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/*
* 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 BSMPolicy : public ReconstructionPolicy<ShardType, QueryType> {
typedef std::vector<std::shared_ptr<InternalLevel<ShardType, QueryType>>>
LevelVector;
public:
BSMPolicy(size_t buffer_size, size_t scale_factor, 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();
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();
}
ReconstructionTask task;
task.target = target_level;
size_t reccnt = 0;
if (target_level < (ssize_t)levels.size() && levels[target_level]->get_record_count() > 0) {
task.sources.push_back({target_level, all_shards_idx});
task.type = ReconstructionType::Merge;
} else {
task.type = ReconstructionType::Append;
}
for (level_index i = target_level - 1; i >= source_level; i--) {
assert(i < (ssize_t)levels.size());
assert(levels[i]->get_record_count() > 0 || i == 0);
task.sources.push_back({i, all_shards_idx});
reccnt += levels[i]->get_record_count();
}
task.reccnt = reccnt;
assert(task.sources.size() > 0);
reconstructions.add_reconstruction(task);
return reconstructions;
}
private:
level_index find_reconstruction_target(LevelVector &levels, size_t reccnt) const {
level_index target_level = invalid_level_idx;
for (level_index i = 1; i < (level_index)levels.size(); i++) {
if (levels[i]->get_record_count() < capacity(i, reccnt)) {
target_level = i;
break;
}
}
return target_level;
}
inline size_t capacity(level_index level, size_t reccnt) const {
size_t base = m_scale_factor * pow(log(reccnt), m_size_modifier);
return m_buffer_size * (base - 1) * pow(base, level + 1);
}
size_t m_scale_factor;
size_t m_buffer_size;
size_t m_size_modifier;
};
} // namespace de
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