From 775c4ebcf441b503134fb1f79e793e78c305ba30 Mon Sep 17 00:00:00 2001
From: Sam Harwell <Sam.Harwell@microsoft.com>
Date: Fri, 24 Jan 2020 08:54:54 -0800
Subject: [PATCH] Replace PooledStopwatch with SharedStopwatch

---
 .../DiagnosticAnalyzer/AnalyzerExecutor.cs    | 11 ++-
 .../InternalUtilities/SharedStopwatch.cs      | 67 +++++++++++++++++++
 ...osoft.CodeAnalysis.PooledObjects.projitems |  1 -
 .../PooledObjects/PooledStopwatch.cs          | 41 ------------
 .../Microsoft.CodeAnalysis.Workspaces.csproj  |  1 +
 5 files changed, 73 insertions(+), 48 deletions(-)
 create mode 100644 src/Compilers/Core/Portable/InternalUtilities/SharedStopwatch.cs
 delete mode 100644 src/Dependencies/PooledObjects/PooledStopwatch.cs

diff --git a/src/Compilers/Core/Portable/DiagnosticAnalyzer/AnalyzerExecutor.cs b/src/Compilers/Core/Portable/DiagnosticAnalyzer/AnalyzerExecutor.cs
index f75b019efe612..85b1658895f54 100644
--- a/src/Compilers/Core/Portable/DiagnosticAnalyzer/AnalyzerExecutor.cs
+++ b/src/Compilers/Core/Portable/DiagnosticAnalyzer/AnalyzerExecutor.cs
@@ -1448,10 +1448,10 @@ private void ExecuteAndCatchIfThrows_NoLock<TArg>(DiagnosticAnalyzer analyzer, A
             {
                 _cancellationToken.ThrowIfCancellationRequested();
 
-                PooledStopwatch timer = null;
+                SharedStopwatch timer = default;
                 if (_analyzerExecutionTimeMapOpt != null)
                 {
-                    timer = PooledStopwatch.StartInstance();
+                    timer = SharedStopwatch.StartNew();
 
                     // This call to Restart isn't required by the API, but is included to avoid measurement errors which
                     // can occur during periods of high allocation activity. In some cases, calls to Stopwatch
@@ -1468,12 +1468,11 @@ private void ExecuteAndCatchIfThrows_NoLock<TArg>(DiagnosticAnalyzer analyzer, A
 
                 analyze(argument);
 
