How to get response headers size in bytes

[let4be]

For statistical purposes I would like to record exact size of headers in an http response(n of bytes), is this possible?

I guess I could estimate this size by running across headers() and summing string lengths, but this seems dirty and slow. Is there a better way?

[seanmonstar]

The number would be different depending on HTTP/1 and HTTP/2. In HTTP/1, hyper emits a trace event about bytes read and parsed into headers. We could probably make that a slightly better structured tracing event with better key/values, so that you can then grab it in a tracing subscriber.