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/*
* include/query/rangequery.h
*
* Copyright (C) 2023 Douglas B. Rumbaugh <drumbaugh@psu.edu>
*
* Distributed under the Modified BSD License.
*
* A query class for single dimensional range queries. This query requires
* that the shard support get_lower_bound(key) and get_record_at(index).
*/
#pragma once
#include "framework/QueryRequirements.h"
#include "psu-ds/PriorityQueue.h"
#include "util/Cursor.h"
namespace de { namespace rq {
template <RecordInterface R>
struct Parms {
decltype(R::key) lower_bound;
decltype(R::key) upper_bound;
};
template <RecordInterface R>
struct State {
size_t start_idx;
size_t stop_idx;
};
template <RecordInterface R>
struct BufferState {
BufferView<R> *buffer;
BufferState(BufferView<R> *buffer)
: buffer(buffer) {}
};
template <ShardInterface S, RecordInterface R>
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) {
auto res = new State<R>();
auto p = (Parms<R> *) parms;
res->start_idx = shard->get_lower_bound(p->lower_bound);
res->stop_idx = shard->get_record_count();
return res;
}
static void* get_buffer_query_state(BufferView<R> *buffer, void *parms) {
auto res = new BufferState<R>(buffer);
return res;
}
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>> records;
auto p = (Parms<R> *) parms;
auto s = (State<R> *) q_state;
/*
* if the returned index is one past the end of the
* records for the PGM, then there are not records
* in the index falling into the specified range.
*/
if (s->start_idx == shard->get_record_count()) {
return records;
}
auto ptr = shard->get_record_at(s->start_idx);
/*
* roll the pointer forward to the first record that is
* greater than or equal to the lower bound.
*/
while(ptr < shard->get_data() + s->stop_idx && ptr->rec.key < p->lower_bound) {
ptr++;
}
while (ptr < shard->get_data() + s->stop_idx && ptr->rec.key <= p->upper_bound) {
records.emplace_back(*ptr);
ptr++;
}
return records;
}
static std::vector<Wrapped<R>> buffer_query(void *state, void *parms) {
auto p = (Parms<R> *) parms;
auto s = (BufferState<R> *) state;
std::vector<Wrapped<R>> records;
for (size_t i=0; i<s->buffer->get_record_count(); i++) {
auto rec = s->buffer->get(i);
if (rec->rec.key >= p->lower_bound && rec->rec.key <= p->upper_bound) {
records.emplace_back(*rec);
}
}
return records;
}
static std::vector<R> merge(std::vector<std::vector<Wrapped<R>>> &results, void *parms) {
std::vector<Cursor<Wrapped<R>>> cursors;
cursors.reserve(results.size());
psudb::PriorityQueue<Wrapped<R>> pq(results.size());
size_t total = 0;
size_t tmp_n = results.size();
for (size_t i = 0; i < tmp_n; ++i)
if (results[i].size() > 0){
auto base = results[i].data();
cursors.emplace_back(Cursor{base, base + results[i].size(), 0, results[i].size()});
assert(i == cursors.size() - 1);
total += results[i].size();
pq.push(cursors[i].ptr, tmp_n - i - 1);
} else {
cursors.emplace_back(Cursor<Wrapped<R>>{nullptr, nullptr, 0, 0});
}
if (total == 0) {
return std::vector<R>();
}
std::vector<R> output;
output.reserve(total);
while (pq.size()) {
auto now = pq.peek();
auto next = pq.size() > 1 ? pq.peek(1) : psudb::queue_record<Wrapped<R>>{nullptr, 0};
if (!now.data->is_tombstone() && next.data != nullptr &&
now.data->rec == next.data->rec && next.data->is_tombstone()) {
pq.pop(); pq.pop();
auto& cursor1 = cursors[tmp_n - now.version - 1];
auto& cursor2 = cursors[tmp_n - next.version - 1];
if (advance_cursor<Wrapped<R>>(cursor1)) pq.push(cursor1.ptr, now.version);
if (advance_cursor<Wrapped<R>>(cursor2)) pq.push(cursor2.ptr, next.version);
} else {
auto& cursor = cursors[tmp_n - now.version - 1];
if (!now.data->is_tombstone()) output.push_back(cursor.ptr->rec);
pq.pop();
if (advance_cursor<Wrapped<R>>(cursor)) pq.push(cursor.ptr, now.version);
}
}
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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