Use precise StartTime and duration on .NET Desktop

7 files changed, 85 insertions, 3 deletions

diff --git a/src/System.Diagnostics.DiagnosticSource/src/AssemblyInfo.Net46.cs b/src/System.Diagnostics.DiagnosticSource/src/AssemblyInfo.netfx.cs
index bfb744e1bc..bfb744e1bc 100644
--- a/src/System.Diagnostics.DiagnosticSource/src/AssemblyInfo.Net46.cs
+++ b/src/System.Diagnostics.DiagnosticSource/src/AssemblyInfo.netfx.cs
diff --git a/src/System.Diagnostics.DiagnosticSource/src/System.Diagnostics.DiagnosticSource.csproj b/src/System.Diagnostics.DiagnosticSource/src/System.Diagnostics.DiagnosticSource.csproj
index 3fc1281f86..19cf56deb9 100644
--- a/src/System.Diagnostics.DiagnosticSource/src/System.Diagnostics.DiagnosticSource.csproj
+++ b/src/System.Diagnostics.DiagnosticSource/src/System.Diagnostics.DiagnosticSource.csproj
@@ -59,6 +59,9 @@
     <TargetingPackReference Include="System" />
     <TargetingPackReference Include="System.Runtime.Remoting" />
   </ItemGroup>
+  <ItemGroup Condition=" '$(TargetGroup)' == 'netcoreapp' OR '$(TargetGroup)' == 'uap' OR '$(TargetGroup)' == 'netstandard1.1' OR '$(TargetGroup)' == 'netstandard1.3' OR '$(TargetGroup)' == 'netstandard'">
+    <Compile Include="System\Diagnostics\Activity.DateTime.corefx.cs" />
+  </ItemGroup>
   <ItemGroup Condition=" '$(TargetGroup)' == 'netstandard1.3' OR '$(TargetGroup)' == 'uap'">
     <Compile Include="System\Diagnostics\Activity.Id.Random.cs" />
   </ItemGroup>
@@ -78,7 +81,8 @@
     <Reference Include="System.Threading" />
   </ItemGroup>
   <ItemGroup Condition="'$(TargetGroup)' == 'net45' OR '$(TargetGroup)' == 'net46' OR '$(TargetGroup)' == 'netfx'">
-    <Compile Include="AssemblyInfo.Net46.cs" />
+    <Compile Include="AssemblyInfo.netfx.cs" />
+    <Compile Include="System\Diagnostics\Activity.DateTime.netfx.cs" />    
     <Reference Include="mscorlib" />
     <Reference Include="System" />
   </ItemGroup>
diff --git a/src/System.Diagnostics.DiagnosticSource/src/System/Diagnostics/Activity.DateTime.corefx.cs b/src/System.Diagnostics.DiagnosticSource/src/System/Diagnostics/Activity.DateTime.corefx.cs
new file mode 100644
index 0000000000..c485b41b7b
--- /dev/null
+++ b/src/System.Diagnostics.DiagnosticSource/src/System/Diagnostics/Activity.DateTime.corefx.cs
@@ -0,0 +1,14 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+namespace System.Diagnostics
+{
+    partial class Activity
+    {
+        private DateTime GetUtcNow()
+        {
+            return DateTime.UtcNow;
+        }
+    }
+}
\ No newline at end of file
diff --git a/src/System.Diagnostics.DiagnosticSource/src/System/Diagnostics/Activity.DateTime.netfx.cs b/src/System.Diagnostics.DiagnosticSource/src/System/Diagnostics/Activity.DateTime.netfx.cs
new file mode 100644
index 0000000000..d7e7ec349e
--- /dev/null
+++ b/src/System.Diagnostics.DiagnosticSource/src/System/Diagnostics/Activity.DateTime.netfx.cs
@@ -0,0 +1,35 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System.Threading;
+
+namespace System.Diagnostics
+{
+    partial class Activity
+    {
+        private DateTime GetUtcNow()
+        {
+            // Timer ticks need to be converted to DateTime ticks
+            long dateTimeTicksDiff = (long)((Stopwatch.GetTimestamp() - syncStopwatchTicks) * 10000000L /
+                                   (double)Stopwatch.Frequency);
+            
+            // DateTime.AddSeconds (or Milliseconds) rounds value to 1 ms, use AddTicks to prevent it
+            return syncUtcNow.AddTicks(dateTimeTicksDiff);
+        }
+
+        private static void Sync()
+        {
+            // wait for DateTime.UtcNow update to the next granular value
+            Thread.Sleep(1);
+            syncStopwatchTicks = Stopwatch.GetTimestamp();
+            syncUtcNow = DateTime.UtcNow;
+        }
+
+        private static DateTime syncUtcNow;
+        private static long syncStopwatchTicks;
+
+        // sync DateTime and Stopwatch ticks every 2 hours
+        private static Timer syncTimeUpdater = new Timer(s => { Sync(); }, null, 0, 7200000);
+    }
+}
\ No newline at end of file
diff --git a/src/System.Diagnostics.DiagnosticSource/src/System/Diagnostics/Activity.cs b/src/System.Diagnostics.DiagnosticSource/src/System/Diagnostics/Activity.cs
index 6342582d28..35f7083e30 100644
--- a/src/System.Diagnostics.DiagnosticSource/src/System/Diagnostics/Activity.cs
+++ b/src/System.Diagnostics.DiagnosticSource/src/System/Diagnostics/Activity.cs
@@ -303,7 +303,9 @@ namespace System.Diagnostics
                 }
 
