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use std::collections::BinaryHeap;
use std::sync::{Condvar, Mutex};
use std::thread;
use std::sync::{Arc};
use std::sync::mpsc::{Sender, Receiver, channel};
use std::cmp::{Ordering, min, max};
use time::{SteadyTime, Duration};
struct ScheduledEvent {
when: SteadyTime,
completion_sink: Sender<()>,
period: Option<u32>,
}
impl Ord for ScheduledEvent {
fn cmp(&self, other: &ScheduledEvent) -> Ordering {
other.when.cmp(&self.when)
}
}
impl PartialEq for ScheduledEvent {
fn eq(&self, other: &ScheduledEvent) -> bool {
let self_ptr: *const ScheduledEvent = self;
let other_ptr: *const ScheduledEvent = other;
self_ptr == other_ptr
}
}
impl Eq for ScheduledEvent {}
impl PartialOrd for ScheduledEvent {
fn partial_cmp(&self, other: &ScheduledEvent) -> Option<Ordering> {
other.when.partial_cmp(&self.when)
}
}
struct SchedulingRequest {
duration: u32,
periodic: bool,
completion_sink: Sender<()>,
}
struct SchedulingInterface {
trigger: Arc<Condvar>,
adder: Sender<SchedulingRequest>,
}
struct ScheduleWorker {
trigger: Arc<Condvar>,
request_source: Receiver<SchedulingRequest>,
schedule: BinaryHeap<ScheduledEvent>,
}
impl ScheduleWorker {
fn new(trigger: Arc<Condvar>, request_source: Receiver<SchedulingRequest>) -> ScheduleWorker {
ScheduleWorker{
trigger: trigger,
request_source: request_source,
schedule: BinaryHeap::new(),
}
}
fn drain_request_queue(&mut self) {
while let Ok(request) = self.request_source.try_recv() {
self.schedule.push(ScheduledEvent{
when: SteadyTime::now() + Duration::milliseconds(request.duration as i64),
period: if request.periodic { Some(request.duration) } else { None },
completion_sink: request.completion_sink
});
}
}
fn has_event_now(&self) -> bool {
if let Some(evt) = self.schedule.peek() {
evt.when < SteadyTime::now()
} else {
false
}
}
fn fire_event(&mut self) {
if let Some(evt) = self.schedule.pop() {
match evt.completion_sink.send( () ) {
Ok( () ) => {
if let Some(period) = evt.period.clone() {
self.schedule.push(ScheduledEvent{
when: evt.when + Duration::milliseconds(period as i64),
period: evt.period,
completion_sink: evt.completion_sink,
});
}
}
Err(_) => {
}
}
}
}
fn ms_until_next_event(&self) -> u32 {
if let Some(evt) = self.schedule.peek() {
max(0, min((evt.when - SteadyTime::now()).num_milliseconds(), 100000)) as u32
} else {
100000
}
}
fn run(&mut self) {
let m = Mutex::new(false);
let mut g = m.lock().unwrap();
loop {
self.drain_request_queue();
loop {
if self.has_event_now() {
self.fire_event();
} else {
break;
}
}
let wait_millis = self.ms_until_next_event();
g = self.trigger.wait_timeout_ms(g, wait_millis).unwrap().0;
}
}
}
lazy_static! {
static ref SCHEDULER_INTERFACE : Mutex<SchedulingInterface> = {
let (sender, receiver) = channel();
let trigger = Arc::new(Condvar::new());
let trigger2 = trigger.clone();
thread::spawn(move|| {
ScheduleWorker::new(trigger2, receiver).run();
});
let interface = SchedulingInterface {
trigger: trigger,
adder: sender
};
Mutex::new(interface)
};
}
fn add_request(duration_ms: u32, periodic: bool) -> Receiver<()> {
let (sender, receiver) = channel();
let interface = SCHEDULER_INTERFACE.lock().ok().expect("Failed to acquire the global scheduling worker");
interface.adder.send(SchedulingRequest{
duration:duration_ms,
completion_sink:sender,
periodic: periodic
}).ok().expect("Failed to send a request to the global scheduling worker");
interface.trigger.notify_one();
receiver
}
pub fn oneshot_ms(ms: u32) -> Receiver<()> {
add_request(ms, false)
}
pub fn periodic_ms(ms: u32) -> Receiver<()> {
add_request(ms, true)
}