What does make_service_fn and service_fn mean?

[kingluo]

I found each HTTP request incoming, make_service_fn gets called once, and server_fn also gets called once.
What's the definition of make_service_fn and service_fn? Why not just one service function instead of two nested functions?

I am very confused, please help!

[seanmonstar]

Does looking at the service docs help?

[kingluo]

MakeService accepts connections, while Service handles requests of one connection.

My understanding is correct?

[davidpdrsn]

Yes that sounds correct.

Said with a few more words: MakeService receives the address of the incoming connection and produces a service that will handle requests from that connection. If your request handling code only cares about the request and not the connection then MakeService might seem a bit redundant. However some use cases requires the address as well for example to set the Forwarded header on responses.

I have a PR that adds a utility to bypass make_service_fn if you don't need it #2541