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#![allow(unknown_lints, unexpected_cfgs)]
#![warn(rust_2018_idioms)]
#![cfg(all(feature = "full", not(target_os = "wasi"), target_has_atomic = "64"))]
use std::sync::mpsc;
use std::time::Duration;
use tokio::runtime::Runtime;
#[test]
fn num_workers() {
let rt = current_thread();
assert_eq!(1, rt.metrics().num_workers());
let rt = threaded();
assert_eq!(2, rt.metrics().num_workers());
}
#[test]
fn num_alive_tasks() {
let rt = current_thread();
let metrics = rt.metrics();
assert_eq!(0, metrics.num_alive_tasks());
rt.block_on(rt.spawn(async move {
assert_eq!(1, metrics.num_alive_tasks());
}))
.unwrap();
assert_eq!(0, rt.metrics().num_alive_tasks());
let rt = threaded();
let metrics = rt.metrics();
assert_eq!(0, metrics.num_alive_tasks());
rt.block_on(rt.spawn(async move {
assert_eq!(1, metrics.num_alive_tasks());
}))
.unwrap();
// try for 10 seconds to see if this eventually succeeds.
// wake_join() is called before the task is released, so in multithreaded
// code, this means we sometimes exit the block_on before the counter decrements.
for _ in 0..100 {
if rt.metrics().num_alive_tasks() == 0 {
break;
}
std::thread::sleep(std::time::Duration::from_millis(100));
}
assert_eq!(0, rt.metrics().num_alive_tasks());
}
#[test]
fn global_queue_depth_current_thread() {
use std::thread;
let rt = current_thread();
let handle = rt.handle().clone();
let metrics = rt.metrics();
thread::spawn(move || {
handle.spawn(async {});
})
.join()
.unwrap();
assert_eq!(1, metrics.global_queue_depth());
}
#[test]
fn global_queue_depth_multi_thread() {
for _ in 0..10 {
let rt = threaded();
let metrics = rt.metrics();
if let Ok(_blocking_tasks) = try_block_threaded(&rt) {
for i in 0..10 {
assert_eq!(i, metrics.global_queue_depth());
rt.spawn(async {});
}
return;
}
}
panic!("exhausted every try to block the runtime");
}
fn try_block_threaded(rt: &Runtime) -> Result<Vec<mpsc::Sender<()>>, mpsc::RecvTimeoutError> {
let (tx, rx) = mpsc::channel();
let blocking_tasks = (0..rt.metrics().num_workers())
.map(|_| {
let tx = tx.clone();
let (task, barrier) = mpsc::channel();
// Spawn a task per runtime worker to block it.
rt.spawn(async move {
tx.send(()).ok();
barrier.recv().ok();
});
task
})
.collect();
// Make sure the previously spawned tasks are blocking the runtime by
// receiving a message from each blocking task.
//
// If this times out we were unsuccessful in blocking the runtime and hit
// a deadlock instead (which might happen and is expected behaviour).
for _ in 0..rt.metrics().num_workers() {
rx.recv_timeout(Duration::from_secs(1))?;
}
// Return senders of the mpsc channels used for blocking the runtime as a
// surrogate handle for the tasks. Sending a message or dropping the senders
// will unblock the runtime.
Ok(blocking_tasks)
}
fn current_thread() -> Runtime {
tokio::runtime::Builder::new_current_thread()
.enable_all()
.build()
.unwrap()
}
fn threaded() -> Runtime {
tokio::runtime::Builder::new_multi_thread()
.worker_threads(2)
.enable_all()
.build()
.unwrap()
}
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