YugabyteDB (2.13.0.0-b42, bfc6a6643e7399ac8a0e81d06a3ee6d6571b33ab)

// Copyright (c) YugaByte, Inc.

//

// 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

//

// 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.

//

#ifndef YB_UTIL_UUID_H

#define YB_UTIL_UUID_H

#include <uuid/uuid.h>

#include <array>

#include <random>

#include <boost/uuid/uuid.hpp>

#include "yb/util/status_fwd.h"

namespace yb {

class Slice;

constexpr size_t kUuidSize = 16;

constexpr int kShaDigestSize = 5;

// Generic class that UUID type and uses the boost implementation underneath.

// Implements a custom comparator that follows the cassandra implementation.

class Uuid {

 public:

  static constexpr size_t kUuidMsbSize = 8;

  static constexpr size_t kUuidLsbSize = kUuidSize - kUuidMsbSize;

  static constexpr size_t kTimeUUIDMacOffset = 10;

  static constexpr size_t kTimeUUIDTotalMacBytes = 6;

  // The timestamp is a 60-bit value.  For UUID version 1, this is

  // represented by Coordinated Universal Time (UTC) as a count of 100-

  // nanosecond intervals since 00:00:00.00, 15 October 1582 (the date of

  // Gregorian reform to the Christian calendar).

  static constexpr int64_t kGregorianOffsetMillis = -12219292800000;

  static constexpr int64_t kMillisPerHundredNanos = 10000;

  Uuid();

  explicit Uuid(const boost::uuids::uuid& boost_uuid) : boost_uuid_(boost_uuid) {}

  explicit Uuid(const uuid_t copy);

  Uuid(const Uuid& other);

  // Generate a new boost uuid

  static Uuid Generate();

  static Uuid Generate(std::mt19937_64* rng);

  static Uuid Nil();

  static Result<Uuid> FromString(const std::string& strval);

  // name is used in error message in case of failure.

  static Result<Uuid> FullyDecode(const Slice& slice, const char* name = nullptr);

  static Uuid TryFullyDecode(const Slice& slice);

  static Result<Uuid> Decode(Slice* slice, const char* name = nullptr);

  // Fills in strval with the string representation of the UUID.

  CHECKED_STATUS ToString(std::string* strval) const;

  // Returns string representation the UUID. This method doesn't return a

  // Status for usecases in the code where we don't support returning a status.

  std::string ToString() const;

  // Fills in the given string with the raw bytes for the appropriate address in network byte order.

  void ToBytes(std::string* bytes) const;

  void ToBytes(std::array<uint8_t, kUuidSize>* out) const;

  Slice AsSlice() const;

  // Encodes the UUID into the time comparable uuid to be stored in RocksDB.

  void EncodeToComparable(uint8_t* output) const;

  void EncodeToComparable(std::string* bytes) const;

  // Given a string holding the raw bytes in network byte order, it builds the appropriate

  // UUID object.

  CHECKED_STATUS FromBytes(const std::string& bytes);

  // Given a string representation of uuid in hex where the bytes are in host byte order, build

  // an appropriate UUID object.

  CHECKED_STATUS FromHexString(const std::string& hex_string);

  std::string ToHexString() const;

  // Decodes the Comparable UUID bytes into a lexical UUID.

  CHECKED_STATUS DecodeFromComparable(const std::string& bytes);

  // Give a slice holding raw bytes in network byte order, build the appropriate UUID

  // object. If size_hint is specified, it indicates the number of bytes to decode from the slice.

  CHECKED_STATUS FromSlice(const Slice& slice, size_t size_hint = 0);

  CHECKED_STATUS DecodeFromComparableSlice(const Slice& slice, size_t size_hint = 0);

  // For time UUIDs only.

  // This function takes a time UUID and generates a SHA hash for the MAC address bits.

  // This is done because it is not secure to generate UUIDs directly from the MAC address.

  CHECKED_STATUS HashMACAddress();

  // Builds the smallest TimeUUID that willl compare as larger than any TimeUUID with the given

  // timestamp.

  CHECKED_STATUS MaxFromUnixTimestamp(int64_t timestamp_ms);

  // Builds the largest TimeUUID that willl compare as smaller than any TimeUUID with the given

  // timestamp.

  CHECKED_STATUS MinFromUnixTimestamp(int64_t timestamp_ms);

  // This function takes a 64 bit integer that represents the timestamp, that is basically the

  // number of milliseconds since epoch.

  CHECKED_STATUS ToUnixTimestamp(int64_t *timestamp_ms) const;

  CHECKED_STATUS IsTimeUuid() const;

  bool IsNil() const {

    return boost_uuid_.is_nil();

  }

  bool operator==(const Uuid& other) const {

    return (boost_uuid_ == other.boost_uuid_);

  }

  bool operator!=(const Uuid& other) const {

    return !(*this == other);

  }

  // A custom comparator that compares UUID v1 according to their timestamp.

  // If not, it will compare the version first and then lexicographically.

  bool operator<(const Uuid& other) const;

  bool operator>(const Uuid& other) const {

    return (other < *this);

  }

  bool operator<=(const Uuid& other) const {

    return !(other < *this);

  }

  bool operator>=(const Uuid& other) const {

    return !(*this < other);

  }

  Uuid& operator=(const Uuid& other) {

    boost_uuid_ = other.boost_uuid_;

    return *this;

  }

  const boost::uuids::uuid& impl() const {

    return boost_uuid_;

  }

  uint8_t* data() {

    return boost_uuid_.data;

  }

  const uint8_t* data() const {

    return boost_uuid_.data;

  }

  size_t size() const {

    return boost_uuid_.size();

  }

  auto version() const {

    return boost_uuid_.version();

  }

 private:

  boost::uuids::uuid boost_uuid_;

  // Encodes the MSB of the uuid into a timestamp based byte stream as follows.

