fix(Core/Pooling): Fixed less and less objects from pools being spawned the longer the server is running (#5572)

src/common/Containers.h

@@ -64,33 +64,63 @@ namespace acore
 
     namespace Containers
     {
-        template<class T>
-        void RandomResizeList(std::list<T>& list, uint32 size)
+        // replace with std::size in C++17
+        template<class C>
+        constexpr inline std::size_t Size(C const& container)
         {
-            size_t list_size = list.size();
-
-            while (list_size > size)
-            {
-                typename std::list<T>::iterator itr = list.begin();
-                std::advance(itr, urand(0, list_size - 1));
-                list.erase(itr);
-                --list_size;
-            }
+            return container.size();
         }
 
-        template<class T, class Predicate>
-        void RandomResizeList(std::list<T>& list, Predicate& predicate, uint32 size)
+        template<class T, std::size_t size>
+        constexpr inline std::size_t Size(T const(&)[size]) noexcept
+        {
+            return size;
+        }
+
+        // resizes <container> to have at most <requestedSize> elements
+        // if it has more than <requestedSize> elements, the elements to keep are selected randomly
+        template<class C>
+        void RandomResize(C& container, std::size_t requestedSize)
+        {
+            static_assert(std::is_base_of<std::forward_iterator_tag, typename std::iterator_traits<typename C::iterator>::iterator_category>::value, "Invalid container passed to acore::Containers::RandomResize");
+            if (Size(container) <= requestedSize)
+            {
+                return;
+            }
+
+            auto keepIt = std::begin(container), curIt = std::begin(container);
+            uint32 elementsToKeep = requestedSize, elementsToProcess = Size(container);
+            while (elementsToProcess)
+            {
+                // this element has chance (elementsToKeep / elementsToProcess) of being kept
+                if (urand(1, elementsToProcess) <= elementsToKeep)
+                {
+                    if (keepIt != curIt)
+                        *keepIt = std::move(*curIt);
+                    ++keepIt;
+                    --elementsToKeep;
+                }
+
+                ++curIt;
+                --elementsToProcess;
+            }
+
+            container.erase(keepIt, std::end(container));
+        }
+
+        template<class C, class Predicate>
+        void RandomResize(C& container, Predicate&& predicate, std::size_t requestedSize)
         {
             //! First use predicate filter
-            std::list<T> listCopy;
-            for (typename std::list<T>::iterator itr = list.begin(); itr != list.end(); ++itr)
-                if (predicate(*itr))
-                    listCopy.push_back(*itr);
+            C containerCopy;
+            std::copy_if(std::begin(container), std::end(container), std::inserter(containerCopy, std::end(containerCopy)), predicate);
 
-            if (size)
-                RandomResizeList(listCopy, size);
+            if (requestedSize)
+            {
+                RandomResize(containerCopy, requestedSize);
+            }
 
-            list = listCopy;
+            container = std::move(containerCopy);
         }
 
         /* Select a random element from a container. Note: make sure you explicitly empty check the container */

src/server/game/AI/CoreAI/UnitAI.h

@@ -261,7 +261,7 @@ public:
             targetList.reverse();
 
         if (targetType == SELECT_TARGET_RANDOM)
-            acore::Containers::RandomResizeList(targetList, maxTargets);
+            acore::Containers::RandomResize(targetList, maxTargets);
         else
             targetList.resize(maxTargets);
     }

src/server/game/AI/ScriptedAI/ScriptedCreature.h

@@ -107,7 +107,7 @@ public:
 
         // We need to use a copy of SummonList here, otherwise original SummonList would be modified
         StorageType listCopy = storage_;
-        acore::Containers::RandomResizeList<ObjectGuid, Predicate>(listCopy, predicate, max);
+        acore::Containers::RandomResize(listCopy, predicate, max);
         for (StorageType::iterator i = listCopy.begin(); i != listCopy.end(); ++i)
         {
             Creature* summon = ObjectAccessor::GetCreature(*me, *i);

src/server/game/AI/SmartScripts/SmartScript.cpp

@@ -734,7 +734,7 @@ void SmartScript::ProcessAction(SmartScriptHolder& e, Unit* unit, uint32 var0, u
                     caster = unit->SummonTrigger(unit->GetPositionX(), unit->GetPositionY(), unit->GetPositionZ(), unit->GetOrientation(), 5000);
 
