The type of the abstract state of happy eyeballs.

create ~happy_eyeballs ~getaddrinfo ~timer_interval () creates an initial state of happy eyeballs with the specified timeouts in nanoseconds - the default for timer_interval is Duration.of_ms 10.

connect_host t host ports establishes a connection to host on ports (tried in sequence).

• raises Failure

  if ports is empty.

connect_ip t addresses establishes a connection to addresses.

• raises Failure

  if addresses is the empty list.

connect t host ports establishes a connection to host on ports, which may be a host name, or an IP address.

• raises Failure

  if ports is the empty list.

inject t getaddrinfo injects a new domain-name resolver into the given happy-eyeballs instance. By default, the happy-eyeballs instance use Lwt_unix.getaddrinfo to be able to resolve domain-name. However, the user can choose to use its own implementation of a DNS resolver (like ocaml-dns).

So, the ceremony for using happy-eyeballs with your own DNS resolver is to create a happy-eyeballs instance, obtain an instance that can resolve domain names (such as ocaml-dns) and inject the latter's implementation into our first happy-eyeballs instance:

  let _ =
    let dns = Dns_client_lwt.create () in
    let happy_eyeballs = Dns_client_lwt.create_happy_eyeballs dns in
    Happy_eyeballs_lwt.connect happy_eyeballs "robur.coop" [ 443 ]
    >>= function
    | Ok (_, fd) -> ...
    | Error _ -> ...