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Efficient reliable UDP unicast, UDP multicast, and IPC transport protocol.
There is a newer version: 1.46.7
/*
 * Copyright 2014-2023 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.exceptions.ControlProtocolException;
import org.agrona.MutableDirectBuffer;

import static io.aeron.ErrorCode.MALFORMED_COMMAND;
import static org.agrona.BitUtil.SIZE_OF_LONG;

/**
 * Base flyweight that can be extended to track a client request.
 * 
 * 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
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 * |                         Client ID                             |
 * |                                                               |
 * +---------------------------------------------------------------+
 * |                       Correlation ID                          |
 * |                                                               |
 * +---------------------------------------------------------------+
 */
public class CorrelatedMessageFlyweight
{
    /**
     * Length of the header.
     */
    public static final int LENGTH = 2 * SIZE_OF_LONG;
    private static final int CLIENT_ID_FIELD_OFFSET = 0;
    static final int CORRELATION_ID_FIELD_OFFSET = CLIENT_ID_FIELD_OFFSET + SIZE_OF_LONG;

    MutableDirectBuffer buffer;
    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 CorrelatedMessageFlyweight wrap(final MutableDirectBuffer buffer, final int offset)
    {
        this.buffer = buffer;
        this.offset = offset;

        return this;
    }

    /**
     * Get client id field.
     *
     * @return client id field.
     */
    public long clientId()
    {
        return buffer.getLong(offset + CLIENT_ID_FIELD_OFFSET);
    }

    /**
     * set client id field
     *
     * @param clientId field value
     * @return this for a fluent API.
     */
    public CorrelatedMessageFlyweight clientId(final long clientId)
    {
        buffer.putLong(offset + CLIENT_ID_FIELD_OFFSET, clientId);

        return this;
    }

    /**
     * Get correlation id field.
     *
     * @return correlation id field.
     */
    public long correlationId()
    {
        return buffer.getLong(offset + CORRELATION_ID_FIELD_OFFSET);
    }

    /**
     * Set correlation id field.
     *
     * @param correlationId field value.
     * @return this for a fluent API.
     */
    public CorrelatedMessageFlyweight correlationId(final long correlationId)
    {
        buffer.putLong(offset + CORRELATION_ID_FIELD_OFFSET, correlationId);

        return this;
    }

    /**
     * Validate buffer length is long enough for message.
     *
     * @param msgTypeId type of message.
     * @param length of message in bytes to validate.
     */
    public void validateLength(final int msgTypeId, final int length)
    {
        if (length < LENGTH)
        {
            throw new ControlProtocolException(
                MALFORMED_COMMAND, "command=" + msgTypeId + " too short: length=" + length);
        }
    }
}