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fix: monster ability queries no longer have side effects (#2716)

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## Problem
`GetMonsterAbilities()` answers three questions through one virtual: which abilities a creature has (`GetAbility`, `AOS.cs` reflect/barrier, bard fire-breath difficulty), which abilities are enabled right now, and where cooldown state must be cleaned up (`InvalidateNextAbilityTriggers` on death and delete). Every caller assumes it is a pure, stable list. About 70 creatures return a static array; only LordOaks computed it:

```
Mobile.Delete()
 → BaseCreature.OnDelete() → CreatureDeletedEvent
 → MonsterAbility.InvalidateNextAbilityTriggers()
 → LordOaks.GetMonsterAbilities() → CheckQueen() → new Silvani().MoveToWorld(...)
```

- Deleting a Lord Oaks nobody had fought (champion reset, `DeleteCreatures`, GM delete) spawned an orphaned Silvani where he stood.
- The spell damage scalar (`AlterDamageScalarFrom`) spawned her too.
- With the queen dead his list was empty, so cleanup skipped his cooldown entries. The static `Dictionary<BaseCreature, long>` on the ability singleton kept a reference to the deleted creature. `MonsterAbilityGroup` children's entries were never cleaned either.
- Neira threw unholy bones from `AlterDamageScalarFrom`, so any caller asking for a damage scalar (a preview gump, for example) could fire the effect.

## Changes
- **Per-creature cooldowns:** a lazy `Dictionary<MonsterAbility, long>` on `BaseCreature` (`IsAbilityOnCooldown`, `SetAbilityCooldown`, `ClearAbilityCooldowns`). The static dictionaries and the query-driven cleanup are gone, and death still resets cooldowns. Tick comparisons are wraparound-safe.
- **Pure contract:** `GetMonsterAbilities()` is documented as pure. The new `virtual bool CanUseAbility(MonsterAbility)` gates abilities that only work some of the time. Every `TriggerAbility*` loop and `GetAbility` check it.
- **LordOaks:** always lists his abilities; `CanUseAbility` and the 10% spell shield read "queen alive". The queen spawns when he is first aggressed or first given a combatant, never on the internal map. Aggression lands before the damage it causes, so the first spell is still shielded, as before.
- **Neira:** the unholy bone throw moves to `OnDamagedBySpell`.

A follow-up PR makes minions such as the queen, pixies and Barracoon's rats belong to their champion spawn, so a spawn reset cleans them up.

## Testing
- `LordOaksTests` covers three cases:
  - querying or deleting an unengaged Lord Oaks spawns nothing;
  - aggression spawns the queen exactly once, and the shield and abilities follow her life;
  - an Oaks on the internal map never spawns her.
- UOContent.Tests: 1234 passed, 2 skipped.
- A local constructor sweep (every Mobile built and deleted repeatedly) no longer reports LordOaks.
This commit is contained in:
Kamron Batman 2026-10-18 17:41:27 -07:00 • committed by GitHub
parent 8cced36794
commit 4e57ec2373
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GPG key ID: B5690EEEBB952194
5 changed files with 182 additions and 61 deletions
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98
Projects/UOContent.Tests/Tests/Mobiles/LordOaksTests.cs Normal file
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@ -0,0 +1,98 @@
using System;
using System.Collections.Generic;
using System.Linq;
using Server;
using Server.Mobiles;
using Xunit;
namespace UOContent.Tests.Mobiles;
// Lord Oaks' abilities and spell shield depend on his queen, so the queen must spawn from combat,
// never from a query such as GetMonsterAbilities or a damage calculation.
[Collection("Sequential UOContent Tests")]
public class LordOaksTests : IDisposable
{
private readonly List<Mobile> _created = [];
public void Dispose()
{
foreach (var m in World.Mobiles.Values.OfType<Silvani>().ToList())
{
m.Delete();
}
for (var i = 0; i < _created.Count; i++)
{
_created[i].Delete();
}
}
private LordOaks NewOaks(Map map)
{
var oaks = new LordOaks();
_created.Add(oaks);
oaks.MoveToWorld(new Point3D(1000, 1000, 0), map);
return oaks;
}
private Mobile NewAttacker()
{
var attacker = new Mongbat();
_created.Add(attacker);
return attacker;
}
private static int SilvaniCount() => World.Mobiles.Values.Count(m => m is Silvani);
[Fact]
public void QueryingOrDeletingAnUnengagedOaks_SpawnsNoQueen()
{
var oaks = NewOaks(Map.Felucca);
var scalar = 1.0;
oaks.AlterDamageScalarFrom(null, ref scalar);
oaks.GetMonsterAbilities();
oaks.Delete();
Assert.Equal(1.0, scalar);
Assert.Equal(0, SilvaniCount());
}
[Fact]
public void Aggression_SpawnsTheQueenOnce_AndShieldsOaksWhileSheLives()
{
var oaks = NewOaks(Map.Felucca);
var attacker = NewAttacker();
oaks.AggressiveAction(attacker, false);
oaks.AggressiveAction(attacker, false);
var queen = World.Mobiles.Values.OfType<Silvani>().Single();
var shielded = 1.0;
oaks.AlterDamageScalarFrom(attacker, ref shielded);
Assert.Equal(0.1, shielded, 6);
Assert.True(oaks.CanUseAbility(MonsterAbilities.SummonPixiesCounter));
queen.Delete();
var exposed = 1.0;
oaks.AlterDamageScalarFrom(attacker, ref exposed);
oaks.AggressiveAction(attacker, false);
Assert.Equal(1.0, exposed);
Assert.False(oaks.CanUseAbility(MonsterAbilities.SummonPixiesCounter));
Assert.Equal(0, SilvaniCount());
}
[Fact]
public void AnOaksOnTheInternalMap_NeverSpawnsTheQueen()
{
var oaks = new LordOaks();
_created.Add(oaks);
oaks.AggressiveAction(NewAttacker(), false);
Assert.Equal(0, SilvaniCount());
}
}

