1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
//! The core reactor driving all I/O
//!
//! This module contains the `Core` type which is the reactor for all I/O
//! happening in `tokio-core`. This reactor (or event loop) is used to run
//! futures, schedule tasks, issue I/O requests, etc.

use std::cell::RefCell;
use std::fmt;
use std::io;
use std::rc::{Rc, Weak};
use std::sync::Arc;
use std::sync::atomic::{AtomicUsize, AtomicBool, ATOMIC_USIZE_INIT, Ordering};
use std::time::{Instant, Duration};

use tokio;
use tokio::executor::current_thread::{CurrentThread, TaskExecutor};
use tokio_executor;
use tokio_executor::park::{Park, Unpark, ParkThread, UnparkThread};
use tokio_timer::timer::{self, Timer};

use futures::{Future, IntoFuture, Async};
use futures::future::{self, Executor, ExecuteError};
use futures::executor::{self, Spawn, Notify};
use futures::sync::mpsc;
use mio;

mod poll_evented;
mod poll_evented2;
mod timeout;
mod interval;
pub use self::poll_evented::PollEvented;
pub(crate) use self::poll_evented2::PollEvented as PollEvented2;
pub use self::timeout::Timeout;
pub use self::interval::Interval;

static NEXT_LOOP_ID: AtomicUsize = ATOMIC_USIZE_INIT;
scoped_thread_local!(static CURRENT_LOOP: Core);

/// An event loop.
///
/// The event loop is the main source of blocking in an application which drives
/// all other I/O events and notifications happening. Each event loop can have
/// multiple handles pointing to it, each of which can then be used to create
/// various I/O objects to interact with the event loop in interesting ways.
// TODO: expand this
pub struct Core {
    /// Uniquely identifies the reactor
    id: usize,

    /// Handle to the Tokio runtime
    rt: tokio::runtime::Runtime,

    /// Executes tasks
    executor: RefCell<CurrentThread<Timer<ParkThread>>>,

    /// Timer handle
    timer_handle: timer::Handle,

    /// Wakes up the thread when the `run` future is notified
    notify_future: Arc<MyNotify>,

    /// Wakes up the thread when a message is posted to `rx`
    notify_rx: Arc<MyNotify>,

    /// Send messages across threads to the core
    tx: mpsc::UnboundedSender<Message>,

    /// Receive messages
    rx: RefCell<Spawn<mpsc::UnboundedReceiver<Message>>>,

    // Shared inner state
    inner: Rc<RefCell<Inner>>,
}

struct Inner {
    // Tasks that need to be spawned onto the executor.
    pending_spawn: Vec<Box<Future<Item = (), Error = ()>>>,
}

/// An unique ID for a Core
///
/// An ID by which different cores may be distinguished. Can be compared and used as an index in
/// a `HashMap`.
///
/// The ID is globally unique and never reused.
#[derive(Clone,Copy,Eq,PartialEq,Hash,Debug)]
pub struct CoreId(usize);

/// Handle to an event loop, used to construct I/O objects, send messages, and
/// otherwise interact indirectly with the event loop itself.
///
/// Handles can be cloned, and when cloned they will still refer to the
/// same underlying event loop.
#[derive(Clone)]
pub struct Remote {
    id: usize,
    tx: mpsc::UnboundedSender<Message>,
    new_handle: tokio::reactor::Handle,
    timer_handle: timer::Handle,
}

/// A non-sendable handle to an event loop, useful for manufacturing instances
/// of `LoopData`.
#[derive(Clone)]
pub struct Handle {
    remote: Remote,
    inner: Weak<RefCell<Inner>>,
    thread_pool: ::tokio::runtime::TaskExecutor,
}

enum Message {
    Run(Box<FnBox>),
}

// ===== impl Core =====

impl Core {
    /// Creates a new event loop, returning any error that happened during the
    /// creation.
    pub fn new() -> io::Result<Core> {
        // Create a new parker
        let timer = Timer::new(ParkThread::new());

        // Create notifiers
        let notify_future = Arc::new(MyNotify::new(timer.unpark()));
        let notify_rx = Arc::new(MyNotify::new(timer.unpark()));

        // New Tokio reactor + threadpool
        let rt = tokio::runtime::Runtime::new()?;

        let timer_handle = timer.handle();