  // [Timestamp Low (32 bits)][Timestamp Mid (16 bits)][Version (4 bits)][Timestamp High (12 bits)]

  // into

  // [Version (4 bits)][Timestamp High (12 bits)][Timestamp Mid (16 bits)][Timestamp Low (32 bits)]

  // So that their lexical comparison of the bytes will result in time based comparison.

  void ToTimestampBytes(uint8_t* output) const {

    output[0] = boost_uuid_.data[6];

    output[1] = boost_uuid_.data[7];

    output[2] = boost_uuid_.data[4];

    output[3] = boost_uuid_.data[5];

    output[4] = boost_uuid_.data[0];

    output[5] = boost_uuid_.data[1];

    output[6] = boost_uuid_.data[2];

    output[7] = boost_uuid_.data[3];

  }

  // Reverse the timestamp based byte stream into regular UUID style MSB.

  // See comments for toTimestampBytes function for more detail.

  void FromTimestampBytes(const uint8_t* input) {

    uint8_t tmp[kUuidMsbSize];

    tmp[0] = input[4];

    tmp[1] = input[5];

    tmp[2] = input[6];

    tmp[3] = input[7];

    tmp[4] = input[2];

    tmp[5] = input[3];

    tmp[6] = input[0];

    tmp[7] = input[1];

    memcpy(boost_uuid_.data, tmp, kUuidMsbSize);

  }

  // Utility method used by minTimeuuid and maxTimeuuid.

  // Set the timestamp bytes of a (time)uuid to the specified value (in hundred nanos).

  // Also ensure that the uuid is a version 1 uuid (i.e. timeuuid) by setting the version.

  void FromTimestamp(int64_t ts_hnanos);

  // Encodes the MSB of the uuid into a version based byte stream as follows.

  // Used for non-time-based UUIDs, i.e. not version 1.

  // [Timestamp Low (32 bits)][Timestamp Mid (16 bits)][Version (4 bits)][Timestamp High (12 bits)]

  // into

  // [Version (4 bits)][Timestamp Low (32 bits)][Timestamp Mid (16 bits)][Timestamp High (12 bits)]

  // So that their lexical comparison of the bytes will result in version based comparison.

  void ToVersionFirstBytes(uint8_t* output) const {

    output[0] = (uint8_t) ( ((boost_uuid_.data[6] & 0xF0))

                          | ((boost_uuid_.data[0] & 0xF0) >> 4));

    output[1] = (uint8_t) ( ((boost_uuid_.data[0] & 0x0F) << 4)

                          | ((boost_uuid_.data[1] & 0xF0) >> 4));

    output[2] = (uint8_t) ( ((boost_uuid_.data[1] & 0x0F) << 4)

                          | ((boost_uuid_.data[2] & 0xF0) >> 4));

    output[3] = (uint8_t) ( ((boost_uuid_.data[2] & 0x0F) << 4)

                          | ((boost_uuid_.data[3] & 0xF0) >> 4));

    output[4] = (uint8_t) ( ((boost_uuid_.data[3] & 0x0F) << 4)

                          | ((boost_uuid_.data[4] & 0xF0) >> 4));

    output[5] = (uint8_t) ( ((boost_uuid_.data[4] & 0x0F) << 4)

                          | ((boost_uuid_.data[5] & 0xF0) >> 4));

    output[6] = (uint8_t) ( ((boost_uuid_.data[5] & 0x0F) << 4)

                          | ((boost_uuid_.data[6] & 0x0F)));

    output[7] = boost_uuid_.data[7];

  }

  // Reverse the version based byte stream into regular UUID style MSB.

  // See comments for toVersionFirstBytes function for more detail.

  void FromVersionFirstBytes(const uint8_t* input) {

    uint8_t tmp[kUuidMsbSize];

    tmp[0] = (uint8_t)  ( ((input[0] & 0x0F) << 4)

                        | ((input[1] & 0xF0) >> 4));

    tmp[1] = (uint8_t)  ( ((input[1] & 0x0F) << 4)

                        | ((input[2] & 0xF0) >> 4));

    tmp[2] = (uint8_t)  ( ((input[2] & 0x0F) << 4)

                        | ((input[3] & 0xF0) >> 4));

    tmp[3] = (uint8_t)  ( ((input[3] & 0x0F) << 4)

                        | ((input[4] & 0xF0) >> 4));

    tmp[4] = (uint8_t)  ( ((input[4] & 0x0F) << 4)

                        | ((input[5] & 0xF0) >> 4));

    tmp[5] = (uint8_t)  ( ((input[5] & 0x0F) << 4)

                        | ((input[6] & 0xF0) >> 4));

    tmp[6] = (uint8_t)  ( ((input[0] & 0xF0))

                        | ((input[6] & 0x0F)));

    tmp[7] = input[7];

    memcpy(boost_uuid_.data, tmp, kUuidMsbSize);

  }

};

} // namespace yb

#endif // YB_UTIL_UUID_H