36
Projects/UOContent/Mobiles/Abilities/MonsterAbility.cs
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@ -1,5 +1,4 @@
using System;
using System.Collections.Generic;
using ModernUO.CodeGeneratedEvents;
namespace Server.Mobiles;
@ -9,8 +8,6 @@ namespace Server.Mobiles;
/// </summary>
public abstract class MonsterAbility
{
private Dictionary<BaseCreature, long> _nextTriggerTicks;
public virtual MonsterAbilityType AbilityType => MonsterAbilityType.Generic;
public virtual MonsterAbilityTrigger AbilityTrigger => MonsterAbilityTrigger.None;
@ -30,18 +27,9 @@ public abstract class MonsterAbility
return false;
}
if (_nextTriggerTicks?.TryGetValue(source, out var nextTrigger) == true)
if (source.IsAbilityOnCooldown(this))
{
if (nextTrigger - Core.TickCount > 0)
{
return false;
}
_nextTriggerTicks.Remove(source);
if (_nextTriggerTicks.Count == 0)
{
_nextTriggerTicks = null;
}
return false;
}
var c = ChanceToTrigger;
@ -65,10 +53,7 @@ public abstract class MonsterAbility
? MinTriggerCooldown
: Utility.RandomMinMax(MinTriggerCooldown, MaxTriggerCooldown);
var nextTrigger = Core.TickCount + (long)randomAmount.TotalMilliseconds;
_nextTriggerTicks ??= new Dictionary<BaseCreature, long>();
_nextTriggerTicks[source] = nextTrigger;
source.SetAbilityCooldown(this, randomAmount);
}
public virtual void AlterMeleeDamageFrom(BaseCreature source, Mobile target, ref int damage)
@ -100,18 +85,5 @@ public abstract class MonsterAbility
}
[OnEvent(nameof(CreatureEvents.CreatureDeathEvent))]
[OnEvent(nameof(CreatureEvents.CreatureDeletedEvent))]
public static void InvalidateNextAbilityTriggers(BaseCreature source)
{
var abilities = source.GetMonsterAbilities();
if (abilities == null || abilities.Length == 0)
{
return;
}
for (var i = 0; i < abilities.Length; i++)
{
abilities[i]._nextTriggerTicks?.Remove(source);
}
}
public static void ResetCooldownsOnDeath(BaseCreature source) => source.ClearAbilityCooldowns();
}

