From e1bc0d955fc639b385b30b070d219c805650f5e6 Mon Sep 17 00:00:00 2001
From: Weihan Li <weihanli@outlook.com>
Date: Fri, 15 May 2026 16:28:43 +0800
Subject: [PATCH 1/7] remove unnecessary RateLimiterHelper

---
 .../src/System.Threading.RateLimiting.csproj  |  1 -
 .../RateLimiting/ConcurrencyLimiter.cs        |  2 +-
 .../RateLimiting/FixedWindowRateLimiter.cs    |  8 +++---
 .../RateLimiting/RateLimiterHelper.cs         | 25 -------------------
 .../RateLimiting/SlidingWindowRateLimiter.cs  |  4 +--
 .../RateLimiting/TokenBucketRateLimiter.cs    |  4 +--
 6 files changed, 9 insertions(+), 35 deletions(-)
 delete mode 100644 src/libraries/System.Threading.RateLimiting/src/System/Threading/RateLimiting/RateLimiterHelper.cs

diff --git a/src/libraries/System.Threading.RateLimiting/src/System.Threading.RateLimiting.csproj b/src/libraries/System.Threading.RateLimiting/src/System.Threading.RateLimiting.csproj
index 3c88d1d10983f4..072eb957316187 100644
--- a/src/libraries/System.Threading.RateLimiting/src/System.Threading.RateLimiting.csproj
+++ b/src/libraries/System.Threading.RateLimiting/src/System.Threading.RateLimiting.csproj
@@ -30,7 +30,6 @@ System.Threading.RateLimiting.RateLimitLease</PackageDescription>
     <Compile Include="System\Threading\RateLimiting\PartitionedRateLimiter.T.cs" />
     <Compile Include="System\Threading\RateLimiting\QueueProcessingOrder.cs" />
     <Compile Include="System\Threading\RateLimiting\RateLimiter.cs" />
-    <Compile Include="System\Threading\RateLimiting\RateLimiterHelper.cs" />
     <Compile Include="System\Threading\RateLimiting\RateLimiterStatistics.cs" />
     <Compile Include="System\Threading\RateLimiting\RateLimitLease.cs" />
     <Compile Include="System\Threading\RateLimiting\RateLimitPartition.cs" />
diff --git a/src/libraries/System.Threading.RateLimiting/src/System/Threading/RateLimiting/ConcurrencyLimiter.cs b/src/libraries/System.Threading.RateLimiting/src/System/Threading/RateLimiting/ConcurrencyLimiter.cs
index a4030f8985e8b8..2750990a1c6f6e 100644
--- a/src/libraries/System.Threading.RateLimiting/src/System/Threading/RateLimiting/ConcurrencyLimiter.cs
+++ b/src/libraries/System.Threading.RateLimiting/src/System/Threading/RateLimiting/ConcurrencyLimiter.cs
@@ -32,7 +32,7 @@ public sealed class ConcurrencyLimiter : RateLimiter
         private object Lock => _queue;
 
         /// <inheritdoc />
-        public override TimeSpan? IdleDuration => RateLimiterHelper.GetElapsedTime(_idleSince);
+        public override TimeSpan? IdleDuration => Stopwatch.GetElapsedTime(_idleSince);
         /// <summary>
         /// Initializes the <see cref="ConcurrencyLimiter"/>.
         /// </summary>
diff --git a/src/libraries/System.Threading.RateLimiting/src/System/Threading/RateLimiting/FixedWindowRateLimiter.cs b/src/libraries/System.Threading.RateLimiting/src/System/Threading/RateLimiting/FixedWindowRateLimiter.cs
index ce241a6a342a07..5d7162ec407cda 100644
--- a/src/libraries/System.Threading.RateLimiting/src/System/Threading/RateLimiting/FixedWindowRateLimiter.cs
+++ b/src/libraries/System.Threading.RateLimiting/src/System/Threading/RateLimiting/FixedWindowRateLimiter.cs
@@ -24,10 +24,10 @@ public sealed class FixedWindowRateLimiter : ReplenishingRateLimiter
 
