Is it possible to detect when an HTTP/1.1 request is being sent on an existing connection versus opening a new connection?

[declanvk]

Is it possible to detect when an HTTP/1.1 request is being sent on an existing connection versus opening a new connection?

I'm interested in monitoring some latency numbers for an HTTP client that I have, and I want to compare the latencies for new connections versus existing connections.

[seanmonstar]

Assuming you are referring to v0.14.x, and the pooling hyper::Client, then: perhaps a couple things that likely will be different in 1.0.

• If you're using tracing, you could look at the events hyper outputs. I believe it has different messages for re-using a connection versus establishing a new one. Those messages are not part of a stable API, though. As in, they could conceivably be changed in new versions to make the wording clearer, or something.
• If using HttpConnector (or a TLS connector that wraps it), you could probably check the HttpInfo on the Response and peek at the local addr to see if the port is new. But then again, once a socket is closed and the kernel's CLOSE_WAIT time has passed, it could assign that port to a new connection...

[declanvk]

For

Those messages are part of a stable API, though

Would that be unstable instead?

Thanks for responding, this helps a lot.

[seanmonstar]

Correct, typo. I've edited the sentence.