/************************************************************************
 *
 * Copyright (c) 2019 Alibaba.com, Inc. All Rights Reserved
 * $Id:  msg_compress.h,v 1.0 01/24/2019 02:05:00 PM aili.xp(aili.xp@alibaba-inc.com) $
 *
 ************************************************************************/

/**
 * @file msg_compress.h
 * @author aili.xp(aili.xp@alibaba-inc.com)
 * @date 01/24/2019 02:05:00 PM
 * @version 1.0
 * @brief paxos msg compression module
 *
 **/

#ifndef msg_compress_INC
#define msg_compress_INC

#include <atomic>

#include "paxos.pb.h"

namespace alisql {

typedef enum MsgCompressionType {
  None = 0,
  LZ4  = 1, // very fast but with low compression rate
  ZSTD = 2, // high compression rate but slower
}MsgCompressionType;

class MsgCompressOption
{
  public:
    MsgCompressOption(MsgCompressionType type = None, size_t sizeThreshold = 0, bool checksum = false)
    :type_((int)type), sizeThreshold_(sizeThreshold), checksum_(checksum) {
      if (type < None || type > ZSTD)
        type_.store((int)None);
      if ((MsgCompressionType)type_.load() != None && sizeThreshold_.load() < 4 * 1024)
        sizeThreshold_.store(4 * 1024); // we don't want the threshold to be too small
      if ((MsgCompressionType)type_.load() != None && sizeThreshold_.load() > 128 * 1024)
        sizeThreshold_.store(128 * 1024); // we don't want the threshold to be too big
    }

    MsgCompressOption(const MsgCompressOption &that)
    :type_(that.type_.load()), sizeThreshold_(that.sizeThreshold_.load()), checksum_(that.checksum_.load()) { }

    MsgCompressOption& operator=(const MsgCompressOption &that) {
      type_.store(that.type_.load());
      sizeThreshold_.store(that.sizeThreshold_.load());
      checksum_.store(that.checksum_.load());
      return *this;
    }

    MsgCompressionType type() const { return (MsgCompressionType)type_.load(); }
    size_t sizeThreshold() const { return sizeThreshold_.load(); }
    bool checksum() const { return checksum_.load();  }

  private:
    std::atomic<int>    type_;
    std::atomic<size_t> sizeThreshold_;
    std::atomic<bool>   checksum_;
};

// return how many bytes compressed
size_t msgCompress(const MsgCompressOption &option, PaxosMsg &msg, size_t sizeHint);

// return true if no compression or decompression is successful
bool msgDecompress(PaxosMsg &msg);

} // namespace alisql

#endif // msg_compress_INC