ModernUO/Projects/UOContent.Tests/Tests/Engines/Pathing/StepCacheLifecycleTests.cs

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using Server.Engines.Pathing.Cache;
using Xunit;
namespace Server.Tests.Pathfinding;
[Collection("Sequential Pathfinding Tests")]
public class StepCacheLifecycleTests
{
[Fact]
public void Singleton_IsAvailable()
{
var cache = StepCache.Instance;
Assert.NotNull(cache);
}
[Fact]
public void Clear_OnEmptyCache_LeavesStatsZero()
{
var cache = StepCache.Instance;
cache.Clear();
var stats = cache.GetStats();
Assert.Equal(0, stats.ResidentChunks);
Assert.Equal(0L, stats.Hits);
Assert.Equal(0L, stats.BuildsTotal);
}
[Fact]
public void TryGetMask_FirstTouchOnUnbuiltChunk_DefersBuildAndReturnsFallthrough()
{
var cache = StepCache.Instance;
cache.Clear();
cache.MissPromotionThreshold = 2;
var map = Map.Maps[1];
Assert.NotNull(map);
// First touch on a chunk that has no resident copy and no lazy reader behind it
// must NOT eagerly build. Caller (BitmapAStarAlgorithm) interprets IsHit=false as
// "use slow path" — pets/hireables passing briefly through a chunk avoid the
// ~700µs BuildChunk cost they'd never amortize.
var lookup = cache.TryGetMask(map, 1500, 1600, sourceZ: 10);
Assert.False(lookup.IsHit);
Assert.Equal(CacheHitKind.Fallthrough_NotBuilt, lookup.HitKind);
var stats = cache.GetStats();
Assert.Equal(0, stats.ResidentChunks);
Assert.Equal(0L, stats.BuildsTotal);
Assert.Equal(0L, stats.MissesNotBuilt);
Assert.Equal(1L, stats.FallthroughNotBuilt);
}
[Fact]
public void TryGetMask_SecondTouchWithinWindow_PromotesAndBuilds()
{
var cache = StepCache.Instance;
cache.Clear();
cache.MissPromotionThreshold = 2;
var map = Map.Maps[1];
// First touch defers; second touch inside the promotion window builds + serves.
// Pinned cell (1500, 1600, z=10): mask=0xC1
var first = cache.TryGetMask(map, 1500, 1600, sourceZ: 10);
Assert.False(first.IsHit);
var second = cache.TryGetMask(map, 1500, 1600, sourceZ: 10);
Assert.True(second.IsHit);
Assert.Equal(CacheHitKind.Miss_NotBuilt, second.HitKind);
Assert.Equal((byte)0xC1, second.WalkMask);
Assert.Equal((sbyte)10, second.WalkZ_N);
var stats = cache.GetStats();
Assert.Equal(1, stats.ResidentChunks);
Assert.Equal(1L, stats.MissesNotBuilt);
Assert.Equal(1L, stats.BuildsTotal);
Assert.Equal(1L, stats.FallthroughNotBuilt);
// Third query of same cell → Hit (chunk now resident).
var third = cache.TryGetMask(map, 1500, 1600, sourceZ: 10);
Assert.True(third.IsHit);
Assert.Equal(CacheHitKind.Hit, third.HitKind);
Assert.Equal((byte)0xC1, third.WalkMask);
}
[Fact]
public void TryGetMask_SecondTouchAfterWindow_RestartsCounterAndDefers()
{
var cache = StepCache.Instance;
cache.Clear();
cache.MissPromotionThreshold = 2;
cache.MissPromotionWindowMs = 1; // 1ms window for testability
var map = Map.Maps[1];
var first = cache.TryGetMask(map, 1500, 1600, sourceZ: 10);
Assert.False(first.IsHit);
System.Threading.Thread.Sleep(20); // exceed the window
// Second touch lands outside the window: tracker resets the count to 1, returns
// Fallthrough_NotBuilt again — chunks the player just glanced through don't get
// promoted just because they get re-touched minutes later by an unrelated NPC.
