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Custom data structure for active objects to get performance *and* safety (#13880)

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sfan5 2024-01-17 20:04:56 +01:00 committed by GitHub
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commit 0383c44f0d
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6 changed files with 434 additions and 78 deletions
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34
src/activeobjectmgr.h
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@ -19,10 +19,9 @@ with this program; if not, write to the Free Software Foundation, Inc.,
#pragma once
#include <map>
#include <memory>
#include <vector>
#include "debug.h"
#include "util/container.h"
#include "irrlichttypes.h"
#include "util/basic_macros.h"
@ -52,24 +51,19 @@ public:
void clear()
{
while (!m_active_objects.empty())
removeObject(m_active_objects.begin()->first);
// on_destruct could add new objects so this has to be a loop
do {
for (auto &it : m_active_objects.iter()) {
if (!it.second)
continue;
m_active_objects.remove(it.first);
}
} while (!m_active_objects.empty());
}
T *getActiveObject(u16 id)
{
auto it = m_active_objects.find(id);
return it != m_active_objects.end() ? it->second.get() : nullptr;
}
std::vector<u16> getAllIds() const
{
std::vector<u16> ids;
ids.reserve(m_active_objects.size());
for (auto &it : m_active_objects) {
ids.push_back(it.first);
}
return ids;
return m_active_objects.get(id).get();
}
protected:
@ -88,11 +82,9 @@ protected:
bool isFreeId(u16 id) const
{
return id != 0 && m_active_objects.find(id) == m_active_objects.end();
return id != 0 && !m_active_objects.get(id);
}
// ordered to fix #10985
// Note: ActiveObjects can access the ActiveObjectMgr. Only erase objects using
// removeObject()!
std::map<u16, std::unique_ptr<T>> m_active_objects;
// Note that this is ordered to fix #10985
ModifySafeMap<u16, std::unique_ptr<T>> m_active_objects;
};

1
src/benchmark/CMakeLists.txt
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@ -3,6 +3,7 @@ set (BENCHMARK_SRCS
${CMAKE_CURRENT_SOURCE_DIR}/benchmark_lighting.cpp
${CMAKE_CURRENT_SOURCE_DIR}/benchmark_serialize.cpp
${CMAKE_CURRENT_SOURCE_DIR}/benchmark_mapblock.cpp
${CMAKE_CURRENT_SOURCE_DIR}/benchmark_mapmodify.cpp
PARENT_SCOPE)
set (BENCHMARK_CLIENT_SRCS

152
src/benchmark/benchmark_mapmodify.cpp Normal file
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@ -0,0 +1,152 @@
/*
Minetest
Copyright (C) 2023 sfan5
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License along
with this program; if not, write to the Free Software Foundation, Inc.,
51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#include "benchmark_setup.h"
#include "util/container.h"
// Testing the standard library is not useful except to compare
//#define TEST_STDLIB
using TestMap = ModifySafeMap<u16, void*>;
static inline void fill(TestMap &map, size_t n)
{
map.clear();
for (size_t i = 0; i < n; i++)
map.put(i, reinterpret_cast<TestMap::mapped_type>(0x40000U + i));
