minetestmapper/db-leveldb.cpp
sfan5 7ff2288627 Optimize database access further by allowing "brute-force" queries instead of listing available blocks
Also adds a heuristic that will enable this behaviour automatically.
2020-03-27 23:38:18 +01:00

115 lines
2.5 KiB
C++

#include <stdexcept>
#include <sstream>
#include "db-leveldb.h"
#include "types.h"
static inline int64_t stoi64(const std::string &s)
{
std::stringstream tmp(s);
int64_t t;
tmp >> t;
return t;
}
static inline std::string i64tos(int64_t i)
{
std::ostringstream os;
os << i;
return os.str();
}
DBLevelDB::DBLevelDB(const std::string &mapdir)
{
leveldb::Options options;
options.create_if_missing = false;
leveldb::Status status = leveldb::DB::Open(options, mapdir + "map.db", &db);
if (!status.ok()) {
throw std::runtime_error(std::string("Failed to open Database: ") + status.ToString());
}
/* LevelDB is a dumb key-value store, so the only optimization we can do
* is to cache the block positions that exist in the db.
*/
loadPosCache();
}
DBLevelDB::~DBLevelDB()
{
delete db;
}
std::vector<BlockPos> DBLevelDB::getBlockPos(BlockPos min, BlockPos max)
{
std::vector<BlockPos> res;
for (const auto &it : posCache) {
if (it.first < min.z || it.first >= max.z)
continue;
for (auto pos2 : it.second) {
if (pos2.first < min.x || pos2.first >= max.x)
continue;
if (pos2.second < min.y || pos2.second >= max.y)
continue;
res.emplace_back(pos2.first, pos2.second, it.first);
}
}
return res;
}
void DBLevelDB::loadPosCache()
{
leveldb::Iterator * it = db->NewIterator(leveldb::ReadOptions());
for (it->SeekToFirst(); it->Valid(); it->Next()) {
int64_t posHash = stoi64(it->key().ToString());
BlockPos pos = decodeBlockPos(posHash);
posCache[pos.z].emplace_back(pos.x, pos.y);
}
delete it;
}
void DBLevelDB::getBlocksOnXZ(BlockList &blocks, int16_t x, int16_t z,
int16_t min_y, int16_t max_y)
{
std::string datastr;
leveldb::Status status;
auto it = posCache.find(z);
if (it == posCache.cend())
return;
for (auto pos2 : it->second) {
if (pos2.first != x)
continue;
if (pos2.second < min_y || pos2.second >= max_y)
continue;
BlockPos pos(x, pos2.second, z);
status = db->Get(leveldb::ReadOptions(), i64tos(encodeBlockPos(pos)), &datastr);
if (status.ok()) {
blocks.emplace_back(
pos, ustring((unsigned char *) datastr.data(), datastr.size())
);
}
}
}
void DBLevelDB::getBlocksByPos(BlockList &blocks,
const std::vector<BlockPos> &positions)
{
std::string datastr;
leveldb::Status status;
for (auto pos : positions) {
status = db->Get(leveldb::ReadOptions(), i64tos(encodeBlockPos(pos)), &datastr);
if (status.ok()) {
blocks.emplace_back(
pos, ustring((unsigned char *) datastr.data(), datastr.size())
);
}
}
}