var second = cache.TryGetMask(map, 1500, 1600, sourceZ: 10);
Assert.False(second.IsHit);
Assert.Equal(CacheHitKind.Fallthrough_NotBuilt, second.HitKind);
Assert.Equal(0, cache.GetStats().ResidentChunks);
Assert.Equal(2L, cache.GetStats().FallthroughNotBuilt);
}
[Fact]
public void TryGetMask_MultipleCallsInSameFindGeneration_StayInFallthrough()
{
var cache = StepCache.Instance;
cache.Clear();
cache.MissPromotionThreshold = 2;
var map = Map.Maps[1];
// Open a pathfind. Multiple TryGetMask calls inside this Find target the same chunk
// (different cells). The promotion gate counts distinct Finds, not raw probes — these
// calls must NOT increment the per-chunk counter, even though there are many of them.
// Without this, A* expansion would trip the gate on the second cell expansion in any
// visited chunk, defeating the whole point of deferred promotion.
cache.BeginFindGeneration();
for (var i = 0; i < 8; i++)
{
// All cells are inside chunk (1500>>4, 1600>>4) = (93, 100).
var lookup = cache.TryGetMask(map, 1500 + i, 1600, sourceZ: 10);
Assert.False(lookup.IsHit);
Assert.Equal(CacheHitKind.Fallthrough_NotBuilt, lookup.HitKind);
}
Assert.Equal(0, cache.GetStats().ResidentChunks);
Assert.Equal(0L, cache.GetStats().BuildsTotal);
Assert.Equal(8L, cache.GetStats().FallthroughNotBuilt);
// Begin a NEW Find — this is the second distinct touch under the per-Find gate.
// The chunk now crosses the threshold and promotes.
cache.BeginFindGeneration();
var promoted = cache.TryGetMask(map, 1500, 1600, sourceZ: 10);
Assert.True(promoted.IsHit);
Assert.Equal(CacheHitKind.Miss_NotBuilt, promoted.HitKind);
Assert.Equal(1, cache.GetStats().ResidentChunks);
Assert.Equal(1L, cache.GetStats().BuildsTotal);
}
[Fact]
public void TryGetMask_TwoFindGenerationsAcrossWindow_RestartsCounter()
{
var cache = StepCache.Instance;
cache.Clear();
cache.MissPromotionThreshold = 2;
cache.MissPromotionWindowMs = 1; // 1ms window for testability
var map = Map.Maps[1];
cache.BeginFindGeneration();
Assert.False(cache.TryGetMask(map, 1500, 1600, sourceZ: 10).IsHit);
System.Threading.Thread.Sleep(20); // exceed window
// Second Find lands outside the window. Even though it's a distinct generation,
// the elapsed-time check resets the counter to 1, so no promotion.
cache.BeginFindGeneration();
var second = cache.TryGetMask(map, 1500, 1600, sourceZ: 10);
Assert.False(second.IsHit);
Assert.Equal(CacheHitKind.Fallthrough_NotBuilt, second.HitKind);
Assert.Equal(0, cache.GetStats().ResidentChunks);
}
[Fact]
public void TryGetMask_DistinctChunks_TrackedIndependently()
{
var cache = StepCache.Instance;
cache.Clear();
cache.MissPromotionThreshold = 2;
var map = Map.Maps[1];
// Two different chunks, one touch each — both must defer (each has its own counter).
