add support for io-uring (#374)

Co-authored-by: Rob Ede <robjtede@icloud.com>

actix-rt/CHANGES.md

@@ -1,9 +1,11 @@
 # Changes
 
 ## Unreleased - 2021-xx-xx
+* Add `io-uring` feature for enabling async file I/O on linux. [#374]
 * The `spawn` method can now resolve with non-unit outputs. [#369]
 
 [#369]: https://github.com/actix/actix-net/pull/369
+[#374]: https://github.com/actix/actix-net/pull/374
 
 
 ## 2.2.0 - 2021-03-29

actix-rt/Cargo.toml

@@ -21,6 +21,7 @@ path = "src/lib.rs"
 [features]
 default = ["macros"]
 macros = ["actix-macros"]
+io-uring = ["tokio-uring"]
 
 [dependencies]
 actix-macros = { version = "0.2.0", optional = true }
@@ -28,6 +29,9 @@ actix-macros = { version = "0.2.0", optional = true }
 futures-core = { version = "0.3", default-features = false }
 tokio = { version = "1.3", features = ["rt", "net", "parking_lot", "signal", "sync", "time"] }
 
+[target.'cfg(target_os = "linux")'.dependencies]
+tokio-uring = { version = "0.1", optional = true }
+
 [dev-dependencies]
 tokio = { version = "1.2", features = ["full"] }
 hyper = { version = "0.14", default-features = false, features = ["server", "tcp", "http1"] }

actix-rt/src/arbiter.rs

@@ -9,12 +9,9 @@ use std::{
 };
 
 use futures_core::ready;
-use tokio::{sync::mpsc, task::LocalSet};
+use tokio::sync::mpsc;
 
-use crate::{
-    runtime::{default_tokio_runtime, Runtime},
-    system::{System, SystemCommand},
-};
+use crate::system::{System, SystemCommand};
 
 pub(crate) static COUNT: AtomicUsize = AtomicUsize::new(0);
 
@@ -98,16 +95,19 @@ impl Arbiter {
     ///
     /// # Panics
     /// Panics if a [System] is not registered on the current thread.
+    #[cfg(not(all(target_os = "linux", feature = "io-uring")))]
     #[allow(clippy::new_without_default)]
     pub fn new() -> Arbiter {
         Self::with_tokio_rt(|| {
-            default_tokio_runtime().expect("Cannot create new Arbiter's Runtime.")
+            crate::runtime::default_tokio_runtime()
+                .expect("Cannot create new Arbiter's Runtime.")
         })
     }
 
     /// Spawn a new Arbiter using the [Tokio Runtime](tokio-runtime) returned from a closure.
     ///
     /// [tokio-runtime]: tokio::runtime::Runtime
+    #[cfg(not(all(target_os = "linux", feature = "io-uring")))]
     #[doc(hidden)]
     pub fn with_tokio_rt<F>(runtime_factory: F) -> Arbiter
     where
@@ -127,7 +127,7 @@ impl Arbiter {
             .spawn({
                 let tx = tx.clone();
                 move || {
-                    let rt = Runtime::from(runtime_factory());
+                    let rt = crate::runtime::Runtime::from(runtime_factory());
                     let hnd = ArbiterHandle::new(tx);
 
                     System::set_current(sys);
@@ -159,15 +159,67 @@ impl Arbiter {
         Arbiter { tx, thread_handle }
     }
 
-    /// Sets up an Arbiter runner in a new System using the provided runtime local task set.
-    pub(crate) fn in_new_system(local: &LocalSet) -> ArbiterHandle {
+    /// Spawn a new Arbiter thread and start its event loop with `tokio-uring` runtime.
+    ///
+    /// # Panics
+    /// Panics if a [System] is not registered on the current thread.
+    #[cfg(all(target_os = "linux", feature = "io-uring"))]
+    #[allow(clippy::new_without_default)]
+    pub fn new() -> Arbiter {
+        let sys = System::current();
+        let system_id = sys.id();
+        let arb_id = COUNT.fetch_add(1, Ordering::Relaxed);
+
+        let name = format!("actix-rt|system:{}|arbiter:{}", system_id, arb_id);
+        let (tx, rx) = mpsc::unbounded_channel();
+
+        let (ready_tx, ready_rx) = std::sync::mpsc::channel::<()>();
+
+        let thread_handle = thread::Builder::new()
+            .name(name.clone())
+            .spawn({
+                let tx = tx.clone();
+                move || {
+                    let hnd = ArbiterHandle::new(tx);
+
+                    System::set_current(sys);
+
+                    HANDLE.with(|cell| *cell.borrow_mut() = Some(hnd.clone()));
+
+                    // register arbiter
+                    let _ = System::current()
+                        .tx()
+                        .send(SystemCommand::RegisterArbiter(arb_id, hnd));
+
+                    ready_tx.send(()).unwrap();
+
+                    // run arbiter event processing loop
+                    tokio_uring::start(ArbiterRunner { rx });
+
+                    // deregister arbiter
+                    let _ = System::current()
+                        .tx()
+                        .send(SystemCommand::DeregisterArbiter(arb_id));
+                }
+            })
+            .unwrap_or_else(|err| {
+                panic!("Cannot spawn Arbiter's thread: {:?}. {:?}", &name, err)
+            });
+
+        ready_rx.recv().unwrap();
+
+        Arbiter { tx, thread_handle }
+    }
+
+    /// Sets up an Arbiter runner in a new System using the environment's local set.
+    pub(crate) fn in_new_system() -> ArbiterHandle {
         let (tx, rx) = mpsc::unbounded_channel();
 
         let hnd = ArbiterHandle::new(tx);
 
