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34 lines
937 B
C++
34 lines
937 B
C++
#pragma once
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#include <base/types.h>
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#include <IO/SeekableReadBuffer.h>
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namespace DB
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{
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/** Allows to read from another SeekableReadBuffer up to `limit_size` bytes starting from `start_offset`.
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* Note that the nested buffer may read slightly more data internally to fill its buffer.
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*/
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class LimitSeekableReadBuffer : public SeekableReadBuffer
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{
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public:
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LimitSeekableReadBuffer(SeekableReadBuffer & in_, UInt64 start_offset_, UInt64 limit_size_);
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LimitSeekableReadBuffer(std::unique_ptr<SeekableReadBuffer> in_, UInt64 start_offset_, UInt64 limit_size_);
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/// Returns adjusted position, i.e. returns `3` if the position in the nested buffer is `start_offset + 3`.
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off_t getPosition() override;
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off_t seek(off_t off, int whence) override;
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private:
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std::unique_ptr<SeekableReadBuffer> in;
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off_t min_offset;
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off_t max_offset;
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std::optional<off_t> need_seek;
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bool nextImpl() override;
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};
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}
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