        // Executor to run !Send futures
        let executor = RefCell::new(CurrentThread::new_with_park(timer));

        // Used to send messages across threads
        let (tx, rx) = mpsc::unbounded();

        // Wrap the rx half with a future context and refcell
        let rx = RefCell::new(executor::spawn(rx));

        let id = NEXT_LOOP_ID.fetch_add(1, Ordering::Relaxed);

        Ok(Core {
            id,
            rt,
            notify_future,
            notify_rx,
            tx,
            rx,
            executor,
            timer_handle,
            inner: Rc::new(RefCell::new(Inner {
                pending_spawn: vec![],
            })),
        })
    }

    /// Returns a handle to this event loop which cannot be sent across threads
    /// but can be used as a proxy to the event loop itself.
    ///
    /// Handles are cloneable and clones always refer to the same event loop.
    /// This handle is typically passed into functions that create I/O objects
    /// to bind them to this event loop.
    pub fn handle(&self) -> Handle {
        Handle {
            remote: self.remote(),
            inner: Rc::downgrade(&self.inner),
            thread_pool: self.rt.executor().clone(),
        }
    }

    /// Returns a reference to the runtime backing the instance
    ///
    /// This provides access to the newer features of Tokio.
    pub fn runtime(&self) -> &tokio::runtime::Runtime {
        &self.rt
    }

    /// Generates a remote handle to this event loop which can be used to spawn
    /// tasks from other threads into this event loop.
    pub fn remote(&self) -> Remote {
        Remote {
            id: self.id,
            tx: self.tx.clone(),
            new_handle: self.rt.reactor().clone(),
            timer_handle: self.timer_handle.clone()
        }
    }

    /// Runs a future until completion, driving the event loop while we're
    /// otherwise waiting for the future to complete.
    ///
    /// This function will begin executing the event loop and will finish once
    /// the provided future is resolved. Note that the future argument here
    /// crucially does not require the `'static` nor `Send` bounds. As a result
    /// the future will be "pinned" to not only this thread but also this stack
    /// frame.
    ///
    /// This function will return the value that the future resolves to once
    /// the future has finished. If the future never resolves then this function
    /// will never return.
    ///
    /// # Panics
    ///
    /// This method will **not** catch panics from polling the future `f`. If
    /// the future panics then it's the responsibility of the caller to catch
    /// that panic and handle it as appropriate.
    pub fn run<F>(&mut self, f: F) -> Result<F::Item, F::Error>
        where F: Future,
    {
        let mut task = executor::spawn(f);
        let handle1 = self.rt.reactor().clone();
        let handle2 = self.rt.reactor().clone();
        let mut executor1 = self.rt.executor().clone();
        let mut executor2 = self.rt.executor().clone();
        let timer_handle = self.timer_handle.clone();

        // Make sure the future will run at least once on enter
        self.notify_future.notify(0);

        loop {
            if self.notify_future.take() {
                let mut enter = tokio_executor::enter()
                    .ok().expect("cannot recursively call into `Core`");

                let notify = &self.notify_future;
                let mut current_thread = self.executor.borrow_mut();

                let res = try!(CURRENT_LOOP.set(self, || {
                    ::tokio_reactor::with_default(&handle1, &mut enter, |enter| {
                        tokio_executor::with_default(&mut executor1, enter, |enter| {
                            timer::with_default(&timer_handle, enter, |enter| {
                                current_thread.enter(enter)
                                    .block_on(future::lazy(|| {
                                        Ok::<_, ()>(task.poll_future_notify(notify, 0))
                                    })).unwrap()
                            })
                        })
                    })
                }));

                if let Async::Ready(e) = res {
                    return Ok(e)
                }
            }

            self.poll(None, &handle2, &mut executor2);
        }
    }

    /// Performs one iteration of the event loop, blocking on waiting for events
    /// for at most `max_wait` (forever if `None`).
    ///
    /// It only makes sense to call this method if you've previously spawned
    /// a future onto this event loop.
    ///
    /// `loop { lp.turn(None) }` is equivalent to calling `run` with an
    /// empty future (one that never finishes).
    pub fn turn(&mut self, max_wait: Option<Duration>) {
        let handle = self.rt.reactor().clone();
        let mut executor = self.rt.executor().clone();
        self.poll(max_wait, &handle, &mut executor);
    }

    fn poll(&mut self, max_wait: Option<Duration>,
            handle: &tokio::reactor::Handle,
            sender: &mut tokio::runtime::TaskExecutor) {
        let mut enter = tokio_executor::enter()
            .ok().expect("cannot recursively call into `Core`");
        let timer_handle = self.timer_handle.clone();

