ModernUO/Projects/UOContent.Tests/Tests/Engines/Pathing/Multi/MultiEdgeCaseTests.cs
Kamron Batman 1c2e114b21
feat(pathfinding): multi-aware mask synthesizer + warm interior cache for house/boat cells (#2479)
## Problem

Houses and boats (multis) were pathed correctly only by **delegation to the slow path**: `StepCache.TryGetMask` returns `Fallthrough_Multi` for any multi-covered cell, and `GetSuccessors` ran `CheckMovement` **8× per cell** (each re-resolving the tile stack via `GetStaticAndMultiTiles`) — a sustained per-step cost near every house/boat. There was also no automated test pinning multi pathfinding.

This branch is the full multi-pathfinding effort in phases on one branch.

## Phase 1 — characterization tests (the oracle)

Implementation-agnostic invariants: a cache-on≡cache-off whole-path invariant, a per-cell sweep vs `CheckMovement` over footprint+halo (incl. destination Z), hand-verified routing (around walls, demolish-reopens, foundation-redesign-honored), classic-house / foundation / boat fixtures, non-vacuity guards. These gate every later phase byte-for-byte.

## Phase 2 — live single-pass synthesizer

`StepProbe.ComputeMultiMaskAt` synthesizes a covered cell's full 8-direction `StepMask` in one pass (the existing surface/step logic over `GetStaticAndMultiTiles` instead of 8× `CheckMovement`). `GetSuccessors` routes `Fallthrough_Multi` cells through it. No new cache, no `.swb` change. **~1.5×**, zero added allocations.

## Phase 3 / 3.1 — warm per-`multiID` interior cache (airtight)

`MultiMaskCache` caches each fixed multi's local-frame `StepMask` for **interior** cells (cell + all 8 neighbours covered → terrain-neighbour-free → position-invariant), keyed by `multiID & 0x3FFF`, built lazily from the MCL. Interior cells become ~20 ns lookups.

The cache is gated on a **per-instance footprint-clean flag** (`BaseMulti.PathInteriorCacheState`): an instance whose whole footprint terrain is below its floor (`maxTerrain < minFloor`) serves from the cache; a **dirty** instance (terrain intrudes — a contrived/GM placement) **degrades to live-synth, never a wrong mask**. This closes a cross-instance soundness gap (the cached mask depends on neighbour terrain too) found in a holistic review. The gate resets whenever the footprint's world-terrain relationship can change — **location, map, or ItemID** (a boat's heading swaps the MCL).

**Boats are cached too.** Their per-`multiID` deck masks are movement-invariant (built once per heading), so a sailing boat never rebuilds them; only the cheap clean-flag rescan repeats per move (and only when pathed near). Narrow existing boats have little interior; wide galleons (`multi.mul`) would gain Castle-class. `HouseFoundation` (per-instance runtime `DesignState`) is the one type that stays on the live path.

## Verification

- `UOContent.Tests` **454/454**, `Server.Tests` **708/708**, 0 failures.
- The Phase-1 oracle (`MultiPathInvariantTests`, cache-on ≡ cache-off) stays **byte-identical** with the synthesizer + interior cache active.
- Tests pin: footprint-cleanliness (clean vs sunk), dirty/cluttered placement degrades to live-synth while still pathing, clean placement serves, and the gate resets on move/ItemID change.

## Performance (modernuo/ModernUO-Benchmarks#8, full-fixture)

Houses at **Green Acres** (flat staff region → clean footprints, the legit-placement case):

| Route | Slow path | Phase 3.1 (interior cache) | Speedup |
|-------|----------:|---------------------------:|--------:|
| `around_a` (29 steps) | 238.3 µs | **49.1 µs** | **4.85×** |
| `around_b` (29 steps) | 224.3 µs | **49.5 µs** | **4.53×** |

~130 of ~167 multi cells/route serve from the cache (~20 ns) vs 37 live-synth. Per-cell, the slow path's 8× `CheckMovement` grows with multi complexity (GuildHouse ~857 ns → Castle ~1,194 ns), the synthesizer is a flat ~780 ns, and the cache serve is ~20 ns — so big/tall multis (and wide galleons) gain most. Identical allocations throughout.
2026-06-09 08:02:05 -07:00