var chunkA = cache.TryGetMask(map, 1500, 1600, sourceZ: 10);
var chunkB = cache.TryGetMask(map, 1600, 1700, sourceZ: 10); // different chunk
Assert.False(chunkA.IsHit);
Assert.False(chunkB.IsHit);
Assert.Equal(0, cache.GetStats().ResidentChunks);
Assert.Equal(2L, cache.GetStats().FallthroughNotBuilt);
}
[Fact]
public void TryGetMask_OffMap_ReturnsFalseFallthrough()
{
var cache = StepCache.Instance;
cache.Clear();
var map = Map.Maps[1];
var lookup = cache.TryGetMask(map, -1, -1, sourceZ: 0);
Assert.False(lookup.IsHit);
Assert.Equal(CacheHitKind.Fallthrough_OffMap, lookup.HitKind);
Assert.Equal((byte)0, lookup.WalkMask);
}
[Fact]
public void MultisVersion_Bump_TriggersDirtyRebuild()
{
var cache = StepCache.Instance;
cache.Clear();
cache.MissPromotionThreshold = 2;
var map = Map.Maps[1];
var sector = map.GetRealSector(1500 >> 4, 1600 >> 4);
// First touch defers (Fallthrough_NotBuilt); second touch promotes and builds.
Assert.Equal(CacheHitKind.Fallthrough_NotBuilt, cache.TryGetMask(map, 1500, 1600, 10).HitKind);
Assert.Equal(CacheHitKind.Miss_NotBuilt, cache.TryGetMask(map, 1500, 1600, 10).HitKind);
// Bump _multisVersion via reflection.
var versionField = typeof(Map.Sector).GetField(
"_multisVersion",
System.Reflection.BindingFlags.NonPublic | System.Reflection.BindingFlags.Instance
);
Assert.NotNull(versionField);
var current = (int)versionField.GetValue(sector);
versionField.SetValue(sector, current + 1);
// Third query: detects version mismatch, rebuilds.
Assert.Equal(CacheHitKind.Miss_DirtyRebuild, cache.TryGetMask(map, 1500, 1600, 10).HitKind);
var stats = cache.GetStats();
Assert.Equal(1L, stats.MissesDirtyRebuild);
Assert.Equal(2L, stats.BuildsTotal);
// Mutual-exclusivity invariant: hits + miss-builds + dirty-rebuilds = served-result count.
// Three calls returned an answer; two were "served from a build" (Miss_NotBuilt + Miss_DirtyRebuild),
// and the first was a Fallthrough_NotBuilt (no build, slow-path signal).
Assert.Equal(2L, stats.MissesNotBuilt + stats.MissesDirtyRebuild + stats.Hits);
Assert.Equal(1L, stats.FallthroughNotBuilt);
Assert.Equal(0L, stats.FallthroughMultiZ);
Assert.Equal(0L, stats.FallthroughOffMap);
}
[Fact]
public void MultiZCell_RoutesToFallthrough()
{
var cache = StepCache.Instance;
cache.Clear();
cache.MissPromotionThreshold = 1; // eager build for prime-then-inspect tests
var map = Map.Maps[1];
// Build a chunk first so it exists.
cache.TryGetMask(map, 1500, 1600, 10);
// Snapshot current FallthroughMultiZ in case (1500, 1600) is naturally multi-Z
// in real tile data; we only assert the synthetic injection produces a delta of 1.
var preInjectionFallthroughMultiZ = cache.GetStats().FallthroughMultiZ;
// Inject a multi-Z bit via reflection on the resident chunk.
var chunksField = typeof(StepCache).GetField(
"_chunks",
System.Reflection.BindingFlags.NonPublic | System.Reflection.BindingFlags.Instance
);
Assert.NotNull(chunksField);
var chunks = (System.Collections.Generic.Dictionary<long, StepChunk>)chunksField.GetValue(cache);
var key = StepCache.EncodeKey(map.MapID, 1500 >> 4, 1600 >> 4);
Assert.True(chunks.ContainsKey(key));
var chunk = chunks[key];
// Inject "this cell has strata but none match the query Z" — proves the cache
// still falls through to slow path when no stratum can answer.