        ::tokio_reactor::with_default(handle, &mut enter, |enter| {
            tokio_executor::with_default(sender, enter, |enter| {
                timer::with_default(&timer_handle, enter, |enter| {
                    let start = Instant::now();

                    // Process all the events that came in, dispatching appropriately
                    if self.notify_rx.take() {
                        CURRENT_LOOP.set(self, || self.consume_queue());
                    }

                    // Drain any futures pending spawn
                    {
                        let mut e = self.executor.borrow_mut();
                        let mut i = self.inner.borrow_mut();

                        for f in i.pending_spawn.drain(..) {
                            // Little hack
                            e.enter(enter).block_on(future::lazy(|| {
                                TaskExecutor::current().spawn_local(f).unwrap();
                                Ok::<_, ()>(())
                            })).unwrap();
                        }
                    }

                    CURRENT_LOOP.set(self, || {
                        self.executor.borrow_mut()
                            .enter(enter)
                            .turn(max_wait)
                            .ok().expect("error in `CurrentThread::turn`");
                    });

                    let after_poll = Instant::now();
                    debug!("loop poll - {:?}", after_poll - start);
                    debug!("loop time - {:?}", after_poll);

                    debug!("loop process, {:?}", after_poll.elapsed());
                })
            });
        });
    }

    fn consume_queue(&self) {
        debug!("consuming notification queue");
        // TODO: can we do better than `.unwrap()` here?
        loop {
            let msg = self.rx.borrow_mut().poll_stream_notify(&self.notify_rx, 0).unwrap();
            match msg {
                Async::Ready(Some(msg)) => self.notify(msg),
                Async::NotReady |
                Async::Ready(None) => break,
            }
        }
    }

    fn notify(&self, msg: Message) {
        let Message::Run(r) = msg;
        r.call_box(self);
    }

    /// Get the ID of this loop
    pub fn id(&self) -> CoreId {
        CoreId(self.id)
    }
}

impl<F> Executor<F> for Core
    where F: Future<Item = (), Error = ()> + 'static,
{
    fn execute(&self, future: F) -> Result<(), ExecuteError<F>> {
        self.handle().execute(future)
    }
}

impl fmt::Debug for Core {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        f.debug_struct("Core")
         .field("id", &self.id())
         .finish()
    }
}

impl Remote {
    fn send(&self, msg: Message) {
        self.with_loop(|lp| {
            match lp {
                Some(lp) => {
                    // We want to make sure that all messages are received in
                    // order, so we need to consume pending messages before
                    // delivering this message to the core. The actually
                    // `consume_queue` function, however, can be somewhat slow
                    // right now where receiving on a channel will acquire a
                    // lock and block the current task.
                    //
                    // To speed this up check the message queue's readiness as a
                    // sort of preflight check to see if we've actually got any
                    // messages. This should just involve some atomics and if it
                    // comes back false then we know for sure there are no
                    // pending messages, so we can immediately deliver our
                    // message.
                    if lp.notify_rx.take() {
                        lp.consume_queue();
                    }
                    lp.notify(msg);
                }
                None => {
                    match self.tx.unbounded_send(msg) {
                        Ok(()) => {}

                        // TODO: this error should punt upwards and we should
                        //       notify the caller that the message wasn't
                        //       received. This is tokio-core#17
                        Err(e) => drop(e),
                    }
                }
            }
        })
    }

    fn with_loop<F, R>(&self, f: F) -> R
        where F: FnOnce(Option<&Core>) -> R
    {
        if CURRENT_LOOP.is_set() {
            CURRENT_LOOP.with(|lp| {
                let same = lp.id == self.id;
                if same {
                    f(Some(lp))
                } else {
                    f(None)
                }
            })
        } else {
            f(None)
        }
    }

