diff options
Diffstat (limited to 'third_party/rust/hyper/src/proto/h2/ping.rs')
| -rw-r--r-- | third_party/rust/hyper/src/proto/h2/ping.rs | 555 |
1 files changed, 555 insertions, 0 deletions
diff --git a/third_party/rust/hyper/src/proto/h2/ping.rs b/third_party/rust/hyper/src/proto/h2/ping.rs new file mode 100644 index 0000000000..1e8386497c --- /dev/null +++ b/third_party/rust/hyper/src/proto/h2/ping.rs @@ -0,0 +1,555 @@ +/// HTTP2 Ping usage +/// +/// hyper uses HTTP2 pings for two purposes: +/// +/// 1. Adaptive flow control using BDP +/// 2. Connection keep-alive +/// +/// Both cases are optional. +/// +/// # BDP Algorithm +/// +/// 1. When receiving a DATA frame, if a BDP ping isn't outstanding: +/// 1a. Record current time. +/// 1b. Send a BDP ping. +/// 2. Increment the number of received bytes. +/// 3. When the BDP ping ack is received: +/// 3a. Record duration from sent time. +/// 3b. Merge RTT with a running average. +/// 3c. Calculate bdp as bytes/rtt. +/// 3d. If bdp is over 2/3 max, set new max to bdp and update windows. + +#[cfg(feature = "runtime")] +use std::fmt; +#[cfg(feature = "runtime")] +use std::future::Future; +#[cfg(feature = "runtime")] +use std::pin::Pin; +use std::sync::{Arc, Mutex}; +use std::task::{self, Poll}; +use std::time::Duration; +#[cfg(not(feature = "runtime"))] +use std::time::Instant; + +use h2::{Ping, PingPong}; +#[cfg(feature = "runtime")] +use tokio::time::{Instant, Sleep}; +use tracing::{debug, trace}; + +type WindowSize = u32; + +pub(super) fn disabled() -> Recorder { + Recorder { shared: None } +} + +pub(super) fn channel(ping_pong: PingPong, config: Config) -> (Recorder, Ponger) { + debug_assert!( + config.is_enabled(), + "ping channel requires bdp or keep-alive config", + ); + + let bdp = config.bdp_initial_window.map(|wnd| Bdp { + bdp: wnd, + max_bandwidth: 0.0, + rtt: 0.0, + ping_delay: Duration::from_millis(100), + stable_count: 0, + }); + + let (bytes, next_bdp_at) = if bdp.is_some() { + (Some(0), Some(Instant::now())) + } else { + (None, None) + }; + + #[cfg(feature = "runtime")] + let keep_alive = config.keep_alive_interval.map(|interval| KeepAlive { + interval, + timeout: config.keep_alive_timeout, + while_idle: config.keep_alive_while_idle, + timer: Box::pin(tokio::time::sleep(interval)), + state: KeepAliveState::Init, + }); + + #[cfg(feature = "runtime")] + let last_read_at = keep_alive.as_ref().map(|_| Instant::now()); + + let shared = Arc::new(Mutex::new(Shared { + bytes, + #[cfg(feature = "runtime")] + last_read_at, + #[cfg(feature = "runtime")] + is_keep_alive_timed_out: false, + ping_pong, + ping_sent_at: None, + next_bdp_at, + })); + + ( + Recorder { + shared: Some(shared.clone()), + }, + Ponger { + bdp, + #[cfg(feature = "runtime")] + keep_alive, + shared, + }, + ) +} + +#[derive(Clone)] +pub(super) struct Config { + pub(super) bdp_initial_window: Option<WindowSize>, + /// If no frames are received in this amount of time, a PING frame is sent. + #[cfg(feature = "runtime")] + pub(super) keep_alive_interval: Option<Duration>, + /// After sending a keepalive PING, the connection will be closed if + /// a pong is not received in this amount of time. + #[cfg(feature = "runtime")] + pub(super) keep_alive_timeout: Duration, + /// If true, sends pings even when there are no active streams. + #[cfg(feature = "runtime")] + pub(super) keep_alive_while_idle: bool, +} + +#[derive(Clone)] +pub(crate) struct Recorder { + shared: Option<Arc<Mutex<Shared>>>, +} + +pub(super) struct Ponger { + bdp: Option<Bdp>, + #[cfg(feature = "runtime")] + keep_alive: Option<KeepAlive>, + shared: Arc<Mutex<Shared>>, +} + +struct Shared { + ping_pong: PingPong, + ping_sent_at: Option<Instant>, + + // bdp + /// If `Some`, bdp is enabled, and this tracks how many bytes have been + /// read during the current sample. + bytes: Option<usize>, + /// We delay a variable amount of time between BDP pings. This allows us + /// to send less pings as the bandwidth stabilizes. + next_bdp_at: Option<Instant>, + + // keep-alive + /// If `Some`, keep-alive is enabled, and the Instant is how long ago + /// the connection read the last frame. + #[cfg(feature = "runtime")] + last_read_at: Option<Instant>, + + #[cfg(feature = "runtime")] + is_keep_alive_timed_out: bool, +} + +struct Bdp { + /// Current BDP in bytes + bdp: u32, + /// Largest bandwidth we've seen so far. + max_bandwidth: f64, + /// Round trip time in seconds + rtt: f64, + /// Delay the next ping by this amount. + /// + /// This will change depending on how stable the current bandwidth is. + ping_delay: Duration, + /// The count of ping round trips where BDP has stayed the same. + stable_count: u32, +} + +#[cfg(feature = "runtime")] +struct KeepAlive { + /// If no frames are received in this amount of time, a PING frame is sent. + interval: Duration, + /// After sending a keepalive PING, the connection will be closed if + /// a pong is not received in this amount of time. + timeout: Duration, + /// If true, sends pings even when there are no active streams. + while_idle: bool, + + state: KeepAliveState, + timer: Pin<Box<Sleep>>, +} + +#[cfg(feature = "runtime")] +enum KeepAliveState { + Init, + Scheduled, + PingSent, +} + +pub(super) enum Ponged { + SizeUpdate(WindowSize), + #[cfg(feature = "runtime")] + KeepAliveTimedOut, +} + +#[cfg(feature = "runtime")] +#[derive(Debug)] +pub(super) struct KeepAliveTimedOut; + +// ===== impl Config ===== + +impl Config { + pub(super) fn is_enabled(&self) -> bool { + #[cfg(feature = "runtime")] + { + self.bdp_initial_window.is_some() || self.keep_alive_interval.is_some() + } + + #[cfg(not(feature = "runtime"))] + { + self.bdp_initial_window.is_some() + } + } +} + +// ===== impl Recorder ===== + +impl Recorder { + pub(crate) fn record_data(&self, len: usize) { + let shared = if let Some(ref shared) = self.shared { + shared + } else { + return; + }; + + let mut locked = shared.lock().unwrap(); + + #[cfg(feature = "runtime")] + locked.update_last_read_at(); + + // are we ready to send another bdp ping? + // if not, we don't need to record bytes either + + if let Some(ref next_bdp_at) = locked.next_bdp_at { + if Instant::now() < *next_bdp_at { + return; + } else { + locked.next_bdp_at = None; + } + } + + if let Some(ref mut bytes) = locked.bytes { + *bytes += len; + } else { + // no need to send bdp ping if bdp is disabled + return; + } + + if !locked.is_ping_sent() { + locked.send_ping(); + } + } + + pub(crate) fn record_non_data(&self) { + #[cfg(feature = "runtime")] + { + let shared = if let Some(ref shared) = self.shared { + shared + } else { + return; + }; + + let mut locked = shared.lock().unwrap(); + + locked.update_last_read_at(); + } + } + + /// If the incoming stream is already closed, convert self into + /// a disabled reporter. + #[cfg(feature = "client")] + pub(super) fn for_stream(self, stream: &h2::RecvStream) -> Self { + if stream.is_end_stream() { + disabled() + } else { + self + } + } + + pub(super) fn ensure_not_timed_out(&self) -> crate::Result<()> { + #[cfg(feature = "runtime")] + { + if let Some(ref shared) = self.shared { + let locked = shared.lock().unwrap(); + if locked.is_keep_alive_timed_out { + return Err(KeepAliveTimedOut.crate_error()); + } + } + } + + // else + Ok(()) + } +} + +// ===== impl Ponger ===== + +impl Ponger { + pub(super) fn poll(&mut self, cx: &mut task::Context<'_>) -> Poll<Ponged> { + let now = Instant::now(); + let mut locked = self.shared.lock().unwrap(); + #[cfg(feature = "runtime")] + let is_idle = self.is_idle(); + + #[cfg(feature = "runtime")] + { + if let Some(ref mut ka) = self.keep_alive { + ka.schedule(is_idle, &locked); + ka.maybe_ping(cx, &mut locked); + } + } + + if !locked.is_ping_sent() { + // XXX: this doesn't register a waker...? + return Poll::Pending; + } + + match locked.ping_pong.poll_pong(cx) { + Poll::Ready(Ok(_pong)) => { + let start = locked + .ping_sent_at + .expect("pong received implies ping_sent_at"); + locked.ping_sent_at = None; + let rtt = now - start; + trace!("recv pong"); + + #[cfg(feature = "runtime")] + { + if let Some(ref mut ka) = self.keep_alive { + locked.update_last_read_at(); + ka.schedule(is_idle, &locked); + } + } + + if let Some(ref mut bdp) = self.bdp { + let bytes = locked.bytes.expect("bdp enabled implies bytes"); + locked.bytes = Some(0); // reset + trace!("received BDP ack; bytes = {}, rtt = {:?}", bytes, rtt); + + let update = bdp.calculate(bytes, rtt); + locked.next_bdp_at = Some(now + bdp.ping_delay); + if let Some(update) = update { + return Poll::Ready(Ponged::SizeUpdate(update)) + } + } + } + Poll::Ready(Err(e)) => { + debug!("pong error: {}", e); + } + Poll::Pending => { + #[cfg(feature = "runtime")] + { + if let Some(ref mut ka) = self.keep_alive { + if let Err(KeepAliveTimedOut) = ka.maybe_timeout(cx) { + self.keep_alive = None; + locked.is_keep_alive_timed_out = true; + return Poll::Ready(Ponged::KeepAliveTimedOut); + } + } + } + } + } + + // XXX: this doesn't register a waker...? + Poll::Pending + } + + #[cfg(feature = "runtime")] + fn is_idle(&self) -> bool { + Arc::strong_count(&self.shared) <= 2 + } +} + +// ===== impl Shared ===== + +impl Shared { + fn send_ping(&mut self) { + match self.ping_pong.send_ping(Ping::opaque()) { + Ok(()) => { + self.ping_sent_at = Some(Instant::now()); + trace!("sent ping"); + } + Err(err) => { + debug!("error sending ping: {}", err); + } + } + } + + fn is_ping_sent(&self) -> bool { + self.ping_sent_at.is_some() + } + + #[cfg(feature = "runtime")] + fn update_last_read_at(&mut self) { + if self.last_read_at.is_some() { + self.last_read_at = Some(Instant::now()); + } + } + + #[cfg(feature = "runtime")] + fn last_read_at(&self) -> Instant { + self.last_read_at.expect("keep_alive expects last_read_at") + } +} + +// ===== impl Bdp ===== + +/// Any higher than this likely will be hitting the TCP flow control. +const BDP_LIMIT: usize = 1024 * 1024 * 16; + +impl Bdp { + fn calculate(&mut self, bytes: usize, rtt: Duration) -> Option<WindowSize> { + // No need to do any math if we're at the limit. + if self.bdp as usize == BDP_LIMIT { + self.stabilize_delay(); + return None; + } + + // average the rtt + let rtt = seconds(rtt); + if self.rtt == 0.0 { + // First sample means rtt is first rtt. + self.rtt = rtt; + } else { + // Weigh this rtt as 1/8 for a moving average. + self.rtt += (rtt - self.rtt) * 0.125; + } + + // calculate the current bandwidth + let bw = (bytes as f64) / (self.rtt * 1.5); + trace!