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-rw-r--r--third_party/rust/mio-extras/src/timer.rs751
1 files changed, 751 insertions, 0 deletions
diff --git a/third_party/rust/mio-extras/src/timer.rs b/third_party/rust/mio-extras/src/timer.rs
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+++ b/third_party/rust/mio-extras/src/timer.rs
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+//! Timer optimized for I/O related operations
+use crate::convert;
+use lazycell::LazyCell;
+use mio::{Evented, Poll, PollOpt, Ready, Registration, SetReadiness, Token};
+use slab::Slab;
+use std::sync::atomic::{AtomicUsize, Ordering};
+use std::sync::Arc;
+use std::time::{Duration, Instant};
+use std::{cmp, fmt, io, iter, thread, u64, usize};
+
+/// A timer.
+///
+/// Typical usage goes like this:
+///
+/// * register the timer with a `mio::Poll`.
+/// * set a timeout, by calling `Timer::set_timeout`. Here you provide some
+/// state to be associated with this timeout.
+/// * poll the `Poll`, to learn when a timeout has occurred.
+/// * retrieve state associated with the timeout by calling `Timer::poll`.
+///
+/// You can omit use of the `Poll` altogether, if you like, and just poll the
+/// `Timer` directly.
+pub struct Timer<T> {
+ // Size of each tick in milliseconds
+ tick_ms: u64,
+ // Slab of timeout entries
+ entries: Slab<Entry<T>>,
+ // Timeout wheel. Each tick, the timer will look at the next slot for
+ // timeouts that match the current tick.
+ wheel: Vec<WheelEntry>,
+ // Tick 0's time instant
+ start: Instant,
+ // The current tick
+ tick: Tick,
+ // The next entry to possibly timeout
+ next: Token,
+ // Masks the target tick to get the slot
+ mask: u64,
+ // Set on registration with Poll
+ inner: LazyCell<Inner>,
+}
+
+/// Used to create a `Timer`.
+pub struct Builder {
+ // Approximate duration of each tick
+ tick: Duration,
+ // Number of slots in the timer wheel
+ num_slots: usize,
+ // Max number of timeouts that can be in flight at a given time.
+ capacity: usize,
+}
+
+/// A timeout, as returned by `Timer::set_timeout`.
+///
+/// Use this as the argument to `Timer::cancel_timeout`, to cancel this timeout.
+#[derive(Clone, Debug)]
+pub struct Timeout {
+ // Reference into the timer entry slab
+ token: Token,
+ // Tick that it should match up with
+ tick: u64,
+}
+
+struct Inner {
+ registration: Registration,
+ set_readiness: SetReadiness,
+ wakeup_state: WakeupState,
+ wakeup_thread: thread::JoinHandle<()>,
+}
+
+impl Drop for Inner {
+ fn drop(&mut self) {
+ // 1. Set wakeup state to TERMINATE_THREAD
+ self.wakeup_state.store(TERMINATE_THREAD, Ordering::Release);
+ // 2. Wake him up
+ self.wakeup_thread.thread().unpark();
+ }
+}
+
+#[derive(Copy, Clone, Debug)]
+struct WheelEntry {
+ next_tick: Tick,
+ head: Token,
+}
+
+// Doubly linked list of timer entries. Allows for efficient insertion /
+// removal of timeouts.
+struct Entry<T> {
+ state: T,
+ links: EntryLinks,
+}
+
+#[derive(Copy, Clone)]
+struct EntryLinks {
+ tick: Tick,
+ prev: Token,
+ next: Token,
+}
+
+type Tick = u64;
+
+const TICK_MAX: Tick = u64::MAX;
+
+// Manages communication with wakeup thread
+type WakeupState = Arc<AtomicUsize>;
+
+const TERMINATE_THREAD: usize = 0;
+const EMPTY: Token = Token(usize::MAX);
+
+impl Builder {
+ /// Set the tick duration. Default is 100ms.
+ pub fn tick_duration(mut self, duration: Duration) -> Builder {
+ self.tick = duration;
+ self
+ }
+
+ /// Set the number of slots. Default is 256.