    /// Spawns a new future into the event loop this remote is associated with.
    ///
    /// This function takes a closure which is executed within the context of
    /// the I/O loop itself. The future returned by the closure will be
    /// scheduled on the event loop and run to completion.
    ///
    /// Note that while the closure, `F`, requires the `Send` bound as it might
    /// cross threads, the future `R` does not.
    ///
    /// # Panics
    ///
    /// This method will **not** catch panics from polling the future `f`. If
    /// the future panics then it's the responsibility of the caller to catch
    /// that panic and handle it as appropriate.
    pub fn spawn<F, R>(&self, f: F)
        where F: FnOnce(&Handle) -> R + Send + 'static,
              R: IntoFuture<Item=(), Error=()>,
              R::Future: 'static,
    {
        self.send(Message::Run(Box::new(|lp: &Core| {
            let f = f(&lp.handle());
            lp.handle().spawn(f.into_future());
        })));
    }

    /// Return the ID of the represented Core
    pub fn id(&self) -> CoreId {
        CoreId(self.id)
    }

    /// Attempts to "promote" this remote to a handle, if possible.
    ///
    /// This function is intended for structures which typically work through a
    /// `Remote` but want to optimize runtime when the remote doesn't actually
    /// leave the thread of the original reactor. This will attempt to return a
    /// handle if the `Remote` is on the same thread as the event loop and the
    /// event loop is running.
    ///
    /// If this `Remote` has moved to a different thread or if the event loop is
    /// running, then `None` may be returned. If you need to guarantee access to
    /// a `Handle`, then you can call this function and fall back to using
    /// `spawn` above if it returns `None`.
    pub fn handle(&self) -> Option<Handle> {
        if CURRENT_LOOP.is_set() {
            CURRENT_LOOP.with(|lp| {
                let same = lp.id == self.id;
                if same {
                    Some(lp.handle())
                } else {
                    None
                }
            })
        } else {
            None
        }
    }
}

impl<F> Executor<F> for Remote
    where F: Future<Item = (), Error = ()> + Send + 'static,
{
    fn execute(&self, future: F) -> Result<(), ExecuteError<F>> {
        self.spawn(|_| future);
        Ok(())
    }
}

impl fmt::Debug for Remote {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        f.debug_struct("Remote")
         .field("id", &self.id())
         .finish()
    }
}

impl Handle {
    /// Returns a reference to the new Tokio handle
    pub fn new_tokio_handle(&self) -> &::tokio::reactor::Handle {
        &self.remote.new_handle
    }

    /// Returns a reference to the underlying remote handle to the event loop.
    pub fn remote(&self) -> &Remote {
        &self.remote
    }

    /// Spawns a new future on the event loop this handle is associated with.
    ///
    /// # Panics
    ///
    /// This method will **not** catch panics from polling the future `f`. If
    /// the future panics then it's the responsibility of the caller to catch
    /// that panic and handle it as appropriate.
    pub fn spawn<F>(&self, f: F)
        where F: Future<Item=(), Error=()> + 'static,
    {
        let inner = match self.inner.upgrade() {
            Some(inner) => inner,
            None => {
                return;
            }
        };

        // Try accessing the executor directly
        if let Ok(mut inner) = inner.try_borrow_mut() {
            inner.pending_spawn.push(Box::new(f));
            return;
        }

        // If that doesn't work, the executor is probably active, so spawn using
        // the global fn.
        let _ = TaskExecutor::current().spawn_local(Box::new(f));
    }

    /// Spawns a new future onto the threadpool
    ///
    /// # Panics
    ///
    /// This function panics if the spawn fails. Failure occurs if the executor
    /// is currently at capacity and is unable to spawn a new future.
    pub fn spawn_send<F>(&self, f: F)
        where F: Future<Item=(), Error=()> + Send + 'static,
    {
        self.thread_pool.spawn(f);
    }

    /// Spawns a closure on this event loop.
    ///
    /// This function is a convenience wrapper around the `spawn` function above
    /// for running a closure wrapped in `futures::lazy`. It will spawn the
    /// function `f` provided onto the event loop, and continue to run the
    /// future returned by `f` on the event loop as well.
    ///
    /// # Panics
    ///
    /// This method will **not** catch panics from polling the future `f`. If
    /// the future panics then it's the responsibility of the caller to catch
    /// that panic and handle it as appropriate.
    pub fn spawn_fn<F, R>(&self, f: F)
        where F: FnOnce() -> R + 'static,
              R: IntoFuture<Item=(), Error=()> + 'static,
    {
        self.spawn(future::lazy(f))
    }

