refactor: dispatch system (#1685)

Dispatch has been refactored to be centralized in just one thread.
Previously, each task was sent to the threads that were free, which
could cause bottlenecks because they were stuck with mutexes, causing
queues depending on how many threads the cpu had.

small illustration of a possible problem:

![image](https://github.com/opentibiabr/canary/assets/2267386/9cfba304-c8aa-4590-9538-48edb95a972a)

Apart from what was mentioned above,, the scheduling class has been
removed and we now have new methods in dispatch, addEvent_async,
scheduleEvent and cycleEvent.

**Note**
- addEvent_async(func, context_id)
- With this method it is now possible to create an asynchronous event
that will be executed before all synchronous events.

**Questions**
- Why Scoped Object
- there is a big cost in allocating(new) and deallocating(delete) an
object from memory and since we don't need to manage the lifetime of the
object or share it, it doesn't make sense to use smart pointer.

**Benchmark**
- Scoped Object vs Smart Pointer

![image](https://github.com/opentibiabr/canary/assets/2267386/7c514967-2087-4d46-ad0b-19820a31e46a)
<details>
  
```c++

struct Teste {
	int i;
};

Benchmark bm;
for (uint_fast32_t i = 0; i < 999; ++i) {
	std::vector<Teste> list;
	for (uint_fast32_t d = 0; d < 99999; ++d) {
		list.emplace_back(d);
	}
	list.clear();
}

g_logger().info("Scoped Object {}ms", bm.duration());

bm.reset();
bm.start();

for (uint_fast32_t i = 0; i < 999; ++i) {
	std::vector<std::unique_ptr<Teste>> list;
	for (uint_fast32_t d = 0; d < 99999; ++d) {
		list.emplace_back(std::make_unique<Teste>(d));
	}
	list.clear();
}

g_logger().info("Smart Pointer {}ms", bm.duration());
```</details>

---------

Co-authored-by: Luan Santos <[email protected]>
Co-authored-by: GitHub Actions <github-actions[bot]@users.noreply.github.com>

src/canary_server.cpp

@@ -46,13 +46,15 @@ CanaryServer::CanaryServer(
 	std::set_new_handler(badAllocationHandler);
 	srand(static_cast<unsigned int>(OTSYS_TIME()));
 
+	g_dispatcher().init();
+
 #ifdef _WIN32
 	SetConsoleTitleA(STATUS_SERVER_NAME);
 #endif
 }
 
 int CanaryServer::run() {
-	g_dispatcher().addTask(
+	g_dispatcher().addEvent(
 		[this] {
 			try {
 				loadConfigLua();
@@ -365,4 +367,5 @@ void CanaryServer::modulesLoadHelper(bool loaded, std::string moduleName) {
 
 void CanaryServer::shutdown() {
 	inject<ThreadPool>().shutdown();
+	g_dispatcher().shutdown();
 }

src/creatures/combat/condition.cpp

@@ -2040,7 +2040,7 @@ bool ConditionFeared::executeCondition(std::shared_ptr<Creature> creature, int32
 		}
 
 		if (getFleePath(creature, currentPos, listDir)) {
-			g_dispatcher().addTask(std::bind(&Game::forcePlayerAutoWalk, &g_game(), creature->getID(), listDir), "ConditionFeared::executeCondition");
+			g_dispatcher().addEvent(std::bind(&Game::forcePlayerAutoWalk, &g_game(), creature->getID(), listDir), "ConditionFeared::executeCondition");
 			g_logger().debug("[ConditionFeared::executeCondition] Walking Scheduled");
 		}
 	}

src/creatures/creature.cpp

@@ -14,7 +14,6 @@
 #include "game/scheduling/dispatcher.hpp"
 #include "game/game.hpp"
 #include "creatures/monsters/monster.hpp"
-#include "game/scheduling/scheduler.hpp"
 #include "game/zones/zone.hpp"
 #include "map/spectators.hpp"
 
@@ -260,15 +259,15 @@ void Creature::addEventWalk(bool firstStep) {
 		g_game().checkCreatureWalk(getID());
 	}
 
