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|
//! Channel tasks of the arti-relay.
//!
//! The tasks are:
//! * [`ChannelHouseKeepingTask`] which is in charge of regularly going over existing channels
//! to clean up expiring ones and prune duplicates. At the start, it will run in
//! [`ChannelHouseKeepingTask::START_TICK_TIME`] seconds and then the channel expiry function
//! tells it how much time to sleep.
//! * [`update_create_request_handler_netparams`] which is in charge of updating the
//! circuit-related network parameters of the [`CreateRequestHandler`], which is shared with
//! the [`ChanMgr`].
use anyhow::Context;
use futures::StreamExt as _;
use std::{
sync::{Arc, Weak},
time::Duration,
};
use tracing::debug;
use tor_chanmgr::ChanMgr;
use tor_error::{into_internal, warn_report};
use tor_netdir::params::NetParameters;
use tor_netdir::{DirEvent, NetDirProvider};
use tor_proto::ccparams::{
CongestionWindowParamsBuilder, FixedWindowParamsBuilder, RoundTripEstimatorParamsBuilder,
VegasParamsBuilder,
};
use tor_proto::relay::{CircNetParameters, CongestionControlNetParams, CreateRequestHandler};
use tor_proto::{CellCount, FlowCtrlParameters};
use tor_rtcompat::Runtime;
use tor_units::Percentage;
/// Channel housekeeping standalone background task.
pub(crate) struct ChannelHouseKeepingTask<R: Runtime> {
/// Weak reference to the ChanMgr. If it disappears, task stops.
mgr: Weak<ChanMgr<R>>,
}
impl<R: Runtime> ChannelHouseKeepingTask<R> {
/// Starting tick time is to run in 3 minutes. The ChanMgr expire channels uses a default of
/// 180 seconds and so we simply align with that for the first run. After that, the channel
/// subsystems will tell us how long to wait if any channels.
const START_TICK_TIME: Duration = Duration::from_secs(180);
/// Constructor.
pub(crate) fn new(mgr: &Arc<ChanMgr<R>>) -> Self {
Self {
mgr: Arc::downgrade(mgr),
}
}
/// Run the background task.
#[allow(clippy::unused_async)] // TODO(relay)
async fn run(&mut self) -> anyhow::Result<Duration> {
let mgr = Weak::upgrade(&self.mgr).context("Channel manager is gone")?;
// Expire any channels that are possibly closing.
let next_expiry = mgr.expire_channels();
// TODO: Another action is to prune duplicate channels like C-tor does in
// channel_update_bad_for_new_circs().
Ok(next_expiry)
}
/// Start the task.
pub(crate) async fn start(&mut self) -> anyhow::Result<void::Void> {
let mut next_tick_in = Self::START_TICK_TIME;
debug!("Channel housekeeping task starting.");
loop {
// Sleep until next tick.
tokio::time::sleep(next_tick_in).await;
// Run this task. The returned value is the next tick.
next_tick_in = self
.run()
.await
.context("Shutting down channel housekeeping task")?;
}
}
}
/// A task which waits for new consensus documents and updates the parameters
/// for a [`CreateRequestHandler`].
pub(crate) async fn update_create_request_handler_netparams(
create_request_handler: Arc<CreateRequestHandler>,
netdir: Arc<dyn NetDirProvider>,
) -> anyhow::Result<void::Void> {
/// A helper to call [`build_circ_net_params()`] and log errors.
fn build_helper(params: &NetParameters) -> Option<CircNetParameters> {
match build_circ_net_params(params) {
Ok(params) => Some(params),
Err(e) => {
// This is weird, but probably not worth shutting down the relay for.
// Let's ignore this and hope that a future consensus is better.
warn_report!(e, "Could not build circuit params for latest consensus");
None
}
}
}
let mut consensus_events = netdir
.events()
.filter(|ev| std::future::ready(matches!(ev, DirEvent::NewConsensus)));
// We do this after subscribing with `events()` above
// so that we don't miss any changes.
