## Motivation
PR #4499 made the `JoinSet` API unstable, but did not add a
documentation note explaining unstable features. In general, since the
docs.rs build includes unstable APIs, it's probably worth including
these notes so that users understand what it means for an API to be
unstable.
## Solution
This branch adds a note on unstable APIs to the `JoinSet` type-level
documentation, similar to the notes for `task::Builder` and the runtime
metrics APIs.
Also, I noticed that there was a broken link to the top-level
documentation on unstable APIs in the docs for `task::Builder`, so I
fixed that as well.
time: resolve TODO
## Motivation
Existing `TODO` comment in `src/time/driver/wheel/level.rs`.
## Solution
`level_range()` always return a strictly positive power of 2. If `b` is a
strictly positive power of 2, `a - (a % b)` is equal to `a & !(b - 1)`.
The major breaking change in Mio v0.8 is TcpSocket type being removed.
Replacing Mio's TcpSocket we switch to the socket2 library which
provides a similar type Socket, as well as SockRef, which provide all
options TcpSocket provided (and more!).
Tokio's TcpSocket type is now backed by Socket2 instead of Mio's
TcpSocket. The main pitfall here is that socket2 isn't non-blocking by
default, which Mio obviously is. As a result we have to do potentially
blocking calls more carefully, specifically we need to handle
would-block-like errors when connecting the TcpSocket ourselves.
One benefit for this change is that adding more socket options to
TcpSocket is now merely a single function call away (in most cases
anyway).
PR #3881 factored out the spawning of local tasks on a `LocalSet` into a
function `spawn_local_inner`, so that the implementation could be shared
with the `task::Builder` API. But, that PR neglected to add a
`#[track_caller]` attribute to `spawn_local_inner`, so the `tracing`
spans for local tasks are all generated with `spawn_local_inner` as
their spawn location, rather than forwarding the actual spawn location
from the calling function.
This causes pretty useless results when using `tokio-console` with code
that spawns a number of local tasks, such as Actix
(https://reddit.com/r/rust/comments/snt5fq/can_tokioconsole_profile_actixrt/)
This commit fixes the issue by adding the missing `#[track_caller]`
attribute.
`Instant::duration_since`, `Instant::elapsed`, and `Instant::sub` may
panic. This is especially dangerous when `Instant::now` travels back in
time. While this isn't supposed to happen, this behavior is highly
platform-dependent (e.g., rust-lang/rust#86470).
This change modifies the behavior of `tokio::time::Instant` to prevent
this class of panic, as proposed for `std::time::Instant` in
rust-lang/rust#89926.
When backporting patches to LTS branches, we often run into CI failures due to
changes in rust. Newer rust versions add more lints, which break CI. We really
don't want to also have to backport patches that fix CI, so instead, LTS branches
should pin the stable rust version in CI (e.g. #4434).
This PR restructures the CI config files to make it a bit easier to set a specific rust
version in CI.
* Several of tokio's features (e.g. the channel implementation) do not
need a runtime to work, and can be compiled and used for
wasm32-unknown-unknown targets
* This change enables running tests for the `sync` and `macros` features
so that we can note any regressions there
Takuya Kajiwara