                 if (e.action.cast.targetsLimit > 0 && targets->size() > e.action.cast.targetsLimit)
-                    acore::Containers::RandomResizeList(*targets, e.action.cast.targetsLimit);
+                    acore::Containers::RandomResize(*targets, e.action.cast.targetsLimit);
 
                 for (ObjectList::const_iterator itr = targets->begin(); itr != targets->end(); ++itr)
                 {
@@ -793,7 +793,7 @@ void SmartScript::ProcessAction(SmartScriptHolder& e, Unit* unit, uint32 var0, u
                     break;
 
                 if (e.action.cast.targetsLimit > 0 && targets->size() > e.action.cast.targetsLimit)
-                    acore::Containers::RandomResizeList(*targets, e.action.cast.targetsLimit);
+                    acore::Containers::RandomResize(*targets, e.action.cast.targetsLimit);
 
                 for (ObjectList::const_iterator itr = targets->begin(); itr != targets->end(); ++itr)
                 {
@@ -3680,7 +3680,7 @@ ObjectList* SmartScript::GetTargets(SmartScriptHolder const& e, Unit* invoker /*
                                 l->push_back(*itr);
 
                     if (e.target.playerRange.maxCount > 0)
-                        acore::Containers::RandomResizeList(*l, e.target.playerRange.maxCount);
+                        acore::Containers::RandomResize(*l, e.target.playerRange.maxCount);
                 }
 
                 delete units;
@@ -3800,7 +3800,7 @@ ObjectList* SmartScript::GetTargets(SmartScriptHolder const& e, Unit* invoker /*
                                 l->push_back(*itr);
 
                 if (e.target.o > 0)
-                    acore::Containers::RandomResizeList(*l, e.target.o);
+                    acore::Containers::RandomResize(*l, e.target.o);
 
                 delete units;
                 break;
@@ -3842,7 +3842,7 @@ ObjectList* SmartScript::GetTargets(SmartScriptHolder const& e, Unit* invoker /*
                         }
 
                 if (e.target.roleSelection.resize > 0)
-                    acore::Containers::RandomResizeList(*l, e.target.roleSelection.resize);
+                    acore::Containers::RandomResize(*l, e.target.roleSelection.resize);
 
                 delete units;
                 break;

src/server/game/Pools/PoolMgr.cpp

@@ -141,34 +141,6 @@ bool PoolGroup<T>::CheckPool() const
     return true;
 }
 
-template <class T>
-PoolObject* PoolGroup<T>::RollOne(ActivePoolData& spawns, uint32 triggerFrom)
-{
-    if (!ExplicitlyChanced.empty())
-    {
-        float roll = (float)rand_chance();
-
-        for (uint32 i = 0; i < ExplicitlyChanced.size(); ++i)
-        {
-            roll -= ExplicitlyChanced[i].chance;
-            // Triggering object is marked as spawned at this time and can be also rolled (respawn case)
-            // so this need explicit check for this case
-            if (roll < 0 && (ExplicitlyChanced[i].guid == triggerFrom || !spawns.IsActiveObject<T>(ExplicitlyChanced[i].guid)))
-                return &ExplicitlyChanced[i];
-        }
-    }
-    if (!EqualChanced.empty())
-    {
-        int32 index = irand(0, EqualChanced.size() - 1);
-        // Triggering object is marked as spawned at this time and can be also rolled (respawn case)
-        // so this need explicit check for this case
-        if (EqualChanced[index].guid == triggerFrom || !spawns.IsActiveObject<T>(EqualChanced[index].guid))
-            return &EqualChanced[index];
-    }
-
-    return nullptr;
-}
-
 // Main method to despawn a creature or gameobject in a pool
 // If no guid is passed, the pool is just removed (event end case)
 // If guid is filled, cache will be used and no removal will occur, it just fill the cache
@@ -321,40 +293,70 @@ void PoolGroup<Pool>::RemoveOneRelation(uint32 child_pool_id)
 template <class T>
 void PoolGroup<T>::SpawnObject(ActivePoolData& spawns, uint32 limit, uint32 triggerFrom)
 {
-    uint32 lastDespawned = 0;
     int count = limit - spawns.GetActiveObjectCount(poolId);
 