         /// <summary>
         /// Function to calculate elapsed time from a given tick value.
-        /// Defaults to <see cref="RateLimiterHelper.GetElapsedTime(long?)"/>.
+        /// Defaults to <see cref="Stopwatch.GetElapsedTime(long?)"/>.
         /// In tests, this field can be reassigned via reflection to inject custom time behavior without modifying the public API.
         /// </summary>
-        private readonly Func<long?, TimeSpan?> _getElapsedTime = RateLimiterHelper.GetElapsedTime;
+        private readonly Func<long?, TimeSpan?> _getElapsedTime = Stopwatch.GetElapsedTime;
 
         private readonly Timer? _renewTimer;
         private readonly FixedWindowRateLimiterOptions _options;
@@ -39,7 +39,7 @@ public sealed class FixedWindowRateLimiter : ReplenishingRateLimiter
         private static readonly RateLimitLease FailedLease = new FixedWindowLease(false, null);
 
         /// <inheritdoc />
-        public override TimeSpan? IdleDuration => RateLimiterHelper.GetElapsedTime(_idleSince);
+        public override TimeSpan? IdleDuration => Stopwatch.GetElapsedTime(_idleSince);
 
         /// <inheritdoc />
         public override bool IsAutoReplenishing => _options.AutoReplenishment;
@@ -301,7 +301,7 @@ private void ReplenishInternal(long nowTicks)
                     return;
                 }
 
-                if (RateLimiterHelper.GetElapsedTime(_lastReplenishmentTick, nowTicks) < _options.Window && !_options.AutoReplenishment)
+                if (Stopwatch.GetElapsedTime(_lastReplenishmentTick, nowTicks) < _options.Window && !_options.AutoReplenishment)
                 {
                     return;
                 }
diff --git a/src/libraries/System.Threading.RateLimiting/src/System/Threading/RateLimiting/RateLimiterHelper.cs b/src/libraries/System.Threading.RateLimiting/src/System/Threading/RateLimiting/RateLimiterHelper.cs
deleted file mode 100644
index e538fc720072dd..00000000000000
--- a/src/libraries/System.Threading.RateLimiting/src/System/Threading/RateLimiting/RateLimiterHelper.cs
+++ /dev/null
@@ -1,25 +0,0 @@
-// Licensed to the .NET Foundation under one or more agreements.
-// The .NET Foundation licenses this file to you under the MIT license.
-
-using System.Diagnostics;
-
-namespace System.Threading.RateLimiting
-{
-    internal static class RateLimiterHelper
-    {
-        public static TimeSpan? GetElapsedTime(long? startTimestamp)
-        {
-            if (startTimestamp is null)
-            {
-                return null;
-            }
-
-            return Stopwatch.GetElapsedTime(startTimestamp.Value);
-        }
-
-        public static TimeSpan GetElapsedTime(long startTimestamp, long endTimestamp)
-        {
-            return Stopwatch.GetElapsedTime(startTimestamp, endTimestamp);
-        }
-    }
-}
diff --git a/src/libraries/System.Threading.RateLimiting/src/System/Threading/RateLimiting/SlidingWindowRateLimiter.cs b/src/libraries/System.Threading.RateLimiting/src/System/Threading/RateLimiting/SlidingWindowRateLimiter.cs
index 29b16440cd8e03..97db943867915b 100644
--- a/src/libraries/System.Threading.RateLimiting/src/System/Threading/RateLimiting/SlidingWindowRateLimiter.cs
+++ b/src/libraries/System.Threading.RateLimiting/src/System/Threading/RateLimiting/SlidingWindowRateLimiter.cs
@@ -36,7 +36,7 @@ public sealed class SlidingWindowRateLimiter : ReplenishingRateLimiter
         private static readonly RateLimitLease FailedLease = new SlidingWindowLease(false, null);
 