-	eventWalk = g_scheduler().addEvent(
+	eventWalk = g_dispatcher().scheduleEvent(
 		static_cast<uint32_t>(ticks), std::bind(&Game::checkCreatureWalk, &g_game(), getID()),
 		"Creature::checkCreatureWalk"
 	);
 }
 
 void Creature::stopEventWalk() {
 	if (eventWalk != 0) {
-		g_scheduler().stopEvent(eventWalk);
+		g_dispatcher().stopEvent(eventWalk);
 		eventWalk = 0;
 	}
 }
@@ -598,7 +597,7 @@ void Creature::onCreatureMove(std::shared_ptr<Creature> creature, std::shared_pt
 	if (followCreature && (creature == getCreature() || creature == followCreature)) {
 		if (hasFollowPath) {
 			isUpdatingPath = true;
-			g_dispatcher().addTask(std::bind(&Game::updateCreatureWalk, &g_game(), getID()), "Game::updateCreatureWalk");
+			g_dispatcher().addEvent(std::bind(&Game::updateCreatureWalk, &g_game(), getID()), "Game::updateCreatureWalk");
 		}
 
 		if (newPos.z != oldPos.z || !canSee(followCreature->getPosition())) {
@@ -613,7 +612,7 @@ void Creature::onCreatureMove(std::shared_ptr<Creature> creature, std::shared_pt
 		} else {
 			if (hasExtraSwing()) {
 				// our target is moving lets see if we can get in hit
-				g_dispatcher().addTask(std::bind(&Game::checkCreatureAttack, &g_game(), getID()), "Game::checkCreatureAttack");
+				g_dispatcher().addEvent(std::bind(&Game::checkCreatureAttack, &g_game(), getID()), "Game::checkCreatureAttack");
 			}
 
 			if (newTile->getZoneType() != oldTile->getZoneType()) {
@@ -754,7 +753,7 @@ bool Creature::dropCorpse(std::shared_ptr<Creature> lastHitCreature, std::shared
 
 				if (player->checkAutoLoot()) {
 					int32_t pos = tile->getStackposOfItem(player, corpse);
-					g_dispatcher().addTask(
+					g_dispatcher().addEvent(
 						std::bind(&Game::playerQuickLoot, &g_game(), mostDamageCreature->getID(), this->getPosition(), corpse->getID(), pos - 1, nullptr, false, true),
 						"Game::playerQuickLoot"
 					);
@@ -801,7 +800,7 @@ void Creature::changeHealth(int32_t healthChange, bool sendHealthChange /* = tru
 		g_game().addCreatureHealth(static_self_cast<Creature>());
 	}
 	if (health <= 0) {
-		g_dispatcher().addTask(std::bind(&Game::executeDeath, &g_game(), getID()), "Game::executeDeath");
+		g_dispatcher().addEvent(std::bind(&Game::executeDeath, &g_game(), getID()), "Game::executeDeath");
 	}
 }
 
@@ -1309,7 +1308,7 @@ void Creature::removeCondition(ConditionType_t conditionType, ConditionId_t cond
 		if (!force && conditionType == CONDITION_PARALYZE) {
 			int32_t walkDelay = getWalkDelay();
 			if (walkDelay > 0) {
-				g_scheduler().addEvent(
+				g_dispatcher().scheduleEvent(
 					walkDelay,
 					std::bind(&Game::forceRemoveCondition, &g_game(), getID(), conditionType, conditionId),
 					"Game::forceRemoveCondition"

src/creatures/interactions/chat.cpp

@@ -12,7 +12,7 @@
 #include "creatures/interactions/chat.hpp"
 #include "game/game.hpp"
 #include "utils/pugicast.hpp"
-#include "game/scheduling/scheduler.hpp"
+#include "game/scheduling/dispatcher.hpp"
 
 bool PrivateChatChannel::isInvited(uint32_t guid) const {
 	if (guid == getOwner()) {
@@ -81,7 +81,7 @@ bool ChatChannel::addUser(const std::shared_ptr<Player> &player) {
 	if (id == CHANNEL_GUILD) {
 		const auto guild = player->getGuild();
 		if (guild && !guild->getMotd().empty()) {
-			g_scheduler().addEvent(150, std::bind(&Game::sendGuildMotd, &g_game(), player->getID()), "Game::sendGuildMotd");
+			g_dispatcher().scheduleEvent(150, std::bind(&Game::sendGuildMotd, &g_game(), player->getID()), "Game::sendGuildMotd");
 		}
 	}
 

src/creatures/monsters/monster.cpp

@@ -340,12 +340,21 @@ void Monster::updateTargetList() {
 
 	auto targetIterator = targetIDList.begin();
 	while (targetIterator != targetIDList.end()) {
-		auto creature = targetListMap[*targetIterator].lock();
-		if (!creature || creature->getHealth() <= 0 || !canSee(creature->getPosition())) {
-			targetIterator = targetIDList.erase(targetIterator);
-			targetListMap.erase(*targetIterator);
+		const uint32_t targetId = *targetIterator;
+
+		auto itTLM = targetListMap.find(targetId);
+		const bool existTarget = itTLM != targetListMap.end();
+
+		if (existTarget) {
+			const auto &creature = itTLM->second.lock();
+			if (!creature || creature->getHealth() <= 0 || !canSee(creature->getPosition())) {
+				targetIterator = targetIDList.erase(targetIterator);
+				targetListMap.erase(itTLM);
+			} else {
+				++targetIterator;
+			}
 		} else {
-			++targetIterator;
+			targetIterator = targetIDList.erase(targetIterator);
 		}
 	}
 