+ pub fn num_slots(mut self, num_slots: usize) -> Builder {
+ self.num_slots = num_slots;
+ self
+ }
+
+ /// Set the capacity. Default is 65536.
+ pub fn capacity(mut self, capacity: usize) -> Builder {
+ self.capacity = capacity;
+ self
+ }
+
+ /// Build a `Timer` with the parameters set on this `Builder`.
+ pub fn build<T>(self) -> Timer<T> {
+ Timer::new(
+ convert::millis(self.tick),
+ self.num_slots,
+ self.capacity,
+ Instant::now(),
+ )
+ }
+}
+
+impl Default for Builder {
+ fn default() -> Builder {
+ Builder {
+ tick: Duration::from_millis(100),
+ num_slots: 1 << 8,
+ capacity: 1 << 16,
+ }
+ }
+}
+
+impl<T> Timer<T> {
+ fn new(tick_ms: u64, num_slots: usize, capacity: usize, start: Instant) -> Timer<T> {
+ let num_slots = num_slots.next_power_of_two();
+ let capacity = capacity.next_power_of_two();
+ let mask = (num_slots as u64) - 1;
+ let wheel = iter::repeat(WheelEntry {
+ next_tick: TICK_MAX,
+ head: EMPTY,
+ })
+ .take(num_slots)
+ .collect();
+
+ Timer {
+ tick_ms,
+ entries: Slab::with_capacity(capacity),
+ wheel,
+ start,
+ tick: 0,
+ next: EMPTY,
+ mask,
+ inner: LazyCell::new(),
+ }
+ }
+
+ /// Set a timeout.
+ ///
+ /// When the timeout occurs, the given state becomes available via `poll`.
+ pub fn set_timeout(&mut self, delay_from_now: Duration, state: T) -> Timeout {
+ let delay_from_start = self.start.elapsed() + delay_from_now;
+ self.set_timeout_at(delay_from_start, state)
+ }
+
+ fn set_timeout_at(&mut self, delay_from_start: Duration, state: T) -> Timeout {
+ let mut tick = duration_to_tick(delay_from_start, self.tick_ms);
+ trace!(
+ "setting timeout; delay={:?}; tick={:?}; current-tick={:?}",
+ delay_from_start,
+ tick,
+ self.tick
+ );
+
+ // Always target at least 1 tick in the future
+ if tick <= self.tick {
+ tick = self.tick + 1;
+ }
+
+ self.insert(tick, state)
+ }
+
+ fn insert(&mut self, tick: Tick, state: T) -> Timeout {
+ // Get the slot for the requested tick
+ let slot = (tick & self.mask) as usize;
+ let curr = self.wheel[slot];
+
+ // Insert the new entry
+ let entry = Entry::new(state, tick, curr.head);
+ let token = Token(self.entries.insert(entry));
+
+ if curr.head != EMPTY {
+ // If there was a previous entry, set its prev pointer to the new
+ // entry
+ self.entries[curr.head.into()].links.prev = token;
+ }
+
+ // Update the head slot
+ self.wheel[slot] = WheelEntry {
+ next_tick: cmp::min(tick, curr.next_tick),
+ head: token,
+ };
+
+ self.schedule_readiness(tick);
+
+ trace!("inserted timout; slot={}; token={:?}", slot, token);
+
+ // Return the new timeout
+ Timeout { token, tick }
+ }
+
+ /// Cancel a timeout.
+ ///
+ /// If the timeout has not yet occurred, the return value holds the
+ /// associated state.
+ pub fn cancel_timeout(&mut self, timeout: &Timeout) -> Option<T> {
+ let links = match self.entries.get(timeout.token.into()) {
+ Some(e) => e.links,
+ None => return None,
+ };
+
+ // Sanity check
+ if links.tick != timeout.tick {
+ return None;
+ }
+
+ self.unlink(&links, timeout.token);
+ Some(self.entries.remove(timeout.token.into()).state)
+ }
+
+ /// Poll for an expired timer.
+ ///
+ /// The return value holds the state associated with the first expired
+ /// timer, if any.