var cellIndex = ((1600 - ((1600 >> 4) << 4)) << 4) | (1500 - ((1500 >> 4) << 4));
var offsets = new ushort[StepChunk.CellsPerChunk];
for (var i = 0; i < offsets.Length; i++)
{
offsets[i] = StepChunk.NoStrata;
}
offsets[cellIndex] = 0; // points to a 0-stratum-count entry → no match
var data = new byte[] { 0 };
chunk.SetStrata(offsets, data);
var lookup = cache.TryGetMask(map, 1500, 1600, 10);
Assert.False(lookup.IsHit);
Assert.Equal(CacheHitKind.Fallthrough_MultiZ, lookup.HitKind);
var stats = cache.GetStats();
Assert.Equal(preInjectionFallthroughMultiZ + 1L, stats.FallthroughMultiZ);
}
[Fact]
public void Tier4Strata_MatchingZ_ReturnsHitFromStratum()
{
var cache = StepCache.Instance;
cache.Clear();
cache.MissPromotionThreshold = 1;
var map = Map.Maps[1];
cache.TryGetMask(map, 1500, 1600, 10);
var chunksField = typeof(StepCache).GetField(
"_chunks",
System.Reflection.BindingFlags.NonPublic | System.Reflection.BindingFlags.Instance
);
var chunks = (System.Collections.Generic.Dictionary<long, StepChunk>)chunksField.GetValue(cache);
var key = StepCache.EncodeKey(map.MapID, 1500 >> 4, 1600 >> 4);
var chunk = chunks[key];
// Inject one stratum at zCenter=42, walkMask=0b00000011 (N + NE).
// Query at sourceZ=42 must hit and return that stratum's data.
var cellIndex = ((1600 - ((1600 >> 4) << 4)) << 4) | (1500 - ((1500 >> 4) << 4));
var offsets = new ushort[StepChunk.CellsPerChunk];
for (var i = 0; i < offsets.Length; i++)
{
offsets[i] = StepChunk.NoStrata;
}
offsets[cellIndex] = 0;
var data = new byte[1 + StepChunk.StratumByteLength];
data[0] = 1; // count
data[1] = 42; // zCenter
data[2] = 0b0000_0011; // walkMask (N | NE)
data[3] = 0; // wetMask
data[4] = 42; data[5] = 42; data[6] = 0; data[7] = 0;
data[8] = 0; data[9] = 0; data[10] = 0; data[11] = 0;
data[12] = 0; data[13] = 0; data[14] = 0; data[15] = 0;
data[16] = 0; data[17] = 0; data[18] = 0; data[19] = 0;
chunk.SetStrata(offsets, data);
var lookup = cache.TryGetMask(map, 1500, 1600, 42);
Assert.True(lookup.IsHit);
Assert.Equal((byte)0b0000_0011, lookup.WalkMask);
Assert.Equal((sbyte)42, lookup.WalkZ_N);
Assert.Equal((sbyte)42, lookup.WalkZ_NE);
}
[Fact]
public void SwimLayer_NotInjected_StaysFallthroughOnSourceZMismatch()
{
// Sanity check: a chunk WITHOUT a swim layer falls through on source-Z mismatch
// exactly like before. Validates we didn't accidentally serve garbage when the
// chunk has no shore cells.
var cache = StepCache.Instance;
cache.Clear();
cache.MissPromotionThreshold = 1;
var map = Map.Maps[1];
cache.TryGetMask(map, 1500, 1600, sourceZ: 10); // build chunk
var beforeMismatch = cache.GetStats().FallthroughSourceZMismatch;
// Same cell but query Z far from baked Z → source-Z guard fires.
var lookup = cache.TryGetMask(map, 1500, 1600, sourceZ: 100);
Assert.False(lookup.IsHit);
Assert.Equal(CacheHitKind.Fallthrough_SourceZMismatch, lookup.HitKind);
Assert.Equal(beforeMismatch + 1L, cache.GetStats().FallthroughSourceZMismatch);
}
[Fact]
public void SwimLayer_InjectedMatchingZ_ReturnsHitFromSwimLayer()
{
// Inject a synthetic swim layer onto a resident chunk and verify a query at the
// swim source Z routes through the swim-layer fallback, returning the swim mask.
