Performance tweaks

- Avoid LINQ to create components.
- Do not recreate `Outcome<T>` for chaos.
- Avoid predicate allocation.
- Use `ArgumentNullException.ThrowIfNull()` where possible.
- Add throw helper for `ObjectDisposedException`.
- Remove unused `Stopwatch`.
- Use `Volatile.Read` instead of `Interlocked.CompareExchange()`.

Cherry-picked from #2664.

Co-Authored-By: Pent Ploompuu <[email protected]>

Author: martincostello

src/Polly.Core/ResiliencePipelineBuilderBase.cs

@@ -121,7 +121,7 @@ internal PipelineComponent BuildPipelineComponent()
 
         _used = true;
 
-        var components = _entries.Select(CreateComponent).ToList();
+        var components = _entries.ConvertAll(CreateComponent);
 
         if (components.Count == 0)
         {

src/Polly.Core/Simmy/Outcomes/ChaosOutcomeStrategy.cs

@@ -20,8 +20,8 @@ protected internal override async ValueTask<Outcome<T>> ExecuteCore<TState>(Func
     {
         try
         {
-            if (await ShouldInjectAsync(context).ConfigureAwait(context.ContinueOnCapturedContext)
-                && await _outcomeGenerator(new(context)).ConfigureAwait(context.ContinueOnCapturedContext) is Outcome<T> outcome)
+            if (await ShouldInjectAsync(context).ConfigureAwait(context.ContinueOnCapturedContext) &&
+                await _outcomeGenerator(new(context)).ConfigureAwait(context.ContinueOnCapturedContext) is Outcome<T> outcome)
             {
                 var args = new OnOutcomeInjectedArguments<T>(context, outcome);
                 _telemetry.Report(new(ResilienceEventSeverity.Information, ChaosOutcomeConstants.OnOutcomeInjectedEvent), context, args);
@@ -31,12 +31,7 @@ protected internal override async ValueTask<Outcome<T>> ExecuteCore<TState>(Func
                     await _onOutcomeInjected(args).ConfigureAwait(context.ContinueOnCapturedContext);
                 }
 
-                if (outcome.HasResult)
-                {
-                    return new Outcome<T>(outcome.Result);
-                }
-
-                return new Outcome<T>(outcome.Exception!);
+                return outcome;
             }
 
             return await StrategyHelper.ExecuteCallbackSafeAsync(callback, context, state).ConfigureAwait(context.ContinueOnCapturedContext);

src/Polly.Core/Utils/DefaultPredicates.cs

@@ -3,10 +3,5 @@
 internal static class DefaultPredicates<TArgs, TResult>
     where TArgs : IOutcomeArguments<TResult>
 {
-    public static readonly Func<TArgs, ValueTask<bool>> HandleOutcome = args => args.Outcome.Exception switch
-    {
-        OperationCanceledException => PredicateResult.False(),
-        Exception => PredicateResult.True(),
-        _ => PredicateResult.False(),
-    };
+    public static readonly Func<TArgs, ValueTask<bool>> HandleOutcome = args => new(args.Outcome.Exception is { } and not OperationCanceledException);
 }

src/Polly.Core/Utils/Guard.cs

@@ -9,10 +9,14 @@ internal static class Guard
     public static T NotNull<T>(T value, [CallerArgumentExpression("value")] string argumentName = "")
         where T : class
     {
+#if NET8_0_OR_GREATER
+        ArgumentNullException.ThrowIfNull(value, argumentName);
+#else
         if (value is null)
         {
             throw new ArgumentNullException(argumentName);
         }
+#endif
 
         return value;
     }

src/Polly.Core/Utils/Pipeline/ComponentDisposeHelper.cs

@@ -26,10 +26,12 @@ public void EnsureNotDisposed()
     {
         if (_disposed)
         {
-            throw new ObjectDisposedException("ResiliencePipeline", "This resilience pipeline has been disposed and cannot be used anymore.");
+            ThrowDisposed();
         }
     }
 
+    private static void ThrowDisposed() => throw new ObjectDisposedException("ResiliencePipeline", "This resilience pipeline has been disposed and cannot be used anymore.");
+
     public ValueTask ForceDisposeAsync()
     {
         _disposed = true;

src/Polly.Core/Utils/Pipeline/ExecutionTrackingComponent.cs

@@ -17,7 +17,7 @@ public ExecutionTrackingComponent(PipelineComponent component, TimeProvider time
 
     public PipelineComponent Component { get; }
 
-    public bool HasPendingExecutions => Interlocked.CompareExchange(ref _pendingExecutions, 0, 0) > 0;
+    public bool HasPendingExecutions => Volatile.Read(ref _pendingExecutions) > 0;
 
     internal override async ValueTask<Outcome<TResult>> ExecuteCore<TResult, TState>(
         Func<ResilienceContext, TState, ValueTask<Outcome<TResult>>> callback,
@@ -39,7 +39,6 @@ internal override async ValueTask<Outcome<TResult>> ExecuteCore<TResult, TState>
     public override async ValueTask DisposeAsync()
     {
         var start = _timeProvider.GetTimestamp();
-        var stopwatch = Stopwatch.StartNew();
 
         // We don't want to introduce locks or any synchronization primitives to main execution path
         // so we will do "dummy" retries until there are no more executions.