library/cpp/on_disk/chunks/writer.h


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#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;
};