         /// <inheritdoc />
-        public override TimeSpan? IdleDuration => RateLimiterHelper.GetElapsedTime(_idleSince);
+        public override TimeSpan? IdleDuration => Stopwatch.GetElapsedTime(_idleSince);
 
         /// <inheritdoc />
         public override bool IsAutoReplenishing => _options.AutoReplenishment;
@@ -293,7 +293,7 @@ private void ReplenishInternal(long nowTicks)
                     return;
                 }
 
-                if (RateLimiterHelper.GetElapsedTime(_lastReplenishmentTick, nowTicks) < ReplenishmentPeriod && !_options.AutoReplenishment)
+                if (Stopwatch.GetElapsedTime(_lastReplenishmentTick, nowTicks) < ReplenishmentPeriod && !_options.AutoReplenishment)
                 {
                     return;
                 }
diff --git a/src/libraries/System.Threading.RateLimiting/src/System/Threading/RateLimiting/TokenBucketRateLimiter.cs b/src/libraries/System.Threading.RateLimiting/src/System/Threading/RateLimiting/TokenBucketRateLimiter.cs
index 5c73c3671eaeff..a0bfc3368a1fff 100644
--- a/src/libraries/System.Threading.RateLimiting/src/System/Threading/RateLimiting/TokenBucketRateLimiter.cs
+++ b/src/libraries/System.Threading.RateLimiting/src/System/Threading/RateLimiting/TokenBucketRateLimiter.cs
@@ -34,7 +34,7 @@ public sealed class TokenBucketRateLimiter : ReplenishingRateLimiter
         private static readonly RateLimitLease FailedLease = new TokenBucketLease(false, null);
 
         /// <inheritdoc />
-        public override TimeSpan? IdleDuration => RateLimiterHelper.GetElapsedTime(_idleSince);
+        public override TimeSpan? IdleDuration => Stopwatch.GetElapsedTime(_idleSince);
 
         /// <inheritdoc />
         public override bool IsAutoReplenishing => _options.AutoReplenishment;
@@ -308,7 +308,7 @@ private void ReplenishInternal(long nowTicks)
                 }
                 else
                 {
-                    add = _fillRate * RateLimiterHelper.GetElapsedTime(_lastReplenishmentTick, nowTicks).Ticks;
+                    add = _fillRate * Stopwatch.GetElapsedTime(_lastReplenishmentTick, nowTicks).Ticks;
                 }
 
                 _tokenCount = Math.Min(_options.TokenLimit, _tokenCount + add);

From a0661b6334840c3553aa48eca66449322ee5e522 Mon Sep 17 00:00:00 2001
From: Weihan Li <weihanli@outlook.com>
Date: Fri, 15 May 2026 16:47:05 +0800
Subject: [PATCH 2/7] add extension for nullable support

---
 .../src/System.Threading.RateLimiting.csproj  |  1 +
 .../RateLimiting/RateLimiterHelper.cs         | 23 +++++++++++++++++++
 2 files changed, 24 insertions(+)
 create mode 100644 src/libraries/System.Threading.RateLimiting/src/System/Threading/RateLimiting/RateLimiterHelper.cs