     // If triggered from some object respawn this object is still marked as spawned
     // and also counted into m_SpawnedPoolAmount so we need increase count to be
     // spawned by 1
     if (triggerFrom)
-        ++count;
-
-    // This will try to spawn the rest of pool, not guaranteed
-    for (int i = 0; i < count; ++i)
     {
-        PoolObject* obj = RollOne(spawns, triggerFrom);
-        if (!obj)
-            continue;
-        if (obj->guid == lastDespawned)
-            continue;
+        ++count;
+    }
 
-        if (obj->guid == triggerFrom)
-        {
-            ReSpawn1Object(obj);
-            triggerFrom = 0;
-            continue;
-        }
-        spawns.ActivateObject<T>(obj->guid, poolId);
-        Spawn1Object(obj);
+    if (count > 0)
+    {
+        PoolObjectList rolledObjects;
+        rolledObjects.reserve(count);
 
-        if (triggerFrom)
+        // roll objects to be spawned
+        if (!ExplicitlyChanced.empty())
         {
-            // One spawn one despawn no count increase
-            DespawnObject(spawns, triggerFrom);
-            lastDespawned = triggerFrom;
-            triggerFrom = 0;
+            float roll = (float)rand_chance();
+
+            for (PoolObject& obj : ExplicitlyChanced)
+            {
+                roll -= obj.chance;
+
+                // Triggering object is marked as spawned at this time and can be also rolled (respawn case)
+                // so this need explicit check for this case
+                if (roll < 0 && (/*obj.guid == triggerFrom ||*/ !spawns.IsActiveObject<T>(obj.guid)))
+                {
+                    rolledObjects.push_back(obj);
+                    break;
+                }
+            }
         }
+
+        if (!EqualChanced.empty() && rolledObjects.empty())
+        {
+            std::copy_if(EqualChanced.begin(), EqualChanced.end(), std::back_inserter(rolledObjects), [/*triggerFrom, */&spawns](PoolObject const& object)
+            {
+                 return /*object.guid == triggerFrom ||*/ !spawns.IsActiveObject<T>(object.guid);
+            });
+
+            acore::Containers::RandomResize(rolledObjects, count);
+        }
+
+        // try to spawn rolled objects
+        for (PoolObject& obj : rolledObjects)
+        {
+            if (obj.guid == triggerFrom)
+            {
+                ReSpawn1Object(&obj);
+                triggerFrom = 0;
+            }
+            else
+            {
+                spawns.ActivateObject<T>(obj.guid, poolId);
+                Spawn1Object(&obj);
+            }
+        }
+    }
+
+    // One spawn one despawn no count increase
+    if (triggerFrom)
+    {
+        DespawnObject(spawns, triggerFrom);
     }
 }
 

src/server/game/Pools/PoolMgr.h

@@ -64,7 +64,6 @@ public:
     bool isEmpty() const { return ExplicitlyChanced.empty() && EqualChanced.empty(); }
     void AddEntry(PoolObject& poolitem, uint32 maxentries);
     bool CheckPool() const;
-    PoolObject* RollOne(ActivePoolData& spawns, uint32 triggerFrom);
     void DespawnObject(ActivePoolData& spawns, ObjectGuid::LowType guid = 0);
     void Despawn1Object(ObjectGuid::LowType guid);
     void SpawnObject(ActivePoolData& spawns, uint32 limit, uint32 triggerFrom);

src/server/game/Spells/Spell.cpp

@@ -1197,7 +1197,7 @@ void Spell::SelectImplicitConeTargets(SpellEffIndex effIndex, SpellImplicitTarge
                     if ((*j)->IsAffectedOnSpell(m_spellInfo))
                         maxTargets += (*j)->GetAmount();
 
-                acore::Containers::RandomResizeList(targets, maxTargets);
+                acore::Containers::RandomResize(targets, maxTargets);
             }
 
             for (std::list<WorldObject*>::iterator itr = targets.begin(); itr != targets.end(); ++itr)
@@ -1280,7 +1280,7 @@ void Spell::SelectImplicitAreaTargets(SpellEffIndex effIndex, SpellImplicitTarge
                 if ((*j)->IsAffectedOnSpell(m_spellInfo))
                     maxTargets += (*j)->GetAmount();
 
