ModernUO/Projects/UOContent/Engines/Factions/Core/PlayerState.cs
Kamron Batman b8d3fec59a
fix(opl): refuse property list invalidation raised from inside GetProperties (#2555)
## The bug

Any property getter reached from `GetProperties` that calls `InvalidateProperties` takes the tooltip build down with it:

```
System.ArgumentNullException: Value cannot be null. (Parameter 'array')
   at Server.ObjectPropertyList.AppendStringDirect(String value)
   at Server.Mobiles.PlayerMobile.GetProperties(IPropertyList list)
```

`InvalidateProperties` rebuilds **in place** — `Reset()`, then `GetProperties()` again on the same instance — and `Reset()` does two destructive things to a build already in flight:

1. **It returns the pooled interpolation buffer.** The compiler rents it in the handler ctor and returns it in the closing `Add`, so *every hole is evaluated while it is live*:

```csharp
var handler = new InterpolatedStringHandler(1, 2, list); // InitializeInterpolation() RENTS
handler.AppendFormatted(pl.Rank.Title);                  // <-- getter runs HERE
handler.AppendLiteral("\t");
handler.AppendFormatted(faction.Definition.PropName);
list.Add(1060776, ref handler);                          // consumes span, RETURNS
```

```
GetProperties(list)
├─ InitializeInterpolation()  -> _arrayToReturnToPool = Rent(256)     buffer LIVE
├─ « hole 1: pl.Rank.Title »
│  └─ PlayerState.Rank.get   (lazy recompute)
│     └─ Invalidate() -> InvalidateProperties() -> m_PropertyList.Reset()
│        └─ Dispose(): Return(buf); _arrayToReturnToPool = null        buffer GONE
└─ handler.AppendFormatted("Knight")
   └─ _arrayToReturnToPool.AsSpan(_pos..)
      └─ ArgumentNullException (Parameter 'array')
```

It surfaces as `ArgumentNullException` rather than `NullReferenceException` because the `Range` overload of `AsSpan` must read `array.Length`, so the BCL null-checks and names the parameter `array`.

2. **It rewinds the packet cursor**, so properties already written are overwritten by the nested pass — a silently corrupted tooltip even where the buffer survives.

## The fix: refuse, don't recover

There is no correct recovery, and retrying the build would only hide the defect. A nested invalidation now logs an error with a stack trace, **throws in `DEBUG`** so it gets found and fixed, and in `RELEASE` returns without touching the list — a possibly stale tooltip, but no crash, no corrupted packet, and nothing leaked back to the pool. Getters that genuinely must invalidate should defer:

```csharp
Timer.DelayCall(InvalidateProperties);
```

The guard flag lives on the `ObjectPropertyList`, not the entity: it is that list's own lifecycle, it costs nothing (both `Item` and `ObjectPropertyList` absorb it in existing padding, and the list is allocated lazily), and it stays correct when builds for different entities nest.

Base instance sizes are unchanged from `main`: Item 128 B, Mobile 792 B, ObjectPropertyList 72 B, PlayerMobile 1216 B.

`PropertyList` also publishes the list into `m_PropertyList` **before** building it rather than assigning through `??=` afterwards, so a nested `InvalidateProperties` sees the build in progress instead of recursing into a second throwaway list whose work is discarded.

`ObjectPropertyList` re-rents its scratch buffer instead of spanning a null array, so a stray `Reset()` from any other caller degrades rather than aborting `GetProperties`.

## Factions `PlayerState`: maintained, not lazily computed

The getter that surfaced this is now a plain field read — the whole `if (m_InvalidateRank)` block and the flag itself are gone:

```csharp
public RankDefinition Rank => m_Rank;
```

`UpdateRank()` recomputes at each point an input actually changes:

| Site | Why |
|---|---|
| `RankIndex` setter | this player's index changed |
| end of `KillPoints` setter | two paths write `m_RankIndex` directly, bypassing the setter; runs once the swap bookkeeping and `ZeroRankOffset` have settled |
| `Faction.AddMember` | *after* the insert — the member count is not settled during the ctor |
| `FactionState` load | once ordering and `ZeroRankOffset` are final |

Supporting fixes this forced out:

- **Both ctors seed the lowest rank.** Nothing recomputes on read any more, so `Rank` has to be usable immediately — including for members that never get a `RankIndex` assigned, which is *every member with no kill points*. Without this, `Rank.Title` NREs.
- **`Rank` always resolves.** Ranks are ordered by `Required` descending ending at `0`, so a *negative* percent (`RankIndex` out of sync with `ZeroRankOffset`) matched nothing and left `m_Rank` null. It no longer divides by a zero `ZeroRankOffset` either.
- **A pre-existing staleness bug.** The `KillPoints` setter writes `m_RankIndex` directly in two places, so the cached rank was never refreshed when a player crossed zero kill points.