diff --git a/src/libraries/System.Threading.RateLimiting/src/System.Threading.RateLimiting.csproj b/src/libraries/System.Threading.RateLimiting/src/System.Threading.RateLimiting.csproj
index 072eb957316187..3c88d1d10983f4 100644
--- a/src/libraries/System.Threading.RateLimiting/src/System.Threading.RateLimiting.csproj
+++ b/src/libraries/System.Threading.RateLimiting/src/System.Threading.RateLimiting.csproj
@@ -30,6 +30,7 @@ System.Threading.RateLimiting.RateLimitLease</PackageDescription>
     <Compile Include="System\Threading\RateLimiting\PartitionedRateLimiter.T.cs" />
     <Compile Include="System\Threading\RateLimiting\QueueProcessingOrder.cs" />
     <Compile Include="System\Threading\RateLimiting\RateLimiter.cs" />
+    <Compile Include="System\Threading\RateLimiting\RateLimiterHelper.cs" />
     <Compile Include="System\Threading\RateLimiting\RateLimiterStatistics.cs" />
     <Compile Include="System\Threading\RateLimiting\RateLimitLease.cs" />
     <Compile Include="System\Threading\RateLimiting\RateLimitPartition.cs" />
diff --git a/src/libraries/System.Threading.RateLimiting/src/System/Threading/RateLimiting/RateLimiterHelper.cs b/src/libraries/System.Threading.RateLimiting/src/System/Threading/RateLimiting/RateLimiterHelper.cs
new file mode 100644
index 00000000000000..f0e2e62f9172f5
--- /dev/null
+++ b/src/libraries/System.Threading.RateLimiting/src/System/Threading/RateLimiting/RateLimiterHelper.cs
@@ -0,0 +1,23 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System.Diagnostics;
+
+namespace System.Threading.RateLimiting
+{
+    internal static class RateLimiterHelper
+    {
+        extension(Stopwatch)
+        {
+            public static TimeSpan? GetElapsedTime(long? startTimestamp)
+            {
+                if (startTimestamp is null)
+                {
+                    return null;
+                }
+
+                return Stopwatch.GetElapsedTime(startTimestamp.Value);
+            }
+        }
+    }
+}
\ No newline at end of file

From 1feec42733d6ed56d3867f93153a65caa038752a Mon Sep 17 00:00:00 2001
From: Weihan Li <weihanli@outlook.com>
Date: Sat, 16 May 2026 08:46:14 +0800
Subject: [PATCH 3/7] fix build

---
 .../src/System/Threading/RateLimiting/FixedWindowRateLimiter.cs | 2 +-
 .../src/System/Threading/RateLimiting/RateLimiterHelper.cs      | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/libraries/System.Threading.RateLimiting/src/System/Threading/RateLimiting/FixedWindowRateLimiter.cs b/src/libraries/System.Threading.RateLimiting/src/System/Threading/RateLimiting/FixedWindowRateLimiter.cs
index 5d7162ec407cda..a1c7b478ab259f 100644
--- a/src/libraries/System.Threading.RateLimiting/src/System/Threading/RateLimiting/FixedWindowRateLimiter.cs
+++ b/src/libraries/System.Threading.RateLimiting/src/System/Threading/RateLimiting/FixedWindowRateLimiter.cs
@@ -24,7 +24,7 @@ public sealed class FixedWindowRateLimiter : ReplenishingRateLimiter
 
         /// <summary>
         /// Function to calculate elapsed time from a given tick value.
-        /// Defaults to <see cref="Stopwatch.GetElapsedTime(long?)"/>.
+        /// Defaults to <see cref="Stopwatch.GetElapsedTime(long)"/> when has value.
         /// In tests, this field can be reassigned via reflection to inject custom time behavior without modifying the public API.
         /// </summary>
         private readonly Func<long?, TimeSpan?> _getElapsedTime = Stopwatch.GetElapsedTime;
diff --git a/src/libraries/System.Threading.RateLimiting/src/System/Threading/RateLimiting/RateLimiterHelper.cs b/src/libraries/System.Threading.RateLimiting/src/System/Threading/RateLimiting/RateLimiterHelper.cs
index f0e2e62f9172f5..2ff6202b3dc950 100644
--- a/src/libraries/System.Threading.RateLimiting/src/System/Threading/RateLimiting/RateLimiterHelper.cs
+++ b/src/libraries/System.Threading.RateLimiting/src/System/Threading/RateLimiting/RateLimiterHelper.cs
@@ -20,4 +20,4 @@ internal static class RateLimiterHelper
             }
         }
     }
-}
\ No newline at end of file
+}

From f2a7a7efc5f62b004d9c44ab88289a3f89a41b35 Mon Sep 17 00:00:00 2001
From: Weihan Li <weihanli@outlook.com>
Date: Sat, 16 May 2026 12:26:16 +0800
Subject: [PATCH 4/7] update comment to remove code reference for
 Stopwatch.GetElapsedTime