-            acore::Containers::RandomResizeList(targets, maxTargets);
+            acore::Containers::RandomResize(targets, maxTargets);
         }
 
         for (std::list<WorldObject*>::iterator itr = targets.begin(); itr != targets.end(); ++itr)

src/server/scripts/EasternKingdoms/MagistersTerrace/boss_priestess_delrissa.cpp

@@ -104,7 +104,7 @@ public:
             std::list<uint32> helpersList;
             for (uint8 i = 0; i < MAX_HELPERS_COUNT; ++i)
                 helpersList.push_back(helpersEntries[i]);
-            acore::Containers::RandomResizeList(helpersList, MAX_ACTIVE_HELPERS);
+            acore::Containers::RandomResize(helpersList, MAX_ACTIVE_HELPERS);
 
             uint8 j = 0;
             for (std::list<uint32>::const_iterator itr = helpersList.begin(); itr != helpersList.end(); ++itr, ++j)

src/server/scripts/EasternKingdoms/SunwellPlateau/boss_kalecgos.cpp

@@ -626,7 +626,7 @@ public:
         void FilterTargets(std::list<WorldObject*>& targets)
         {
             targets.remove_if(SpectralBlastCheck(GetCaster()->GetVictim()));
-            acore::Containers::RandomResizeList(targets, 1);
+            acore::Containers::RandomResize(targets, 1);
         }
 
         void HandleDummy(SpellEffIndex effIndex)

src/server/scripts/EasternKingdoms/SunwellPlateau/boss_muru.cpp

@@ -394,7 +394,7 @@ public:
 
         void FilterTargets(std::list<WorldObject*>& targets)
         {
-            acore::Containers::RandomResizeList(targets, GetCaster()->GetAI()->GetData(DATA_NEGATIVE_ENERGY_TARGETS));
+            acore::Containers::RandomResize(targets, GetCaster()->GetAI()->GetData(DATA_NEGATIVE_ENERGY_TARGETS));
         }
 
         void HandleScriptEffect(SpellEffIndex effIndex)

src/server/scripts/Kalimdor/RuinsOfAhnQiraj/boss_moam.cpp

@@ -137,7 +137,7 @@ public:
                                         targetList.push_back((*itr)->getTarget());
                             }
 
-                            acore::Containers::RandomResizeList(targetList, 5);
+                            acore::Containers::RandomResize(targetList, 5);
 
                             for (std::list<Unit*>::iterator itr = targetList.begin(); itr != targetList.end(); ++itr)
                                 DoCast(*itr, SPELL_DRAIN_MANA);

src/server/scripts/Northrend/IcecrownCitadel/boss_blood_queen_lana_thel.cpp

@@ -420,7 +420,7 @@ public:
                             if (Player* p = itr->GetSource())
                                 if (p->IsAlive() && p != me->GetVictim() && p->GetGUID() != _offtankGUID && !p->IsGameMaster() && p->GetDistance(me) < 100.0f && !p->HasAura(SPELL_UNCONTROLLABLE_FRENZY))
                                     myList.push_back(p);
-                        acore::Containers::RandomResizeList(myList, Is25ManRaid() ? 3 : 2);
+                        acore::Containers::RandomResize(myList, Is25ManRaid() ? 3 : 2);
                         if (myList.size() > 1)
                         {
                             Talk(SAY_PACT_OF_THE_DARKFALLEN);
@@ -446,7 +446,7 @@ public:
 
                         if (!myList.empty())
                         {
-                            acore::Containers::RandomResizeList(myList, 1);
+                            acore::Containers::RandomResize(myList, 1);
                             Player* target = myList.front();
                             Talk(EMOTE_SWARMING_SHADOWS, target);
                             Talk(SAY_SWARMING_SHADOWS);
@@ -468,7 +468,7 @@ public:
                                 if (p->IsAlive() && p != me->GetVictim() && p->GetGUID() != _offtankGUID && !p->IsGameMaster() && !p->HasAura(SPELL_PACT_OF_THE_DARKFALLEN) && !p->HasAura(SPELL_UNCONTROLLABLE_FRENZY))
                                     myList.push_back(p);
 
