1#pragma once
2
3#include "CompressedReadBufferBase.h"
4#include <IO/ReadBufferFromFileBase.h>
5#include <time.h>
6#include <memory>
7#include <port/clock.h>
8
9
10namespace DB
11{
12
13
14/// Unlike CompressedReadBuffer, it can do seek.
15class CompressedReadBufferFromFile : public CompressedReadBufferBase, public BufferWithOwnMemory<ReadBuffer>
16{
17private:
18 /** At any time, one of two things is true:
19 * a) size_compressed = 0
20 * b)
21 * - `working_buffer` contains the entire block.
22 * - `file_in` points to the end of this block.
23 * - `size_compressed` contains the compressed size of this block.
24 */
25 std::unique_ptr<ReadBufferFromFileBase> p_file_in;
26 ReadBufferFromFileBase & file_in;
27 size_t size_compressed = 0;
28
29 bool nextImpl() override;
30
31public:
32 CompressedReadBufferFromFile(
33 const std::string & path, size_t estimated_size, size_t aio_threshold, size_t buf_size = DBMS_DEFAULT_BUFFER_SIZE);
34
35 void seek(size_t offset_in_compressed_file, size_t offset_in_decompressed_block);
36
37 size_t readBig(char * to, size_t n) override;
38
39 void setProfileCallback(const ReadBufferFromFileBase::ProfileCallback & profile_callback_, clockid_t clock_type_ = CLOCK_MONOTONIC_COARSE)
40 {
41 file_in.setProfileCallback(profile_callback_, clock_type_);
42 }
43};
44
45}
46