[Question] Unused middleware code in grpc interceptor?

[ionling]

Is this unused middleware code in grpc interceptor?
The result returns by the middleware.Chain() is ignored.

kratos/transport/grpc/interceptor.go

Lines 87 to 89 in f8b97f6

	if next := s.streamMiddleware.Match(info.FullMethod); len(next) > 0 {
	middleware.Chain(next...)(h)
	}

And the code above conflicts with the following logic

kratos/transport/grpc/interceptor.go

Lines 124 to 126 in f8b97f6

	if next := w.middleware.Match(info.Operation()); len(next) > 0 {
	h = middleware.Chain(next...)(h)
	}

[dosubot]

The concern raised about the middleware.Chain() function in the interceptor.go file of the Kratos framework suggests that the result of this function is not being utilized, which could indicate unused or incorrectly integrated middleware code. In the context of gRPC interceptors, middleware.Chain() is intended to wrap a handler function with middleware, allowing for request and response processing. If the result of this chaining is not used, it means the middleware is not being applied as expected.

The specific lines mentioned (87-89 and 124-126) seem to involve logic where the result of middleware.Chain() should be integrated into the gRPC interceptor's logic. Typically, this would involve using the chained middleware to wrap the handler function, ensuring that the middleware is executed during request handling. If this is not happening, it could lead to middleware being defined but not actually applied, which might be a bug or oversight in the code.

To resolve this, a review of the code should ensure that the result of middleware.Chain() is used to wrap the handler function, thereby integrating the middleware into the gRPC interceptor logic. This would involve checking that the handler is correctly wrapped with the middleware chain in both the unary and stream interceptor implementations ^[1].

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