}
static inline void pollute(TestMap &map)
{
auto dummy = reinterpret_cast<TestMap::mapped_type>(123);
// produce some garbage to avoid best case behaviour
map.put(0xffff, dummy);
for (auto it : map.iter()) {
(void)it;
map.remove(0xffff);
break;
}
}
static inline void remove(TestMap &map, size_t offset, size_t count)
{
for (size_t i = 0; i < count; i++)
map.remove(static_cast<TestMap::key_type>(i + offset));
}
#define BENCH_ITERATE_(_label, _count, _best) \
BENCHMARK_ADVANCED(_label)(Catch::Benchmark::Chronometer meter) { \
TestMap map; \
fill(map, _count); \
if (!_best) pollute(map); \
meter.measure([&] { \
size_t x = map.size(); \
for (auto &it : map.iter()) { \
if (!it.second) \
continue; \
x ^= reinterpret_cast<intptr_t>(it.second); \
} \
return x; \
}); \
};
#define BENCH_ITERATE(_count) \
BENCH_ITERATE_("iterate_" #_count, _count, 0) \
BENCH_ITERATE_("iterate_bestcase_" #_count, _count, 1)
#define BENCH_REMOVE(_count) \
BENCHMARK_ADVANCED("remove_" #_count)(Catch::Benchmark::Chronometer meter) { \
TestMap map; \
fill(map, _count); \
meter.measure([&] { \
for (auto it : map.iter()) { \
(void)it; \
remove(map, (_count) / 7, (_count) / 2); /* delete half */ \
break; \
} \
}); \
};
TEST_CASE("ModifySafeMap") {
BENCH_ITERATE(50)
BENCH_ITERATE(400)
BENCH_ITERATE(1000)
BENCH_REMOVE(50)
BENCH_REMOVE(400)
BENCH_REMOVE(1000)
}
using TestMap2 = std::map<u16, void*>;
static inline void fill2(TestMap2 &map, size_t n)
{
map.clear();
for (size_t i = 0; i < n; i++)
map.emplace(i, reinterpret_cast<TestMap2::mapped_type>(0x40000U + i));
}
static inline void remove2(TestMap2 &map, size_t offset, size_t count)
{
for (size_t i = 0; i < count; i++)
map.erase(static_cast<TestMap2::key_type>(i + offset));
}
#define BENCH2_ITERATE(_count) \
BENCHMARK_ADVANCED("iterate_" #_count)(Catch::Benchmark::Chronometer meter) { \
TestMap2 map; \
fill2(map, _count); \
meter.measure([&] { \
size_t x = map.size(); \
/* mirrors what ActiveObjectMgr::step used to do */ \
std::vector<TestMap2::key_type> keys; \
keys.reserve(x); \
for (auto &it : map) \
keys.push_back(it.first); \
for (auto key : keys) { \
auto it = map.find(key); \
if (it == map.end()) \
continue; \
x ^= reinterpret_cast<intptr_t>(it->second); \
} \
return x; \
}); \
};
#define BENCH2_REMOVE(_count) \
BENCHMARK_ADVANCED("remove_" #_count)(Catch::Benchmark::Chronometer meter) { \
TestMap2 map; \
fill2(map, _count); \
meter.measure([&] { \
/* no overhead so no fake iteration */ \
remove2(map, (_count) / 7, (_count) / 2); \
}); \
};
#ifdef TEST_STDLIB
TEST_CASE("std::map") {
BENCH2_ITERATE(50)
BENCH2_ITERATE(400)
BENCH2_ITERATE(1000)
BENCH2_REMOVE(50)
BENCH2_REMOVE(400)
BENCH2_REMOVE(1000)
}
#endif

35
src/client/activeobjectmgr.cpp
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@ -37,17 +37,14 @@ ActiveObjectMgr::~ActiveObjectMgr()
void ActiveObjectMgr::step(
float dtime, const std::function<void(ClientActiveObject *)> &f)
{
g_profiler->avg("ActiveObjectMgr: CAO count [#]", m_active_objects.size());
// Same as in server activeobjectmgr.
