Change GetCustomMovementLayers to expose an array, not a dictionary.

As there are few custom movement layers, using an array is good for improving lookup speed. Additionally, we can simplify some code by reserving index 0 of the array for the ground layer. Code that needs to maintain a state for the ground layer and every custom movement layer can now maintain a flat array of state using index 0 for the ground layer, and the the ICustomMovementLayer.Index for the custom movement layer. This removes a lot of ternary statements checking for the ground layer special case.

OpenRA.Mods.Common/Pathfinder/PathGraph.cs

@@ -88,22 +88,23 @@ namespace OpenRA.Mods.Common.Pathfinder
 		readonly Locomotor locomotor;
 		readonly CellInfoLayerPool.PooledCellInfoLayer pooledLayer;
 		readonly bool checkTerrainHeight;
-		CellLayer<CellInfo> groundInfo;
+		readonly CellLayer<CellInfo>[] cellInfoForLayer;
-
-		readonly Dictionary<byte, (ICustomMovementLayer Layer, CellLayer<CellInfo> Info)> customLayerInfo =
-			new Dictionary<byte, (ICustomMovementLayer, CellLayer<CellInfo>)>();
 
 		public PathGraph(CellInfoLayerPool layerPool, Locomotor locomotor, Actor actor, World world, BlockedByActor check)
 		{
-			pooledLayer = layerPool.Get();
-			groundInfo = pooledLayer.GetLayer();
-			var locomotorInfo = locomotor.Info;
 			this.locomotor = locomotor;
 
+			// As we support a search over the whole map area,
+			// use the pool to grab the CellInfos we need to track the graph state.
+			// This allows us to avoid the cost of allocating large arrays constantly.
 			// PERF: Avoid LINQ
-			foreach (var cml in world.GetCustomMovementLayers().Values)
+			var cmls = world.GetCustomMovementLayers();
-				if (cml.EnabledForLocomotor(locomotorInfo))
+			pooledLayer = layerPool.Get();
-					customLayerInfo[cml.Index] = (cml, pooledLayer.GetLayer());
+			cellInfoForLayer = new CellLayer<CellInfo>[cmls.Length];
+			cellInfoForLayer[0] = pooledLayer.GetLayer();
+			foreach (var cml in cmls)
+				if (cml != null && cml.EnabledForLocomotor(locomotor.Info))
+					cellInfoForLayer[cml.Index] = pooledLayer.GetLayer();
 
 			World = world;
 			Actor = actor;
@@ -132,8 +133,8 @@ namespace OpenRA.Mods.Common.Pathfinder
 
 		public List<GraphConnection> GetConnections(CPos position)
 		{
-			var posLayer = position.Layer;
+			var layer = position.Layer;
-			var info = posLayer == 0 ? groundInfo : customLayerInfo[posLayer].Info;
+			var info = cellInfoForLayer[layer];
 			var previousPos = info[position].PreviousPos;
 
 			var dx = position.X - previousPos.X;
@@ -141,7 +142,7 @@ namespace OpenRA.Mods.Common.Pathfinder
 			var index = dy * 3 + dx + 4;
 
 			var directions = DirectedNeighbors[index];
-			var validNeighbors = new List<GraphConnection>(directions.Length + (posLayer == 0 ? customLayerInfo.Count : 1));
+			var validNeighbors = new List<GraphConnection>(directions.Length + (layer == 0 ? cellInfoForLayer.Length : 1));
 			for (var i = 0; i < directions.Length; i++)
 			{
 				var dir = directions[i];
@@ -153,12 +154,16 @@ namespace OpenRA.Mods.Common.Pathfinder
 					validNeighbors.Add(new GraphConnection(neighbor, pathCost));
 			}
 