+ pub fn poll(&mut self) -> Option<T> {
+ let target_tick = current_tick(self.start, self.tick_ms);
+ self.poll_to(target_tick)
+ }
+
+ fn poll_to(&mut self, mut target_tick: Tick) -> Option<T> {
+ trace!(
+ "tick_to; target_tick={}; current_tick={}",
+ target_tick,
+ self.tick
+ );
+
+ if target_tick < self.tick {
+ target_tick = self.tick;
+ }
+
+ while self.tick <= target_tick {
+ let curr = self.next;
+
+ trace!("ticking; curr={:?}", curr);
+
+ if curr == EMPTY {
+ self.tick += 1;
+
+ let slot = self.slot_for(self.tick);
+ self.next = self.wheel[slot].head;
+
+ // Handle the case when a slot has a single timeout which gets
+ // canceled before the timeout expires. In this case, the
+ // slot's head is EMPTY but there is a value for next_tick. Not
+ // resetting next_tick here causes the timer to get stuck in a
+ // loop.
+ if self.next == EMPTY {
+ self.wheel[slot].next_tick = TICK_MAX;
+ }
+ } else {
+ let slot = self.slot_for(self.tick);
+
+ if curr == self.wheel[slot].head {
+ self.wheel[slot].next_tick = TICK_MAX;
+ }
+
+ let links = self.entries[curr.into()].links;
+
+ if links.tick <= self.tick {
+ trace!("triggering; token={:?}", curr);
+
+ // Unlink will also advance self.next
+ self.unlink(&links, curr);
+
+ // Remove and return the token
+ return Some(self.entries.remove(curr.into()).state);
+ } else {
+ let next_tick = self.wheel[slot].next_tick;
+ self.wheel[slot].next_tick = cmp::min(next_tick, links.tick);
+ self.next = links.next;
+ }
+ }
+ }
+
+ // No more timeouts to poll
+ if let Some(inner) = self.inner.borrow() {
+ trace!("unsetting readiness");
+ let _ = inner.set_readiness.set_readiness(Ready::empty());
+
+ if let Some(tick) = self.next_tick() {
+ self.schedule_readiness(tick);
+ }
+ }
+
+ None
+ }
+
+ fn unlink(&mut self, links: &EntryLinks, token: Token) {
+ trace!(
+ "unlinking timeout; slot={}; token={:?}",
+ self.slot_for(links.tick),
+ token
+ );
+
+ if links.prev == EMPTY {
+ let slot = self.slot_for(links.tick);
+ self.wheel[slot].head = links.next;
+ } else {
+ self.entries[links.prev.into()].links.next = links.next;
+ }
+
+ if links.next != EMPTY {
+ self.entries[links.next.into()].links.prev = links.prev;
+
+ if token == self.next {
+ self.next = links.next;
+ }
+ } else if token == self.next {
+ self.next = EMPTY;
+ }
+ }
+
+ fn schedule_readiness(&self, tick: Tick) {
+ if let Some(inner) = self.inner.borrow() {
+ // Coordinate setting readiness w/ the wakeup thread
+ let mut curr = inner.wakeup_state.load(Ordering::Acquire);
+
+ loop {
+ if curr as Tick <= tick {
+ // Nothing to do, wakeup is already scheduled
+ return;
+ }
+
+ // Attempt to move the wakeup time forward
+ trace!("advancing the wakeup time; target={}; curr={}", tick, curr);
+ let actual =
+ inner
+ .wakeup_state
+ .compare_and_swap(curr, tick as usize, Ordering::Release);
+
+ if actual == curr {
+ // Signal to the wakeup thread that the wakeup time has
+ // been changed.