-                        acore::Containers::RandomResizeList<Player*>(myList, uint32(Is25ManRaid() ? 4 : 2));
+                        acore::Containers::RandomResize(myList, uint32(Is25ManRaid() ? 4 : 2));
                         for (std::list<Player*>::iterator itr = myList.begin(); itr != myList.end(); ++itr)
                             me->CastSpell(*itr, SPELL_TWILIGHT_BLOODBOLT, false);
                         me->CastSpell(me, SPELL_TWILIGHT_BLOODBOLT_TARGET, false);
@@ -723,7 +723,7 @@ public:
         {
             uint32 targetCount = (targets.size() + 2) / 3;
             targets.remove_if(BloodboltHitCheck(static_cast<LanaThelAI*>(GetCaster()->GetAI())));
-            acore::Containers::RandomResizeList(targets, targetCount);
+            acore::Containers::RandomResize(targets, targetCount);
             // mark targets now, effect hook has missile travel time delay (might cast next in that time)
             for (std::list<WorldObject*>::const_iterator itr = targets.begin(); itr != targets.end(); ++itr)
                 GetCaster()->GetAI()->SetGUID((*itr)->GetGUID(), GUID_BLOODBOLT);

src/server/scripts/Northrend/IcecrownCitadel/boss_deathbringer_saurfang.cpp

@@ -1315,7 +1315,7 @@ public:
                 targets.push_back(target);
             }
             else
-                acore::Containers::RandomResizeList(targets, 3);
+                acore::Containers::RandomResize(targets, 3);
         }
 
         void Register() override

src/server/scripts/Northrend/IcecrownCitadel/boss_icecrown_gunship_battle.cpp

@@ -2208,7 +2208,7 @@ public:
         void SelectTarget(std::list<WorldObject*>& targets)
         {
             targets.remove_if(IgbExplosionCheck(GetCaster()));
-            acore::Containers::RandomResizeList(targets, 1);
+            acore::Containers::RandomResize(targets, 1);
         }
 
         void Register() override

src/server/scripts/Northrend/IcecrownCitadel/boss_professor_putricide.cpp

@@ -1257,7 +1257,7 @@ public:
             }
 
             targets.remove_if(acore::UnitAuraCheck(true, sSpellMgr->GetSpellIdForDifficulty(SPELL_UNBOUND_PLAGUE, GetCaster())));
-            acore::Containers::RandomResizeList(targets, 1);
+            acore::Containers::RandomResize(targets, 1);
         }
 
         void HandleScript(SpellEffIndex /*effIndex*/)

src/server/scripts/Northrend/IcecrownCitadel/boss_sindragosa.cpp

@@ -908,10 +908,10 @@ public:
             uint32 maxSize = uint32(GetCaster()->GetMap()->GetSpawnMode() & 1 ? 3 : 1);
             healList.remove_if(UnchainedMagicTargetSelector(false));
             if (healList.size() > maxSize)
-                acore::Containers::RandomResizeList(healList, maxSize);
+                acore::Containers::RandomResize(healList, maxSize);
             dpsList.remove_if(UnchainedMagicTargetSelector(true));
             if (dpsList.size() > maxSize)
-                acore::Containers::RandomResizeList(dpsList, maxSize);
+                acore::Containers::RandomResize(dpsList, maxSize);
             unitList.splice(unitList.begin(), healList);
             unitList.splice(unitList.begin(), dpsList);
         }

src/server/scripts/Northrend/IcecrownCitadel/boss_valithria_dreamwalker.cpp

@@ -1368,7 +1368,7 @@ public:
                     return;
                 summoners = list_copy;
             }
-            acore::Containers::RandomResizeList(summoners, 2);
+            acore::Containers::RandomResize(summoners, 2);
 
             for (uint32 i = 0; i < 3; ++i)
                 caster->CastSpell(summoners.front(), SPELL_SUMMON_SUPPRESSER, true);

src/server/scripts/Northrend/IcecrownCitadel/icecrown_citadel.cpp

@@ -2159,7 +2159,7 @@ public:
         void RemoveAliveTarget(std::list<WorldObject*>& targets)
         {
             targets.remove_if(AliveCheck());
-            acore::Containers::RandomResizeList(targets, 2);
+            acore::Containers::RandomResize(targets, 2);
         }
 
         void Land(SpellEffIndex /*effIndex*/)