-			if (posLayer == 0)
+			var cmls = World.GetCustomMovementLayers();
+			if (layer == 0)
 			{
-				foreach (var cli in customLayerInfo.Values)
+				foreach (var cml in cmls)
 				{
-					var layerPosition = new CPos(position.X, position.Y, cli.Layer.Index);
+					if (cml == null || !cml.EnabledForLocomotor(locomotor.Info))
-					var entryCost = cli.Layer.EntryMovementCost(locomotor.Info, layerPosition);
+						continue;
+
+					var layerPosition = new CPos(position.X, position.Y, cml.Index);
+					var entryCost = cml.EntryMovementCost(locomotor.Info, layerPosition);
 					if (entryCost != MovementCostForUnreachableCell)
 						validNeighbors.Add(new GraphConnection(layerPosition, entryCost));
 				}
@@ -166,7 +171,7 @@ namespace OpenRA.Mods.Common.Pathfinder
 			else
 			{
 				var layerPosition = new CPos(position.X, position.Y, 0);
-				var exitCost = customLayerInfo[posLayer].Layer.ExitMovementCost(locomotor.Info, layerPosition);
+				var exitCost = cmls[layer].ExitMovementCost(locomotor.Info, layerPosition);
 				if (exitCost != MovementCostForUnreachableCell)
 					validNeighbors.Add(new GraphConnection(layerPosition, exitCost));
 			}
@@ -226,14 +231,12 @@ namespace OpenRA.Mods.Common.Pathfinder
 
 		public CellInfo this[CPos pos]
 		{
-			get => (pos.Layer == 0 ? groundInfo : customLayerInfo[pos.Layer].Info)[pos];
+			get => cellInfoForLayer[pos.Layer][pos];
-			set => (pos.Layer == 0 ? groundInfo : customLayerInfo[pos.Layer].Info)[pos] = value;
+			set => cellInfoForLayer[pos.Layer][pos] = value;
 		}
 
 		public void Dispose()
 		{
-			groundInfo = null;
-			customLayerInfo.Clear();
 			pooledLayer.Dispose();
 		}
 	}

OpenRA.Mods.Common/Traits/Mobile.cs

@@ -428,10 +428,8 @@ namespace OpenRA.Mods.Common.Traits
 			if (ToCell.Layer == 0)
 				return true;
 
-			if (self.World.GetCustomMovementLayers().TryGetValue(ToCell.Layer, out var layer))
+			var layer = self.World.GetCustomMovementLayers()[ToCell.Layer];
-				return layer.InteractsWithDefaultLayer;
+			return layer == null || layer.InteractsWithDefaultLayer;
-
-			return true;
 		}
 
 		#endregion
@@ -862,9 +860,7 @@ namespace OpenRA.Mods.Common.Traits
 				return;
 			}
 
-			var cml = self.World.WorldActor.TraitsImplementing<ICustomMovementLayer>()
+			var cml = self.World.GetCustomMovementLayers()[self.Location.Layer];
-				.First(l => l.Index == self.Location.Layer);
-
 			if (!cml.ReturnToGroundLayerOnIdle)
 				return;
 

OpenRA.Mods.Common/Traits/World/ActorMap.cs

@@ -171,9 +171,10 @@ namespace OpenRA.Mods.Common.Traits
 		readonly Dictionary<int, ProximityTrigger> proximityTriggers = new Dictionary<int, ProximityTrigger>();
 		int nextTriggerId;
 
-		readonly CellLayer<InfluenceNode> influence;
+		CellLayer<InfluenceNode>[] influence;
-		readonly Dictionary<int, CellLayer<InfluenceNode>> customInfluence = new Dictionary<int, CellLayer<InfluenceNode>>();
+
-		public readonly Dictionary<int, ICustomMovementLayer> CustomMovementLayers = new Dictionary<int, ICustomMovementLayer>();
+		// Index 0 is kept null as layer 0 is used for the ground layer.
+		public ICustomMovementLayer[] CustomMovementLayers = new ICustomMovementLayer[] { null };
 		public event Action<CPos> CellUpdated;
 		readonly Bin[] bins;
 		readonly int rows, cols;
@@ -191,7 +192,7 @@ namespace OpenRA.Mods.Common.Traits
 		{
 			this.info = info;
 			map = world.Map;
-			influence = new CellLayer<InfluenceNode>(world.Map);
+			influence = new[] { new CellLayer<InfluenceNode>(world.Map) };
 