---
 .../src/System/Threading/RateLimiting/FixedWindowRateLimiter.cs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/libraries/System.Threading.RateLimiting/src/System/Threading/RateLimiting/FixedWindowRateLimiter.cs b/src/libraries/System.Threading.RateLimiting/src/System/Threading/RateLimiting/FixedWindowRateLimiter.cs
index a1c7b478ab259f..c4fa3898e4d280 100644
--- a/src/libraries/System.Threading.RateLimiting/src/System/Threading/RateLimiting/FixedWindowRateLimiter.cs
+++ b/src/libraries/System.Threading.RateLimiting/src/System/Threading/RateLimiting/FixedWindowRateLimiter.cs
@@ -24,7 +24,7 @@ public sealed class FixedWindowRateLimiter : ReplenishingRateLimiter
 
         /// <summary>
         /// Function to calculate elapsed time from a given tick value.
-        /// Defaults to <see cref="Stopwatch.GetElapsedTime(long)"/> when has value.
+        /// Defaults to <c>Stopwatch.GetElapsedTime(long)</c> when has value.
         /// In tests, this field can be reassigned via reflection to inject custom time behavior without modifying the public API.
         /// </summary>
         private readonly Func<long?, TimeSpan?> _getElapsedTime = Stopwatch.GetElapsedTime;

From d7ef08e280c6c8bac422476fc1e3f43e93529cec Mon Sep 17 00:00:00 2001
From: Weihan Li <weihanli@outlook.com>
Date: Sat, 16 May 2026 22:31:22 +0800
Subject: [PATCH 5/7] improve comments

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>
---
 .../src/System/Threading/RateLimiting/FixedWindowRateLimiter.cs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/libraries/System.Threading.RateLimiting/src/System/Threading/RateLimiting/FixedWindowRateLimiter.cs b/src/libraries/System.Threading.RateLimiting/src/System/Threading/RateLimiting/FixedWindowRateLimiter.cs
index c4fa3898e4d280..2af3c948ba0e64 100644
--- a/src/libraries/System.Threading.RateLimiting/src/System/Threading/RateLimiting/FixedWindowRateLimiter.cs
+++ b/src/libraries/System.Threading.RateLimiting/src/System/Threading/RateLimiting/FixedWindowRateLimiter.cs
@@ -24,7 +24,7 @@ public sealed class FixedWindowRateLimiter : ReplenishingRateLimiter
 
         /// <summary>
         /// Function to calculate elapsed time from a given tick value.
-        /// Defaults to <c>Stopwatch.GetElapsedTime(long)</c> when has value.
+        /// Defaults to the <c>Stopwatch.GetElapsedTime(long?)</c> extension which returns <see langword="null"/> when the timestamp is <see langword="null"/>.
         /// In tests, this field can be reassigned via reflection to inject custom time behavior without modifying the public API.
         /// </summary>
         private readonly Func<long?, TimeSpan?> _getElapsedTime = Stopwatch.GetElapsedTime;

From b9cf51106d5a4515789e35596af7b88b933cda2b Mon Sep 17 00:00:00 2001
From: Weihan Li <weihanli@outlook.com>
Date: Sat, 16 May 2026 22:46:24 +0800
Subject: [PATCH 6/7] not use the extension to fix copilot comments

