Improve PerfTimer output

OpenRA.Game/Support/PerfTimer.cs

@@ -9,6 +9,7 @@
 #endregion
 
 using System;
+using System.Linq;
 
 namespace OpenRA.Support
 {
@@ -16,27 +17,53 @@ namespace OpenRA.Support
 	{
 		readonly Stopwatch sw = new Stopwatch();
 		readonly string Name;
+
+		// Hacks to give the output a tree-like structure
 		static System.Threading.ThreadLocal<int> depth = new System.Threading.ThreadLocal<int>();
+		static System.Threading.ThreadLocal<string> prevHeader = new System.Threading.ThreadLocal<string>();
 
 		public PerfTimer(string name)
 		{
+			if (prevHeader.Value != null)
+			{
+				Log.Write("perf", prevHeader.Value);
+				prevHeader.Value = null;
+			}
+
 			this.Name = name;
+
+			prevHeader.Value = string.Format("{0}{1}", Indentation, this.Name);
 			depth.Value++;
 		}
 
+		private static string Indentation
+		{
+			get
+			{
+				var d = depth.Value;
+				if (d == 1)
+					return "|   ";
+				else if (d <= 0)
+					return string.Empty;
+				else
+					return string.Concat(Enumerable.Repeat("|   ", depth.Value));
+			}
+		}
+
 		public void Dispose()
 		{
-			string indentation;
-
-			if (--depth.Value >= 0)
-				indentation = new string('\t', depth.Value);
+			string format;
+			if (prevHeader.Value == null)
+			{
+				format = "{0}: {2} ms";
+			}
 			else
 			{
-				depth.Value = 0;
-				indentation = string.Empty;
+				format = "{0}{1}: {2} ms";
+				prevHeader.Value = null;
 			}
-
-			Log.Write("perf", "{0}{1}: {2} ms", indentation, this.Name, Math.Round(this.sw.Elapsed.TotalMilliseconds));
+			depth.Value--;
+			Log.Write("perf", format, Indentation, this.Name, Math.Round(this.sw.Elapsed.TotalMilliseconds));
 		}
 	}
 }