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
|
/*
* include/framework/reconstruction/LevelingPolicy.h
*
* Copyright (C) 2023-2024 Douglas B. Rumbaugh <drumbaugh@psu.edu>
* Dong Xie <dongx@psu.edu>
*
* Distributed under the Modified BSD License.
*
*/
#pragma once
#include <cmath>
#include "framework/reconstruction/ReconstructionPolicy.h"
#include "framework/scheduling/Version.h"
#include "util/types.h"
namespace de {
template <ShardInterface ShardType, QueryInterface<ShardType> QueryType>
class LevelingPolicy : public ReconstructionPolicy<ShardType, QueryType> {
typedef std::vector<std::shared_ptr<InternalLevel<ShardType, QueryType>>>
LevelVector;
public:
LevelingPolicy(size_t scale_factor, size_t buffer_size, size_t modifier=0)
: m_scale_factor(scale_factor), m_buffer_size(buffer_size), m_size_modifier(modifier) {}
std::vector<ReconstructionVector>
get_reconstruction_tasks(const Version<ShardType, QueryType> *version, LockManager &lock_mngr) const override {
return {};
}
ReconstructionVector
get_flush_tasks(const Version<ShardType, QueryType> *version) const override {
ReconstructionVector reconstructions;
auto levels = version->get_structure()->get_level_vector();
/*
* on the very first flush, the whole structure will be empty, so
* there isn't anything to merge into level 1 from level 0 yet.
*/
if (version->get_structure()->get_record_count() == 0) {
return reconstructions;
}
level_index target_level = find_reconstruction_target(levels, version->get_structure()->get_record_count());
assert(target_level != -1);
level_index source_level = 0;
if (target_level == invalid_level_idx) {
/* grow */
target_level = levels.size();
}
for (level_index i = target_level; i > source_level; i--) {
size_t target_reccnt =
(i < (level_index)levels.size()) ? levels[i]->get_record_count() : 0;
size_t total_reccnt =
(i == 0) ? m_buffer_size + target_reccnt
: levels[i - 1]->get_record_count() + target_reccnt;
if (total_reccnt > 0) {
auto type = (i >= (level_index) levels.size()) ? ReconstructionType::Append : ReconstructionType::Merge;
reconstructions.add_reconstruction(i - 1, i, total_reccnt, type);
}
}
return reconstructions;
}
private:
level_index find_reconstruction_target(LevelVector &levels, size_t reccnt) const {
level_index target_level = invalid_level_idx;
size_t incoming_records = m_buffer_size;
for (level_index i = 1; i < (level_index)levels.size(); i++) {
if (levels[i]->get_record_count() + incoming_records < capacity(i, reccnt)) {
target_level = i;
break;
}
incoming_records = levels[i]->get_record_count();
}
return target_level;
}
inline size_t capacity(level_index level, size_t reccnt) const {
return m_buffer_size * pow(m_scale_factor * pow(std::log(reccnt), m_size_modifier), level);
}
size_t m_scale_factor;
size_t m_buffer_size;
size_t m_size_modifier;
};
} // namespace de
|