@@ -662,7 +671,7 @@ bool Monster::selectTarget(std::shared_ptr<Creature> creature) {
 
 	if (isHostile() || isSummon()) {
 		if (setAttackedCreature(creature)) {
-			g_dispatcher().addTask(std::bind(&Game::checkCreatureAttack, &g_game(), getID()), "Game::checkCreatureAttack");
+			g_dispatcher().addEvent(std::bind(&Game::checkCreatureAttack, &g_game(), getID()), "Game::checkCreatureAttack");
 		}
 	}
 	return setFollowCreature(creature);

src/creatures/monsters/spawns/spawn_monster.cpp

@@ -12,7 +12,7 @@
 #include "creatures/monsters/spawns/spawn_monster.hpp"
 #include "game/game.hpp"
 #include "creatures/monsters/monster.hpp"
-#include "game/scheduling/scheduler.hpp"
+#include "game/scheduling/dispatcher.hpp"
 #include "game/scheduling/events_scheduler.hpp"
 #include "lua/creature/events.hpp"
 #include "lua/callbacks/event_callback.hpp"
@@ -144,7 +144,7 @@ bool SpawnsMonster::isInZone(const Position &centerPos, int32_t radius, const Po
 
 void SpawnMonster::startSpawnMonsterCheck() {
 	if (checkSpawnMonsterEvent == 0) {
-		checkSpawnMonsterEvent = g_scheduler().addEvent(getInterval(), std::bind(&SpawnMonster::checkSpawnMonster, this), "SpawnMonster::checkSpawnMonster");
+		checkSpawnMonsterEvent = g_dispatcher().scheduleEvent(getInterval(), std::bind(&SpawnMonster::checkSpawnMonster, this), "SpawnMonster::checkSpawnMonster");
 	}
 }
 
@@ -239,7 +239,7 @@ void SpawnMonster::checkSpawnMonster() {
 	}
 
 	if (spawnedMonsterMap.size() < spawnMonsterMap.size()) {
-		checkSpawnMonsterEvent = g_scheduler().addEvent(getInterval(), std::bind(&SpawnMonster::checkSpawnMonster, this), "SpawnMonster::checkSpawnMonster");
+		checkSpawnMonsterEvent = g_dispatcher().scheduleEvent(getInterval(), std::bind(&SpawnMonster::checkSpawnMonster, this), "SpawnMonster::checkSpawnMonster");
 	}
 }
 
@@ -248,7 +248,7 @@ void SpawnMonster::scheduleSpawn(uint32_t spawnMonsterId, spawnBlock_t &sb, uint
 		spawnMonster(spawnMonsterId, sb.monsterType, sb.pos, sb.direction);
 	} else {
 		g_game().addMagicEffect(sb.pos, CONST_ME_TELEPORT);
-		g_scheduler().addEvent(1400, std::bind(&SpawnMonster::scheduleSpawn, this, spawnMonsterId, sb, interval - NONBLOCKABLE_SPAWN_MONSTER_INTERVAL), "SpawnMonster::scheduleSpawn");
+		g_dispatcher().scheduleEvent(1400, std::bind(&SpawnMonster::scheduleSpawn, this, spawnMonsterId, sb, interval - NONBLOCKABLE_SPAWN_MONSTER_INTERVAL), "SpawnMonster::scheduleSpawn");
 	}
 }
 
@@ -298,7 +298,7 @@ void SpawnMonster::removeMonster(std::shared_ptr<Monster> monster) {
 
 void SpawnMonster::stopEvent() {
 	if (checkSpawnMonsterEvent != 0) {
-		g_scheduler().stopEvent(checkSpawnMonsterEvent);
+		g_dispatcher().stopEvent(checkSpawnMonsterEvent);
 		checkSpawnMonsterEvent = 0;
 	}
 }

src/creatures/npcs/npc.cpp

@@ -15,7 +15,6 @@
 #include "game/game.hpp"
 #include "lua/callbacks/creaturecallback.hpp"
 #include "game/scheduling/dispatcher.hpp"
-#include "game/scheduling/scheduler.hpp"
 #include "map/spectators.hpp"
 
