fix: Remove pending timer logic (#1416)

* remove pending timers

they serve no purpose anymore since iterator invalidation is a non-issue.  I added this initially to make it so if you added a timer this frame, there would be at least 1 frame before you would start it, but this in practice doesnt serve a purpose

* timers still work

dGame/Entity.cpp

@@ -1243,12 +1243,18 @@ void Entity::Update(const float deltaTime) {
 		// If the timer is expired, erase it and dont increment the position because the next timer will be at the same position.
 		// Before: [0, 1, 2, 3, ..., n]
 		// timerPosition  ^
-		// After:  [0, 1, 3, ..., n]
+		// After:  [0, 1, n, ..., n - 1] 2 is expired and removed now
 		// timerPosition  ^
 		if (timer.GetTime() <= 0) {
 			// Remove the timer from the list of timers first so that scripts and events can remove timers without causing iterator invalidation
 			auto timerName = timer.GetName();
-			m_Timers.erase(m_Timers.begin() + timerPosition);
+			// We don't need to copy the element if there is only 1 element nor do we need to copy if we are on the last element.
+			// This is a clever removal trick that avoids having to copy the entire vector and instead replaces this now expired
+			// element with the last element in the vector and then removes the last element.
+			if (m_Timers.size() > 1 && timerPosition < m_Timers.size() - 1) {
+				m_Timers[timerPosition] = m_Timers[m_Timers.size() - 1];
+			}
+			m_Timers.erase(m_Timers.end() - 1);
 			for (CppScripts::Script* script : CppScripts::GetEntityScripts(this)) {
 				script->OnTimerDone(this, timerName);
 			}
@@ -1264,31 +1270,26 @@ void Entity::Update(const float deltaTime) {
 		// If the timer is expired, erase it and dont increment the position because the next timer will be at the same position.
 		// Before: [0, 1, 2, 3, ..., n]
 		// timerPosition  ^
-		// After:  [0, 1, 3, ..., n]
+		// After:  [0, 1, n, ..., n - 1] 2 is expired and removed now
 		// timerPosition  ^
 		auto& callbackTimer = m_CallbackTimers[timerPosition];
 		callbackTimer.Update(deltaTime);
 		if (callbackTimer.GetTime() <= 0) {
 			// Remove the timer from the list of timers first so that callbacks can remove timers without causing iterator invalidation
 			auto callback = callbackTimer.GetCallback();
-			m_CallbackTimers.erase(m_CallbackTimers.begin() + timerPosition);
+			// We don't need to copy the element if there is only 1 element nor do we need to copy if we are on the last element.
+			// This is a clever removal trick that avoids having to copy the entire vector and instead replaces this now expired
+			// element with the last element in the vector and then removes the last element.
+			if (m_CallbackTimers.size() > 1 && timerPosition < m_CallbackTimers.size() - 1) {
+				m_CallbackTimers[timerPosition] = m_CallbackTimers[m_CallbackTimers.size() - 1];
+			}
+			m_CallbackTimers.erase(m_CallbackTimers.end() - 1);
 			callback();
 		} else {
 			timerPosition++;
 		}
 	}
 
-	// Add pending timers to the list of timers so they start next tick.
-	if (!m_PendingTimers.empty()) {
-		m_Timers.insert(m_Timers.end(), m_PendingTimers.begin(), m_PendingTimers.end());
-		m_PendingTimers.clear();
-	}
-
-	if (!m_PendingCallbackTimers.empty()) {
-		m_CallbackTimers.insert(m_CallbackTimers.end(), m_PendingCallbackTimers.begin(), m_PendingCallbackTimers.end());
-		m_PendingCallbackTimers.clear();
-	}
-
 	if (IsSleeping()) {
 		Sleep();
 
@@ -1724,11 +1725,11 @@ void Entity::RemoveParent() {
 }
 
 void Entity::AddTimer(std::string name, float time) {
-	m_PendingTimers.emplace_back(name, time);
+	m_Timers.emplace_back(name, time);
 }
 
 void Entity::AddCallbackTimer(float time, std::function<void()> callback) {
-	m_PendingCallbackTimers.emplace_back(time, callback);
+	m_CallbackTimers.emplace_back(time, callback);
 }
 
 bool Entity::HasTimer(const std::string& name) {
@@ -1737,7 +1738,6 @@ bool Entity::HasTimer(const std::string& name) {
 
 void Entity::CancelCallbackTimers() {
 	m_CallbackTimers.clear();
-	m_PendingCallbackTimers.clear();
 }
 
 void Entity::ScheduleKillAfterUpdate(Entity* murderer) {
@@ -1759,9 +1759,7 @@ void Entity::CancelTimer(const std::string& name) {
 
 void Entity::CancelAllTimers() {
 	m_Timers.clear();
-	m_PendingTimers.clear();
 	m_CallbackTimers.clear();
-	m_PendingCallbackTimers.clear();
 }
 
 bool Entity::IsPlayer() const {

dGame/Entity.h

@@ -330,9 +330,7 @@ protected:
 
 	std::unordered_map<eReplicaComponentType, Component*> m_Components;
 	std::vector<EntityTimer> m_Timers;
-	std::vector<EntityTimer> m_PendingTimers;
 	std::vector<EntityCallbackTimer> m_CallbackTimers;
-	std::vector<EntityCallbackTimer> m_PendingCallbackTimers;
 
 	bool m_ShouldDestroyAfterUpdate = false;