refactor(creature): replace polling-based pathfinding with event-driven follow system

config.lua.dist

@@ -38,13 +38,6 @@ replaceKickOnLogin = true
 maxPacketsPerSecond = 25
 enableTwoFactorAuth = true
 
--- Pathfinding
--- pathfindingInterval handles how often paths are force drawn
--- pathfindingDelay delays any recently drawn paths from drawing again
--- pathfindingDelay does not delay pathfindingInterval
-pathfindingInterval = 200
-pathfindingDelay = 300
-
 -- Deaths
 -- NOTE: Leave deathLosePercent as -1 if you want to use the default
 -- death penalty formula. For the old formula, set it to 10. For

src/configmanager.cpp

@@ -286,8 +286,6 @@ bool ConfigManager::load()
 	integer[QUEST_TRACKER_PREMIUM_LIMIT] = getGlobalNumber(L, "questTrackerPremiumLimit", 15);
 	integer[STAMINA_REGEN_MINUTE] = getGlobalNumber(L, "timeToRegenMinuteStamina", 3 * 60);
 	integer[STAMINA_REGEN_PREMIUM] = getGlobalNumber(L, "timeToRegenMinutePremiumStamina", 6 * 60);
-	integer[PATHFINDING_INTERVAL] = getGlobalNumber(L, "pathfindingInterval", 200);
-	integer[PATHFINDING_DELAY] = getGlobalNumber(L, "pathfindingDelay", 300);
 
 	expStages = loadXMLStages();
 	if (expStages.empty()) {

src/configmanager.h

@@ -119,8 +119,6 @@ enum integer_config_t
 	QUEST_TRACKER_PREMIUM_LIMIT,
 	STAMINA_REGEN_MINUTE,
 	STAMINA_REGEN_PREMIUM,
-	PATHFINDING_INTERVAL,
-	PATHFINDING_DELAY,
 
 	LAST_INTEGER_CONFIG /* this must be the last one */
 };

src/creature.cpp

@@ -126,14 +126,19 @@ void Creature::onThink(uint32_t interval)
 	tfs::events::creature::onThink(asCreature(), interval);
 }
 
-void Creature::forceUpdatePath()
+void Creature::updateFollowPath()
 {
-	if (attackedCreature.expired() && followCreature.expired()) {
+	if (eventFollowPath != 0) {
+		g_scheduler.stopEvent(eventFollowPath);
+		eventFollowPath = 0;
+	}
+
+	if (followCreature.expired()) {
 		return;
 	}
 
-	lastPathUpdate = OTSYS_TIME() + getNumber(ConfigManager::PATHFINDING_DELAY);
-	g_dispatcher.addTask(createTask([id = getID()]() { g_game.updateCreatureWalk(id); }));
+	eventFollowPath = g_scheduler.addEvent(
+	    createSchedulerTask(EVENT_CHECK_CREATURE_INTERVAL, [id = getID()]() { g_game.updateCreatureWalk(id); }));
 }
 
 void Creature::onIdleStatus()
@@ -166,8 +171,6 @@ void Creature::onWalk()
 		}
 	}
 
-	updateFollowersPaths();
-
 	if (cancelNextWalk) {
 		listWalkDir.clear();
 		onWalkAborted();
@@ -179,12 +182,7 @@ void Creature::onWalk()
 		addEventWalk();
 	}
 
-	if (!attackedCreature.expired() || !followCreature.expired()) {
-		if (lastPathUpdate < OTSYS_TIME()) {
-			g_dispatcher.addTask(createTask([id = getID()]() { g_game.updateCreatureWalk(id); }));
-			lastPathUpdate = OTSYS_TIME() + getNumber(ConfigManager::PATHFINDING_DELAY);
-		}
-	}
+	updateFollowersPaths();
 }
 
 void Creature::onWalk(Direction& dir)
@@ -315,7 +313,8 @@ void Creature::updateFollowCreaturePath(FindPathParams& fpp)
 {
 	listWalkDir.clear();
 
