[internal] disposable performance helpers

Xamarin.Forms.Build.Tasks/PerformanceProvider.cs

@@ -0,0 +1,93 @@
+using System;
+using System.Collections.Generic;
+using System.Diagnostics;
+using System.Linq;
+using System.Runtime.CompilerServices;
+using Xamarin.Forms.Internals;
+
+namespace Xamarin.Forms.Build.Tasks
+{
+	[Preserve(AllMembers = true)]
+	internal class PerformanceProvider : IPerformanceProvider
+	{
+		internal class Statistic
+		{
+			public readonly List<Tuple<string, long>> StartTimes = new List<Tuple<string, long>>();
+			public int CallCount;
+			public long TotalTime;
+			public bool IsDetail;
+		}
+
+		readonly Dictionary<string, Statistic> _Statistics = new Dictionary<string, Statistic>();
+
+		public Dictionary<string, Statistic> Statistics {
+			get { return _Statistics; }
+		}
+
+		public void Clear()
+		{
+			Statistics.Clear();
+		}
+
+		public void Start(string reference, string tag = null, [CallerFilePath] string path = null, [CallerMemberName] string member = null)
+		{
+			string id = GetId(tag, path, member);
+
+			Statistic stats = GetStat(id);
+
+			if (tag != null)
+				stats.IsDetail = true;
+
+			stats.CallCount++;
+			stats.StartTimes.Add(new Tuple<string, long>(reference, Stopwatch.GetTimestamp()));
+		}
+
+		public void Stop(string reference, string tag = null, [CallerFilePath] string path = null, [CallerMemberName] string member = null)
+		{
+			string id = GetId(tag, path, member);
+			long stop = Stopwatch.GetTimestamp();
+
+			Statistic stats = GetStat(id);
+
+			if (!stats.StartTimes.Any())
+				return;
+
+			long start = stats.StartTimes.Single(s => s.Item1 == reference).Item2;
+			stats.TotalTime += stop - start;
+		}
+
+		public IEnumerable<string> GetStats()
+		{
+			yield return "ID                                                                                 | Call Count | Total Time | Avg Time";
+			foreach (KeyValuePair<string, Statistic> kvp in Statistics.OrderBy(kvp => kvp.Key)) {
+				string key = ShortenPath(kvp.Key);
+				double total = TimeSpan.FromTicks(kvp.Value.TotalTime).TotalMilliseconds;
+				double avg = total / kvp.Value.CallCount;
+				yield return string.Format("{0,-80} | {1,-10} | {2,-10}ms | {3,-8}ms", key, kvp.Value.CallCount, total, avg);
+			}
+		}
+
+		static string ShortenPath(string path)
+		{
+			int index = path.IndexOf("Xamarin.Forms.");
+			if (index > -1)
+				path = path.Substring(index + 14);
+
+			return path;
+		}
+
+		static string GetId(string tag, string path, string member)
+		{
+			return string.Format("{0}:{1}{2}", path, member, (tag != null ? "-" + tag : string.Empty));
+		}
+
+		Statistic GetStat(string id)
+		{
+			Statistic stats;
+			if (!Statistics.TryGetValue(id, out stats)) {
+				Statistics[id] = stats = new Statistic();
+			}
+			return stats;
+		}
+	}
+}

Xamarin.Forms.Core/Performance.cs

@@ -1,5 +1,6 @@
 using System.ComponentModel;
 using System.Runtime.CompilerServices;
+using System;
 
 namespace Xamarin.Forms.Internals
 {
@@ -30,5 +31,32 @@ namespace Xamarin.Forms.Internals
 		{
 			Provider?.Stop(reference, tag, path, member);
 		}
+
+		internal static IDisposable StartNew(string tag = null, [CallerFilePath] string path = null, [CallerMemberName] string member = null)
+		{
+			return new DisposablePerformanceReference(tag, path, member);
+		}
+
+		class DisposablePerformanceReference : IDisposable
+		{
+			string _reference;
+			string _tag;
+			string _path;
+			string _member;
+
+			public DisposablePerformanceReference(string tag, string path, string member)
+			{
+				_reference = Guid.NewGuid().ToString();
+				_tag = tag;
+				_path = path;
+				_member = member;
+				Start(_reference, _tag, _path, _member);
+			}
+
+			public void Dispose()
+			{
+				Stop(_reference, _tag, _path, _member);
+			}
+		}
 	}
 }