GCC Code Coverage Report

Directory: cvmfs/
File: cvmfs/ingestion/chunk_detector.cc
Date: 2025-06-22 02:36:02
Exec Total Coverage
Lines: 56 56 100.0%
Branches: 33 46 71.7%
Line Branch Exec Source
1 /**
2 * This file is part of the CernVM File System.
3 */
4
5
6 #include "chunk_detector.h"
7
8 #include <algorithm>
9 #include <cassert>
10 #include <limits>
11
12 #include "ingestion/item.h"
13
14
15 2327677 uint64_t ChunkDetector::FindNextCutMark(BlockItem *block) {
16 2327677 const uint64_t result = DoFindNextCutMark(block);
17
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 2327675 if (result == 0)
18 200604 offset_ += block->size();
19 2327675 return result;
20 }
21
22
23 //------------------------------------------------------------------------------
24
25
26 2050080 uint64_t StaticOffsetDetector::DoFindNextCutMark(BlockItem *buffer) {
27
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 2050080 assert(buffer->type() == BlockItem::kBlockData);
28
29 2050080 const uint64_t beginning = offset();
30 2050080 const uint64_t end = offset() + buffer->size();
31
32 2050080 const uint64_t next_cut = last_cut() + chunk_size_;
33
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 2050080 if (next_cut >= beginning && next_cut < end) {
34 2048020 return DoCut(next_cut);
35 }
36
37 2060 return NoCut(next_cut);
38 }
39
40
41 //------------------------------------------------------------------------------
42
43
44 // This defines the center of the interval where the xor32 rolling checksum is
45 // queried. You should never change this number, since it affects the definition
46 // of cut marks.
47 const int32_t Xor32Detector::kMagicNumber = std::numeric_limits<uint32_t>::max()
48 / 2;
49
50
51 332567 Xor32Detector::Xor32Detector(const uint64_t minimal_chunk_size,
52 const uint64_t average_chunk_size,
53 332567 const uint64_t maximal_chunk_size)
54 332567 : minimal_chunk_size_(minimal_chunk_size)
55 332567 , average_chunk_size_(average_chunk_size)
56 332567 , maximal_chunk_size_(maximal_chunk_size)
57 14 , threshold_(
58 (average_chunk_size > 0)
59 332553 ? (std::numeric_limits<uint32_t>::max() / average_chunk_size)
60 : 0)
61 332567 , xor32_ptr_(0)
62
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 332567 , xor32_(0) {
63
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 332567 assert((average_chunk_size_ == 0) || (minimal_chunk_size_ > 0));
64
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 332567 if (minimal_chunk_size_ > 0) {
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 332553 assert(minimal_chunk_size_ >= kXor32Window);
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 332553 assert(minimal_chunk_size_ < average_chunk_size_);
67
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 332553 assert(average_chunk_size_ < maximal_chunk_size_);
68 }
69 332567 }
70
71
72 277597 uint64_t Xor32Detector::DoFindNextCutMark(BlockItem *buffer) {
73
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 277597 assert(minimal_chunk_size_ > 0);
74 277597 const unsigned char *data = buffer->data();
75
76 // Get the offset where the next xor32 computation needs to be continued
77 // Note: this could be after collecting at least kMinChunkSize bytes in the
78 // current chunk, or directly at the beginning of the buffer, when a
79 // cut mark is currently searched
80 277589 const uint64_t global_offset = std::max(
81 277589 last_cut() + static_cast<uint64_t>(minimal_chunk_size_ - kXor32Window),
82 277592 xor32_ptr_);
83
84 // Check if the next xor32 computation is taking place in the current buffer
85
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 277589 if (global_offset >= offset() + static_cast<uint64_t>(buffer->size())) {
86
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 97821 return NoCut(global_offset);
87 }
88
89 // get the byte offset in the current buffer
90 179782 uint64_t internal_offset = global_offset - offset();
91
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 179782 assert(internal_offset < static_cast<uint64_t>(buffer->size()));
92
93 // Precompute the xor32 rolling checksum for finding the next cut mark
94 // Note: this might be skipped, if the precomputation was already performed
95 // for the current rolling checksum
96 // (internal_precompute_end will be negative --> loop is not entered)
97 179782 const uint64_t precompute_end = last_cut() + minimal_chunk_size_;
98 179782 const int64_t internal_precompute_end = std::min(
99 179782 static_cast<int64_t>(precompute_end - offset()),
100 179782 static_cast<int64_t>(buffer->size()));
101
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 179782 assert(internal_precompute_end - static_cast<int64_t>(internal_offset)
102 <= static_cast<int64_t>(kXor32Window));
103
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 2712322 for (; static_cast<int64_t>(internal_offset) < internal_precompute_end;
104 ++internal_offset) {
105 2532540 xor32(data[internal_offset]);
106 }
107
108 // Do the actual computation and try to find a xor32 based cut mark
109 // Note: this loop is bound either by kMaxChunkSize or by the size of the
110 // current buffer, thus the computation would continue later
111 179782 const uint64_t internal_max_chunk_size_end = last_cut() + maximal_chunk_size_
112 179782 - offset();
113 179780 const uint64_t internal_compute_end = std::min(
114 179781 internal_max_chunk_size_end, static_cast<uint64_t>(buffer->size()));
115
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 5878046071 for (; internal_offset < internal_compute_end; ++internal_offset) {
116 5877944684 xor32(data[internal_offset]);
117
118 // check if we found a cut mark
119
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 5876600851 if (CheckThreshold()) {
120
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 78396 return DoCut(internal_offset + offset());
121 }
122 }
123
124 // Check if the loop was exited because we reached kMaxChunkSize and do a
125 // hard cut in this case. If not, it exited because we ran out of data in this
126 // buffer --> continue computation with the next buffer
127
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 101387 if (internal_offset == internal_max_chunk_size_end) {
128
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 656 return DoCut(internal_offset + offset());
129 } else {
130
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 100731 return NoCut(internal_offset + offset());
131 }
132 }
133