All six readers of `Rank` were checked; none relied on the old side effect.

One behaviour change worth flagging: rank refreshes are now **eager** where they used to be lazy, so a `KillPoints` change invalidates each swapped player as it happens. The swap loops break as soon as ordering is satisfied — typically 0–2 swaps — but it is on the path that runs on every faction kill.

## Documentation

The rule is written down so it is enforceable rather than folklore:

- **CLAUDE.md** audit rule 19
- **`dev-docs/property-lists.md`** — new "Never Invalidate From Inside `GetProperties`" section with the failing/passing pattern
- **`dev-docs/claude-skills/modernuo-property-lists.md`** — key rule + anti-pattern
- **`dev-docs/claude-skills/modernuo-code-audit.md`** — rule 19, ERROR severity

## Tests

- `ObjectPropertyListReentrancyTests` — `Reset()` and `Dispose()` re-entered mid-hole (both red against `main` with the exact exception above), nesting behaviour, and the new contract: `DEBUG` throws, `RELEASE` survives, and the build is never retried into a loop.
- `FactionRankTests` — `Rank` is populated before anything reads it, tracks `RankIndex` without a read, is stable across reads, and still resolves when `RankIndex` is out of sync with `ZeroRankOffset`. Red-verified: removing the ctor seed fails the first one.

793/793 `Server.Tests` and 608/608 `UOContent.Tests` pass.

## Noted, not addressed here

`~ObjectPropertyList()` returns the rented array to `STArrayPool<char>.Shared` from the **finalizer thread**, and that pool is single-threaded by design. Left alone as a separate concern.
2026-07-28 21:29:03 -07:00