                 if (StartTimeUtc == default(DateTime))
-                    StartTimeUtc = DateTime.UtcNow;
+                {
+                    StartTimeUtc = GetUtcNow();
+                }
 
                 Id = GenerateId();
                 Current = this;
@@ -331,7 +333,9 @@ namespace System.Diagnostics
                 isFinished = true;
 
                 if (Duration == TimeSpan.Zero)
-                    SetEndTime(DateTime.UtcNow);
+                {
+                    SetEndTime(GetUtcNow());
+                }
 
                 Current = Parent;
             }
diff --git a/src/System.Diagnostics.DiagnosticSource/tests/ActivityDateTimeTests.cs b/src/System.Diagnostics.DiagnosticSource/tests/ActivityDateTimeTests.cs
new file mode 100644
index 0000000000..feb17e2f13
--- /dev/null
+++ b/src/System.Diagnostics.DiagnosticSource/tests/ActivityDateTimeTests.cs
@@ -0,0 +1,24 @@
+using System.Threading;
+using Xunit;
+
+namespace System.Diagnostics.Tests
+{
+    public class ActivityDateTimeTests
+    {
+        [Fact]
+        public void StartStopReturnsPreciseDuration()
+        {
+            var activity = new Activity("test");
+
+            var sw = Stopwatch.StartNew();
+
+            activity.Start();
+            SpinWait.SpinUntil(() => sw.ElapsedMilliseconds > 1, 3);
+            activity.Stop();
+            
+            sw.Stop();
+
+            Assert.True(activity.Duration.TotalMilliseconds > 1 && activity.Duration.TotalMilliseconds <= sw.ElapsedMilliseconds);
+        }
+    }
+}
\ No newline at end of file
diff --git a/src/System.Diagnostics.DiagnosticSource/tests/System.Diagnostics.DiagnosticSource.Tests.csproj b/src/System.Diagnostics.DiagnosticSource/tests/System.Diagnostics.DiagnosticSource.Tests.csproj
index 10c2589941..b02dba964f 100644
--- a/src/System.Diagnostics.DiagnosticSource/tests/System.Diagnostics.DiagnosticSource.Tests.csproj
+++ b/src/System.Diagnostics.DiagnosticSource/tests/System.Diagnostics.DiagnosticSource.Tests.csproj
@@ -31,6 +31,7 @@
   </ItemGroup>
   <ItemGroup Condition=" '$(TargetGroup)' == 'netfx'">
     <Compile Include="HttpHandlerDiagnosticListenerTests.cs" />
+    <Compile Include="ActivityDateTimeTests.cs" />    
   </ItemGroup>
   <Import Project="$([MSBuild]::GetDirectoryNameOfFileAbove($(MSBuildThisFileDirectory), dir.targets))\dir.targets" />
 </Project>
\ No newline at end of file