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Test combinations of task behavior #3967

Merged
merged 16 commits into from
Jul 22, 2021
43 changes: 31 additions & 12 deletions tokio/src/runtime/task/harness.rs
Original file line number Diff line number Diff line change
Expand Up @@ -112,6 +112,8 @@ where
}

pub(super) fn drop_join_handle_slow(self) {
let mut maybe_panic = None;

// Try to unset `JOIN_INTEREST`. This must be done as a first step in
// case the task concurrently completed.
if self.header().state.unset_join_interested().is_err() {
Expand All @@ -120,11 +122,20 @@ where
// the scheduler or `JoinHandle`. i.e. if the output remains in the
// task structure until the task is deallocated, it may be dropped
// by a Waker on any arbitrary thread.
self.core().stage.drop_future_or_output();
let panic = panic::catch_unwind(panic::AssertUnwindSafe(|| {
self.core().stage.drop_future_or_output();
}));
if let Err(panic) = panic {
maybe_panic = Some(panic);
}
}

// Drop the `JoinHandle` reference, possibly deallocating the task
self.drop_reference();

if let Some(panic) = maybe_panic {
panic::resume_unwind(panic);
}
}

// ===== waker behavior =====
Expand Down Expand Up @@ -183,17 +194,25 @@ where
// ====== internal ======

fn complete(self, output: super::Result<T::Output>, is_join_interested: bool) {
if is_join_interested {
// Store the output. The future has already been dropped
//
// Safety: Mutual exclusion is obtained by having transitioned the task
// state -> Running
let stage = &self.core().stage;
stage.store_output(output);

// Transition to `Complete`, notifying the `JoinHandle` if necessary.
transition_to_complete(self.header(), stage, &self.trailer());
}
// We catch panics here because dropping the output may panic.
//
// Dropping the output can also happen in the first branch inside
// transition_to_complete.
let _ = panic::catch_unwind(panic::AssertUnwindSafe(|| {
if is_join_interested {
// Store the output. The future has already been dropped
//
// Safety: Mutual exclusion is obtained by having transitioned the task
// state -> Running
let stage = &self.core().stage;
stage.store_output(output);

// Transition to `Complete`, notifying the `JoinHandle` if necessary.
transition_to_complete(self.header(), stage, &self.trailer());
} else {
drop(output);
}
}));

// The task has completed execution and will no longer be scheduled.
//
Expand Down
3 changes: 3 additions & 0 deletions tokio/src/runtime/tests/mod.rs
Original file line number Diff line number Diff line change
Expand Up @@ -40,6 +40,9 @@ cfg_loom! {
cfg_not_loom! {
mod queue;

#[cfg(not(miri))]
mod task_combinations;

#[cfg(miri)]
mod task;
}
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