emqx / esockd / 609

67%

master: 67%

Pull #228

github

feat: wait_with_first_data - probe first bytes inside esockd's wait

Move the "first bytes or already-dead socket" detection for plain-TCP and
proxy-protocol connections into esockd's wait machinery, where the proxy
header and TLS handshake upgrade funs already run:

- esockd_transport:wait_with_first_data/1 runs the upgrade funs, then does a
  zero-timeout recv(Sock, 0, 0) on TCP-ish sockets (TLS skipped: the
  handshake already engaged the client, and handshake-stage deaths are
  handled by the upgrade funs):
    {ok, Sock, Data}  first bytes already in hand, returned as a binary;
    {ok, Sock}        peer silent but alive: caller activates as usual;
    closed/econnreset peer already gone before sending anything: exit with
                      the {shutdown, {pre_establishment, _}} marker, the
                      same mechanism as the TLS handshake marker, so the
                      caller never sees this case and does not need to know
                      the marker shape (conn-rate token refund design).
  Only closed/econnreset are treated as peer-gone: other errors (einval on
  an active-mode socket, timeout, ...) fall back to the normal path.
- closed is normalized to tcp_closed to match the active-mode
  {tcp_closed, _} message tag, keeping the shutdown_count key unchanged.
- wait/1 is unchanged for consumers that do not opt in (STOMP, exproto).

Tests: real-socket cases for data return, FIN/RST marked exit, silent
fallback, TLS skip, proxy inner-socket probe, upgrade-fun chains.

The emqx side (paired commit) switches emqx_connection:init to this API.

35 of 38 new or added lines in 4 files covered. (92.11%)

787 of 1137 relevant lines covered (69.22%)

198.91 hits per line