---
 .../Threading/RateLimiting/ConcurrencyLimiter.cs    |  2 +-
 .../RateLimiting/FixedWindowRateLimiter.cs          |  4 ++--
 .../Threading/RateLimiting/RateLimiterHelper.cs     | 13 +++++--------
 .../RateLimiting/SlidingWindowRateLimiter.cs        |  2 +-
 .../RateLimiting/TokenBucketRateLimiter.cs          |  2 +-
 5 files changed, 10 insertions(+), 13 deletions(-)

diff --git a/src/libraries/System.Threading.RateLimiting/src/System/Threading/RateLimiting/ConcurrencyLimiter.cs b/src/libraries/System.Threading.RateLimiting/src/System/Threading/RateLimiting/ConcurrencyLimiter.cs
index 2750990a1c6f6e..a4030f8985e8b8 100644
--- a/src/libraries/System.Threading.RateLimiting/src/System/Threading/RateLimiting/ConcurrencyLimiter.cs
+++ b/src/libraries/System.Threading.RateLimiting/src/System/Threading/RateLimiting/ConcurrencyLimiter.cs
@@ -32,7 +32,7 @@ public sealed class ConcurrencyLimiter : RateLimiter
         private object Lock => _queue;
 
         /// <inheritdoc />
-        public override TimeSpan? IdleDuration => Stopwatch.GetElapsedTime(_idleSince);
+        public override TimeSpan? IdleDuration => RateLimiterHelper.GetElapsedTime(_idleSince);
         /// <summary>
         /// Initializes the <see cref="ConcurrencyLimiter"/>.
         /// </summary>
diff --git a/src/libraries/System.Threading.RateLimiting/src/System/Threading/RateLimiting/FixedWindowRateLimiter.cs b/src/libraries/System.Threading.RateLimiting/src/System/Threading/RateLimiting/FixedWindowRateLimiter.cs
index 2af3c948ba0e64..19aab999fb8371 100644
--- a/src/libraries/System.Threading.RateLimiting/src/System/Threading/RateLimiting/FixedWindowRateLimiter.cs
+++ b/src/libraries/System.Threading.RateLimiting/src/System/Threading/RateLimiting/FixedWindowRateLimiter.cs
@@ -24,10 +24,10 @@ public sealed class FixedWindowRateLimiter : ReplenishingRateLimiter
 
         /// <summary>
         /// Function to calculate elapsed time from a given tick value.
-        /// Defaults to the <c>Stopwatch.GetElapsedTime(long?)</c> extension which returns <see langword="null"/> when the timestamp is <see langword="null"/>.
+        /// Defaults to the <see cref="RateLimiterHelper.GetElapsedTime(long?)"/> which returns <see langword="null"/> when the timestamp is <see langword="null"/>, and returns <c>Stopwatch.GetElapsedTime(long)</c> when not null.
         /// In tests, this field can be reassigned via reflection to inject custom time behavior without modifying the public API.
         /// </summary>
-        private readonly Func<long?, TimeSpan?> _getElapsedTime = Stopwatch.GetElapsedTime;
+        private readonly Func<long?, TimeSpan?> _getElapsedTime = RateLimiterHelper.GetElapsedTime;
 
         private readonly Timer? _renewTimer;
         private readonly FixedWindowRateLimiterOptions _options;
diff --git a/src/libraries/System.Threading.RateLimiting/src/System/Threading/RateLimiting/RateLimiterHelper.cs b/src/libraries/System.Threading.RateLimiting/src/System/Threading/RateLimiting/RateLimiterHelper.cs
index 2ff6202b3dc950..97184ba515082a 100644
--- a/src/libraries/System.Threading.RateLimiting/src/System/Threading/RateLimiting/RateLimiterHelper.cs
+++ b/src/libraries/System.Threading.RateLimiting/src/System/Threading/RateLimiting/RateLimiterHelper.cs
@@ -7,17 +7,14 @@ namespace System.Threading.RateLimiting
 {
     internal static class RateLimiterHelper
     {
-        extension(Stopwatch)
+        public static TimeSpan? GetElapsedTime(long? startTimestamp)
         {
-            public static TimeSpan? GetElapsedTime(long? startTimestamp)
+            if (startTimestamp is null)
             {
-                if (startTimestamp is null)
-                {
-                    return null;
-                }
-
-                return Stopwatch.GetElapsedTime(startTimestamp.Value);
+                return null;
             }
+
+            return Stopwatch.GetElapsedTime(startTimestamp.Value);
         }
     }
 }
diff --git a/src/libraries/System.Threading.RateLimiting/src/System/Threading/RateLimiting/SlidingWindowRateLimiter.cs b/src/libraries/System.Threading.RateLimiting/src/System/Threading/RateLimiting/SlidingWindowRateLimiter.cs
index 97db943867915b..ba2855cc888832 100644
--- a/src/libraries/System.Threading.RateLimiting/src/System/Threading/RateLimiting/SlidingWindowRateLimiter.cs
+++ b/src/libraries/System.Threading.RateLimiting/src/System/Threading/RateLimiting/SlidingWindowRateLimiter.cs
@@ -36,7 +36,7 @@ public sealed class SlidingWindowRateLimiter : ReplenishingRateLimiter
         private static readonly RateLimitLease FailedLease = new SlidingWindowLease(false, null);
 