52
Projects/UOContent/Mobiles/BaseCreature.cs
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@ -1,4 +1,4 @@
using System;
using System;
using System.Collections.Generic;
using System.Runtime.CompilerServices;
using ModernUO.Serialization;
@ -1500,10 +1500,47 @@ namespace Server.Mobiles
public List<MLQuest> MLQuests =>
(m_MLQuests ??= StaticMLQuester ? MLQuestSystem.FindQuestList(GetType()) : ConstructQuestList()) ?? MLQuestSystem.EmptyList;
/// <summary>
/// The abilities this creature has. Must be a pure, stable query: it is called from lookups, damage
/// calculations and cleanup, so it must not spawn, mutate state, or change with the creature's state.
/// Gate abilities that should only work some of the time with <see cref="CanUseAbility" />.
/// </summary>
public virtual MonsterAbility[] GetMonsterAbilities() => null;
/// <summary>
/// Whether <paramref name="ability" /> may trigger or be looked up right now. Must be a pure read.
/// </summary>
public virtual bool CanUseAbility(MonsterAbility ability) => true;
private MonsterAbilityTrigger _activeTriggers;
// Deadlines in Core.TickCount, keyed by ability. Lives on the creature so it is collected with it.
private Dictionary<MonsterAbility, long> _abilityCooldowns;
public bool IsAbilityOnCooldown(MonsterAbility ability)
{
if (_abilityCooldowns?.TryGetValue(ability, out var nextTrigger) != true)
{
return false;
}
if (nextTrigger - Core.TickCount > 0)
{
return true;
}
_abilityCooldowns.Remove(ability);
return false;
}
public void SetAbilityCooldown(MonsterAbility ability, TimeSpan cooldown)
{
_abilityCooldowns ??= new Dictionary<MonsterAbility, long>();
_abilityCooldowns[ability] = Core.TickCount + (long)cooldown.TotalMilliseconds;
}
public void ClearAbilityCooldowns() => _abilityCooldowns = null;
public virtual MonsterAbility GetAbility(MonsterAbilityType type)
{
var abilities = GetMonsterAbilities();
@ -1516,6 +1553,11 @@ namespace Server.Mobiles
for (var i = 0; i < abilities.Length; i++)
{
var ability = abilities[i];
if (!CanUseAbility(ability))
{
continue;
}
if (ability is MonsterAbilityGroup group)
{
ability = group.GetAbilityWithType(type);
@ -1579,7 +1621,7 @@ namespace Server.Mobiles
for (var i = 0; i < abilities.Length; i++)
{
var ability = abilities[i];
if (ability.CanTrigger(this, trigger))
if (CanUseAbility(ability) && ability.CanTrigger(this, trigger))
{
ability.Trigger(trigger, this, defender);
triggered = true;
@ -1606,7 +1648,7 @@ namespace Server.Mobiles
for (var i = 0; i < abilities.Length; i++)
{
var ability = abilities[i];
if (ability.CanTrigger(this, trigger))
if (CanUseAbility(ability) && ability.CanTrigger(this, trigger))
{
ability.Move(this, d);
}
@ -1625,7 +1667,7 @@ namespace Server.Mobiles
for (var i = 0; i < abilities.Length; i++)
{
var ability = abilities[i];
if (ability.CanTrigger(this, trigger))
if (CanUseAbility(ability) && ability.CanTrigger(this, trigger))
{
if ((trigger & MonsterAbilityTrigger.GiveMeleeDamage) != 0)
{
@ -1666,7 +1708,7 @@ namespace Server.Mobiles
for (var i = 0; i < abilities.Length; i++)
{
var ability = abilities[i];
if (ability.CanTrigger(this, trigger))
if (CanUseAbility(ability) && ability.CanTrigger(this, trigger))
{
if ((trigger & MonsterAbilityTrigger.GiveSpellDamage) != 0)
{

51
Projects/UOContent/Mobiles/Special/LordOaks.cs
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@ -86,7 +86,11 @@ public partial class LordOaks : BaseChampion
public override Poison PoisonImmune => Poison.Deadly;
private static MonsterAbility[] _abilities = { MonsterAbilities.SummonPixiesCounter };
public override MonsterAbility[] GetMonsterAbilities() => CheckQueen() ? _abilities : MonsterAbilities.Empty;
public override MonsterAbility[] GetMonsterAbilities() => _abilities;
public override bool CanUseAbility(MonsterAbility ability) => IsQueenAlive;
private bool IsQueenAlive => _queen?.Deleted == false;
public override void GenerateLoot()
{
@ -103,36 +107,41 @@ public partial class LordOaks : BaseChampion
public override int GetDeathSound() => 0x2F7;
public bool CheckQueen()
// Aggression lands before the damage it causes, so the queen is up before the first hit is scaled.
public override void AggressiveAction(Mobile aggressor, bool criminal)
{
if (Map == null)
base.AggressiveAction(aggressor, criminal);
SpawnQueen();
}
public override void OnCombatantChange()
{
base.OnCombatantChange();
if (Combatant != null)
{
return false;
SpawnQueen();
}
}
private void SpawnQueen()
{
if (_spawnedQueen || Deleted || Map == null || Map == Map.Internal)
{
return;
}
if (!_spawnedQueen)
{
Say(1042153); // Come forth my queen!
Say(1042153); // Come forth my queen!
_queen = new Silvani { Team = Team };
_queen.MoveToWorld(Location, Map);
Queen = new Silvani { Team = Team };
Queen.MoveToWorld(Location, Map);
_spawnedQueen = true;
return true;
}
if (_queen?.Deleted != false)
{
_queen = null;
return false;
}
return true;
SpawnedQueen = true;
}
public override void AlterDamageScalarFrom(Mobile caster, ref double scalar)
{
if (CheckQueen())
if (IsQueenAlive)
{
scalar *= 0.1;
}

6
Projects/UOContent/Mobiles/Special/Neira.cs
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@ -163,13 +163,13 @@ public partial class Neira : BaseChampion
}
}
public override void AlterDamageScalarFrom(Mobile caster, ref double scalar)
public override void OnDamagedBySpell(Mobile from, int damage)
{
base.AlterDamageScalarFrom(caster, ref scalar);
base.OnDamagedBySpell(from, damage);
if (Utility.RandomDouble() < 0.1) // 10% chance to throw an unholy bone
{
AddUnholyBone(caster, 1.0);
AddUnholyBone(from, 1.0);
}
}