diff options
author | Sean McArthur <sean@seanmonstar.com> | 2020-09-23 13:02:15 -0700 |
---|---|---|
committer | GitHub <noreply@github.com> | 2020-09-23 13:02:15 -0700 |
commit | a0557840eb424e174bf81a0175c40f9e176a2cc2 (patch) | |
tree | 676d33bf4144f0c0aac5af9f826ecc216a1d50e2 /tokio-util | |
parent | f25f12d57638a2928b3f738b3b1392d8773e276e (diff) |
io: use intrusive wait list for I/O driver (#2828)
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
Diffstat (limited to 'tokio-util')
-rw-r--r-- | tokio-util/Cargo.toml | 3 | ||||
-rw-r--r-- | tokio-util/src/cfg.rs | 2 | ||||
-rw-r--r-- | tokio-util/src/lib.rs | 5 | ||||
-rw-r--r-- | tokio-util/tests/udp.rs | 2 |
4 files changed, 10 insertions, 2 deletions
diff --git a/tokio-util/Cargo.toml b/tokio-util/Cargo.toml index 85b4e592..45daa2b1 100644 --- a/tokio-util/Cargo.toml +++ b/tokio-util/Cargo.toml @@ -25,11 +25,10 @@ publish = false default = [] # Shorthand for enabling everything -full = ["codec", "udp", "compat", "io"] +full = ["codec", "compat", "io"] compat = ["futures-io",] codec = ["tokio/stream"] -udp = ["tokio/udp"] io = [] [dependencies] diff --git a/tokio-util/src/cfg.rs b/tokio-util/src/cfg.rs index 2efa5f09..f9176747 100644 --- a/tokio-util/src/cfg.rs +++ b/tokio-util/src/cfg.rs @@ -18,6 +18,7 @@ macro_rules! cfg_compat { } } +/* macro_rules! cfg_udp { ($($item:item)*) => { $( @@ -27,6 +28,7 @@ macro_rules! cfg_udp { )* } } +*/ macro_rules! cfg_io { ($($item:item)*) => { diff --git a/tokio-util/src/lib.rs b/tokio-util/src/lib.rs index 24a8af95..b96d9044 100644 --- a/tokio-util/src/lib.rs +++ b/tokio-util/src/lib.rs @@ -30,9 +30,14 @@ cfg_codec! { pub mod codec; } +/* +Disabled due to removal of poll_ functions on UdpSocket. + +See https://github.com/tokio-rs/tokio/issues/2830 cfg_udp! { pub mod udp; } +*/ cfg_compat! { pub mod compat; diff --git a/tokio-util/tests/udp.rs b/tokio-util/tests/udp.rs index 4820ac72..99763854 100644 --- a/tokio-util/tests/udp.rs +++ b/tokio-util/tests/udp.rs @@ -1,3 +1,4 @@ +/* #![warn(rust_2018_idioms)] use tokio::{net::UdpSocket, stream::StreamExt}; @@ -100,3 +101,4 @@ async fn send_framed_lines_codec() -> std::io::Result<()> { Ok(()) } +*/ |