var cache = StepCache.Instance;
cache.Clear();
cache.MissPromotionThreshold = 1;
var map = Map.Maps[1];
cache.TryGetMask(map, 1500, 1600, sourceZ: 10);
var chunksField = typeof(StepCache).GetField(
"_chunks",
System.Reflection.BindingFlags.NonPublic | System.Reflection.BindingFlags.Instance
);
var chunks = (System.Collections.Generic.Dictionary<long, StepChunk>)chunksField!.GetValue(cache)!;
var key = StepCache.EncodeKey(map.MapID, 1500 >> 4, 1600 >> 4);
var chunk = chunks[key];
chunk.AllocateSwimLayer();
var cellIndex = ((1600 - ((1600 >> 4) << 4)) << 4) | (1500 - ((1500 >> 4) << 4));
chunk.SwimSourceZ[cellIndex] = -5;
chunk.SwimMask[cellIndex] = 0b0000_0011;
chunk.SwimZN_Layer[cellIndex] = -5;
chunk.SwimZNE_Layer[cellIndex] = -5;
// Other directions stay 0 — Mask bits 0 and 1 cover N and NE.
// Query at the chunk's primary SourceZ — primary path serves walk-layer data,
// swim layer not consulted.
var bakedSourceZ = chunk.SourceZ[cellIndex];
var walkLookup = cache.TryGetMask(map, 1500, 1600, bakedSourceZ);
Assert.True(walkLookup.IsHit);
Assert.Equal(CacheHitKind.Hit, walkLookup.HitKind);
// Walk-layer query produces walk-layer walkMask (whatever the bake found), NOT
// the synthetic swim mask we injected.
// Query at the swim source Z — primary source-Z guard fails (|5 bakedZ| > 2
// assuming baked Z is land surface), swim-layer fallback serves with our mask.
if (System.Math.Abs(-5 - bakedSourceZ) <= 2)
{
// Bake landed near water Z — adjust the test to a clearer swim Z.
chunk.SwimSourceZ[cellIndex] = (sbyte)(bakedSourceZ - 20);
}
var swimLookup = cache.TryGetMask(map, 1500, 1600, chunk.SwimSourceZ[cellIndex]);
Assert.True(swimLookup.IsHit);
Assert.Equal(CacheHitKind.Hit, swimLookup.HitKind);
Assert.Equal((byte)0, swimLookup.WalkMask); // walk = 0 at swim Z
Assert.Equal(chunk.SwimMask[cellIndex], swimLookup.WetMask);
Assert.Equal(chunk.SwimZN_Layer[cellIndex], swimLookup.SwimZ_N);
Assert.Equal(chunk.SwimZNE_Layer[cellIndex], swimLookup.SwimZ_NE);
}
[Fact]
public void SwimLayer_InjectedButCellHasNoSentinel_FallsThrough()
{
// Chunk has the swim layer (some other cell is shore), but THIS cell is inland
// (SwimSourceZ = NoSwimLayerCell). Query at non-matching walk Z must fall through,
// not erroneously match -128 against the query.
var cache = StepCache.Instance;
cache.Clear();
cache.MissPromotionThreshold = 1;
var map = Map.Maps[1];
cache.TryGetMask(map, 1500, 1600, sourceZ: 10);
var chunksField = typeof(StepCache).GetField(
"_chunks",
System.Reflection.BindingFlags.NonPublic | System.Reflection.BindingFlags.Instance
);
var chunks = (System.Collections.Generic.Dictionary<long, StepChunk>)chunksField!.GetValue(cache)!;
var key = StepCache.EncodeKey(map.MapID, 1500 >> 4, 1600 >> 4);
var chunk = chunks[key];
// Allocate layer but leave THIS cell at the sentinel.