 			cols = CellCoordToBinIndex(world.Map.MapSize.X) + 1;
 			rows = CellCoordToBinIndex(world.Map.MapSize.Y) + 1;
@@ -210,10 +211,18 @@ namespace OpenRA.Mods.Common.Traits
 
 		void INotifyCreated.Created(Actor self)
 		{
-			foreach (var cml in self.TraitsImplementing<ICustomMovementLayer>())
+			var cmls = self.TraitsImplementing<ICustomMovementLayer>().ToList();
+			if (cmls.Count == 0)
+				return;
+
+			var length = cmls.Max(cml => cml.Index) + 1;
+			Array.Resize(ref CustomMovementLayers, length);
+			Array.Resize(ref influence, length);
+
+			foreach (var cml in cmls)
 			{
 				CustomMovementLayers[cml.Index] = cml;
-				customInfluence.Add(cml.Index, new CellLayer<InfluenceNode>(self.World.Map));
+				influence[cml.Index] = new CellLayer<InfluenceNode>(self.World.Map);
 			}
 		}
 
@@ -259,21 +268,21 @@ namespace OpenRA.Mods.Common.Traits
 		{
 			// PERF: Custom enumerator for efficiency - using `yield` is slower.
 			var uv = a.ToMPos(map);
-			if (!influence.Contains(uv))
+			var layer = influence[a.Layer];
+			if (!layer.Contains(uv))
 				return Enumerable.Empty<Actor>();
 
-			var layer = a.Layer == 0 ? influence : customInfluence[a.Layer];
 			return new ActorsAtEnumerable(layer[uv]);
 		}
 
 		public IEnumerable<Actor> GetActorsAt(CPos a, SubCell sub)
 		{
 			var uv = a.ToMPos(map);
-			if (!influence.Contains(uv))
+			var layer = influence[a.Layer];
+			if (!layer.Contains(uv))
 				yield break;
 
 			var always = sub == SubCell.FullCell || sub == SubCell.Any;
-			var layer = a.Layer == 0 ? influence : customInfluence[a.Layer];
 			for (var i = layer[uv]; i != null; i = i.Next)
 				if (!i.Actor.Disposed && (i.SubCell == sub || i.SubCell == SubCell.FullCell || always))
 					yield return i.Actor;
@@ -287,17 +296,18 @@ namespace OpenRA.Mods.Common.Traits
 		public SubCell FreeSubCell(CPos cell, SubCell preferredSubCell = SubCell.Any, bool checkTransient = true)
 		{
 			var uv = cell.ToMPos(map);
-			if (!influence.Contains(uv))
+			var layer = influence[cell.Layer];
+			if (!layer.Contains(uv))
 				return preferredSubCell != SubCell.Any ? preferredSubCell : SubCell.First;
 
-			if (preferredSubCell != SubCell.Any && !AnyActorsAt(uv, cell, preferredSubCell, checkTransient))
+			if (preferredSubCell != SubCell.Any && !AnyActorsAt(uv, cell, layer, preferredSubCell, checkTransient))
 				return preferredSubCell;
 
-			if (!AnyActorsAt(uv, cell.Layer))
+			if (!AnyActorsAt(uv, layer))
 				return map.Grid.DefaultSubCell;
 
 			for (var i = (int)SubCell.First; i < map.Grid.SubCellOffsets.Length; i++)
-				if (i != (int)preferredSubCell && !AnyActorsAt(uv, cell, (SubCell)i, checkTransient))
+				if (i != (int)preferredSubCell && !AnyActorsAt(uv, cell, layer, (SubCell)i, checkTransient))
 					return (SubCell)i;
 
 			return SubCell.Invalid;
@@ -306,26 +316,26 @@ namespace OpenRA.Mods.Common.Traits
 		public SubCell FreeSubCell(CPos cell, SubCell preferredSubCell, Func<Actor, bool> checkIfBlocker)
 		{
 			var uv = cell.ToMPos(map);
-			if (!influence.Contains(uv))
+			var layer = influence[cell.Layer];
+			if (!layer.Contains(uv))
 				return preferredSubCell != SubCell.Any ? preferredSubCell : SubCell.First;
 
