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_FAST_VARINT_H

#define YB_UTIL_FAST_VARINT_H

#include <string>

#include <glog/logging.h>

#include "yb/util/cast.h"

#include "yb/util/slice.h"

#include "yb/util/status.h"

namespace yb {

namespace util {

constexpr size_t kMaxVarIntBufferSize = 16;

// Computes the number of bytes needed to represent the given number as a signed VarInt.

int SignedPositiveVarIntLength(uint64_t v);

void FastEncodeSignedVarInt(int64_t v, uint8_t *dest, size_t *size);

std::string FastEncodeSignedVarIntToStr(int64_t v);

template <class Buffer>

void FastAppendSignedVarIntToBuffer(int64_t v, Buffer* dest) {

  char buf[kMaxVarIntBufferSize];

  size_t len = 0;

  FastEncodeSignedVarInt(v, to_uchar_ptr(buf), &len);

  DCHECK_LE(len, 10);

  dest->append(buf, len);

}

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void FastAppendSignedVarIntToBuffer(int64_t v, Buffer* dest) {

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  char buf[kMaxVarIntBufferSize];

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  size_t len = 0;

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  FastEncodeSignedVarInt(v, to_uchar_ptr(buf), &len);

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  DCHECK_LE(len, 10);

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  dest->append(buf, len);

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}

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void FastAppendSignedVarIntToBuffer(int64_t v, Buffer* dest) {

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  char buf[kMaxVarIntBufferSize];

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  size_t len = 0;

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  FastEncodeSignedVarInt(v, to_uchar_ptr(buf), &len);

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  DCHECK_LE(len, 10);

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  dest->append(buf, len);

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}

// Returns status, decoded value and size consumed from source.

// Might use effective performance optimization that reads before src, but not before

// read_allowed_from.

CHECKED_STATUS FastDecodeSignedVarInt(

    const uint8_t* src, size_t src_size, const uint8_t* read_allowed_from, int64_t* v,

    size_t* decoded_size);

inline CHECKED_STATUS FastDecodeSignedVarInt(

    const char* src, size_t src_size, const char* read_allowed_from, int64_t* v,

    size_t* decoded_size) {

  return FastDecodeSignedVarInt(

      to_uchar_ptr(src), src_size, to_uchar_ptr(read_allowed_from), v,

      decoded_size);

}

// WARNING:

// FastDecodeSignedVarIntUnsafe functions below are optimized for performance, but require from

// caller to guarantee that we can read some bytes (up to 7) before src.

// Consumes decoded part of the slice.

Result<int64_t> FastDecodeSignedVarIntUnsafe(Slice* slice);

CHECKED_STATUS FastDecodeSignedVarIntUnsafe(const uint8_t* src,

                                      size_t src_size,

                                      int64_t* v,

                                      size_t* decoded_size);

// The same as FastDecodeSignedVarIntUnsafe but takes a regular char pointer.

inline CHECKED_STATUS FastDecodeSignedVarIntUnsafe(

    const char* src, size_t src_size, int64_t* v, size_t* decoded_size) {

  return FastDecodeSignedVarIntUnsafe(to_uchar_ptr(src), src_size, v, decoded_size);

}

CHECKED_STATUS FastDecodeSignedVarIntUnsafe(

    const std::string& encoded, int64_t* v, size_t* decoded_size);

// Encoding a "descending VarInt" is simply decoding -v as a VarInt.

inline char* FastEncodeDescendingSignedVarInt(int64_t v, char *buf) {

  size_t size = 0;

  FastEncodeSignedVarInt(-v, to_uchar_ptr(buf), &size);

  return buf + size;

}

inline void FastEncodeDescendingSignedVarInt(int64_t v, std::string *dest) {

  char buf[kMaxVarIntBufferSize];

  auto* end = FastEncodeDescendingSignedVarInt(v, buf);

  dest->append(buf, end);

}

// Decode a "descending VarInt" encoded by FastEncodeDescendingVarInt.

CHECKED_STATUS FastDecodeDescendingSignedVarIntUnsafe(Slice *slice, int64_t *dest);

Result<int64_t> FastDecodeDescendingSignedVarIntUnsafe(Slice* slice);

size_t UnsignedVarIntLength(uint64_t v);

void FastAppendUnsignedVarIntToStr(uint64_t v, std::string* dest);

void FastEncodeUnsignedVarInt(uint64_t v, uint8_t *dest, size_t *size);

CHECKED_STATUS FastDecodeUnsignedVarInt(

    const uint8_t* src, size_t src_size, uint64_t* v, size_t* decoded_size);

Result<uint64_t> FastDecodeUnsignedVarInt(Slice* slice);

Result<uint64_t> FastDecodeUnsignedVarInt(const Slice& slice);

}  // namespace util

}  // namespace yb

#endif  // YB_UTIL_FAST_VARINT_H