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
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
|
#include <IO/Lz4DeflatingWriteBuffer.h>
#include <Common/Exception.h>
namespace DB
{
namespace ErrorCodes
{
extern const int LZ4_ENCODER_FAILED;
}
Lz4DeflatingWriteBuffer::Lz4DeflatingWriteBuffer(
std::unique_ptr<WriteBuffer> out_, int compression_level, size_t buf_size, char * existing_memory, size_t alignment)
: WriteBufferWithOwnMemoryDecorator(std::move(out_), buf_size, existing_memory, alignment)
, in_data(nullptr)
, out_data(nullptr)
, in_capacity(0)
, out_capacity(0)
{
kPrefs = {
{LZ4F_max256KB,
LZ4F_blockLinked,
LZ4F_noContentChecksum,
LZ4F_frame,
0 /* unknown content size */,
0 /* no dictID */,
LZ4F_noBlockChecksum},
compression_level, /* compression level; 0 == default */
1, /* autoflush */
0, /* favor decompression speed */
{0, 0, 0}, /* reserved, must be set to 0 */
};
size_t ret = LZ4F_createCompressionContext(&ctx, LZ4F_VERSION);
if (LZ4F_isError(ret))
throw Exception(
ErrorCodes::LZ4_ENCODER_FAILED,
"creation of LZ4 compression context failed. LZ4F version: {}",
LZ4F_VERSION);
}
Lz4DeflatingWriteBuffer::~Lz4DeflatingWriteBuffer() = default;
void Lz4DeflatingWriteBuffer::nextImpl()
{
if (!offset())
return;
in_data = reinterpret_cast<void *>(working_buffer.begin());
in_capacity = offset();
out_capacity = out->buffer().end() - out->position();
out_data = reinterpret_cast<void *>(out->position());
try
{
if (first_time)
{
if (out_capacity < LZ4F_HEADER_SIZE_MAX)
{
out->next();
out_capacity = out->buffer().end() - out->position();
out_data = reinterpret_cast<void *>(out->position());
}
/// write frame header and check for errors
size_t header_size = LZ4F_compressBegin(ctx, out_data, out_capacity, &kPrefs);
if (LZ4F_isError(header_size))
throw Exception(
ErrorCodes::LZ4_ENCODER_FAILED,
"LZ4 failed to start stream encoding. LZ4F version: {}",
LZ4F_VERSION);
out_capacity -= header_size;
out->position() = out->buffer().end() - out_capacity;
out_data = reinterpret_cast<void *>(out->position());
first_time = false;
}
do
{
/// Ensure that there is enough space for compressed block of minimal size
size_t min_compressed_block_size = LZ4F_compressBound(1, &kPrefs);
if (out_capacity < min_compressed_block_size)
{
out->next();
out_capacity = out->buffer().end() - out->position();
out_data = reinterpret_cast<void *>(out->position());
}
/// LZ4F_compressUpdate compresses whole input buffer at once so we need to shink it manually
size_t cur_buffer_size = in_capacity;
if (out_capacity >= min_compressed_block_size) /// We cannot shrink the input buffer if it's already too small.
{
while (out_capacity < LZ4F_compressBound(cur_buffer_size, &kPrefs))
cur_buffer_size /= 2;
}
size_t compressed_size = LZ4F_compressUpdate(ctx, out_data, out_capacity, in_data, cur_buffer_size, nullptr);
if (LZ4F_isError(compressed_size))
throw Exception(
ErrorCodes::LZ4_ENCODER_FAILED,
"LZ4 failed to encode stream. LZ4F version: {}",
LZ4F_VERSION);
in_capacity -= cur_buffer_size;
in_data = reinterpret_cast<void *>(working_buffer.end() - in_capacity);
out_capacity -= compressed_size;
out->position() = out->buffer().end() - out_capacity;
out_data = reinterpret_cast<void *>(out->position());
}
while (in_capacity > 0);
}
catch (...)
{
out->position() = out->buffer().begin();
throw;
}
out->next();
out_capacity = out->buffer().end() - out->position();
}
void Lz4DeflatingWriteBuffer::finalizeBefore()
{
next();
out_capacity = out->buffer().end() - out->position();
out_data = reinterpret_cast<void *>(out->position());
if (out_capacity < LZ4F_compressBound(0, &kPrefs))
{
out->next();
out_capacity = out->buffer().end() - out->position();
out_data = reinterpret_cast<void *>(out->position());
}
/// compression end
size_t end_size = LZ4F_compressEnd(ctx, out_data, out_capacity, nullptr);
if (LZ4F_isError(end_size))
throw Exception(
ErrorCodes::LZ4_ENCODER_FAILED,
"LZ4 failed to end stream encoding. LZ4F version: {}",
LZ4F_VERSION);
out_capacity -= end_size;
out->position() = out->buffer().end() - out_capacity;
out_data = reinterpret_cast<void *>(out->position());
}
void Lz4DeflatingWriteBuffer::finalizeAfter()
{
LZ4F_freeCompressionContext(ctx);
}
}
|
