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Java中协议缓冲区分隔的I / O功能是否有C ++等效项?

Java中协议缓冲区分隔的I / O功能是否有C ++等效项?

在这里参加聚会有点晚,但是下面的实现包括其他答案中缺少的一些优化,并且在输入64MB后不会失败(尽管它仍然对每个单独的消息强制执行64MB的限制,只是对整个消息流没有限制))。

(我是C ++和Java protobuf库的作者,但我不再在Google上工作。很抱歉,此代码从未将其添加到官方lib中。如果有的话,它的样子。)

bool writeDelimitedTo(
    const google::protobuf::MessageLite& message,
    google::protobuf::io::ZeroCopyOutputStream* rawOutput) {
  // We create a new coded stream for each message.  Don't worry, this is fast.
  google::protobuf::io::CodedOutputStream output(rawOutput);

  // Write the size.
  const int size = message.ByteSize();
  output.WriteVarint32(size);

  uint8_t* buffer = output.GetDirectBufferForNBytesAndAdvance(size);
  if (buffer != NULL) {
    // Optimization:  The message fits in one buffer, so use the faster
    // direct-to-array serialization path.
    message.SerializeWithCachedSizesToArray(buffer);
  } else {
    // Slightly-slower path when the message is multiple buffers.
    message.SerializeWithCachedSizes(&output);
    if (output.HadError()) return false;
  }

  return true;
}

bool readDelimitedFrom(
    google::protobuf::io::ZeroCopyInputStream* rawInput,
    google::protobuf::MessageLite* message) {
  // We create a new coded stream for each message.  Don't worry, this is fast,
  // and it makes sure the 64MB total size limit is imposed per-message rather
  // than on the whole stream.  (See the CodedInputStream interface for more
  // info on this limit.)
  google::protobuf::io::CodedInputStream input(rawInput);

  // Read the size.
  uint32_t size;
  if (!input.ReadVarint32(&size)) return false;

  // Tell the stream not to read beyond that size.
  google::protobuf::io::CodedInputStream::Limit limit =
      input.PushLimit(size);

  // Parse the message.
  if (!message->MergeFromCodedStream(&input)) return false;
  if (!input.ConsumedEntireMessage()) return false;

  // Release the limit.
  input.PopLimit(limit);

  return true;
}
java 2022/1/1 18:17:39 有601人围观

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