1 #![warn(rust_2018_idioms)]
2 #![cfg(feature = "full")]
3
4 use tokio::net::TcpListener;
5 use tokio::runtime;
6 use tokio_test::{assert_ok, assert_pending};
7
8 use futures::task::{waker_ref, ArcWake};
9 use std::future::Future;
10 use std::net::TcpStream;
11 use std::pin::Pin;
12 use std::sync::{mpsc, Arc, Mutex};
13 use std::task::Context;
14
15 struct Task<T> {
16 future: Mutex<Pin<Box<T>>>,
17 }
18
19 impl<T: Send> ArcWake for Task<T> {
wake_by_ref(_: &Arc<Self>)20 fn wake_by_ref(_: &Arc<Self>) {
21 // Do nothing...
22 }
23 }
24
25 impl<T> Task<T> {
new(future: T) -> Task<T>26 fn new(future: T) -> Task<T> {
27 Task {
28 future: Mutex::new(Box::pin(future)),
29 }
30 }
31 }
32
33 #[test]
test_drop_on_notify()34 fn test_drop_on_notify() {
35 // When the reactor receives a kernel notification, it notifies the
36 // task that holds the associated socket. If this notification results in
37 // the task being dropped, the socket will also be dropped.
38 //
39 // Previously, there was a deadlock scenario where the reactor, while
40 // notifying, held a lock and the task being dropped attempted to acquire
41 // that same lock in order to clean up state.
42 //
43 // To simulate this case, we create a fake executor that does nothing when
44 // the task is notified. This simulates an executor in the process of
45 // shutting down. Then, when the task handle is dropped, the task itself is
46 // dropped.
47
48 let mut rt = runtime::Builder::new()
49 .basic_scheduler()
50 .enable_all()
51 .build()
52 .unwrap();
53
54 let (addr_tx, addr_rx) = mpsc::channel();
55
56 // Define a task that just drains the listener
57 let task = Arc::new(Task::new(async move {
58 // Create a listener
59 let mut listener = assert_ok!(TcpListener::bind("127.0.0.1:0").await);
60
61 // Send the address
62 let addr = listener.local_addr().unwrap();
63 addr_tx.send(addr).unwrap();
64
65 loop {
66 let _ = listener.accept().await;
67 }
68 }));
69
70 {
71 rt.enter(|| {
72 let waker = waker_ref(&task);
73 let mut cx = Context::from_waker(&waker);
74 assert_pending!(task.future.lock().unwrap().as_mut().poll(&mut cx));
75 });
76 }
77
78 // Get the address
79 let addr = addr_rx.recv().unwrap();
80
81 drop(task);
82
83 // Establish a connection to the acceptor
84 let _s = TcpStream::connect(&addr).unwrap();
85
86 // Force the reactor to turn
87 rt.block_on(async {});
88 }
89