//! A timer service for the beacon node.
//!
//! This service allows task execution on the beacon node for various functionality.
use beacon_chain::{BeaconChain, BeaconChainTypes};
use futures::{future, prelude::*};
use slog::error;
use slot_clock::SlotClock;
use std::sync::Arc;
use std::time::{Duration, Instant};
use tokio::runtime::TaskExecutor;
use tokio::timer::Interval;
/// Spawns a timer service which periodically executes tasks for the beacon chain
pub fn spawn<T: BeaconChainTypes>(
executor: &TaskExecutor,
beacon_chain: Arc<BeaconChain<T>>,
milliseconds_per_slot: u64,
log: slog::Logger,
) -> Result<tokio::sync::oneshot::Sender<()>, &'static str> {
let (exit_signal, exit) = tokio::sync::oneshot::channel();
let start_instant = Instant::now()
+ beacon_chain
.slot_clock
.duration_to_next_slot()
.ok_or_else(|| "slot_notifier unable to determine time to next slot")?;
let timer_future = Interval::new(start_instant, Duration::from_millis(milliseconds_per_slot))
.map_err(move |e| {
error!(
log,
"Beacon chain timer failed";
"error" => format!("{:?}", e)
)
})
.for_each(move |_| {
beacon_chain.per_slot_task();
future::ok(())
});
executor.spawn(
exit.map_err(|_| ())
.select(timer_future)
.map(|_| ())
.map_err(|_| ()),
);
Ok(exit_signal)
}