This patch fixes an issue where the `CancellationToken::run_until_cancelled` never cancels the `Future` that returns `Ready` at the first `poll`.
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Co-authored-by: Luca BRUNO <lucab@lucabruno.net>
# 1.46.1 (July 4th, 2025)
This release fixes incorrect spawn locations in runtime task hooks for tasks
spawned using `tokio::spawn` rather than `Runtime::spawn`. This issue only
effected the spawn location in `TaskMeta::spawned_at`, and did not effect task
locations in Tracing events.
## Unstable
- runtime: add `TaskMeta::spawn_location` tracking where a task was spawned
([#7440)])
[#7440]: https://github.com/tokio-rs/tokio/pull/7440
## Motivation
Unfortunately, due to an oversight on my part, the capturing of spawn
locations was only tested with the `Runtime::spawn` method, and *not*
with `tokio::spawn`/`tokio::task::spawn`, which is how most tasks are
spawned in Real Life. And, it turned out that because this was not
tested...well, it was broken. Agh. My bad.
## Solution
Although the whole call chain for spawning tasks using `tokio::spawn`
was correctly annotated with `#[track_caller]`, the location wasn't
propagated correctly because of the `context::with_current(|handle| {
... })` closure that accesses the current runtime. Because the call to
spawn the task occurs inside a closure, the *closure*'s location is
captured instead of the caller. This means any task spawned by
`tokio::spawn` records its location as being in
`tokio/src/task/spawn.rs`, which is not what we'd like. This commit
fixes that by capturing the spawn location outside the `with_current`
closure and passing it in explicitly.
I've updated the tests to also spawn a task with `tokio::spawn`, so that
we ensure this works correctly.
As described in issue #7411, task spawning APIs are currently annotated
with `#[track_caller]`, allowing us to capture the location in the user
source code where the task was spawned. This is used for `tracing`
events used by `tokio-console` and friends. However, this information is
*not* exposed to the runtime `on_task_spawn`, `on_before_task_poll`,
`on_after_task_poll`, and `on_task_terminate` hooks, which is a shame,
as it would be useful there as well.
This branch adds the task's spawn location to the `TaskMeta` struct
provided to the runtime's task hooks. This is implemented by storing a
`&'static Location<'static>` in the task's `Core` alongside the
`task::Id`. In [this comment][1], @ADD-SP suggested storing the
`Location` in the task's `Trailer`.
I opted to store it in the `Core` instead, as the `Trailer` is intended
to store "cold" data that is only accessed when the task _completes_,
and not on every poll. Since the task meta is passed to the
`on_before_task_poll` and `on_after_task_poll` hooks, we would be
accessing the `Trailer` on polls if we stored the `Location` there.
Therefore, I put it in the `Core`, instead, which contains data that we
access every time the task is polled.
Closes#7411
[1]: https://github.com/tokio-rs/tokio/issues/7411#issuecomment-2993377045
