Dropping a timer on the millisecond that it was scheduled for, when it was on
the pending list, could result in a panic previously, as we did not record the
pending-list state in cached_when.
Hopefully fixes: ZcashFoundation/zebra#1452
Previously, the runtime shutdown logic would first-hand control over all cores
to a single thread, which would sequentially shut down all tasks on the core
and then wait for them to complete.
This could deadlock when one task is waiting for a later core's task to
complete. For example, in the newly added test, we have a `block_in_place` task
that is waiting for another task to be dropped. If the latter task adds its
core to the shutdown list later than the former, we end up waiting forever for
the `block_in_place` task to complete.
Additionally, there also was a bug wherein we'd attempt to park on the parker
after shutting it down which was fixed as part of the refactors above.
This change restructures the code to bring all tasks to a halt (and do any
parking needed) before we collapse to a single thread to avoid this deadlock.
There was also an issue in which canceled tasks would not unpark the
originating thread, due to what appears to be some sort of optimization gone
wrong. This has been fixed to be much more conservative in selecting when not
to unpark the source thread (this may be too conservative; please take a look
at the changes to `release()`).
Fixes: #2789
This removes the last slab dependency by replacing the current slab-based
JoinHandle tracking with one based on HashMap instead.
Co-authored-by: Bryan Donlan <[email protected]>
* io: Add AsyncFd
This adds AsyncFd, a unix-only structure to allow for read/writability states
to be monitored for arbitrary file descriptors.
Issue: #2728
* driver: fix shutdown notification unreliability
Previously, there was a race window in which an IO driver shutting down could
fail to notify ScheduledIo instances of this state; in particular, notification
of outstanding ScheduledIo registrations was driven by `Driver::drop`, but
registrations bypass `Driver` and go directly to a `Weak<Inner>`. The `Driver`
holds the `Arc<Inner>` keeping `Inner` alive, but it's possible that a new
handle could be registered (or a new readiness future created for an existing
handle) after the `Driver::drop` handler runs and prior to `Inner` being
dropped.
This change fixes this in two parts: First, notification of outstanding
ScheduledIo handles is pushed down into the drop method of `Inner` instead,
and, second, we add state to ScheduledIo to ensure that we remember that the IO
driver we're bound to has shut down after the initial shutdown notification, so
that subsequent readiness future registrations can immediately return (instead
of potentially blocking indefinitely).
Fixes: #2924
This change is intended to do the minimum to unblock 0.3; as such, for now, we
duplicate the internal `time::wheel` structures in tokio-util, rather than trying
to refactor things at this stage.
Co-authored-by: Bryan Donlan <[email protected]>
As we go into 0.3 we no longer need to support older versions of Rust where
IoSlice did not implement Copy and Clone, so we can more easily initialize the
IoSlice array in net::tcp::stream.
Co-authored-by: Bryan Donlan <[email protected]>
Dropping a runtime normally involves waiting for any outstanding blocking tasks
to complete. When this drop happens in an asynchronous context, we previously
would issue a cryptic panic due to trying to block in an asynchronous context.
This change improves the panic message, and adds a `shutdown_blocking()` function
which can be used to shutdown a runtime without blocking at all, as an out for
cases where this really is necessary.
Co-authored-by: Bryan Donlan <[email protected]>
Co-authored-by: Alice Ryhl <[email protected]>
A fast path in block_on_place was failing to call exit() in the case where we
were in a block_on call.
Fixes: #2639
Co-authored-by: Bryan Donlan <[email protected]>
bdonlan