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47 lines
1.3 KiB
C++
47 lines
1.3 KiB
C++
#pragma once
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#include <string>
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#include <fcntl.h>
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#include <DB/IO/ReadBuffer.h>
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#include <DB/IO/BufferWithOwnMemory.h>
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namespace DB
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{
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class ReadBufferFromFileBase : public BufferWithOwnMemory<ReadBuffer>
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{
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public:
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ReadBufferFromFileBase(size_t buf_size, char * existing_memory, size_t alignment);
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virtual ~ReadBufferFromFileBase();
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off_t seek(off_t off, int whence = SEEK_SET);
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virtual off_t getPositionInFile() = 0;
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virtual std::string getFileName() const = 0;
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virtual int getFD() const = 0;
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/// Есть возможность получать информацию о времени каждого чтения.
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struct ProfileInfo
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{
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size_t bytes_requested;
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size_t bytes_read;
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size_t nanoseconds;
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};
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using ProfileCallback = std::function<void(ProfileInfo)>;
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/// CLOCK_MONOTONIC_COARSE более чем достаточно для отслеживания долгих чтений - например, залипаний на секунды.
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void setProfileCallback(const ProfileCallback & profile_callback_, clockid_t clock_type_ = CLOCK_MONOTONIC_COARSE)
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{
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profile_callback = profile_callback_;
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clock_type = clock_type_;
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}
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protected:
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ProfileCallback profile_callback;
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clockid_t clock_type;
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virtual off_t doSeek(off_t off, int whence) = 0;
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};
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}
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