-	if (const auto& followCreature = getFollowCreature(); getPathTo(followCreature->getPosition(), listWalkDir, fpp)) {
+	if (const auto& followCreature = getFollowCreature();
+	    followCreature && getPathTo(followCreature->getPosition(), listWalkDir, fpp)) {
 		hasFollowPath = true;
 		startAutoWalk();
 	} else {
@@ -341,6 +340,11 @@ void Creature::onCreatureMove(const std::shared_ptr<Creature>& creature, const s
                               const Position& newPos, const std::shared_ptr<const Tile>& oldTile,
                               const Position& oldPos, bool teleport)
 {
+	if (const auto& followCreature = getFollowCreature();
+	    (creature == followCreature || (creature.get() == this && followCreature))) {
+		updateFollowPath();
+	}
+
 	if (creature.get() == this) {
 		lastStep = OTSYS_TIME();
 		lastStepCost = 1;
@@ -688,15 +692,12 @@ void Creature::setAttackedCreature(const std::shared_ptr<Creature>& creature)
 	}
 
 	attackedCreature = creature;
-	creature->addFollower(asCreature());
 	onAttackedCreature(creature);
 
 	if (const auto& player = creature->asPlayer()) {
 		player->addInFightTicks();
 	}
 
-	forceUpdatePath();
-
 	for (const auto& summon : summons | tfs::views::lock_weak_ptrs) {
 		summon->setAttackedCreature(creature);
 	}
@@ -740,15 +741,29 @@ void Creature::setFollowCreature(const std::shared_ptr<Creature>& creature)
 		return;
 	}
 
-	followCreature = creature;
+	if (const auto& oldFollow = getFollowCreature()) {
+		oldFollow->removeFollower(asCreature());
+	}
 	creature->addFollower(asCreature());
+
+	followCreature = creature;
 	hasFollowPath = false;
 	onFollowCreature(creature);
-	forceUpdatePath();
+
+	updateFollowPath();
 }
 
 void Creature::removeFollowCreature()
 {
+	if (const auto& oldFollow = getFollowCreature()) {
+		oldFollow->removeFollower(asCreature());
+	}
+
+	if (eventFollowPath != 0) {
+		g_scheduler.stopEvent(eventFollowPath);
+		eventFollowPath = 0;
+	}
+
 	followCreature.reset();
 	onUnfollowCreature();
 }
@@ -790,12 +805,7 @@ void Creature::updateFollowersPaths()
 	            std::ranges::to<decltype(followers)>();
 
 	for (const auto& follower : followers | tfs::views::lock_weak_ptrs) {
-		if (follower->lastPathUpdate < OTSYS_TIME()) {
-			continue;
-		}
-
-		g_dispatcher.addTask(createTask([id = follower->getID()]() { g_game.updateCreatureWalk(id); }));
-		follower->lastPathUpdate = OTSYS_TIME() + getNumber(ConfigManager::PATHFINDING_DELAY);
+		follower->updateFollowPath();
 	}
 }
 

src/creature.h

@@ -213,6 +213,7 @@ class Creature : public Thing
 	{
 		return tfs::owner_equal(followCreature, creature);
 	}
+	void completeEventFollowWalk() { eventFollowPath = 0; }
 
 	// follow events
 	virtual void onFollowCreature(const std::shared_ptr<const Creature>&);
@@ -317,7 +318,7 @@ class Creature : public Thing
 	virtual void onThink(uint32_t interval);
 	virtual void onAttacking(uint32_t) {}
 
-	virtual void forceUpdatePath();
+	virtual void updateFollowPath();
 	virtual void onWalk();
 	virtual bool getNextStep(Direction& dir, uint32_t& flags);
 
