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An off-by-one bug results in freeing the incorrect page. This
also adds an `asan` CI job.
Fixes: 3014
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tokio:
merge rt-core and rt-util as rt
rename rt-threaded to rt-multi-thread
tokio-util:
rename rt-core to rt
Closes #2942
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Co-authored-by: Alice Ryhl <alice@ryhl.io>
Co-authored-by: Carl Lerche <me@carllerche.com>
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As tokio does not rely on poisoning, we can
avoid always unwrapping when locking by handling
the `PoisonError` in the Mutex shim.
Signed-off-by: Zahari Dichev <zaharidichev@gmail.com>
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This refactors I/O registration in a few ways:
- Cleans up the cached readiness in `PollEvented`. This cache used to
be helpful when readiness was a linked list of `*mut Node`s in
`Registration`. Previous refactors have turned `Registration` into just
an `AtomicUsize` holding the current readiness, so the cache is just
extra work and complexity. Gone.
- Polling the `Registration` for readiness now gives a `ReadyEvent`,
which includes the driver tick. This event must be passed back into
`clear_readiness`, so that the readiness is only cleared from `Registration`
if the tick hasn't changed. Previously, it was possible to clear the
readiness even though another thread had *just* polled the driver and
found the socket ready again.
- Registration now also contains an `async fn readiness`, which stores
wakers in an instrusive linked list. This allows an unbounded number
of tasks to register for readiness (previously, only 1 per direction (read
and write)). By using the intrusive linked list, there is no concern of
leaking the storage of the wakers, since they are stored inside the `async fn`
and released when the future is dropped.
- Registration retains a `poll_readiness(Direction)` method, to support
`AsyncRead` and `AsyncWrite`. They aren't able to use `async fn`s, and
so there are 2 reserved slots for those methods.
- IO types where it makes sense to have multiple tasks waiting on them
now take advantage of this new `async fn readiness`, such as `UdpSocket`
and `UnixDatagram`.
Additionally, this makes the `io-driver` "feature" internal-only (no longer
documented, not part of public API), and adds a second internal-only
feature, `io-readiness`, to group together linked list part of registration
that is only used by some of the IO types.
After a bit of discussion, changing stream-based transports (like
`TcpStream`) to have `async fn read(&self)` is punted, since that
is likely too easy of a footgun to activate.
Refs: #2779, #2728
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The I/O driver uses a slab to store per-resource state. Doing this
provides two benefits. First, allocating state is streamlined. Second,
resources may be safely indexed using a `usize` type. The `usize` is
used passed to the OS's selector when registering for receiving events.
The original slab implementation used a `Vec` backed by `RwLock`. This
primarily caused contention when reading state. This implementation also
only **grew** the slab capacity but never shrank. In #1625, the slab was
rewritten to use a lock-free strategy. The lock contention was removed
but this implementation was still grow-only.
This change adds the ability to release memory. Similar to the previous
implementation, it structures the slab to use a vector of pages. This
enables growing the slab without having to move any previous entries. It
also adds the ability to release pages. This is done by introducing a
lock when allocating/releasing slab entries. This does not impact
benchmarks, primarily due to the existing implementation not being
"done" and also having a lock around allocating and releasing.
A `Slab::compact()` function is added. Pages are iterated. When a page
is found with no slots in use, the page is freed. The `compact()`
function is called occasionally by the I/O driver.
Fixes #2505
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