Closed DimiDimit closed 3 years ago
Seems fair; should do that in the next release. BTW, do you know if tokio supports any APIs to check if the current thread is a worker thread of the thread-pool? The current support for tokio panics if block_in_place
is called outside the thread-pool.
I had a look at both the documentation and the source code, but the only things I found are pub(crate)
...
For reference, here's how tokio
checks it in worker.rs
:
// Tracks thread-local state
scoped_thread_local!(static CURRENT: Context);
// [...]
pub(crate) fn block_in_place<F, R>(f: F) -> R
where
F: FnOnce() -> R,
{
// [...]
CURRENT.with(|maybe_cx| {
match (crate::runtime::enter::context(), maybe_cx.is_some()) {
(EnterContext::Entered { .. }, true) => {
// We are on a thread pool runtime thread, so we just need to set up blocking.
// [...]
}
(EnterContext::Entered { allow_blocking }, false) => {
// We are on an executor, but _not_ on the thread pool.
// That is _only_ okay if we are in a thread pool runtime's block_on method:
if allow_blocking {
// [...]
} else {
// This probably means we are on the basic_scheduler or in a LocalSet,
// where it is _not_ okay to block.
panic!("can call blocking only when running on the multi-threaded runtime");
}
}
(EnterContext::NotEntered, true) => {
// This is a nested call to block_in_place (we already exited).
// [...]
}
(EnterContext::NotEntered, false) => {
// We are outside of the tokio runtime, so blocking is fine.
// [...]
}
}
// [...]
});
// [...]
}
Thanks for looking into this @DimiDimit ; I'll try asking the tokio authors if they could support something like that. Meanwhile, 0.6.0 has been released , and depends on tokio 1.0
It seems that changing
Cargo.toml
"just works", but I haven't tested it much.