Feature Request: Tracking # of HTTP requests made on the current TCP connection

For persistent connections, some servers are configured to reset them after a certain number of HTTP requests. Net::HTTP::Persistent added a max_requests variable to preemptively close your connection after a certain amount of HTTP requests are made for this reason in https://github.com/drbrain/net-http-persistent/pull/42

However, without changes to Net::HTTP, Net::HTTP::Persistent can only track how many times it makes a request of it's Net::HTTP instance. But this isn't perfect: begin_transport can re-connect on a new TCP connection if it finds the socket was closed some time after the last time you used it, like if the server closed the connection, and Net::HTTP::Persistent will never know there's a new TCP connection, and that it should therefor reset its count of requests over the TCP connection back to 0.

My suggestion is that we make an instance variable here in Net::HTTP called @num_requests_on_connection, that gets set to 0 at the end of connect, and is incremented at the end of begin_transport after the reconnection attempts. I believe that way we could get an accurate count!

@raggi @drbrain

Start in lib/net/http.rb at the referenced connect and begin_transport locations, and trace how persistent connections are established and reused. Verify the request count resets when a TCP connection is created and increments after transport attempts, so callers can accurately observe requests made on the current connection.