// https://gitlab.torproject.org/tpo/core/arti/-/issues/2420
if let Some(params) = build_helper(netdir.params().as_ref().as_ref()) {
create_request_handler.update_params(params);
}
// Loop forever waiting for consensus updates.
loop {
let _event = consensus_events
.next()
.await
.context("netdir consensus event stream ended unexpectedly")?;
let Some(params) = build_helper(netdir.params().as_ref().as_ref()) else {
continue;
};
// Update the handler with the latest parameters.
create_request_handler.update_params(params);
}
}
/// Build a [`CircNetParameters`] from a [`NetParameters`].
///
/// This should just copy values from the network status into a `CircNetParameters`,
/// which is how a [`CreateRequestHandler`] accepts network parameters for building circuits.
// TODO: This shares a bunch of code with `exit_circparams_from_netparams()`.
// It would be nice if we could simplify/dedup this somehow.
pub(crate) fn build_circ_net_params(params: &NetParameters) -> anyhow::Result<CircNetParameters> {
// TODO(arti#2442): The builder pattern throughout seems like a footgun.
let vegas_exit_params = (
params.cc_vegas_alpha_exit.into(),
params.cc_vegas_beta_exit.into(),
params.cc_vegas_delta_exit.into(),
params.cc_vegas_gamma_exit.into(),
params.cc_vegas_sscap_exit.into(),
);
let vegas_exit = VegasParamsBuilder::default()
.cell_in_queue_params(vegas_exit_params.into())
.ss_cwnd_max(params.cc_ss_max.into())
.cwnd_full_gap(params.cc_cwnd_full_gap.into())
.cwnd_full_min_pct(Percentage::new(
params.cc_cwnd_full_minpct.as_percent().get() as u32,
))
.cwnd_full_per_cwnd(params.cc_cwnd_full_per_cwnd.into())
.build()
.map_err(into_internal!("Unable to build VegasParams"))?;
let fixed_window = FixedWindowParamsBuilder::default()
.circ_window_start(params.circuit_window.get() as u16)
.circ_window_min(params.circuit_window.lower() as u16)
.circ_window_max(params.circuit_window.upper() as u16)
.build()
.map_err(into_internal!("Unable to build FixedWindowParams"))?;
let cwnd = CongestionWindowParamsBuilder::default()
.cwnd_init(params.cc_cwnd_init.into())
.cwnd_inc_pct_ss(Percentage::new(
params.cc_cwnd_inc_pct_ss.as_percent().get() as u32,
))
.cwnd_inc(params.cc_cwnd_inc.into())
.cwnd_inc_rate(params.cc_cwnd_inc_rate.into())
.cwnd_min(params.cc_cwnd_min.into())
.cwnd_max(params.cc_cwnd_max.into())
.sendme_inc(params.cc_sendme_inc.into())
.build()
.map_err(into_internal!("Unable to build CongestionWindowParams"))?;
let rtt = RoundTripEstimatorParamsBuilder::default()
.ewma_cwnd_pct(Percentage::new(
params.cc_ewma_cwnd_pct.as_percent().get() as u32
))
.ewma_max(params.cc_ewma_max.into())
.ewma_ss_max(params.cc_ewma_ss.into())
.rtt_reset_pct(Percentage::new(
params.cc_rtt_reset_pct.as_percent().get() as u32
))
.build()
.map_err(into_internal!("Unable to build RoundTripEstimatorParams"))?;
let flow_ctrl = FlowCtrlParameters {
cc_xoff_client: CellCount::new(params.cc_xoff_client.get_u32()),
cc_xoff_exit: CellCount::new(params.cc_xoff_exit.get_u32()),
cc_xon_rate: CellCount::new(params.cc_xon_rate.get_u32()),
cc_xon_change_pct: params.cc_xon_change_pct.get_u32(),
cc_xon_ewma_cnt: params.cc_xon_ewma_cnt.get_u32(),
};
let cc = CongestionControlNetParams {
fixed_window,
vegas_exit,
cwnd,
rtt,
flow_ctrl,
};
Ok(CircNetParameters {
extend_by_ed25519_id: params.extend_by_ed25519_id.into(),
cc,
})
}
|