-			if (preferredSubCell != SubCell.Any && !AnyActorsAt(uv, cell, preferredSubCell, checkIfBlocker))
+			if (preferredSubCell != SubCell.Any && !AnyActorsAt(uv, layer, preferredSubCell, checkIfBlocker))
 				return preferredSubCell;
 
-			if (!AnyActorsAt(uv, cell.Layer))
+			if (!AnyActorsAt(uv, layer))
 				return map.Grid.DefaultSubCell;
 
 			for (var i = (byte)SubCell.First; i < map.Grid.SubCellOffsets.Length; i++)
-				if (i != (byte)preferredSubCell && !AnyActorsAt(uv, cell, (SubCell)i, checkIfBlocker))
+				if (i != (byte)preferredSubCell && !AnyActorsAt(uv, layer, (SubCell)i, checkIfBlocker))
 					return (SubCell)i;
 
 			return SubCell.Invalid;
 		}
 
 		// NOTE: pos required to be in map bounds
-		bool AnyActorsAt(MPos uv, int layerIndex)
+		bool AnyActorsAt(MPos uv, CellLayer<InfluenceNode> layer)
 		{
-			var layer = layerIndex == 0 ? influence : customInfluence[layerIndex];
 			return layer[uv] != null;
 		}
 
@@ -333,17 +343,17 @@ namespace OpenRA.Mods.Common.Traits
 		public bool AnyActorsAt(CPos a)
 		{
 			var uv = a.ToMPos(map);
-			if (!influence.Contains(uv))
+			var layer = influence[a.Layer];
+			if (!layer.Contains(uv))
 				return false;
 
-			return AnyActorsAt(uv, a.Layer);
+			return AnyActorsAt(uv, layer);
 		}
 
 		// NOTE: pos required to be in map bounds
-		bool AnyActorsAt(MPos uv, CPos a, SubCell sub, bool checkTransient)
+		bool AnyActorsAt(MPos uv, CPos a, CellLayer<InfluenceNode> layer, SubCell sub, bool checkTransient)
 		{
 			var always = sub == SubCell.FullCell || sub == SubCell.Any;
-			var layer = a.Layer == 0 ? influence : customInfluence[a.Layer];
 			for (var i = layer[uv]; i != null; i = i.Next)
 			{
 				if (always || i.SubCell == sub || i.SubCell == SubCell.FullCell)
@@ -364,17 +374,17 @@ namespace OpenRA.Mods.Common.Traits
 		public bool AnyActorsAt(CPos a, SubCell sub, bool checkTransient = true)
 		{
 			var uv = a.ToMPos(map);
-			if (!influence.Contains(uv))
+			var layer = influence[a.Layer];
+			if (!layer.Contains(uv))
 				return false;
 
-			return AnyActorsAt(uv, a, sub, checkTransient);
+			return AnyActorsAt(uv, a, layer, sub, checkTransient);
 		}
 
 		// NOTE: can not check aircraft
-		bool AnyActorsAt(MPos uv, CPos a, SubCell sub, Func<Actor, bool> withCondition)
+		bool AnyActorsAt(MPos uv, CellLayer<InfluenceNode> layer, SubCell sub, Func<Actor, bool> withCondition)
 		{
 			var always = sub == SubCell.FullCell || sub == SubCell.Any;
-			var layer = a.Layer == 0 ? influence : customInfluence[a.Layer];
 			for (var i = layer[uv]; i != null; i = i.Next)
 				if ((always || i.SubCell == sub || i.SubCell == SubCell.FullCell) && !i.Actor.Disposed && withCondition(i.Actor))
 					return true;
@@ -386,10 +396,11 @@ namespace OpenRA.Mods.Common.Traits
 		public bool AnyActorsAt(CPos a, SubCell sub, Func<Actor, bool> withCondition)
 		{
 			var uv = a.ToMPos(map);
-			if (!influence.Contains(uv))
+			var layer = influence[a.Layer];
+			if (!layer.Contains(uv))
 				return false;
 
