1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
|
#include "CompressedReadBuffer.h"
#include <Compression/LZ4_decompress_faster.h>
namespace DB
{
bool CompressedReadBuffer::nextImpl()
{
size_t size_decompressed;
size_t size_compressed_without_checksum;
size_compressed = readCompressedData(size_decompressed, size_compressed_without_checksum, false);
if (!size_compressed)
return false;
auto additional_size_at_the_end_of_buffer = codec->getAdditionalSizeAtTheEndOfBuffer();
/// This is for clang static analyzer.
assert(size_decompressed + additional_size_at_the_end_of_buffer > 0);
memory.resize(size_decompressed + additional_size_at_the_end_of_buffer);
working_buffer = Buffer(memory.data(), &memory[size_decompressed]);
decompress(working_buffer, size_decompressed, size_compressed_without_checksum);
return true;
}
size_t CompressedReadBuffer::readBig(char * to, size_t n)
{
size_t bytes_read = 0;
/// If there are unread bytes in the buffer, then we copy necessary to `to`.
if (pos < working_buffer.end())
bytes_read += read(to, std::min(static_cast<size_t>(working_buffer.end() - pos), n));
/// If you need to read more - we will, if possible, uncompress at once to `to`.
while (bytes_read < n)
{
size_t size_decompressed;
size_t size_compressed_without_checksum;
if (!readCompressedData(size_decompressed, size_compressed_without_checksum, false))
return bytes_read;
auto additional_size_at_the_end_of_buffer = codec->getAdditionalSizeAtTheEndOfBuffer();
/// If the decompressed block fits entirely where it needs to be copied.
if (size_decompressed + additional_size_at_the_end_of_buffer <= n - bytes_read)
{
decompressTo(to + bytes_read, size_decompressed, size_compressed_without_checksum);
bytes_read += size_decompressed;
bytes += size_decompressed;
}
else
{
bytes += offset();
/// This is for clang static analyzer.
assert(size_decompressed + additional_size_at_the_end_of_buffer > 0);
memory.resize(size_decompressed + additional_size_at_the_end_of_buffer);
working_buffer = Buffer(memory.data(), &memory[size_decompressed]);
decompress(working_buffer, size_decompressed, size_compressed_without_checksum);
pos = working_buffer.begin();
bytes_read += read(to + bytes_read, n - bytes_read);
break;
}
}
return bytes_read;
}
}
|