std::vector<u16> ids = getAllIds();
for (u16 id : ids) {
auto it = m_active_objects.find(id);
if (it == m_active_objects.end())
continue; // obj was removed
f(it->second.get());
size_t count = 0;
for (auto &ao_it : m_active_objects.iter()) {
if (!ao_it.second)
continue;
count++;
f(ao_it.second.get());
}
g_profiler->avg("ActiveObjectMgr: CAO count [#]", count);
}
bool ActiveObjectMgr::registerObject(std::unique_ptr<ClientActiveObject> obj)
@ -71,7 +68,7 @@ bool ActiveObjectMgr::registerObject(std::unique_ptr<ClientActiveObject> obj)
}
infostream << "Client::ActiveObjectMgr::registerObject(): "
<< "added (id=" << obj->getId() << ")" << std::endl;
m_active_objects[obj->getId()] = std::move(obj);
m_active_objects.put(obj->getId(), std::move(obj));
return true;
}
@ -79,16 +76,14 @@ void ActiveObjectMgr::removeObject(u16 id)
{
verbosestream << "Client::ActiveObjectMgr::removeObject(): "
<< "id=" << id << std::endl;
auto it = m_active_objects.find(id);
if (it == m_active_objects.end()) {
std::unique_ptr<ClientActiveObject> obj = m_active_objects.take(id);
if (!obj) {
infostream << "Client::ActiveObjectMgr::removeObject(): "
<< "id=" << id << " not found" << std::endl;
return;
}
std::unique_ptr<ClientActiveObject> obj = std::move(it->second);
m_active_objects.erase(it);
obj->removeFromScene(true);
}
@ -96,8 +91,10 @@ void ActiveObjectMgr::getActiveObjects(const v3f &origin, f32 max_d,
std::vector<DistanceSortedActiveObject> &dest)
{
f32 max_d2 = max_d * max_d;
for (auto &ao_it : m_active_objects) {
for (auto &ao_it : m_active_objects.iter()) {
ClientActiveObject *obj = ao_it.second.get();
if (!obj)
continue;
f32 d2 = (obj->getPosition() - origin).getLengthSQ();
@ -114,8 +111,10 @@ std::vector<DistanceSortedActiveObject> ActiveObjectMgr::getActiveSelectableObje
f32 max_d = shootline.getLength();
v3f dir = shootline.getVector().normalize();
for (auto &ao_it : m_active_objects) {
for (auto &ao_it : m_active_objects.iter()) {
ClientActiveObject *obj = ao_it.second.get();
if (!obj)
continue;
aabb3f selection_box;
if (!obj->getSelectionBox(&selection_box))

71
src/server/activeobjectmgr.cpp
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@ -36,19 +36,12 @@ ActiveObjectMgr::~ActiveObjectMgr()
void ActiveObjectMgr::clearIf(const std::function<bool(ServerActiveObject *, u16)> &cb)
{
// Make a defensive copy of the ids in case the passed callback changes the
// set of active objects.
// The callback is called for newly added objects iff they happen to reuse
// an old id.
std::vector<u16> ids = getAllIds();
for (u16 id : ids) {
auto it = m_active_objects.find(id);
if (it == m_active_objects.end())
continue; // obj was already removed
if (cb(it->second.get(), id)) {
// erase by id, `it` can be invalid now
removeObject(id);
for (auto &it : m_active_objects.iter()) {
if (!it.second)
continue;
if (cb(it.second.get(), it.first)) {
// Remove reference from m_active_objects
m_active_objects.remove(it.first);
}
}
}
@ -56,17 +49,16 @@ void ActiveObjectMgr::clearIf(const std::function<bool(ServerActiveObject *, u16
void ActiveObjectMgr::step(
float dtime, const std::function<void(ServerActiveObject *)> &f)
{
g_profiler->avg("ActiveObjectMgr: SAO count [#]", m_active_objects.size());
size_t count = 0;
// See above.
std::vector<u16> ids = getAllIds();
for (u16 id : ids) {
auto it = m_active_objects.find(id);
if (it == m_active_objects.end())
continue; // obj was removed
f(it->second.get());
for (auto &ao_it : m_active_objects.iter()) {
if (!ao_it.second)
continue;
count++;
f(ao_it.second.get());
}
g_profiler->avg("ActiveObjectMgr: SAO count [#]", count);
}
bool ActiveObjectMgr::registerObject(std::unique_ptr<ServerActiveObject> obj)
@ -99,12 +91,17 @@ bool ActiveObjectMgr::registerObject(std::unique_ptr<ServerActiveObject> obj)
return false;
}
auto obj_p = obj.get();
m_active_objects[obj->getId()] = std::move(obj);
auto obj_id = obj->getId();
m_active_objects.put(obj_id, std::move(obj));
auto new_size = m_active_objects.size();
verbosestream << "Server::ActiveObjectMgr::addActiveObjectRaw(): "
<< "Added id=" << obj_p->getId() << "; there are now "
<< m_active_objects.size() << " active objects." << std::endl;
<< "Added id=" << obj_id << "; there are now ";
if (new_size == decltype(m_active_objects)::unknown)
verbosestream << "???";
else
verbosestream << new_size;
verbosestream << " active objects." << std::endl;
return true;
}
@ -112,17 +109,13 @@ void ActiveObjectMgr::removeObject(u16 id)
{
verbosestream << "Server::ActiveObjectMgr::removeObject(): "
<< "id=" << id << std::endl;
auto it = m_active_objects.find(id);
if (it == m_active_objects.end()) {
// this will take the object out of the map and then destruct it
bool ok = m_active_objects.remove(id);
if (!ok) {
infostream << "Server::ActiveObjectMgr::removeObject(): "
<< "id=" << id << " not found" << std::endl;
return;
}
// Delete the obj before erasing, as the destructor may indirectly access
// m_active_objects.
