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use super::{
H2Driver,
types::{CloseOutcome, DriverState},
};
use crate::{
Conn,
graceful_close::GracefulClose,
h2::{H2Error, H2ErrorCode, stream_state::StreamEvent, transport::H2Transport},
};
use futures_lite::io::{AsyncRead, AsyncWrite};
use std::{
io,
pin::Pin,
task::{Context, Poll},
};
impl<T> H2Driver<T>
where
T: AsyncRead + AsyncWrite + Unpin + Send,
{
/// Convert the current `close_outcome` into the terminal return of [`Self::drive`]. Must
/// only be called after outbound bytes have been flushed. Graceful closes return `None`;
/// errors surface as a final `Some(Err(...))` before subsequent polls return `None`.
pub(super) fn finish_with_current_outcome(
&mut self,
) -> Option<Result<Conn<H2Transport>, H2Error>> {
self.finished = true;
// Shut the connection swansong down on every exit path, not just peer GOAWAY:
// it is the signal reuse decisions key on (`open_stream`, `can_open_stream`, and
// pooling clients' classify). A driver that dies on an I/O error or peer FIN while
// leaving the swansong running turns the connection into a landmine — a pool hands
// it out as available, `open_stream` publishes a stream no driver will ever
// service, and the response waiter parks forever. Must happen *before* the shared-
// map walk below: `open_stream` checks the swansong under the streams lock, so any
// stream that slips in concurrently either observes the shutdown and is refused,
// or was published before we take the lock and gets reset by the walk.
self.connection.shut_down();
// Complete every outstanding `H2Connection::send_ping` future with an error so
// awaiting callers don't block forever. Safe to call regardless of outcome —
// a no-op if no pings are in flight.
self.connection.fail_pending_pings(
io::ErrorKind::ConnectionAborted,
"h2 connection closed before PING ACK",
);
// Wake any `PeerSettings` waiters so a peer that disconnects without ever sending
// SETTINGS doesn't strand them. Their `poll` rechecks swansong state and returns
// Ready; the caller's follow-up operation surfaces the connection-closed error.
self.connection.wake_peer_settings_waiters();
// Resolve every still-live stream's recv-side waiters. A connection that dies with
// an in-flight stream (server GOAWAY + close, peer FIN, I/O error) leaves any task
// parked on the response — `response_headers`, a body `poll_read`, an upgrade
// `poll_write` — with no other wake source. Without this a client request hangs
// forever on a graceful server shutdown. Mirror the per-stream RST teardown:
// terminal `Reset` (recv reports eof → `ResponseHeaders` yields `ConnectionAborted`,
// reads return EOF, writes `BrokenPipe`) + the same waker fan-out.
let reset_code = match &self.close_outcome {
Some(CloseOutcome::Protocol(code)) => *code,
_ => H2ErrorCode::NoError,
};
// Walk the *shared* map, not the driver-private mirror: a client stream published
// between the driver's last pickup pass and this teardown exists only in the shared
// map, and every conn-task waiter (`response_headers`, body reads, `SubmitSend`)
// reaches its stream through the shared map — so this walk covers all of them.
for state in self.connection.streams_lock().values() {
// Move each still-live stream to `Closed{Reset}` (a no-op on streams already closed, so
// an existing reason isn't clobbered), then fan out every recv/send waker so parked
// tasks observe the close instead of hanging.
let _ = state.apply_event(StreamEvent::RecvReset(reset_code));
state.recv.waker.wake();
state.recv.response_headers_waker.wake();
state.send.outbound_write_waker.wake();
// A handler already parked in `SubmitSend` (response staged, awaiting the driver to
// frame it) needs this wake to re-poll and observe the now-reset stream — the recv
// fan-out above doesn't reach the send-completion waiter.
state.send.completion_waker.wake();
}
match self.close_outcome.take() {
None | Some(CloseOutcome::Graceful) => None,
Some(CloseOutcome::Protocol(code)) => Some(Err(H2Error::Protocol(code))),
Some(CloseOutcome::Io(e)) => Some(Err(H2Error::Io(e))),
}
}
/// Enter the closing state: record the outcome and queue a GOAWAY (only for outcomes
/// that warrant one). The main loop will drain `write_buf` and then finish.
pub(super) fn begin_close(&mut self, outcome: CloseOutcome) {
// Idempotent: with the recv pump now running in Closing (so we keep
// decoding inbound frames for in-flight streams across GOAWAY), a peer
// GOAWAY arriving after we've already begun closing would otherwise
// re-queue our own GOAWAY and re-enter Closing, ping-ponging forever
// with a peer that mirrors the behavior.
