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 org.agrona.concurrent.broadcast;
  
  import static org.agrona.BitUtil.*;
  
  /**
   * Layout of the broadcast buffer. The buffer consists of a ring of messages that is a power of 2 in size.
   * This is followed by a trailer section containing state information about the ring.
   */
  public final class BroadcastBufferDescriptor
  {
      /**
       * Offset within the trailer for where the tail intended value is stored.
       */
      public static final int TAIL_INTENT_COUNTER_OFFSET;
  
      /**
       * Offset within the trailer for where the tail value is stored.
       */
      public static final int TAIL_COUNTER_OFFSET;
  
      /**
       * Offset within the trailer for where the latest sequence value is stored.
       */
      public static final int LATEST_COUNTER_OFFSET;
  
      /**
       * Total size of the trailer.
       */
      public static final int TRAILER_LENGTH;
  
      static
      {
          int offset = 0;
          TAIL_INTENT_COUNTER_OFFSET = offset;
  
          offset += SIZE_OF_LONG;
          TAIL_COUNTER_OFFSET = offset;
  
          offset += SIZE_OF_LONG;
          LATEST_COUNTER_OFFSET = offset;
  
          TRAILER_LENGTH = CACHE_LINE_LENGTH * 2;
      }
  
      private BroadcastBufferDescriptor()
      {
      }
  
      /**
       * Check the buffer capacity is the correct size.
       *
       * @param capacity to be checked.
       * @throws IllegalStateException if the buffer capacity is not a power of 2.
       */
      public static void checkCapacity(final int capacity)
      {
          if (!isPowerOfTwo(capacity))
          {
              final String msg = "capacity must be a positive power of 2 + TRAILER_LENGTH: capacity=" + capacity;
              throw new IllegalStateException(msg);
          }
      }
  }
  