120 lines
3.7 KiB
C++
120 lines
3.7 KiB
C++
// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
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// This source code is licensed under both the GPLv2 (found in the
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// COPYING file in the root directory) and Apache 2.0 License
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// (found in the LICENSE.Apache file in the root directory).
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#pragma once
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#include <cstdio>
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#include <cstring>
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#include <memory>
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#include <string>
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#include <unordered_map>
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#include <vector>
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#include "util/coding.h"
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#include "utilities/col_buf_encoder.h"
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namespace rocksdb {
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struct ColDeclaration;
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// ColBufDecoder is a class to decode column buffers. It can be populated from a
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// ColDeclaration. Before starting decoding, a Init() method should be called.
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// Each time it takes a column value into Decode() method.
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class ColBufDecoder {
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public:
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virtual ~ColBufDecoder() = 0;
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virtual size_t Init(const char* src) { return 0; }
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virtual size_t Decode(const char* src, char** dest) = 0;
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static ColBufDecoder* NewColBufDecoder(const ColDeclaration& col_declaration);
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protected:
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std::string buffer_;
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static inline bool IsRunLength(ColCompressionType type) {
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return type == kColRle || type == kColRleVarint ||
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type == kColRleDeltaVarint || type == kColRleDict;
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}
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};
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class FixedLengthColBufDecoder : public ColBufDecoder {
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public:
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explicit FixedLengthColBufDecoder(
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size_t size, ColCompressionType col_compression_type = kColNoCompression,
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bool nullable = false, bool big_endian = false)
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: size_(size),
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col_compression_type_(col_compression_type),
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nullable_(nullable),
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big_endian_(big_endian),
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remain_runs_(0),
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run_val_(0),
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last_val_(0) {}
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size_t Init(const char* src) override;
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size_t Decode(const char* src, char** dest) override;
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~FixedLengthColBufDecoder() {}
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private:
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size_t size_;
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ColCompressionType col_compression_type_;
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bool nullable_;
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bool big_endian_;
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// for decoding
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std::vector<uint64_t> dict_vec_;
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uint64_t remain_runs_;
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uint64_t run_val_;
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uint64_t last_val_;
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};
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class LongFixedLengthColBufDecoder : public ColBufDecoder {
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public:
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LongFixedLengthColBufDecoder(size_t size, bool nullable)
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: size_(size), nullable_(nullable) {}
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size_t Decode(const char* src, char** dest) override;
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~LongFixedLengthColBufDecoder() {}
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private:
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size_t size_;
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bool nullable_;
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};
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class VariableLengthColBufDecoder : public ColBufDecoder {
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public:
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size_t Decode(const char* src, char** dest) override;
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~VariableLengthColBufDecoder() {}
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};
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class VariableChunkColBufDecoder : public VariableLengthColBufDecoder {
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public:
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size_t Init(const char* src) override;
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size_t Decode(const char* src, char** dest) override;
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explicit VariableChunkColBufDecoder(ColCompressionType col_compression_type)
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: col_compression_type_(col_compression_type) {}
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VariableChunkColBufDecoder() : col_compression_type_(kColNoCompression) {}
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private:
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ColCompressionType col_compression_type_;
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std::unordered_map<uint64_t, uint64_t> dictionary_;
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std::vector<uint64_t> dict_vec_;
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};
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struct KVPairColBufDecoders {
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std::vector<std::unique_ptr<ColBufDecoder>> key_col_bufs;
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std::vector<std::unique_ptr<ColBufDecoder>> value_col_bufs;
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std::unique_ptr<ColBufDecoder> value_checksum_buf;
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explicit KVPairColBufDecoders(const KVPairColDeclarations& kvp_cd) {
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for (auto kcd : *kvp_cd.key_col_declarations) {
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key_col_bufs.emplace_back(
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std::move(ColBufDecoder::NewColBufDecoder(kcd)));
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}
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for (auto vcd : *kvp_cd.value_col_declarations) {
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value_col_bufs.emplace_back(
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std::move(ColBufDecoder::NewColBufDecoder(vcd)));
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}
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value_checksum_buf.reset(
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ColBufDecoder::NewColBufDecoder(*kvp_cd.value_checksum_declaration));
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}
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};
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} // namespace rocksdb
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