    /// Return the ID of the represented Core
    pub fn id(&self) -> CoreId {
        self.remote.id()
    }
}

impl<F> Executor<F> for Handle
    where F: Future<Item = (), Error = ()> + 'static,
{
    fn execute(&self, future: F) -> Result<(), ExecuteError<F>> {
        self.spawn(future);
        Ok(())
    }
}

impl fmt::Debug for Handle {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        f.debug_struct("Handle")
         .field("id", &self.id())
         .finish()
    }
}

struct MyNotify {
    unpark: UnparkThread,
    notified: AtomicBool,
}

impl MyNotify {
    fn new(unpark: UnparkThread) -> Self {
        MyNotify {
            unpark,
            notified: AtomicBool::new(true),
        }
    }

    fn take(&self) -> bool {
        self.notified.swap(false, Ordering::SeqCst)
    }
}

impl Notify for MyNotify {
    fn notify(&self, _: usize) {
        self.notified.store(true, Ordering::SeqCst);
        self.unpark.unpark();
    }
}

trait FnBox: Send + 'static {
    fn call_box(self: Box<Self>, lp: &Core);
}

impl<F: FnOnce(&Core) + Send + 'static> FnBox for F {
    fn call_box(self: Box<Self>, lp: &Core) {
        (*self)(lp)
    }
}

const READ: usize = 1 << 0;
const WRITE: usize = 1 << 1;

fn ready2usize(ready: mio::Ready) -> usize {
    let mut bits = 0;
    if ready.is_readable() {
        bits |= READ;
    }
    if ready.is_writable() {
        bits |= WRITE;
    }
    bits | platform::ready2usize(ready)
}

fn usize2ready(bits: usize) -> mio::Ready {
    let mut ready = mio::Ready::empty();
    if bits & READ != 0 {
        ready.insert(mio::Ready::readable());
    }
    if bits & WRITE != 0 {
        ready.insert(mio::Ready::writable());
    }
    ready | platform::usize2ready(bits)
}

#[cfg(all(unix, not(target_os = "fuchsia")))]
mod platform {
    use mio::Ready;
    use mio::unix::UnixReady;

    const HUP: usize = 1 << 2;
    const ERROR: usize = 1 << 3;
    const AIO: usize = 1 << 4;

    #[cfg(any(target_os = "dragonfly", target_os = "freebsd"))]
    fn is_aio(ready: &Ready) -> bool {
        UnixReady::from(*ready).is_aio()
    }

    #[cfg(not(any(target_os = "dragonfly", target_os = "freebsd")))]
    fn is_aio(_ready: &Ready) -> bool {
        false
    }

    pub fn ready2usize(ready: Ready) -> usize {
        let ready = UnixReady::from(ready);
        let mut bits = 0;
        if is_aio(&ready) {
            bits |= AIO;
        }
        if ready.is_error() {
            bits |= ERROR;
        }
        if ready.is_hup() {
            bits |= HUP;
        }
        bits
    }

    #[cfg(any(target_os = "dragonfly", target_os = "freebsd", target_os = "ios",
              target_os = "macos"))]
    fn usize2ready_aio(ready: &mut UnixReady) {
        ready.insert(UnixReady::aio());
    }

    #[cfg(not(any(target_os = "dragonfly",
        target_os = "freebsd", target_os = "ios", target_os = "macos")))]
    fn usize2ready_aio(_ready: &mut UnixReady) {
        // aio not available here → empty
    }

    pub fn usize2ready(bits: usize) -> Ready {
        let mut ready = UnixReady::from(Ready::empty());
        if bits & AIO != 0 {
            usize2ready_aio(&mut ready);
        }
        if bits & HUP != 0 {
            ready.insert(UnixReady::hup());
        }
        if bits & ERROR != 0 {
            ready.insert(UnixReady::error());
        }
        ready.into()
    }
}

#[cfg(any(windows, target_os = "fuchsia"))]
mod platform {
    use mio::Ready;

    pub fn ready2usize(_r: Ready) -> usize {
        0
    }

    pub fn usize2ready(_r: usize) -> Ready {
        Ready::empty()
    }
}