+ trace!("unparking wakeup thread");
+ inner.wakeup_thread.thread().unpark();
+ return;
+ }
+
+ curr = actual;
+ }
+ }
+ }
+
+ // Next tick containing a timeout
+ fn next_tick(&self) -> Option<Tick> {
+ if self.next != EMPTY {
+ let slot = self.slot_for(self.entries[self.next.into()].links.tick);
+
+ if self.wheel[slot].next_tick == self.tick {
+ // There is data ready right now
+ return Some(self.tick);
+ }
+ }
+
+ self.wheel.iter().map(|e| e.next_tick).min()
+ }
+
+ fn slot_for(&self, tick: Tick) -> usize {
+ (self.mask & tick) as usize
+ }
+}
+
+impl<T> Default for Timer<T> {
+ fn default() -> Timer<T> {
+ Builder::default().build()
+ }
+}
+
+impl<T> Evented for Timer<T> {
+ fn register(
+ &self,
+ poll: &Poll,
+ token: Token,
+ interest: Ready,
+ opts: PollOpt,
+ ) -> io::Result<()> {
+ if self.inner.borrow().is_some() {
+ return Err(io::Error::new(
+ io::ErrorKind::Other,
+ "timer already registered",
+ ));
+ }
+
+ let (registration, set_readiness) = Registration::new2();
+ poll.register(&registration, token, interest, opts)?;
+ let wakeup_state = Arc::new(AtomicUsize::new(usize::MAX));
+ let thread_handle = spawn_wakeup_thread(
+ Arc::clone(&wakeup_state),
+ set_readiness.clone(),
+ self.start,
+ self.tick_ms,
+ );
+
+ self.inner
+ .fill(Inner {
+ registration,
+ set_readiness,
+ wakeup_state,
+ wakeup_thread: thread_handle,
+ })
+ .expect("timer already registered");
+
+ if let Some(next_tick) = self.next_tick() {
+ self.schedule_readiness(next_tick);
+ }
+
+ Ok(())
+ }
+
+ fn reregister(
+ &self,
+ poll: &Poll,
+ token: Token,
+ interest: Ready,
+ opts: PollOpt,
+ ) -> io::Result<()> {
+ match self.inner.borrow() {
+ Some(inner) => poll.reregister(&inner.registration, token, interest, opts),
+ None => Err(io::Error::new(
+ io::ErrorKind::Other,
+ "receiver not registered",
+ )),
+ }
+ }
+
+ fn deregister(&self, poll: &Poll) -> io::Result<()> {
+ match self.inner.borrow() {
+ Some(inner) => poll.deregister(&inner.registration),
+ None => Err(io::Error::new(
+ io::ErrorKind::Other,
+ "receiver not registered",
+ )),
+ }
+ }
+}
+
+impl fmt::Debug for Inner {
+ fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+ fmt.debug_struct("Inner")
+ .field("registration", &self.registration)
+ .field("wakeup_state", &self.wakeup_state.load(Ordering::Relaxed))
+ .finish()
+ }
+}
+
+fn spawn_wakeup_thread(
+ state: WakeupState,
+ set_readiness: SetReadiness,
+ start: Instant,
+ tick_ms: u64,
+) -> thread::JoinHandle<()> {
+ thread::spawn(move || {
+ let mut sleep_until_tick = state.load(Ordering::Acquire) as Tick;
+
+ loop {
+ if sleep_until_tick == TERMINATE_THREAD as Tick {
+ return;
+ }
+
+ let now_tick = current_tick(start, tick_ms);
+
+ trace!(
+ "wakeup thread: sleep_until_tick={:?}; now_tick={:?}",
+ sleep_until_tick,
+ now_tick
+ );
+
+ if now_tick < sleep_until_tick {
+ // Calling park_timeout with u64::MAX leads to undefined
+ // behavior in pthread, causing the park to return immediately
+ // and causing the thread to tightly spin. Instead of u64::MAX
+ // on large values, simply use a blocking park.