-			return AnyActorsAt(uv, a, sub, withCondition);
+			return AnyActorsAt(uv, layer, sub, withCondition);
 		}
 
 		public void AddInfluence(Actor self, IOccupySpace ios)
@@ -397,10 +408,10 @@ namespace OpenRA.Mods.Common.Traits
 			foreach (var c in ios.OccupiedCells())
 			{
 				var uv = c.Cell.ToMPos(map);
-				if (!influence.Contains(uv))
+				var layer = influence[c.Cell.Layer];
+				if (!layer.Contains(uv))
 					continue;
 
-				var layer = c.Cell.Layer == 0 ? influence : customInfluence[c.Cell.Layer];
 				layer[uv] = new InfluenceNode { Next = layer[uv], SubCell = c.SubCell, Actor = self };
 
 				if (cellTriggerInfluence.TryGetValue(c.Cell, out var triggers))
@@ -416,10 +427,10 @@ namespace OpenRA.Mods.Common.Traits
 			foreach (var c in ios.OccupiedCells())
 			{
 				var uv = c.Cell.ToMPos(map);
-				if (!influence.Contains(uv))
+				var layer = influence[c.Cell.Layer];
+				if (!layer.Contains(uv))
 					continue;
 
-				var layer = c.Cell.Layer == 0 ? influence : customInfluence[c.Cell.Layer];
 				var temp = layer[uv];
 				RemoveInfluenceInner(ref temp, self);
 				layer[uv] = temp;
@@ -496,9 +507,10 @@ namespace OpenRA.Mods.Common.Traits
 			var t = new CellTrigger(cells, onEntry, onExit);
 			cellTriggers.Add(id, t);
 
+			var layer = influence[0];
 			foreach (var c in cells)
 			{
-				if (!influence.Contains(c))
+				if (!layer.Contains(c))
 					continue;
 
 				if (!cellTriggerInfluence.ContainsKey(c))
@@ -649,7 +661,15 @@ namespace OpenRA.Mods.Common.Traits
 
 	public static class ActorMapWorldExts
 	{
-		public static Dictionary<int, ICustomMovementLayer> GetCustomMovementLayers(this World world)
+		/// <summary>
+		/// Returns an array of custom movement layers.
+		/// The <see cref="ICustomMovementLayer.Index"/> of a layer is used to index into this array.
+		/// This array may contain null entries for layers which are not present in the world.
+		/// This array is guaranteed to have a length of at least one. Index 0 is always null.
+		/// Index 0 is kept null as layer 0 is used for the ground layer, consumers can combine
+		/// the ground layer and custom layers into a single array for easy indexing.
+		/// </summary>
+		public static ICustomMovementLayer[] GetCustomMovementLayers(this World world)
 		{
 			return ((ActorMap)world.ActorMap).CustomMovementLayers;
 		}

OpenRA.Mods.Common/Traits/World/Locomotor.cs

@@ -144,18 +144,16 @@ namespace OpenRA.Mods.Common.Traits
 
 		public readonly LocomotorInfo Info;
 		public readonly uint MovementClass;
-		CellLayer<short> cellsCost;
-		CellLayer<CellCache> blockingCache;
-
-		readonly Dictionary<byte, CellLayer<short>> customLayerCellsCost = new Dictionary<byte, CellLayer<short>>();
-		readonly Dictionary<byte, CellLayer<CellCache>> customLayerBlockingCache = new Dictionary<byte, CellLayer<CellCache>>();
 
 		readonly LocomotorInfo.TerrainInfo[] terrainInfos;
 		readonly World world;
 		readonly HashSet<CPos> dirtyCells = new HashSet<CPos>();
+		readonly bool sharesCell;
+
+		CellLayer<short>[] cellsCost;
+		CellLayer<CellCache>[] blockingCache;
 
