------+
 *  |                         Error Code                            |
 *  +---------------------------------------------------------------+
 *  |                   Error Message Length                        |
 *  +---------------------------------------------------------------+
 *  |                       Error Message                          ...
 * ...                                                              |
 *  +---------------------------------------------------------------+
 * 
 */
public class ErrorResponseFlyweight
{
    private static final int OFFENDING_COMMAND_CORRELATION_ID_OFFSET = 0;
    private static final int ERROR_CODE_OFFSET = OFFENDING_COMMAND_CORRELATION_ID_OFFSET + BitUtil.SIZE_OF_LONG;
    private static final int ERROR_MESSAGE_OFFSET = ERROR_CODE_OFFSET + BitUtil.SIZE_OF_INT;

    private MutableDirectBuffer buffer;
    private int offset;

    /**
     * Wrap the buffer at a given offset for updates.
     *
     * @param buffer to wrap.
     * @param offset at which the message begins.
     * @return this for a fluent API.
     */
    public final ErrorResponseFlyweight wrap(final MutableDirectBuffer buffer, final int offset)
    {
        this.buffer = buffer;
        this.offset = offset;

        return this;
    }

    /**
     * Return correlation ID of the offending command.
     *
     * @return correlation ID of the offending command
     */
    public long offendingCommandCorrelationId()
    {
        return buffer.getLong(offset + OFFENDING_COMMAND_CORRELATION_ID_OFFSET);
    }

    /**
     * Set correlation ID of the offending command.
     *
     * @param correlationId of the offending command.
     * @return this for a fluent API.
     */
    public ErrorResponseFlyweight offendingCommandCorrelationId(final long correlationId)
    {
        buffer.putLong(offset + OFFENDING_COMMAND_CORRELATION_ID_OFFSET, correlationId);
        return this;
    }

    /**
     * Error code for the command.
     *
     * @return error code for the command.
     */
    public ErrorCode errorCode()
    {
        return ErrorCode.get(buffer.getInt(offset + ERROR_CODE_OFFSET));
    }

    /**
     * Error code value for the command.
     *
     * @return error code value for the command.
     */
    public int errorCodeValue()
    {
        return buffer.getInt(offset + ERROR_CODE_OFFSET);
    }

    /**
     * Set the error code for the command.
     *
     * @param code for the error.
     * @return this for a fluent API.
     */
    public ErrorResponseFlyweight errorCode(final ErrorCode code)
    {
        buffer.putInt(offset + ERROR_CODE_OFFSET, code.value());
        return this;
    }

    /**
     * Error message associated with the error.
     *
     * @return error message
     */
    public String errorMessage()
    {
        return buffer.getStringAscii(offset + ERROR_MESSAGE_OFFSET);
    }

    /**
     * Append the error message to an appendable without allocation.
     *
     * @param appendable to append error message to.
     * @return number bytes copied.
     */
    public int appendMessage(final Appendable appendable)
    {
        return buffer.getStringAscii(offset + ERROR_MESSAGE_OFFSET, appendable);
    }

    /**
     * Set the error message.
     *
     * @param message to associate with the error.
     * @return this for a fluent API.
     */
    public ErrorResponseFlyweight errorMessage(final String message)
    {
        buffer.putStringAscii(offset + ERROR_MESSAGE_OFFSET, message);
        return this;
    }

    /**
     * Length of the error response in bytes.
     *
     * @return length of the error response in bytes.
     */
    public int length()
    {
        return ERROR_MESSAGE_OFFSET + BitUtil.SIZE_OF_INT + buffer.getInt(offset + ERROR_MESSAGE_OFFSET);
    }
}