src/server/scripts/Northrend/Ulduar/Ulduar/boss_hodir.cpp

@@ -426,7 +426,7 @@ public:
                             targets.push_back(itr->GetSource());
                         targets.remove_if(acore::ObjectTypeIdCheck(TYPEID_PLAYER, false));
                         targets.remove_if(acore::UnitAuraCheck(true, SPELL_FLASH_FREEZE_TRAPPED_PLAYER));
-                        acore::Containers::RandomResizeList(targets, (RAID_MODE(2,3)));
+                        acore::Containers::RandomResize(targets, (RAID_MODE(2,3)));
                         for (std::list<Unit*>::const_iterator itr = targets.begin(); itr != targets.end(); ++itr)
                         {
                             float prevZ = (*itr)->GetPositionZ();
@@ -1273,7 +1273,7 @@ public:
         {
             targets.remove_if(acore::ObjectTypeIdCheck(TYPEID_PLAYER, false));
             targets.remove_if(acore::UnitAuraCheck(true, SPELL_FLASH_FREEZE_TRAPPED_PLAYER));
-            acore::Containers::RandomResizeList(targets, 1);
+            acore::Containers::RandomResize(targets, 1);
         }
 
         void Register() override

src/server/scripts/Northrend/zone_dragonblight.cpp

@@ -1193,7 +1193,7 @@ public:
         void FilterTargets(std::list<WorldObject*>& targets)
         {
             targets.remove_if(GhoulTargetCheck(GetSpellInfo()->Id == 70790));
-            acore::Containers::RandomResizeList(targets, 2);
+            acore::Containers::RandomResize(targets, 2);
         }
 
         void HandleScript(SpellEffIndex effIndex)

src/server/scripts/Outland/CoilfangReservoir/SerpentShrine/boss_morogrim_tidewalker.cpp

@@ -199,7 +199,7 @@ public:
 
         void FilterTargets(std::list<WorldObject*>& unitList)
         {
-            acore::Containers::RandomResizeList(unitList, 1);
+            acore::Containers::RandomResize(unitList, 1);
         }
 
         void HandleDummy(SpellEffIndex effIndex)

src/server/scripts/Outland/HellfireCitadel/ShatteredHalls/instance_shattered_halls.cpp

@@ -241,7 +241,7 @@ public:
 
         void FilterTargets(std::list<WorldObject*>& unitList)
         {
-            acore::Containers::RandomResizeList(unitList, 1);
+            acore::Containers::RandomResize(unitList, 1);
         }
 
         void HandleScriptEffect(SpellEffIndex effIndex)

src/server/scripts/Outland/TempestKeep/Eye/boss_kaelthas.cpp

@@ -993,7 +993,7 @@ public:
                     targetList.push_back(target);
             }
 
-            acore::Containers::RandomResizeList(targetList, 5);
+            acore::Containers::RandomResize(targetList, 5);
             for (std::list<Unit*>::const_iterator itr = targetList.begin(); itr != targetList.end(); ++itr)
                 GetCaster()->CastSpell(*itr, SPELL_NETHER_BEAM_DAMAGE, true);
         }

src/server/scripts/Spells/spell_druid.cpp

@@ -1050,7 +1050,7 @@ public:
 
         void FilterTargets(std::list<WorldObject*>& targets)
         {
-            acore::Containers::RandomResizeList(targets, 2);
+            acore::Containers::RandomResize(targets, 2);
         }
 
         void HandleDummy(SpellEffIndex /*effIndex*/)

src/server/scripts/Spells/spell_generic.cpp

@@ -768,7 +768,7 @@ public:
         void FilterTargets(std::list<WorldObject*>& targets)
         {
             targets.remove(GetCaster());
-            acore::Containers::RandomResizeList(targets, _count);
+            acore::Containers::RandomResize(targets, _count);
         }
 
         void Register() override

src/server/scripts/Spells/spell_paladin.cpp

@@ -652,7 +652,7 @@ public:
 
         void CountTargets(std::list<WorldObject*>& targetList)
         {
-            acore::Containers::RandomResizeList(targetList, GetSpellValue()->MaxAffectedTargets);
+            acore::Containers::RandomResize(targetList, GetSpellValue()->MaxAffectedTargets);
             _targetCount = targetList.size();
         }