it->second.reset();
m_active_objects.erase(id); // `it` can be invalid now
}
void ActiveObjectMgr::getObjectsInsideRadius(const v3f &pos, float radius,
@ -130,8 +123,10 @@ void ActiveObjectMgr::getObjectsInsideRadius(const v3f &pos, float radius,
std::function<bool(ServerActiveObject *obj)> include_obj_cb)
{
float r2 = radius * radius;
for (auto &activeObject : m_active_objects) {
for (auto &activeObject : m_active_objects.iter()) {
ServerActiveObject *obj = activeObject.second.get();
if (!obj)
continue;
const v3f &objectpos = obj->getBasePosition();
if (objectpos.getDistanceFromSQ(pos) > r2)
continue;
@ -145,8 +140,10 @@ void ActiveObjectMgr::getObjectsInArea(const aabb3f &box,
std::vector<ServerActiveObject *> &result,
std::function<bool(ServerActiveObject *obj)> include_obj_cb)
{
for (auto &activeObject : m_active_objects) {
for (auto &activeObject : m_active_objects.iter()) {
ServerActiveObject *obj = activeObject.second.get();
if (!obj)
continue;
const v3f &objectpos = obj->getBasePosition();
if (!box.isPointInside(objectpos))
continue;
@ -167,7 +164,7 @@ void ActiveObjectMgr::getAddedActiveObjectsAroundPos(const v3f &player_pos, f32
- discard objects that are found in current_objects.
- add remaining objects to added_objects
*/
for (auto &ao_it : m_active_objects) {
for (auto &ao_it : m_active_objects.iter()) {
u16 id = ao_it.first;
// Get object

219
src/util/container.h
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@ -28,9 +28,11 @@ with this program; if not, write to the Free Software Foundation, Inc.,
#include <map>
#include <set>
#include <queue>
#include <cassert>
#include <limits>
/*
Queue with unique values with fast checking of value existence
Queue with unique values with fast checking of value existence
*/
template<typename Value>
@ -75,6 +77,10 @@ private:
std::queue<Value> m_queue;
};
/*
Thread-safe map
*/
template<typename Key, typename Value>
class MutexedMap
{
@ -116,7 +122,9 @@ private:
};
// Thread-safe Double-ended queue
/*
Thread-safe double-ended queue
*/
template<typename T>
class MutexedQueue
@ -237,6 +245,10 @@ protected:
Semaphore m_signal;
};
/*
LRU cache
*/
template<typename K, typename V>
class LRUCache
{
@ -305,3 +317,206 @@ private:
// we can't use std::deque here, because its iterators get invalidated
std::list<K> m_queue;
};
/*
Map that can be safely modified (insertion, deletion) during iteration
Caveats:
- you cannot insert null elements
- you have to check for null elements during iteration, those are ones already deleted
- size() and empty() don't work during iteration
- not thread-safe in any way
How this is implemented:
- there are two maps: new and real
- if inserting duration iteration, the value is inserted into the "new" map
- if deleting during iteration, the value is set to null (to be GC'd later)
- when iteration finishes the "new" map is merged into the "real" map
*/
template<typename K, typename V>
class ModifySafeMap
{
public:
// this allows bare pointers but also e.g. std::unique_ptr
static_assert(std::is_default_constructible<V>::value,
"Value type must be default constructible");
static_assert(std::is_constructible<bool, V>::value,
"Value type must be convertible to bool");
static_assert(std::is_move_assignable<V>::value,
"Value type must be move-assignable");
typedef K key_type;
typedef V mapped_type;
ModifySafeMap() {
// the null value must convert to false and all others to true, but
// we can't statically check the latter.