         /// <inheritdoc />
-        public override TimeSpan? IdleDuration => Stopwatch.GetElapsedTime(_idleSince);
+        public override TimeSpan? IdleDuration => RateLimiterHelper.GetElapsedTime(_idleSince);
 
         /// <inheritdoc />
         public override bool IsAutoReplenishing => _options.AutoReplenishment;
diff --git a/src/libraries/System.Threading.RateLimiting/src/System/Threading/RateLimiting/TokenBucketRateLimiter.cs b/src/libraries/System.Threading.RateLimiting/src/System/Threading/RateLimiting/TokenBucketRateLimiter.cs
index a0bfc3368a1fff..dfb8ba7316ef6f 100644
--- a/src/libraries/System.Threading.RateLimiting/src/System/Threading/RateLimiting/TokenBucketRateLimiter.cs
+++ b/src/libraries/System.Threading.RateLimiting/src/System/Threading/RateLimiting/TokenBucketRateLimiter.cs
@@ -34,7 +34,7 @@ public sealed class TokenBucketRateLimiter : ReplenishingRateLimiter
         private static readonly RateLimitLease FailedLease = new TokenBucketLease(false, null);
 
         /// <inheritdoc />
-        public override TimeSpan? IdleDuration => Stopwatch.GetElapsedTime(_idleSince);
+        public override TimeSpan? IdleDuration => RateLimiterHelper.GetElapsedTime(_idleSince);
 
         /// <inheritdoc />
         public override bool IsAutoReplenishing => _options.AutoReplenishment;

From a2562fda4afbed5b49b5c129dcdafc2d1744af5f Mon Sep 17 00:00:00 2001
From: Weihan Li <weihanli@outlook.com>
Date: Sat, 16 May 2026 22:52:17 +0800
Subject: [PATCH 7/7] revert one more RateLimiterHelper.GetElapsedTime

---
 .../src/System/Threading/RateLimiting/FixedWindowRateLimiter.cs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/libraries/System.Threading.RateLimiting/src/System/Threading/RateLimiting/FixedWindowRateLimiter.cs b/src/libraries/System.Threading.RateLimiting/src/System/Threading/RateLimiting/FixedWindowRateLimiter.cs
index 19aab999fb8371..09fd69e770f65d 100644
--- a/src/libraries/System.Threading.RateLimiting/src/System/Threading/RateLimiting/FixedWindowRateLimiter.cs
+++ b/src/libraries/System.Threading.RateLimiting/src/System/Threading/RateLimiting/FixedWindowRateLimiter.cs
@@ -39,7 +39,7 @@ public sealed class FixedWindowRateLimiter : ReplenishingRateLimiter
         private static readonly RateLimitLease FailedLease = new FixedWindowLease(false, null);
 
         /// <inheritdoc />
-        public override TimeSpan? IdleDuration => Stopwatch.GetElapsedTime(_idleSince);
+        public override TimeSpan? IdleDuration => RateLimiterHelper.GetElapsedTime(_idleSince);
 
         /// <inheritdoc />
         public override bool IsAutoReplenishing => _options.AutoReplenishment;