         HANDLE.with(|cell| *cell.borrow_mut() = Some(hnd.clone()));
 
-        local.spawn_local(ArbiterRunner { rx });
+        crate::spawn(ArbiterRunner { rx });
 
         hnd
     }

actix-rt/src/lib.rs

@@ -32,6 +32,10 @@
 //! arbiter.stop();
 //! arbiter.join().unwrap();
 //! ```
+//!
+//! # `io-uring` Support
+//! There is experimental support for using io-uring with this crate by enabling the
+//! `io-uring` feature. For now, it is semver exempt.
 
 #![deny(rust_2018_idioms, nonstandard_style)]
 #![allow(clippy::type_complexity)]
@@ -39,6 +43,9 @@
 #![doc(html_logo_url = "https://actix.rs/img/logo.png")]
 #![doc(html_favicon_url = "https://actix.rs/favicon.ico")]
 
+#[cfg(all(not(target_os = "linux"), feature = "io-uring"))]
+compile_error!("io_uring is a linux only feature.");
+
 use std::future::Future;
 
 use tokio::task::JoinHandle;

actix-rt/src/runtime.rs

@@ -31,11 +31,6 @@ impl Runtime {
         })
     }
 
-    /// Reference to local task set.
-    pub(crate) fn local_set(&self) -> &LocalSet {
-        &self.local
-    }
-
     /// Offload a future onto the single-threaded runtime.
     ///
     /// The returned join handle can be used to await the future's result.

actix-rt/src/system.rs

@@ -54,7 +54,7 @@ impl System {
         let (sys_tx, sys_rx) = mpsc::unbounded_channel();
 
         let rt = Runtime::from(runtime_factory());
-        let sys_arbiter = Arbiter::in_new_system(rt.local_set());
+        let sys_arbiter = rt.block_on(async { Arbiter::in_new_system() });
         let system = System::construct(sys_tx, sys_arbiter.clone());
 
         system

actix-rt/tests/tests.rs

@@ -1,10 +1,6 @@
 use std::{
     future::Future,
-    sync::{
-        atomic::{AtomicBool, Ordering},
-        mpsc::channel,
-        Arc,
-    },
+    sync::mpsc::channel,
     thread,
     time::{Duration, Instant},
 };
@@ -221,8 +217,8 @@ fn system_stop_stops_arbiters() {
     System::current().stop();
     sys.run().unwrap();
 
-    // account for slightly slow thread de-spawns (only observed on windows)
-    thread::sleep(Duration::from_millis(100));
+    // account for slightly slow thread de-spawns
+    thread::sleep(Duration::from_millis(500));
 
     // arbiter should be dead and return false
     assert!(!Arbiter::current().spawn_fn(|| {}));
@@ -231,6 +227,7 @@ fn system_stop_stops_arbiters() {
     arb.join().unwrap();
 }
 
+#[cfg(not(feature = "io-uring"))]
 #[test]
 fn new_system_with_tokio() {
     let (tx, rx) = channel();
@@ -263,8 +260,14 @@ fn new_system_with_tokio() {
     assert_eq!(rx.recv().unwrap(), 42);
 }
 
+#[cfg(not(feature = "io-uring"))]
 #[test]
 fn new_arbiter_with_tokio() {
+    use std::sync::{
+        atomic::{AtomicBool, Ordering},
+        Arc,
+    };
+
     let _ = System::new();
 
     let arb = Arbiter::with_tokio_rt(|| {
@@ -323,3 +326,32 @@ fn spawn_local() {
         h(actix_rt::spawn(async { 1 }));
     })
 }
+
+#[cfg(all(target_os = "linux", feature = "io-uring"))]
+#[test]
+fn tokio_uring_arbiter() {
+    let system = System::new();
+    let (tx, rx) = std::sync::mpsc::channel();
+
+    Arbiter::new().spawn(async move {
+        let handle = actix_rt::spawn(async move {
+            let f = tokio_uring::fs::File::create("test.txt").await.unwrap();
+            let buf = b"Hello World!";
+
+            let (res, _) = f.write_at(&buf[..], 0).await;
+            assert!(res.is_ok());
+
+            f.sync_all().await.unwrap();
+            f.close().await.unwrap();
+
+            std::fs::remove_file("test.txt").unwrap();
+        });
+
+        handle.await.unwrap();
+        tx.send(true).unwrap();
+    });
+
+    assert!(rx.recv().unwrap());
+
+    drop(system);
+}