sanity_check(!null_value);
}
~ModifySafeMap() {
assert(!m_iterating);
}
// possible to implement but we don't need it
DISABLE_CLASS_COPY(ModifySafeMap)
ALLOW_CLASS_MOVE(ModifySafeMap)
const V &get(const K &key) const {
if (m_iterating) {
auto it = m_new.find(key);
if (it != m_new.end())
return it->second;
}
auto it = m_values.find(key);
return it == m_values.end() ? null_value : it->second;
}
void put(const K &key, const V &value) {
if (!value) {
assert(false);
return;
}
if (m_iterating)
m_new.emplace(key, value);
else
m_values.emplace(key, value);
}
void put(const K &key, V &&value) {
if (!value) {
assert(false);
return;
}
if (m_iterating)
m_new.emplace(key, std::move(value));
else
m_values.emplace(key, std::move(value));
}
V take(const K &key) {
V ret = V();
if (m_iterating) {
auto it = m_new.find(key);
if (it != m_new.end()) {
ret = std::move(it->second);
m_new.erase(it);
}
}
auto it = m_values.find(key);
if (it == m_values.end())
return ret;
ret = std::move(it->second);
if (m_iterating) {
it->second = V();
m_garbage++;
} else {
m_values.erase(it);
}
return ret;
}
bool remove(const K &key) {
return !!take(key);
}
// Warning: not constant-time!
size_t size() const {
if (m_iterating) {
// This is by no means impossible to determine, it's just annoying
// to code and we happen to not need this.
return unknown;
}
assert(m_new.empty());
if (m_garbage == 0)
return m_values.size();
size_t n = 0;
for (auto &it : m_values)
n += !it.second ? 0 : 1;
return n;
}
// Warning: not constant-time!
bool empty() const {
if (m_iterating)
return false; // maybe
if (m_garbage == 0)
return m_values.empty();
for (auto &it : m_values) {
if (!!it.second)
return false;
}
return true;
}
auto iter() { return IterationHelper(this); }
void clear() {
if (m_iterating) {
for (auto &it : m_values)
it.second = V();
m_garbage = m_values.size();
} else {
m_values.clear();
m_garbage = 0;
}
}
static inline const V null_value = V();
// returned by size() if called during iteration
static constexpr size_t unknown = static_cast<size_t>(-1);
protected:
void merge_new() {
assert(!m_iterating);
if (!m_new.empty()) {
m_new.merge(m_values); // entries in m_new take precedence
m_values.clear();
std::swap(m_values, m_new);
}
}
void collect_garbage() {
assert(!m_iterating);
if (m_values.size() < GC_MIN_SIZE || m_garbage < m_values.size() / 2)
return;
for (auto it = m_values.begin(); it != m_values.end(); ) {
if (!it->second)
it = m_values.erase(it);
else
++it;
}
m_garbage = 0;
}
struct IterationHelper {
friend class ModifySafeMap<K, V>;
~IterationHelper() {
assert(m->m_iterating);
m->m_iterating--;
if (!m->m_iterating) {
m->merge_new();
m->collect_garbage();
}
}
auto begin() { return m->m_values.cbegin(); }
auto end() { return m->m_values.cend(); }
private:
IterationHelper(ModifySafeMap<K, V> *parent) : m(parent) {
assert(m->m_iterating < std::numeric_limits<decltype(m_iterating)>::max());
m->m_iterating++;
}
ModifySafeMap<K, V> *m;
};
private:
std::map<K, V> m_values;
std::map<K, V> m_new;
unsigned int m_iterating = 0;
size_t m_garbage = 0; // upper bound for null-placeholders in m_values
static constexpr size_t GC_MIN_SIZE = 30;
};