Run providers in parallel when determining if we should show the lightbulb icon

src/Features/Core/Portable/CodeRefactorings/CodeRefactoringService.cs

@@ -89,18 +89,58 @@ public async Task<bool> HasRefactoringsAsync(
         CodeActionOptionsProvider options,
         CancellationToken cancellationToken)
     {
-        foreach (var provider in GetProviders(document))
-        {
-            cancellationToken.ThrowIfCancellationRequested();
+        // A token for controlling the inner work we do calling out to each provider.  Once we have a single provider
+        // that returns a refactoring, we can cancel the work we're doing with all other providers.
+        using var linkedTokenSource = CancellationTokenSource.CreateLinkedTokenSource(cancellationToken);
+
+        // This await will not complete until all providers have been called (though we'll attempt to bail out of any of
+        // them once we have a single refactoring found).  So there's no concern here about produceItems running after
+        // linkedTokenSource has been diposed.
+        return await ProducerConsumer<VoidResult>.RunParallelAsync(
+            source: this.GetProviders(document),
+            produceItems: static async (provider, callback, args, cancellationToken) =>
+            {
+                var (@this, document, state, options, linkedTokenSource) = args;
 
-            var refactoring = await GetRefactoringFromProviderAsync(
-                document, state, provider, options, cancellationToken).ConfigureAwait(false);
+                // Do no work if either the outer request canceled, or another provider already found a refactoring.
+                if (cancellationToken.IsCancellationRequested || linkedTokenSource.Token.IsCancellationRequested)
+                    return;
 
-            if (refactoring != null)
-                return true;
-        }
+                try
+                {
+                    // We want to pass linkedTokenSource.Token here so that we can cancel the inner operation once the
+                    // outer ProducerConsumer sees a single refactoring returned by any provider.
+                    var refactoring = await @this.GetRefactoringFromProviderAsync(
+                        document, state, provider, options, linkedTokenSource.Token).ConfigureAwait(false);
+
+                    // If we have a refactoring, send a single VoidResult value to the consumer so it can cancel the
+                    // other concurrent operations, and can return 'true' to the caller to indicate that there are
+                    // refactorings.
+                    if (refactoring != null)
+                        callback(default(VoidResult));
+                }
+                catch (OperationCanceledException)
+                {
+                    // Ensure that the cancellation of the inner token doesn't bubble outside.  We are not canceling the
+                    // entire operation just because one provider succeeded and canceled the rest.
+                }
+            },
+            consumeItems: static async (items, args, cancellationToken) =>
+            {
+                // Try to consume from the results that produceItems is sending us.  The moment we get a single result,
+                // we know we're done and we have at least one refactoring.
+                await foreach (var unused in items)
+                {
+                    // Cancel all the other items that are still running (or are asked to run in the future).
+                    args.linkedTokenSource.Cancel();
+                    return true;
+                }
 
-        return false;
+                return false;
+            },
+            args: (this, document, state, options, linkedTokenSource),
+            // intentionally using the outer token here.  The linked token is only used to cancel the inner operations.
+            cancellationToken).ConfigureAwait(false);
     }
 
     public async Task<ImmutableArray<CodeRefactoring>> GetRefactoringsAsync(