chunk.AllocateSwimLayer();
var cellIndex = ((1600 - ((1600 >> 4) << 4)) << 4) | (1500 - ((1500 >> 4) << 4));
Assert.Equal(StepChunk.NoSwimLayerCell, chunk.SwimSourceZ[cellIndex]);
var beforeMismatch = cache.GetStats().FallthroughSourceZMismatch;
// Query at -128 (the sentinel value) — must NOT match. The guard short-circuits
// on the sentinel before computing |sourceZ - SwimSourceZ|.
var lookup = cache.TryGetMask(map, 1500, 1600, sbyte.MinValue);
Assert.False(lookup.IsHit);
Assert.Equal(CacheHitKind.Fallthrough_SourceZMismatch, lookup.HitKind);
Assert.Equal(beforeMismatch + 1L, cache.GetStats().FallthroughSourceZMismatch);
}
[Fact]
public void Tier4Strata_NonMatchingZ_FallsThrough()
{
var cache = StepCache.Instance;
cache.Clear();
cache.MissPromotionThreshold = 1;
var map = Map.Maps[1];
cache.TryGetMask(map, 1500, 1600, 10);
var chunksField = typeof(StepCache).GetField(
"_chunks",
System.Reflection.BindingFlags.NonPublic | System.Reflection.BindingFlags.Instance
);
var chunks = (System.Collections.Generic.Dictionary<long, StepChunk>)chunksField.GetValue(cache);
var key = StepCache.EncodeKey(map.MapID, 1500 >> 4, 1600 >> 4);
var chunk = chunks[key];
// Stratum at zCenter=42; query at sourceZ=10 (delta > StepHeight=2). Must fallthrough.
var cellIndex = ((1600 - ((1600 >> 4) << 4)) << 4) | (1500 - ((1500 >> 4) << 4));
var offsets = new ushort[StepChunk.CellsPerChunk];
for (var i = 0; i < offsets.Length; i++)
{
offsets[i] = StepChunk.NoStrata;
}
offsets[cellIndex] = 0;
var data = new byte[1 + StepChunk.StratumByteLength];
data[0] = 1; data[1] = 42; // zCenter=42, all other bytes 0
chunk.SetStrata(offsets, data);
var lookup = cache.TryGetMask(map, 1500, 1600, 10);
Assert.False(lookup.IsHit);
Assert.Equal(CacheHitKind.Fallthrough_MultiZ, lookup.HitKind);
}
[Fact]
public void LruCap_OverflowEvictsToCap()
{
var cache = StepCache.Instance;
cache.Clear();
cache.MaxResidentChunks = 4;
cache.MissPromotionThreshold = 1;
try
{
var map = Map.Maps[1];
// Build 5 distinct chunks by querying different sectors.
for (var i = 0; i < 5; i++)
{
var x = 1500 + i * 16;
var y = 1600;
cache.TryGetMask(map, x, y, 10);
System.Threading.Thread.Sleep(2); // ensure LastTouchedTicks differs
}
cache.EnforceLruCap();
Assert.Equal(4, cache.GetStats().ResidentChunks);
Assert.True(cache.GetStats().EvictionsByLruCap >= 1L);
// _keysList must stay in lockstep with _chunks. A desync would silently
// break sampled eviction (KeyNotFoundException on stale keys, or a stuck
// resident set on missing keys).
var chunksField = typeof(StepCache).GetField(
"_chunks",
System.Reflection.BindingFlags.NonPublic | System.Reflection.BindingFlags.Instance
);
var keysListField = typeof(StepCache).GetField(
"_keysList",
System.Reflection.BindingFlags.NonPublic | System.Reflection.BindingFlags.Instance
);
var chunks = (System.Collections.Generic.Dictionary<long, StepChunk>)chunksField.GetValue(cache);
var keysList = (System.Collections.Generic.List<long>)keysListField.GetValue(cache);
Assert.Equal(chunks.Count, keysList.Count);
foreach (var k in keysList)
{
Assert.True(chunks.ContainsKey(k), $"keysList holds key {k} not in _chunks");
}
}
finally
{
cache.MaxResidentChunks = 8192;
}
}
}