content: /*
   * Copyright 2014-2025 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_INT;
  
  /**
   * Control message for getting next available session id from the media driver
   * ({@link ControlProtocolEvents#GET_NEXT_AVAILABLE_SESSION_ID}).
   * <pre>
   *   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                            |
   *  |                                                               |
   *  +---------------------------------------------------------------+
   *  |                    Command Correlation ID                     |
   *  |                                                               |
   *  +---------------------------------------------------------------+
   *  |                         Stream Id                             |
   *  +---------------------------------------------------------------+
   * </pre>
   */
  public final class GetNextAvailableSessionIdMessageFlyweight extends CorrelatedMessageFlyweight
  {
      private static final int STREAM_ID_OFFSET = CorrelatedMessageFlyweight.LENGTH;
      /**
       * Length of the header.
       */
      public static final int LENGTH = STREAM_ID_OFFSET + SIZE_OF_INT;
  
      /**
       * 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 GetNextAvailableSessionIdMessageFlyweight wrap(final MutableDirectBuffer buffer, final int offset)
      {
          super.wrap(buffer, offset);
  
          return this;
      }
  
      /**
       * Get the stream id.
       *
       * @return the stream id.
       */
      public int streamId()
      {
          return buffer.getInt(offset + STREAM_ID_OFFSET);
      }
  
      /**
       * Set the stream id.
       *
       * @param streamId the channel id.
       * @return this for a fluent API.
       */
      public GetNextAvailableSessionIdMessageFlyweight streamId(final int streamId)
      {
          buffer.putInt(offset + STREAM_ID_OFFSET, streamId);
  
          return this;
      }
  
      /**
       * Length of the message in bytes. Only valid after the channel is set.
       *
       * @return length of the message in bytes.
       */
      public int length()
      {
          return LENGTH;
      }
  
      /**
       * 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);
          }
      }
  }
  