mirror of
https://github.com/dragonflydb/dragonfly.git
synced 2025-05-11 02:15:45 +02:00
9a05343b5f
* feat: add huffman coding to compact object Read path and tests will follow in the next PR. Partially addresses #4880 Signed-off-by: Roman Gershman <roman@dragonflydb.io> * Update src/core/compact_object.cc Co-authored-by: Kostas Kyrimis <kostas@dragonflydb.io> Signed-off-by: Roman Gershman <romange@gmail.com> --------- Signed-off-by: Roman Gershman <roman@dragonflydb.io> Signed-off-by: Roman Gershman <romange@gmail.com> Co-authored-by: Kostas Kyrimis <kostas@dragonflydb.io>
72 lines
1.9 KiB
C++
72 lines
1.9 KiB
C++
// Copyright 2025, DragonflyDB authors. All rights reserved.
|
|
// See LICENSE for licensing terms.
|
|
//
|
|
|
|
#pragma once
|
|
|
|
#include <cstdint>
|
|
#include <memory>
|
|
#include <string_view>
|
|
|
|
namespace dfly {
|
|
|
|
class HuffmanEncoder {
|
|
public:
|
|
bool Build(const unsigned hist[], unsigned max_symbol, std::string* error_msg);
|
|
|
|
bool Encode(std::string_view data, uint8_t* dest, uint32_t* dest_size,
|
|
std::string* error_msg) const;
|
|
|
|
size_t EstimateCompressedSize(const unsigned hist[], unsigned max_symbol) const;
|
|
|
|
void Reset();
|
|
|
|
// Load using the serialized data produced by Export().
|
|
bool Load(std::string_view binary_data, std::string* error_msg);
|
|
|
|
// Exports a binary representation of the table, that can be loaded using Load().
|
|
std::string Export() const;
|
|
|
|
uint8_t num_bits() const {
|
|
return num_bits_;
|
|
}
|
|
|
|
bool valid() const {
|
|
return bool(huf_ctable_);
|
|
}
|
|
|
|
unsigned max_symbol() const {
|
|
return table_max_symbol_;
|
|
}
|
|
|
|
unsigned GetNBits(uint8_t symbol) const;
|
|
|
|
// Estimation of the size of the destination buffer needed to store the compressed data.
|
|
// destination of this size must be passed to Encode().
|
|
size_t CompressedBound(size_t src_size) const;
|
|
|
|
private:
|
|
using HUF_CElt = size_t;
|
|
std::unique_ptr<HUF_CElt[]> huf_ctable_;
|
|
unsigned table_max_symbol_ = 0;
|
|
uint8_t num_bits_ = 0;
|
|
};
|
|
|
|
class HuffmanDecoder {
|
|
public:
|
|
bool Load(std::string_view binary_data, std::string* error_msg);
|
|
bool valid() const {
|
|
return bool(huf_dtable_);
|
|
}
|
|
|
|
// decoded_size should be the *precise* size of the decoded data, otherwise the function will
|
|
// fail. dest should point to a buffer of at least decoded_size bytes.
|
|
// Returns true if decompression was successful, false if the data is corrupted.
|
|
bool Decode(std::string_view src, size_t decoded_size, char* dest) const;
|
|
|
|
private:
|
|
using HUF_DTable = uint32_t;
|
|
std::unique_ptr<HUF_DTable[]> huf_dtable_;
|
|
};
|
|
|
|
} // namespace dfly
|