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/*
* include/query/knn.h
*
* Copyright (C) 2023 Douglas B. Rumbaugh <drumbaugh@psu.edu>
*
* Distributed under the Modified BSD License.
*
* A query class for k-NN queries, designed for use with the VPTree
* shard.
*
* FIXME: no support for tombstone deletes just yet. This would require a
* query resumption mechanism, most likely.
*/
#pragma once
#include "framework/QueryRequirements.h"
#include "psu-ds/PriorityQueue.h"
namespace de { namespace knn {
using psudb::PriorityQueue;
template <NDRecordInterface R>
struct Parms {
R point;
size_t k;
};
template <NDRecordInterface R>
struct State {
size_t k;
};
template <NDRecordInterface R>
struct BufferState {
BufferView<R> *buffer;
BufferState(BufferView<R> *buffer)
: buffer(buffer) {}
};
template <NDRecordInterface R, ShardInterface<R> S>
class Query {
public:
constexpr static bool EARLY_ABORT=false;
constexpr static bool SKIP_DELETE_FILTER=true;
static void *get_query_state(S *shard, void *parms) {
return nullptr;
}
static void* get_buffer_query_state(BufferView<R> *buffer, void *parms) {
return new BufferState<R>(buffer);
}
static void process_query_states(void *query_parms, std::vector<void*> &shard_states, void* buffer_state) {
return;
}
static std::vector<Wrapped<R>> query(S *shard, void *q_state, void *parms) {
std::vector<Wrapped<R>> results;
Parms<R> *p = (Parms<R> *) parms;
Wrapped<R> wrec;
wrec.rec = p->point;
wrec.header = 0;
PriorityQueue<Wrapped<R>, DistCmpMax<Wrapped<R>>> pq(p->k, &wrec);
shard->search(p->point, p->k, pq);
while (pq.size() > 0) {
results.emplace_back(*pq.peek().data);
pq.pop();
}
return results;
}
static std::vector<Wrapped<R>> buffer_query(void *state, void *parms) {
Parms<R> *p = (Parms<R> *) parms;
BufferState<R> *s = (BufferState<R> *) state;
Wrapped<R> wrec;
wrec.rec = p->point;
wrec.header = 0;
size_t k = p->k;
PriorityQueue<Wrapped<R>, DistCmpMax<Wrapped<R>>> pq(k, &wrec);
for (size_t i=0; i<s->buffer->get_record_count(); i++) {
// Skip over deleted records (under tagging)
if (s->buffer->get(i)->is_deleted()) {
continue;
}
if (pq.size() < k) {
pq.push(s->buffer->get(i));
} else {
double head_dist = pq.peek().data->rec.calc_distance(wrec.rec);
double cur_dist = (s->buffer->get(i))->rec.calc_distance(wrec.rec);
if (cur_dist < head_dist) {
pq.pop();
pq.push(s->buffer->get(i));
}
}
}
std::vector<Wrapped<R>> results;
while (pq.size() > 0) {
results.emplace_back(*(pq.peek().data));
pq.pop();
}
return results;
}
static std::vector<R> merge(std::vector<std::vector<Wrapped<R>>> &results, void *parms) {
Parms<R> *p = (Parms<R> *) parms;
R rec = p->point;
size_t k = p->k;
PriorityQueue<R, DistCmpMax<R>> pq(k, &rec);
for (size_t i=0; i<results.size(); i++) {
for (size_t j=0; j<results[i].size(); j++) {
if (pq.size() < k) {
pq.push(&results[i][j].rec);
} else {
double head_dist = pq.peek().data->calc_distance(rec);
double cur_dist = results[i][j].rec.calc_distance(rec);
if (cur_dist < head_dist) {
pq.pop();
pq.push(&results[i][j].rec);
}
}
}
}
std::vector<R> output;
while (pq.size() > 0) {
output.emplace_back(*pq.peek().data);
pq.pop();
}
return output;
}
static void delete_query_state(void *state) {
auto s = (State<R> *) state;
delete s;
}
static void delete_buffer_query_state(void *state) {
auto s = (BufferState<R> *) state;
delete s;
}
};
}}
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