339 lines
No EOL
8.8 KiB
C#

using System;
using System.Collections.Generic;
using Server.Mobiles;
namespace Server.Factions;
public class PlayerState : IComparable<PlayerState>
{
private Town m_Finance;
private int m_KillPoints;
private MerchantTitle m_MerchantTitle;
private RankDefinition m_Rank;
private int m_RankIndex = -1;
private Town m_Sheriff;
public PlayerState(Mobile mob, Faction faction, List<PlayerState> owner)
{
Mobile = mob;
Faction = faction;
Owner = owner;
// Owner does not contain this state yet, so the count is short by one; the caller ranks it
// after inserting.
SeedLowestRank();
Attach();
Invalidate();
}
public PlayerState(IGenericReader reader, Faction faction, List<PlayerState> owner)
{
Faction = faction;
Owner = owner;
var version = reader.ReadEncodedInt();
switch (version)
{
case 1:
{
IsActive = reader.ReadBool();
LastHonorTime = reader.ReadDateTime();
goto case 0;
}
case 0:
{
Mobile = reader.ReadEntity<Mobile>();
m_KillPoints = reader.ReadEncodedInt();
m_MerchantTitle = (MerchantTitle)reader.ReadEncodedInt();
Leaving = reader.ReadDateTime();
break;
}
}
// Members are still being read; FactionState ranks everyone once the ordering settles.
SeedLowestRank();
Attach();
}
public Mobile Mobile { get; }
public Faction Faction { get; }
public List<PlayerState> Owner { get; }
public MerchantTitle MerchantTitle
{
get => m_MerchantTitle;
set
{
m_MerchantTitle = value;
Invalidate();
}
}
public Town Sheriff
{
get => m_Sheriff;
set
{
m_Sheriff = value;
Invalidate();
}
}
public Town Finance
{
get => m_Finance;
set
{
m_Finance = value;
Invalidate();
}
}
public List<SilverGivenEntry> SilverGiven { get; private set; }
public int KillPoints
{
get => m_KillPoints;
set
{
if (m_KillPoints != value)
{
if (value > m_KillPoints)
{
if (m_KillPoints <= 0)
{
if (value <= 0)
{
m_KillPoints = value;
Invalidate();
return;
}
Owner.Remove(this);
Owner.Insert(Faction.ZeroRankOffset, this);
// Direct, not through RankIndex: ZeroRankOffset is mid-update. The
// UpdateRank() at the end of this setter covers it.
m_RankIndex = Faction.ZeroRankOffset;
Faction.ZeroRankOffset++;
}
while (m_RankIndex - 1 >= 0)
{
var p = Owner[m_RankIndex - 1];
if (value > p.KillPoints)
{
Owner[m_RankIndex] = p;
Owner[m_RankIndex - 1] = this;
RankIndex--;
p.RankIndex++;
}
else
{
break;
}
}
}
else
{
if (value <= 0)
{
if (m_KillPoints <= 0)
{
m_KillPoints = value;
Invalidate();
return;
}
while (m_RankIndex + 1 < Faction.ZeroRankOffset)
{
var p = Owner[m_RankIndex + 1];
Owner[m_RankIndex + 1] = this;
Owner[m_RankIndex] = p;
RankIndex++;
p.RankIndex--;
}
m_RankIndex = -1;
Faction.ZeroRankOffset--;
}
else
{
while (m_RankIndex + 1 < Faction.ZeroRankOffset)
{
var p = Owner[m_RankIndex + 1];
if (value < p.KillPoints)
{
Owner[m_RankIndex + 1] = this;
Owner[m_RankIndex] = p;
RankIndex++;
p.RankIndex--;
}
else
{
break;
}
}
}
}
m_KillPoints = value;
UpdateRank();
Invalidate();
}
}
}
public int RankIndex
{
get => m_RankIndex;
set
{
if (m_RankIndex != value)
{
m_RankIndex = value;
UpdateRank();
Invalidate();
}
}
}
/// <summary>
/// Read from PlayerMobile.GetProperties, so it must stay a plain field read -- recomputing or
/// invalidating here re-enters the property list build. Maintained by <see cref="UpdateRank"/>.
/// </summary>
public RankDefinition Rank => m_Rank;
// Lowest rank (Required 0): correct for an unranked member, and never null, so Rank.Title
// cannot NRE before the first UpdateRank().
private void SeedLowestRank()
{
var ranks = Faction.Definition.Ranks;
if (ranks.Length > 0)
{
m_Rank = ranks[^1];
}
}
/// <summary>
/// Recomputes the cached rank. Call whenever <see cref="RankIndex"/>, the faction's
/// ZeroRankOffset, or the member count changes -- and only once they have settled.
/// </summary>
public void UpdateRank()
{
var ranks = Faction.Definition.Ranks;
if (ranks.Length == 0)
{
return;
}
int percent;
if (Owner.Count == 1)
{
percent = 1000;
}
else if (m_RankIndex == -1 || Faction.ZeroRankOffset <= 0)
{
percent = 0;
}
else
{
percent = (Faction.ZeroRankOffset - m_RankIndex) * 1000 / Faction.ZeroRankOffset;
}
// Ranks run Required-descending ending at 0, so anything >= 0 matches below. A negative
// percent (RankIndex out of sync with ZeroRankOffset) would otherwise leave it null.
m_Rank = ranks[^1];
for (var i = 0; i < ranks.Length; i++)
{
var check = ranks[i];
if (percent >= check.Required)
{
m_Rank = check;
break;
}
}
}
public DateTime LastHonorTime { get; set; }
public DateTime Leaving { get; set; }
public bool IsLeaving => Leaving > DateTime.MinValue;
public bool IsActive { get; set; }
public int CompareTo(PlayerState ps) => (ps?.m_KillPoints ?? 0) - m_KillPoints;
public bool CanGiveSilverTo(Mobile mob)
{
for (var i = 0; i < SilverGiven?.Count; ++i)
{
var sge = SilverGiven[i];
if (sge.IsExpired)
{
SilverGiven.RemoveAt(i--);
}
else if (sge.GivenTo == mob)
{
return false;
}
}
return true;
}
public void OnGivenSilverTo(Mobile mob)
{
SilverGiven ??= [];
SilverGiven.Add(new SilverGivenEntry(mob));
}
public void Invalidate()
{
(Mobile as PlayerMobile)?.InvalidateProperties();
}
public void Attach()
{
if (Mobile is PlayerMobile mobile)
{
mobile.FactionPlayerState = this;
}
}
public void Serialize(IGenericWriter writer)
{
writer.WriteEncodedInt(1); // version
writer.Write(IsActive);
writer.Write(LastHonorTime);
writer.Write(Mobile);
writer.WriteEncodedInt(m_KillPoints);
writer.WriteEncodedInt((int)m_MerchantTitle);
writer.Write(Leaving);
}
public static PlayerState Find(Mobile mob) => mob is PlayerMobile mobile ? mobile.FactionPlayerState : null;
}