Add Generator to wrap some async calls in Task.Run().Result (#896)

Brightspace · Jul 13, 2023 · f73f16c · f73f16c
1 parent 549b42c
commit f73f16c
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Showing 2 changed files with 35 additions and 0 deletions.
diff --git a/src/D2L.CodeStyle.Analyzers/Async/Generator/AsyncToSyncMethodTransformer.cs b/src/D2L.CodeStyle.Analyzers/Async/Generator/AsyncToSyncMethodTransformer.cs
@@ -11,6 +11,9 @@ public AsyncToSyncMethodTransformer(
 		CancellationToken token
 	) : base( model, token ) { }
 
+	// Need to disable D2L0018 in the method if we add Task.Run() to syncify something
+	private bool m_disableTaskRunWarningFlag;
+
 	public TransformResult<MethodDeclarationSyntax> Transform( MethodDeclarationSyntax decl ) {
 		// TODO: remove CancellationToken parameters
 		decl = decl.WithAttributeLists( ReplaceGenerateSyncAttribute( decl.AttributeLists ) )
@@ -19,6 +22,18 @@ public TransformResult<MethodDeclarationSyntax> Transform( MethodDeclarationSynt
 			.WithReturnType( TransformType( decl.ReturnType, isReturnType: true ) )
 			.WithExpressionBody( MaybeTransform( decl.ExpressionBody, Transform ) )
 			.WithBody( MaybeTransform( decl.Body, Transform ) );
+
+		if ( m_disableTaskRunWarningFlag ) {
+			PragmaWarningDirectiveTriviaSyntax restorePragma = SyntaxFactory.PragmaWarningDirectiveTrivia( SyntaxFactory.Token( SyntaxKind.RestoreKeyword ), true )
+				.AddErrorCodes( SyntaxFactory.IdentifierName( "D2L0018" ) ).NormalizeWhitespace().WithLeadingTrivia( SyntaxFactory.SyntaxTrivia( SyntaxKind.EndOfLineTrivia, "\n" ) ); ;
+			PragmaWarningDirectiveTriviaSyntax disablePragma = SyntaxFactory.PragmaWarningDirectiveTrivia( SyntaxFactory.Token( SyntaxKind.DisableKeyword ), true )
+				.AddErrorCodes( SyntaxFactory.IdentifierName( "D2L0018" ) ).NormalizeWhitespace();
+			decl = decl
+				.WithLeadingTrivia( decl.GetLeadingTrivia().Add( SyntaxFactory.Trivia( disablePragma ) ) )
+				.WithTrailingTrivia( decl.GetTrailingTrivia().Insert( 0, SyntaxFactory.Trivia( restorePragma ) ) );
+			m_disableTaskRunWarningFlag = false;
+		}
+
 		return GetResult( decl );
 	}
 
@@ -272,19 +287,30 @@ private ExpressionSyntax Transform( InvocationExpressionSyntax invocationExpr) {
 				newExpr = memberAccess.Expression;
 				return Transform( newExpr );
 			}
+		} else if( memberAccess is not null && ShouldWrapMemberAccessInTaskRun( memberAccess ) ) {
+			m_disableTaskRunWarningFlag = true;
+			return SyntaxFactory.ParseExpression( $"Task.Run(() => {invocationExpr}).Result" );
 		}
+
 		return invocationExpr
 			.WithExpression( Transform( invocationExpr.Expression ) )
 			.WithArgumentList( TransformAll( invocationExpr.ArgumentList, Transform ) );
 	}
 
+	// TODO: These two methods may need future modification for more specificity (make sure it's Task.FromResult or Content.ReadAsStringAsync)
 	bool ShouldRemoveReturnedMemberAccess( MemberAccessExpressionSyntax memberAccessExpr )
 	  => memberAccessExpr.Name.Identifier.ValueText switch {
 		  "FromResult" => true,
 		  "CompletedTask" => true,
 		  _ => false
 	  };
 
+	bool ShouldWrapMemberAccessInTaskRun( MemberAccessExpressionSyntax memberAccessExpr )
+	  => memberAccessExpr.Name.Identifier.ValueText switch {
+		  "ReadAsStringAsync" => true,
+		  _ => false
+	  };
+
 	private ExpressionSyntax Transform( MemberAccessExpressionSyntax memberAccessExpr ) {
 		if( memberAccessExpr.IsKind( SyntaxKind.SimpleMemberAccessExpression ) ) {
 			if( ShouldRemoveReturnedMemberAccess( memberAccessExpr ) &&

diff --git a/tests/D2L.CodeStyle.Analyzers.Test/Async/Generator/AsyncToSyncMethodTransformerTests.cs b/tests/D2L.CodeStyle.Analyzers.Test/Async/Generator/AsyncToSyncMethodTransformerTests.cs
@@ -175,6 +175,15 @@ public void SimpleLambda() {
 		Assert.AreEqual( "[Blocking] void Bar() { Func<int, Task> baz = quux => fred.Delay( 2*y ); }", actual.Value.ToFullString() );
 	}
 
+	[Test]
+	public void WrapInTaskRun() {
+		var actual = Transform( @"[GenerateSync] async Task BarAsync() { string baz = await response.Content.ReadAsStringAsync(); }" );
+
+		Assert.IsTrue( actual.Success );
+		Assert.IsEmpty( actual.Diagnostics );
+		Assert.AreEqual( "#pragma warning disable D2L0018\r\n[Blocking] void Bar() { string baz = Task.Run(() => response.Content.ReadAsStringAsync()).Result; }\n#pragma warning restore D2L0018\r\n", actual.Value.ToFullString() );
+	}
+
 	[Test]
 	public void TryCatch() {
 		var actual = Transform( @"[GenerateSync]