@@ -393,7 +394,7 @@ class Creature : public Thing
 	std::vector<Direction> listWalkDir;
 
 	uint64_t lastStep = 0;
-	int64_t lastPathUpdate = 0;
+	uint32_t eventFollowPath = 0;
 	uint32_t id = 0;
 	uint32_t scriptEventsBitField = 0;
 	uint32_t eventWalk = 0;

src/game.cpp

@@ -52,8 +52,6 @@ void Game::start(ServiceManager* manager)
 	serviceManager = manager;
 
 	g_scheduler.addEvent(createSchedulerTask(EVENT_CREATURE_THINK_INTERVAL, [this]() { checkCreatures(0); }));
-	g_scheduler.addEvent(
-	    createSchedulerTask(getNumber(ConfigManager::PATHFINDING_INTERVAL), [this]() { updateCreaturesPath(0); }));
 	g_scheduler.addEvent(createSchedulerTask(EVENT_DECAYINTERVAL, [this]() { checkDecay(); }));
 }
 
@@ -3182,8 +3180,6 @@ void Game::playerSetAttackedCreature(uint32_t playerId, uint32_t creatureId)
 	}
 
 	player->setAttackedCreature(attackCreature);
-
-	g_dispatcher.addTask([this, id = player->getID()]() { updateCreatureWalk(id); });
 }
 
 void Game::playerFollowCreature(uint32_t playerId, uint32_t creatureId)
@@ -3200,8 +3196,6 @@ void Game::playerFollowCreature(uint32_t playerId, uint32_t creatureId)
 	} else {
 		player->removeFollowCreature();
 	}
-
-	g_dispatcher.addTask([this, id = player->getID()]() { updateCreatureWalk(id); });
 }
 
 void Game::playerSetFightModes(uint32_t playerId, fightMode_t fightMode, bool chaseMode, bool secureMode)
@@ -3726,6 +3720,7 @@ void Game::updateCreatureWalk(uint32_t creatureId)
 	if (const auto& creature = getCreatureByID(creatureId)) {
 		if (!creature->isDead()) {
 			creature->goToFollowCreature();
+			creature->completeEventFollowWalk();
 		}
 	}
 }
@@ -3789,18 +3784,6 @@ void Game::checkCreatures(size_t index)
 	cleanup();
 }
 
-void Game::updateCreaturesPath(size_t index)
-{
-	g_scheduler.addEvent(createSchedulerTask(getNumber(ConfigManager::PATHFINDING_INTERVAL),
-	                                         [=, this]() { updateCreaturesPath((index + 1) % EVENT_CREATURECOUNT); }));
-
-	for (const auto& creature : checkCreatureLists[index] | tfs::views::lock_weak_ptrs) {
-		if (!creature->isDead()) {
-			creature->forceUpdatePath();
-		}
-	}
-}
-
 void Game::changeSpeed(const std::shared_ptr<Creature>& creature, int32_t varSpeedDelta)
 {
 	int32_t varSpeed = creature->getSpeed() - creature->getBaseSpeed();

src/game.h

@@ -423,7 +423,6 @@ class Game
 	void updateCreatureWalk(uint32_t creatureId);
 	void checkCreatureAttack(uint32_t creatureId);
 	void checkCreatures(size_t index);
-	void updateCreaturesPath(size_t index);
 
 	bool combatBlockHit(CombatDamage& damage, const std::shared_ptr<Creature>& attacker,
 	                    const std::shared_ptr<Creature>& target, bool checkDefense, bool checkArmor, bool field,

src/player.cpp

@@ -1267,11 +1267,6 @@ void Player::onCreatureMove(const std::shared_ptr<Creature>& creature, const std
 {
 	Creature::onCreatureMove(creature, newTile, newPos, oldTile, oldPos, teleport);
 
-	if (const auto& followCreature = getFollowCreature();
-	    hasFollowPath && (creature == followCreature || (creature.get() == this && followCreature))) {
-		g_dispatcher.addTask([id = getID()]() { g_game.updateCreatureWalk(id); });
-	}
-
 	if (creature.get() != this) {
 		return;
 	}