if self.state == DriverState::Closing || self.state == DriverState::Drained {
log::trace!(
"h2 driver: begin_close({outcome:?}) — already in {:?}, ignoring",
self.state,
);
return;
}
// Don't overwrite a prior outcome (e.g. if an error fires in the middle of a
// graceful shutdown, keep the error).
let code = match &outcome {
CloseOutcome::Graceful => Some(H2ErrorCode::NoError),
CloseOutcome::Protocol(code) => Some(*code),
CloseOutcome::Io(_) => None,
};
let reason = match &outcome {
CloseOutcome::Graceful => "graceful close",
CloseOutcome::Protocol(_) => "protocol error",
CloseOutcome::Io(_) => "i/o error",
};
if self.close_outcome.is_none() {
self.close_outcome = Some(outcome);
}
if let Some(code) = code {
self.queue_goaway(self.last_peer_stream_id, code);
}
self.set_state(DriverState::Closing, reason);
}
/// Log which in-flight streams are blocking the `Closing → Drained` transition.
/// Called from the closing-state check when at least one predicate (`has_active_send_cursors`
/// or `has_pending_recv`) is still true, so a trace log shows exactly which streams the
/// driver is waiting on.
pub(super) fn log_closing_blockers(&self) {
if !log::log_enabled!(log::Level::Trace) {
return;
}
for (id, entry) in &self.streams {
let lifecycle = *entry.shared.lifecycle_lock();
let queued = !entry
.shared
.send
.queue
.lock()
.expect("send queue mutex poisoned")
.is_empty();
if entry.send.is_some() || queued || !lifecycle.recv_closed() {
log::trace!(
"h2 driver: Closing — stream {id} blocking drain (lifecycle={lifecycle:?}, \
cursor_present={}, queued={queued})",
entry.send.is_some(),
);
}
}
}
/// Post-GOAWAY, drain whatever inbound bytes are *immediately* available from the
/// peer so our Drop sends a clean FIN (no unread data → no TCP RST) while the peer
/// sees the GOAWAY we just emitted. Read loops internally: consume each Ready chunk,
/// discard it, ask for more. Exits as soon as the transport returns `Pending` (no
/// bytes available right now) OR `Ready(0)` (peer FIN already arrived) OR any error.
///
/// Does **not** register the waker on `Pending` — we're actively closing, not
/// observing the peer. Bytes the peer sends after this returns are [`Self::close`]'s to
/// wait out; dropping the transport instead answers them with a TCP reset.
///
/// Returning `Ready(())` unconditionally (no `Pending` case) lets the caller finalize
/// immediately. The `Poll` wrapper is kept for symmetry with the rest of the driver's
/// poll-style methods.
pub(super) fn poll_drain_peer(&mut self, cx: &mut Context<'_>) -> Poll<()> {
// A peer flooding us with bytes could keep this loop going a long time. Cap it
// so a pathological client can't pin our close-out forever.
const MAX_DISCARD_ITERATIONS: usize = 256;
// Lightweight scratch — we're throwing it away. 512 balances "drain in few
// iterations" against "don't hold a large buffer for a rare path."
let mut scratch = [0u8; 512];
for _ in 0..MAX_DISCARD_ITERATIONS {
// We pass `cx` through for the benefit of the transport's `poll_read` contract,
// but we *interpret* `Pending` as "done draining" rather than parking on it —
// we're actively closing, not observing.
match Pin::new(&mut self.transport).poll_read(cx, &mut scratch) {
Poll::Ready(Ok(0) | Err(_)) | Poll::Pending => {
return Poll::Ready(());
}
Poll::Ready(Ok(_)) => {}
}
}
Poll::Ready(())
}
/// Close the connection: shut down our sending side of the transport, then read and discard
/// whatever the peer still sends until it closes its side.
///
/// If the transport is dropped while the peer is still sending, the operating system answers
/// the peer's data with a TCP reset, which can destroy data the peer hasn't read yet — our
/// final GOAWAY, or the end of a response. Waiting for the peer to close avoids that. A peer
/// that never closes keeps this waiting indefinitely, so bound it with a timeout.
///
/// Call this once [`Self::next`] returns `None` or an error. Closing a driver that hasn't
/// finished ends the connection without a GOAWAY, resetting any streams still in flight.
pub async fn close(mut self) {
if !self.finished {
self.finish_with_current_outcome();
}
let reads_per_yield = self.config.copy_loops_per_yield();
GracefulClose::new(self.transport, self.read_buf, reads_per_yield).await;
}
}