-                if (timer != null)
+                if (_analyzerExecutionTimeMapOpt != null)
                 {
-                    timer.Stop();
+                    var elapsed = timer.Elapsed.Ticks;
                     StrongBox<long> totalTicks = _analyzerExecutionTimeMapOpt.GetOrAdd(analyzer, _ => new StrongBox<long>(0));
-                    Interlocked.Add(ref totalTicks.Value, timer.Elapsed.Ticks);
-                    timer.Free();
+                    Interlocked.Add(ref totalTicks.Value, elapsed);
                 }
             }
             catch (Exception e) when (ExceptionFilter(e))
diff --git a/src/Compilers/Core/Portable/InternalUtilities/SharedStopwatch.cs b/src/Compilers/Core/Portable/InternalUtilities/SharedStopwatch.cs
new file mode 100644
index 0000000000000..af862c08955d7
--- /dev/null
+++ b/src/Compilers/Core/Portable/InternalUtilities/SharedStopwatch.cs
@@ -0,0 +1,67 @@
+// 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;
+using System.Diagnostics;
+
+namespace Roslyn.Utilities
+{
+    internal struct SharedStopwatch
+    {
+        private static readonly Stopwatch s_stopwatch = Stopwatch.StartNew();
+
+        private TimeSpan _accumulated;
+        private TimeSpan _started;
+
+        public readonly TimeSpan Elapsed
+        {
+            get
+            {
+                if (IsRunning)
+                    return _accumulated + s_stopwatch.Elapsed - _started;
+
+                return _accumulated;
+            }
+        }
+
+        public readonly long ElapsedMilliseconds => (long)Elapsed.TotalMilliseconds;
+        public readonly bool IsRunning => _started != TimeSpan.Zero;
+
+        public static SharedStopwatch StartNew()
+        {
+            var result = new SharedStopwatch();
+            result.Start();
+            return result;
+        }
+
+        public void Reset()
+        {
+            Stop();
+            _accumulated = TimeSpan.Zero;
+        }
+
+        public void Restart()
+        {
+            Reset();
+            Start();
+        }
+
+        public void Start()
+        {
+            if (!IsRunning)
+            {
+                _started = s_stopwatch.Elapsed;
+            }
+        }
+
+        public void Stop()
+        {
+            if (IsRunning)
+            {
+                _accumulated += s_stopwatch.Elapsed - _started;
+                _started = TimeSpan.Zero;
+            }
+        }
+    }
+}
diff --git a/src/Dependencies/PooledObjects/Microsoft.CodeAnalysis.PooledObjects.projitems b/src/Dependencies/PooledObjects/Microsoft.CodeAnalysis.PooledObjects.projitems
index 48f150a955713..13eaee66873fc 100644
--- a/src/Dependencies/PooledObjects/Microsoft.CodeAnalysis.PooledObjects.projitems
+++ b/src/Dependencies/PooledObjects/Microsoft.CodeAnalysis.PooledObjects.projitems
@@ -15,7 +15,6 @@
     <Compile Include="$(MSBuildThisFileDirectory)ObjectPool`1.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)PooledDictionary.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)PooledHashSet.cs" />
-    <Compile Include="$(MSBuildThisFileDirectory)PooledStopwatch.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)PooledStringBuilder.cs" />
   </ItemGroup>
 </Project>
\ No newline at end of file
diff --git a/src/Dependencies/PooledObjects/PooledStopwatch.cs b/src/Dependencies/PooledObjects/PooledStopwatch.cs
deleted file mode 100644
index 15fe84796d380..0000000000000
--- a/src/Dependencies/PooledObjects/PooledStopwatch.cs
+++ /dev/null
@@ -1,41 +0,0 @@
-// 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;
-using System.Diagnostics;
-
-namespace Microsoft.CodeAnalysis.PooledObjects
-{
-    internal class PooledStopwatch : Stopwatch
-    {
-        private static readonly ObjectPool<PooledStopwatch> s_poolInstance = CreatePool();
-
-        private readonly ObjectPool<PooledStopwatch> _pool;
-
-        private PooledStopwatch(ObjectPool<PooledStopwatch> pool)
-        {
-            _pool = pool;
-        }
-
-        public void Free()
-        {
-            Reset();
-            _pool?.Free(this);
-        }
-
-        public static ObjectPool<PooledStopwatch> CreatePool()
-        {
-            ObjectPool<PooledStopwatch> pool = null;
-            pool = new ObjectPool<PooledStopwatch>(() => new PooledStopwatch(pool), 128);
-            return pool;
-        }
-
-        public static PooledStopwatch StartInstance()
-        {
-            var instance = s_poolInstance.Allocate();
-            instance.Restart();
-            return instance;
-        }
-    }
-}
diff --git a/src/Workspaces/Core/Portable/Microsoft.CodeAnalysis.Workspaces.csproj b/src/Workspaces/Core/Portable/Microsoft.CodeAnalysis.Workspaces.csproj
index 524bc035d673b..06c554c4babbc 100644
--- a/src/Workspaces/Core/Portable/Microsoft.CodeAnalysis.Workspaces.csproj
+++ b/src/Workspaces/Core/Portable/Microsoft.CodeAnalysis.Workspaces.csproj
@@ -27,6 +27,7 @@
   <ItemGroup Label="Linked Files">
     <Compile Remove="Storage\Sqlite\**\*.cs" Condition="'$(DotNetBuildFromSource)' == 'true'" />
     <Compile Include="..\..\..\CodeStyle\Core\CodeFixes\FixAllContextHelper.cs" Link="CodeFixes\FixAllOccurrences\FixAllContextHelper.cs" />
+    <Compile Include="..\..\..\Compilers\Core\Portable\InternalUtilities\SharedStopwatch.cs" Link="InternalUtilities\SharedStopwatch.cs" />
     <Compile Include="..\..\..\Compilers\Shared\DesktopAnalyzerAssemblyLoader.cs">
       <Link>Execution\Desktop\DesktopAnalyzerAssemblyLoader.cs</Link>
     </Compile>