ob_coding.h

/* Copyright (c) 2021 OceanBase and/or its affiliates. All rights reserved.
miniob is licensed under Mulan PSL v2.
You can use this software according to the terms and conditions of the Mulan PSL v2.
You may obtain a copy of Mulan PSL v2 at:
         http://license.coscl.org.cn/MulanPSL2
THIS SOFTWARE IS PROVIDED ON AN "AS IS" BASIS, WITHOUT WARRANTIES OF ANY KIND,
EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO NON-INFRINGEMENT,
MERCHANTABILITY OR FIT FOR A PARTICULAR PURPOSE.
See the Mulan PSL v2 for more details. */
 
#pragma once
 
#include "common/lang/string.h"
 
namespace oceanbase {
 
static const uint8_t SEQ_SIZE               = 8;
static const uint8_t LOOKUP_KEY_PREFIX_SIZE = 8;
 
template <typename T>
void put_numeric(string *dst, T v)
{
  dst->append(reinterpret_cast<char *>(&v), sizeof(T));
}
 
template <typename T>
T get_numeric(const char *src)
{
  T value;
  memcpy(&value, src, sizeof(T));
  return value;
}
 
inline string_view extract_user_key(const string_view &internal_key)
{
  return string_view(internal_key.data(), internal_key.size() - SEQ_SIZE);
}
 
inline uint64_t extract_sequence(const string_view &internal_key)
{
  return get_numeric<uint64_t>(internal_key.data() + internal_key.size() - SEQ_SIZE);
}
 
inline size_t user_key_size_from_lookup_key(const string_view &lookup_key)
{
  return lookup_key.size() - SEQ_SIZE - LOOKUP_KEY_PREFIX_SIZE;
}
 
inline string_view extract_user_key_from_lookup_key(const string_view &lookup_key)
{
  return string_view(lookup_key.data() + LOOKUP_KEY_PREFIX_SIZE, user_key_size_from_lookup_key(lookup_key));
}
 
inline string_view extract_internal_key(const string_view &lookup_key)
{
  return string_view(lookup_key.data() + LOOKUP_KEY_PREFIX_SIZE, lookup_key.size() - LOOKUP_KEY_PREFIX_SIZE);
}
 
inline string_view get_length_prefixed_string(const char *data)
{
  size_t      len = get_numeric<size_t>(data);
  const char *p   = data + sizeof(size_t);
  return string_view(p, len);
}
 
}  // namespace oceanbase