+ match tick_ms.checked_mul(sleep_until_tick - now_tick) {
+ Some(sleep_duration) => {
+ trace!(
+ "sleeping; tick_ms={}; now_tick={}; sleep_until_tick={}; duration={:?}",
+ tick_ms,
+ now_tick,
+ sleep_until_tick,
+ sleep_duration
+ );
+ thread::park_timeout(Duration::from_millis(sleep_duration));
+ }
+ None => {
+ trace!(
+ "sleeping; tick_ms={}; now_tick={}; blocking sleep",
+ tick_ms,
+ now_tick
+ );
+ thread::park();
+ }
+ }
+ sleep_until_tick = state.load(Ordering::Acquire) as Tick;
+ } else {
+ let actual =
+ state.compare_and_swap(sleep_until_tick as usize, usize::MAX, Ordering::AcqRel)
+ as Tick;
+
+ if actual == sleep_until_tick {
+ trace!("setting readiness from wakeup thread");
+ let _ = set_readiness.set_readiness(Ready::readable());
+ sleep_until_tick = usize::MAX as Tick;
+ } else {
+ sleep_until_tick = actual as Tick;
+ }
+ }
+ }
+ })
+}
+
+fn duration_to_tick(elapsed: Duration, tick_ms: u64) -> Tick {
+ // Calculate tick rounding up to the closest one
+ let elapsed_ms = convert::millis(elapsed);
+ elapsed_ms.saturating_add(tick_ms / 2) / tick_ms
+}
+
+fn current_tick(start: Instant, tick_ms: u64) -> Tick {
+ duration_to_tick(start.elapsed(), tick_ms)
+}
+
+impl<T> Entry<T> {
+ fn new(state: T, tick: u64, next: Token) -> Entry<T> {
+ Entry {
+ state,
+ links: EntryLinks {
+ tick,
+ prev: EMPTY,
+ next,
+ },
+ }
+ }
+}
+
+#[cfg(test)]
+mod test {
+ use super::*;
+ use std::time::{Duration, Instant};
+
+ #[test]
+ pub fn test_timeout_next_tick() {
+ let mut t = timer();
+ let mut tick;
+
+ t.set_timeout_at(Duration::from_millis(100), "a");
+
+ tick = ms_to_tick(&t, 50);
+ assert_eq!(None, t.poll_to(tick));
+
+ tick = ms_to_tick(&t, 100);
+ assert_eq!(Some("a"), t.poll_to(tick));
+ assert_eq!(None, t.poll_to(tick));
+
+ tick = ms_to_tick(&t, 150);
+ assert_eq!(None, t.poll_to(tick));
+
+ tick = ms_to_tick(&t, 200);
+ assert_eq!(None, t.poll_to(tick));
+
+ assert_eq!(count(&t), 0);
+ }
+
+ #[test]
+ pub fn test_clearing_timeout() {
+ let mut t = timer();
+ let mut tick;
+
+ let to = t.set_timeout_at(Duration::from_millis(100), "a");
+ assert_eq!("a", t.cancel_timeout(&to).unwrap());
+
+ tick = ms_to_tick(&t, 100);
+ assert_eq!(None, t.poll_to(tick));
+
+ tick = ms_to_tick(&t, 200);
+ assert_eq!(None, t.poll_to(tick));
+
+ assert_eq!(count(&t), 0);
+ }
+
+ #[test]
+ pub fn test_multiple_timeouts_same_tick() {
+ let mut t = timer();
+ let mut tick;
+
+ t.set_timeout_at(Duration::from_millis(100), "a");
+ t.set_timeout_at(Duration::from_millis(100), "b");
+
+ let mut rcv = vec![];
+
+ tick = ms_to_tick(&t, 100);
+ rcv.push(t.poll_to(tick).unwrap());
+ rcv.push(t.poll_to(tick).unwrap());
+
+ assert_eq!(None, t.poll_to(tick));
+
+ rcv.sort();
+ assert!(rcv == ["a", "b"], "actual={:?}", rcv);
+
+ tick = ms_to_tick(&t, 200);
+ assert_eq!(None, t.poll_to(tick));
+
+ assert_eq!(count(&t), 0);
+ }
+
+ #[test]
+ pub fn test_multiple_timeouts_diff_tick() {
+ let mut t = timer();
+ let mut tick;