 		IActorMap actorMap;
-		bool sharesCell;
 
 		public Locomotor(Actor self, LocomotorInfo info)
 		{
@@ -177,7 +175,7 @@ namespace OpenRA.Mods.Common.Traits
 			if (!world.Map.Contains(cell))
 				return PathGraph.MovementCostForUnreachableCell;
 
-			return cell.Layer == 0 ? cellsCost[cell] : customLayerCellsCost[cell.Layer][cell];
+			return cellsCost[cell.Layer][cell];
 		}
 
 		public int MovementSpeedForCell(CPos cell)
@@ -193,7 +191,7 @@ namespace OpenRA.Mods.Common.Traits
 			if (!world.Map.Contains(destNode))
 				return PathGraph.MovementCostForUnreachableCell;
 
-			var cellCost = destNode.Layer == 0 ? cellsCost[destNode] : customLayerCellsCost[destNode.Layer][destNode];
+			var cellCost = cellsCost[destNode.Layer][destNode];
 
 			if (cellCost == PathGraph.MovementCostForUnreachableCell ||
 				!CanMoveFreelyInto(actor, destNode, check, ignoreActor))
@@ -359,8 +357,8 @@ namespace OpenRA.Mods.Common.Traits
 			actorMap = w.ActorMap;
 			actorMap.CellUpdated += CellUpdated;
 
-			blockingCache = new CellLayer<CellCache>(map);
+			cellsCost = new[] { new CellLayer<short>(map) };
-			cellsCost = new CellLayer<short>(map);
+			blockingCache = new[] { new CellLayer<CellCache>(map) };
 
 			foreach (var cell in map.AllCells)
 				UpdateCellCost(cell);
@@ -371,12 +369,17 @@ namespace OpenRA.Mods.Common.Traits
 			// This section needs to run after WorldLoaded() because we need to be sure that all types of ICustomMovementLayer have been initialized.
 			w.AddFrameEndTask(_ =>
 			{
-				var customMovementLayers = w.WorldActor.TraitsImplementing<ICustomMovementLayer>();
+				var cmls = world.GetCustomMovementLayers();
-				foreach (var cml in customMovementLayers)
+				Array.Resize(ref cellsCost, cmls.Length);
+				Array.Resize(ref blockingCache, cmls.Length);
+				foreach (var cml in cmls)
 				{
+					if (cml == null)
+						continue;
+
 					var cellLayer = new CellLayer<short>(map);
-					customLayerCellsCost[cml.Index] = cellLayer;
+					cellsCost[cml.Index] = cellLayer;
-					customLayerBlockingCache[cml.Index] = new CellLayer<CellCache>(map);
+					blockingCache[cml.Index] = new CellLayer<CellCache>(map);
 
 					foreach (var cell in map.AllCells)
 					{
@@ -395,13 +398,10 @@ namespace OpenRA.Mods.Common.Traits
 
 		CellCache GetCache(CPos cell)
 		{
-			if (dirtyCells.Contains(cell))
+			if (dirtyCells.Remove(cell))
-			{
 				UpdateCellBlocking(cell);
-				dirtyCells.Remove(cell);
-			}
 
-			var cache = cell.Layer == 0 ? blockingCache : customLayerBlockingCache[cell.Layer];
+			var cache = blockingCache[cell.Layer];
 
 			return cache[cell];
 		}
@@ -422,7 +422,7 @@ namespace OpenRA.Mods.Common.Traits
 			if (index != byte.MaxValue)
 				cost = terrainInfos[index].Cost;
 
-			var cache = cell.Layer == 0 ? cellsCost : customLayerCellsCost[cell.Layer];
+			var cache = cellsCost[cell.Layer];
 
 			cache[cell] = cost;
 		}
@@ -431,7 +431,7 @@ namespace OpenRA.Mods.Common.Traits
 		{
 			using (new PerfSample("locomotor_cache"))
 			{
-				var cache = cell.Layer == 0 ? blockingCache : customLayerBlockingCache[cell.Layer];
+				var cache = blockingCache[cell.Layer];
 
 				var actors = actorMap.GetActorsAt(cell);
 				var cellFlag = CellFlag.HasFreeSpace;