ydb/library/cpp/on_disk/chunks/writer.h

#pragma once

#include <util/generic/vector.h>
#include <util/stream/output.h>

template <typename T>
inline void WriteBin(IOutputStream* out, typename TTypeTraits<T>::TFuncParam t) {
    out->Write(&t, sizeof(T));
}

class TChunkedDataWriter: public IOutputStream {
public:
    TChunkedDataWriter(IOutputStream& slave);
    ~TChunkedDataWriter() override;

    void NewBlock();

    template <typename T>
    inline void WriteBinary(typename TTypeTraits<T>::TFuncParam t) {
        this->Write(&t, sizeof(T));
    }

    void WriteFooter();

    size_t GetCurrentBlockOffset() const;
    size_t GetBlockCount() const;

protected:
    void DoWrite(const void* buf, size_t len) override {
        Slave.Write(buf, len);
        Offset += len;
    }

private:
    static inline size_t PaddingSize(size_t size, size_t boundary) noexcept {
        const size_t boundaryViolation = size % boundary;

        return boundaryViolation == 0 ? 0 : boundary - boundaryViolation;
    }

    inline void Pad(size_t boundary) {
        const size_t newOffset = Offset + PaddingSize(Offset, boundary);

        while (Offset < newOffset) {
            Write('\0');
        }
    }

private:
    static const ui64 Version = 1;

    IOutputStream& Slave;

    size_t Offset;
    TVector<ui64> Offsets;
    TVector<ui64> Lengths;
};