158 lines
6.4 KiB
C#

using Server.Engines.Pathing.Cache;
using Server.Items;
using Xunit;
namespace Server.Tests.Pathfinding;
[Collection("Sequential Pathfinding Tests")]
public class MultiEdgeCaseTests
{
private const int MapId = 1; // Trammel
private const int GuildHouseId = 0x74;
// GuildHouse placement (mirrors MultiMaskSynthesisTests) — open Trammel ground.
private const int HouseX = 1480;
private const int HouseY = 1620;
// Open water in the south-Britain bay (mirrors BoatPathTests).
private const int BoatMultiId = 0x0; // SmallBoat North heading
private const int WaterX = 1450;
private const int WaterY = 1770;
private const sbyte DeckZ = 0; // boat deck floor tiles stand at world Z 0 (not the water avgZ)
/// <summary>
/// Two overlapping GuildHouse multis whose footprints intersect. At the stacked cells
/// <c>GetStaticAndMultiTiles</c> yields tiles from BOTH multis; the synthesizer must still
/// agree with CheckMovement everywhere over the union footprint + halo.
/// </summary>
[Fact]
public void OverlappingMultis_SynthesizerMatchesCheckMovement()
{
StepCache.Instance.Clear();
var map = Map.Maps[MapId];
map.GetAverageZ(HouseX, HouseY, out _, out var z, out _);
var locA = new Point3D(HouseX, HouseY, (sbyte)z);
// Origins 3 tiles apart on X so the GuildHouse footprints overlap.
var locB = new Point3D(HouseX + 3, HouseY, (sbyte)z);
var multiA = new TestMulti(GuildHouseId);
var multiB = new TestMulti(GuildHouseId);
try
{
multiA.MoveToWorld(locA, map);
multiB.MoveToWorld(locB, map);
// Non-vacuity: prove the two footprints actually intersect at the chosen 3-tile
// separation. The per-sweep touchedMulti guard only proves each multi touched its OWN
// footprint; without this, "overlapping" would be an unverified comment.
var overlap = MultiArt.FootprintCells(multiA);
var setB = new System.Collections.Generic.HashSet<MultiArt.Cell>(MultiArt.FootprintCells(multiB));
overlap.RemoveAll(c => !setB.Contains(c));
Assert.NotEmpty(overlap); // the two footprints must actually intersect, else the test is meaningless
// The synthesizer must match the oracle over BOTH footprints (each sweep crosses
// the shared, doubly-covered cells).
MultiTestSupport.AssertSynthesizerMatchesCheckMovement(multiA, map);
MultiTestSupport.AssertSynthesizerMatchesCheckMovement(multiB, map);
}
finally
{
multiA.Delete();
multiB.Delete();
}
}
/// <summary>
/// A boat placed over open water: deck surface tiles are walkable, surrounding water blocks
/// the (non-swimming) walker. Exercises the synthesizer over water-adjacent deck-edge geometry.
/// </summary>
/// <remarks>
/// The boat is placed at Z=0 (the deck's world Z), NOT at the water average Z (-15 here).
/// The deck floor tiles stand at world Z 0, so a non-swimming walker only finds walkable
/// transitions when the sweep origin Z equals the deck Z. Placing at the water avgZ makes the
/// sweep vacuous ("no walkable transitions") because the deck is 15 tiles overhead and water
/// blocks the rest — that vacuity is a fixture concern, not a synthesizer divergence (the
/// synthesizer agrees with the oracle at every direction either way).
/// </remarks>
[Fact]
public void BoatOverWater_SynthesizerMatchesCheckMovement()
{
StepCache.Instance.Clear();
var map = Map.Maps[MapId];
var boat = new TestMulti(BoatMultiId);
boat.MoveToWorld(new Point3D(WaterX, WaterY, DeckZ), map);
try
{
MultiTestSupport.AssertSynthesizerMatchesCheckMovement(boat, map);
}
finally
{
boat.Delete();
}
}
/// <summary>
/// Redesign a foundation in place (Internalize -> swap MCL -> MoveToWorld back, the same
/// re-registration pattern HouseFoundation uses on commit) and assert the synthesizer reads
/// the LIVE, post-redesign <c>Components</c> — i.e. it matches CheckMovement on the NEW shape.
/// </summary>
[Fact]
public void RedesignedFoundation_SynthesizerMatchesNewFootprint()
{
StepCache.Instance.Clear();
var map = Map.Maps[MapId];
var foundation = new SwappableFoundation(GuildHouseId);
map.GetAverageZ(HouseX, HouseY, out _, out var z, out _);
var loc = new Point3D(HouseX, HouseY, (sbyte)z);
foundation.MoveToWorld(loc, map);
try
{
// Redesign, RE-REGISTERED so sectors track the new footprint (model a real commit).
// Internalize() fires Map.OnLeave (removes the OLD footprint's registration); we swap
// the MCL and MoveToWorld back, firing Map.OnEnter -> AddMulti against the new shape.
foundation.Internalize();
foundation.Redesign(MultiData.GetComponents(0x7A)); // Tower footprint (different shape)
foundation.MoveToWorld(loc, map);
MultiTestSupport.AssertSynthesizerMatchesCheckMovement(foundation, map);
}
finally
{
if (!foundation.Deleted)
{
foundation.Delete();
}
}
}
/// <summary>
/// Extensible slot for repo-owner-supplied gnarly placements. The assertion already covers
/// any (map,x,y) by construction — only the coordinates need filling in.
///
/// TODO(coords): repo owner to supply (map,x,y) for a static tree inside a footprint and a
/// dungeon cave-wall corner; add InlineData rows here — the assertion already covers them by
/// construction. (Left intentionally unhunted: do not invent tree/dungeon coords.)
/// </summary>
[Theory]
[InlineData(MapId, HouseX, HouseY)] // known-good open Trammel placement (passes today)
public void UserSuppliedScenarios_SynthesizerMatchesCheckMovement(int mapId, int x, int y)
{
StepCache.Instance.Clear();
var map = Map.Maps[mapId];
var multi = new TestMulti(GuildHouseId);
map.GetAverageZ(x, y, out _, out var z, out _);
multi.MoveToWorld(new Point3D(x, y, (sbyte)z), map);
try
{
MultiTestSupport.AssertSynthesizerMatchesCheckMovement(multi, map);
}
finally
{
multi.Delete();
}
}
}