("current bandwidth = {:.1}B/s", bw); + + if bw < self.max_bandwidth { + // not a faster bandwidth, so don't update + self.stabilize_delay(); + return None; + } else { + self.max_bandwidth = bw; + } + + // if the current `bytes` sample is at least 2/3 the previous + // bdp, increase to double the current sample. + if bytes >= self.bdp as usize * 2 / 3 { + self.bdp = (bytes * 2).min(BDP_LIMIT) as WindowSize; + trace!("BDP increased to {}", self.bdp); + + self.stable_count = 0; + self.ping_delay /= 2; + Some(self.bdp) + } else { + self.stabilize_delay(); + None + } + } + + fn stabilize_delay(&mut self) { + if self.ping_delay < Duration::from_secs(10) { + self.stable_count += 1; + + if self.stable_count >= 2 { + self.ping_delay *= 4; + self.stable_count = 0; + } + } + } +} + +fn seconds(dur: Duration) -> f64 { + const NANOS_PER_SEC: f64 = 1_000_000_000.0; + let secs = dur.as_secs() as f64; + secs + (dur.subsec_nanos() as f64) / NANOS_PER_SEC +} + +// ===== impl KeepAlive ===== + +#[cfg(feature = "runtime")] +impl KeepAlive { + fn schedule(&mut self, is_idle: bool, shared: &Shared) { + match self.state { + KeepAliveState::Init => { + if !self.while_idle && is_idle { + return; + } + + self.state = KeepAliveState::Scheduled; + let interval = shared.last_read_at() + self.interval; + self.timer.as_mut().reset(interval); + } + KeepAliveState::PingSent => { + if shared.is_ping_sent() { + return; + } + + self.state = KeepAliveState::Scheduled; + let interval = shared.last_read_at() + self.interval; + self.timer.as_mut().reset(interval); + } + KeepAliveState::Scheduled => (), + } + } + + fn maybe_ping(&mut self, cx: &mut task::Context<'_>, shared: &mut Shared) { + match self.state { + KeepAliveState::Scheduled => { + if Pin::new(&mut self.timer).poll(cx).is_pending() { + return; + } + // check if we've received a frame while we were scheduled + if shared.last_read_at() + self.interval > self.timer.deadline() { + self.state = KeepAliveState::Init; + cx.waker().wake_by_ref(); // schedule us again + return; + } + trace!("keep-alive interval ({:?}) reached", self.interval); + shared.send_ping(); + self.state = KeepAliveState::PingSent; + let timeout = Instant::now() + self.timeout; + self.timer.as_mut().reset(timeout); + } + KeepAliveState::Init | KeepAliveState::PingSent => (), + } + } + + fn maybe_timeout(&mut self, cx: &mut task::Context<'_>) -> Result<(), KeepAliveTimedOut> { + match self.state { + KeepAliveState::PingSent => { + if Pin::new(&mut self.timer).poll(cx).is_pending() { + return Ok(()); + } + trace!("keep-alive timeout ({:?}) reached", self.timeout); + Err(KeepAliveTimedOut) + } + KeepAliveState::Init | KeepAliveState::Scheduled => Ok(()), + } + } +} + +// ===== impl KeepAliveTimedOut ===== + +#[cfg(feature = "runtime")] +impl KeepAliveTimedOut { + pub(super) fn crate_error(self) -> crate::Error { + crate::Error::new(crate::error::Kind::Http2).with(self) + } +} + +#[cfg(feature = "runtime")] +impl fmt::Display for KeepAliveTimedOut { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + f.write_str("keep-alive timed out") + } +} + +#[cfg(feature = "runtime")] +impl std::error::Error for KeepAliveTimedOut { + fn source(&self) -> Option<&(dyn std::error::Error + 'static)> { + Some(&crate::error::TimedOut) + } +} |