Provide names and pools when creating MiniYaml.

- Rename the filename parameter to name and make it mandatory. Review all callers and ensure a useful string is provided as input, to ensure sufficient context is included for logging and debugging. This can be a filename, url, or any arbitrary text so include whatever context seems reasonable.
- When several MiniYamls are created that have similar content, provide a shared string pool. This allows strings that are common between all the yaml to be shared, reducing long term memory usage. We also change the pool from a dictionary to a set. Originally a Dictionary had to be used so we could call TryGetValue to get a reference to the pooled string. Now that more recent versions of dotnet provide a TryGetValue on HashSet, we can use a set directly without the memory wasted by having to store both keys and values in a dictionary.

OpenRA.Game/Map/Map.cs

@@ -361,7 +361,7 @@ namespace OpenRA
 			if (!Package.Contains("map.yaml") || !Package.Contains("map.bin"))
 				throw new InvalidDataException($"Not a valid map\n File: {package.Name}");
 
-			var yaml = new MiniYaml(null, MiniYaml.FromStream(Package.GetStream("map.yaml"), package.Name));
+			var yaml = new MiniYaml(null, MiniYaml.FromStream(Package.GetStream("map.yaml"), $"{package.Name}:map.yaml"));
 			foreach (var field in YamlFields)
 				field.Deserialize(this, yaml);
 

OpenRA.Game/Map/MapCache.cs

@@ -38,7 +38,7 @@ namespace OpenRA
 		readonly object syncRoot = new();
 		readonly Queue<MapPreview> generateMinimap = new();
 
-		public Dictionary<string, string> StringPool { get; } = new Dictionary<string, string>();
+		public HashSet<string> StringPool { get; } = new();
 
 		readonly List<MapDirectoryTracker> mapDirectoryTrackers = new();
 
@@ -238,6 +238,7 @@ namespace OpenRA
 			Task.Run(async () =>
 			{
 				var client = HttpClientFactory.Create();
+				var stringPool = new HashSet<string>(); // Reuse common strings in YAML
 
 				// Limit each query to 50 maps at a time to avoid request size limits
 				for (var i = 0; i < queryUids.Count; i += 50)
@@ -249,7 +250,7 @@ namespace OpenRA
 						var httpResponseMessage = await client.GetAsync(url);
 						var result = await httpResponseMessage.Content.ReadAsStreamAsync();
 
-						var yaml = MiniYaml.FromStream(result);
+						var yaml = MiniYaml.FromStream(result, url, stringPool: stringPool);
 						foreach (var kv in yaml)
 							previews[kv.Key].UpdateRemoteSearch(MapStatus.DownloadAvailable, kv.Value, modData.Manifest.MapCompatibility, mapDetailsReceived);
 

OpenRA.Game/Map/MapPreview.cs

@@ -140,9 +140,10 @@ namespace OpenRA
 							files = files.Append(mapFiles);
 						}
 
+						var stringPool = new HashSet<string>(); // Reuse common strings in YAML
 						var sources =
 							modDataRules.Select(x => x.Where(IsLoadableRuleDefinition).ToList())
-							.Concat(files.Select(s => MiniYaml.FromStream(fileSystem.Open(s), s).Where(IsLoadableRuleDefinition).ToList()));
+							.Concat(files.Select(s => MiniYaml.FromStream(fileSystem.Open(s), s, stringPool: stringPool).Where(IsLoadableRuleDefinition).ToList()));
 						if (RuleDefinitions.Nodes.Length > 0)
 							sources = sources.Append(RuleDefinitions.Nodes.Where(IsLoadableRuleDefinition).ToList());
 
@@ -334,7 +335,7 @@ namespace OpenRA
 				if (yamlStream == null)
 					throw new FileNotFoundException("Required file map.yaml not present in this map");
 
-				yaml = new MiniYaml(null, MiniYaml.FromStream(yamlStream, "map.yaml", stringPool: cache.StringPool)).ToDictionary();
+				yaml = new MiniYaml(null, MiniYaml.FromStream(yamlStream, $"{p.Name}:map.yaml", stringPool: cache.StringPool)).ToDictionary();
 			}
 
 			Package = p;
@@ -475,10 +476,12 @@ namespace OpenRA
 					}
 
 					var playersString = Encoding.UTF8.GetString(Convert.FromBase64String(r.players_block));
-					newData.Players = new MapPlayers(MiniYaml.FromString(playersString));
+					newData.Players = new MapPlayers(MiniYaml.FromString(playersString,
+						$"{yaml.NodeWithKey(nameof(r.players_block)).Location.Name}:{nameof(r.players_block)}"));
 
 					var rulesString = Encoding.UTF8.GetString(Convert.FromBase64String(r.rules));
-					var rulesYaml = new MiniYaml("", MiniYaml.FromString(rulesString)).ToDictionary();
+					var rulesYaml = new MiniYaml("", MiniYaml.FromString(rulesString,
+						$"{yaml.NodeWithKey(nameof(r.rules)).Location.Name}:{nameof(r.rules)}")).ToDictionary();
 					newData.SetCustomRules(modData, this, rulesYaml, null);
 
 					// Map is for a different mod: update its information so it can be displayed