content: /**
   * Licensed to the Apache Software Foundation (ASF) under one or more
   * contributor license agreements.  See the NOTICE file distributed with
   * this work for additional information regarding copyright ownership.
   * The ASF licenses this file to You 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
   * 
   *    http://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.jafka.message;
  
  import java.io.IOException;
  import java.nio.ByteBuffer;
  import java.nio.channels.GatheringByteChannel;
  
  /**
   * Message set helper functions
   * 
   * @author adyliu (imxylz@gmail.com)
   * @since 1.0
   */
  public abstract class MessageSet implements Iterable<MessageAndOffset> {
  
      public static final MessageSet Empty = new ByteBufferMessageSet(ByteBuffer.allocate(0));
  
      public static final int LogOverhead = 4;
  
      public static ByteBuffer createByteBuffer(CompressionCodec compressionCodec, Message... messages) {
          if (compressionCodec == CompressionCodec.NoCompressionCodec) {
              ByteBuffer buffer = ByteBuffer.allocate(messageSetSize(messages));
              for (Message message : messages) {
                  message.serializeTo(buffer);
              }
              buffer.rewind();
              return buffer;
          }
          //
          if (messages.length == 0) {
              ByteBuffer buffer = ByteBuffer.allocate(messageSetSize(messages));
              buffer.rewind();
              return buffer;
          }
          //
          Message message = CompressionUtils.compress(messages, compressionCodec);
          ByteBuffer buffer = ByteBuffer.allocate(message.serializedSize());
          message.serializeTo(buffer);
          buffer.rewind();
          return buffer;
      }
  
      public static int entrySize(Message message) {
          return LogOverhead + message.getSizeInBytes();
      }
  
      public static int messageSetSize(Iterable<Message> messages) {
          int size = 0;
          for (Message message : messages) {
              size += entrySize(message);
          }
          return size;
      }
  
      public static int messageSetSize(Message... messages) {
          int size = 0;
          for (Message message : messages) {
              size += entrySize(message);
          }
          return size;
      }
  
      /**
       * get the total size of this message set in bytes
       * @return size of total message
       */
      public abstract long getSizeInBytes();
  
      /**
       * Validate the checksum of all the messages in the set. Throws an
       * InvalidMessageException if the checksum doesn't match the payload
       * for any message.
       */
      public void validate() {
          for (MessageAndOffset messageAndOffset : this)
              if (!messageAndOffset.message.isValid()) {
                  throw new InvalidMessageException();
              }
      }
  
      /////////////////////////////////////////////////////////////////////////
      //                             abstract method
      /////////////////////////////////////////////////////////////////////////
      /**
       * Write the messages in this set to the given channel starting at the
       * given offset byte. Less than the complete amount may be written, but
       * no more than maxSize can be. The number of bytes written is returned
       * @param channel IOChannel
       * @param offset offset of message
       * @param maxSize size of message
       * @throws IOException any exception
       * @return size of result
       */
      public abstract long writeTo(GatheringByteChannel channel, long offset, long maxSize) throws IOException;
  }
  