 int32_t Npc::despawnRange;
@@ -350,7 +349,7 @@ void Npc::onPlayerSellAllLoot(uint32_t playerId, uint16_t itemId, bool ignore, u
 			return;
 		}
 		if (hasMore) {
-			g_scheduler().addEvent(SCHEDULER_MINTICKS, std::bind(&Npc::onPlayerSellAllLoot, this, player->getID(), itemId, ignore, totalPrice), __FUNCTION__);
+			g_dispatcher().scheduleEvent(SCHEDULER_MINTICKS, std::bind(&Npc::onPlayerSellAllLoot, this, player->getID(), itemId, ignore, totalPrice), __FUNCTION__);
 			return;
 		}
 		ss << "You sold all of the items from your loot pouch for ";
@@ -365,7 +364,7 @@ void Npc::onPlayerSellItem(std::shared_ptr<Player> player, uint16_t itemId, uint
 		return;
 	}
 	if (itemId == ITEM_GOLD_POUCH) {
-		g_scheduler().addEvent(SCHEDULER_MINTICKS, std::bind(&Npc::onPlayerSellAllLoot, this, player->getID(), itemId, ignore, 0), __FUNCTION__);
+		g_dispatcher().scheduleEvent(SCHEDULER_MINTICKS, std::bind(&Npc::onPlayerSellAllLoot, this, player->getID(), itemId, ignore, 0), __FUNCTION__);
 		return;
 	}
 

src/creatures/npcs/spawns/spawn_npc.cpp

@@ -12,7 +12,7 @@
 #include "creatures/npcs/spawns/spawn_npc.hpp"
 #include "creatures/npcs/npc.hpp"
 #include "game/game.hpp"
-#include "game/scheduling/scheduler.hpp"
+#include "game/scheduling/dispatcher.hpp"
 #include "lua/creature/events.hpp"
 #include "lua/callbacks/event_callback.hpp"
 #include "lua/callbacks/events_callbacks.hpp"
@@ -131,7 +131,7 @@ bool SpawnsNpc::isInZone(const Position &centerPos, int32_t radius, const Positi
 
 void SpawnNpc::startSpawnNpcCheck() {
 	if (checkSpawnNpcEvent == 0) {
-		checkSpawnNpcEvent = g_scheduler().addEvent(getInterval(), std::bind(&SpawnNpc::checkSpawnNpc, this), "SpawnNpc::checkSpawnNpc");
+		checkSpawnNpcEvent = g_dispatcher().scheduleEvent(getInterval(), std::bind(&SpawnNpc::checkSpawnNpc, this), "SpawnNpc::checkSpawnNpc");
 	}
 }
 
@@ -216,7 +216,7 @@ void SpawnNpc::checkSpawnNpc() {
 	}
 
 	if (spawnedNpcMap.size() < spawnNpcMap.size()) {
-		checkSpawnNpcEvent = g_scheduler().addEvent(getInterval(), std::bind(&SpawnNpc::checkSpawnNpc, this), __FUNCTION__);
+		checkSpawnNpcEvent = g_dispatcher().scheduleEvent(getInterval(), std::bind(&SpawnNpc::checkSpawnNpc, this), __FUNCTION__);
 	}
 }
 
@@ -225,7 +225,7 @@ void SpawnNpc::scheduleSpawnNpc(uint32_t spawnId, spawnBlockNpc_t &sb, uint16_t
 		spawnNpc(spawnId, sb.npcType, sb.pos, sb.direction);
 	} else {
 		g_game().addMagicEffect(sb.pos, CONST_ME_TELEPORT);
-		g_scheduler().addEvent(1400, std::bind(&SpawnNpc::scheduleSpawnNpc, this, spawnId, sb, interval - NONBLOCKABLE_SPAWN_NPC_INTERVAL), __FUNCTION__);
+		g_dispatcher().scheduleEvent(1400, std::bind(&SpawnNpc::scheduleSpawnNpc, this, spawnId, sb, interval - NONBLOCKABLE_SPAWN_NPC_INTERVAL), __FUNCTION__);
 	}
 }
 
@@ -275,7 +275,7 @@ void SpawnNpc::removeNpc(std::shared_ptr<Npc> npc) {
 
 void SpawnNpc::stopEvent() {
 	if (checkSpawnNpcEvent != 0) {
-		g_scheduler().stopEvent(checkSpawnNpcEvent);
+		g_dispatcher().stopEvent(checkSpawnNpcEvent);
 		checkSpawnNpcEvent = 0;
 	}
 }