+
+ t.set_timeout_at(Duration::from_millis(110), "a");
+ t.set_timeout_at(Duration::from_millis(220), "b");
+ t.set_timeout_at(Duration::from_millis(230), "c");
+ t.set_timeout_at(Duration::from_millis(440), "d");
+ t.set_timeout_at(Duration::from_millis(560), "e");
+
+ tick = ms_to_tick(&t, 100);
+ assert_eq!(Some("a"), t.poll_to(tick));
+ assert_eq!(None, t.poll_to(tick));
+
+ tick = ms_to_tick(&t, 200);
+ assert_eq!(Some("c"), t.poll_to(tick));
+ assert_eq!(Some("b"), t.poll_to(tick));
+ assert_eq!(None, t.poll_to(tick));
+
+ tick = ms_to_tick(&t, 300);
+ assert_eq!(None, t.poll_to(tick));
+
+ tick = ms_to_tick(&t, 400);
+ assert_eq!(Some("d"), t.poll_to(tick));
+ assert_eq!(None, t.poll_to(tick));
+
+ tick = ms_to_tick(&t, 500);
+ assert_eq!(None, t.poll_to(tick));
+
+ tick = ms_to_tick(&t, 600);
+ assert_eq!(Some("e"), t.poll_to(tick));
+ assert_eq!(None, t.poll_to(tick));
+ }
+
+ #[test]
+ pub fn test_catching_up() {
+ let mut t = timer();
+
+ t.set_timeout_at(Duration::from_millis(110), "a");
+ t.set_timeout_at(Duration::from_millis(220), "b");
+ t.set_timeout_at(Duration::from_millis(230), "c");
+ t.set_timeout_at(Duration::from_millis(440), "d");
+
+ let tick = ms_to_tick(&t, 600);
+ assert_eq!(Some("a"), t.poll_to(tick));
+ assert_eq!(Some("c"), t.poll_to(tick));
+ assert_eq!(Some("b"), t.poll_to(tick));
+ assert_eq!(Some("d"), t.poll_to(tick));
+ assert_eq!(None, t.poll_to(tick));
+ }
+
+ #[test]
+ pub fn test_timeout_hash_collision() {
+ let mut t = timer();
+ let mut tick;
+
+ t.set_timeout_at(Duration::from_millis(100), "a");
+ t.set_timeout_at(Duration::from_millis(100 + TICK * SLOTS as u64), "b");
+
+ tick = ms_to_tick(&t, 100);
+ assert_eq!(Some("a"), t.poll_to(tick));
+ assert_eq!(1, count(&t));
+
+ tick = ms_to_tick(&t, 200);
+ assert_eq!(None, t.poll_to(tick));
+ assert_eq!(1, count(&t));
+
+ tick = ms_to_tick(&t, 100 + TICK * SLOTS as u64);
+ assert_eq!(Some("b"), t.poll_to(tick));
+ assert_eq!(0, count(&t));
+ }
+
+ #[test]
+ pub fn test_clearing_timeout_between_triggers() {
+ let mut t = timer();
+ let mut tick;
+
+ let a = t.set_timeout_at(Duration::from_millis(100), "a");
+ let _ = t.set_timeout_at(Duration::from_millis(100), "b");
+ let _ = t.set_timeout_at(Duration::from_millis(200), "c");
+
+ tick = ms_to_tick(&t, 100);
+ assert_eq!(Some("b"), t.poll_to(tick));
+ assert_eq!(2, count(&t));
+
+ t.cancel_timeout(&a);
+ assert_eq!(1, count(&t));
+
+ assert_eq!(None, t.poll_to(tick));
+
+ tick = ms_to_tick(&t, 200);
+ assert_eq!(Some("c"), t.poll_to(tick));
+ assert_eq!(0, count(&t));
+ }
+
+ const TICK: u64 = 100;
+ const SLOTS: usize = 16;
+ const CAPACITY: usize = 32;
+
+ fn count<T>(timer: &Timer<T>) -> usize {
+ timer.entries.len()
+ }
+
+ fn timer() -> Timer<&'static str> {
+ Timer::new(TICK, SLOTS, CAPACITY, Instant::now())
+ }
+
+ fn ms_to_tick<T>(timer: &Timer<T>, ms: u64) -> u64 {
+ ms / timer.tick_ms
+ }
+}
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