add support for io-uring (#374)

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

actix-server/CHANGES.md

@@ -3,11 +3,13 @@
 ## Unreleased - 2021-xx-xx
 * Remove `config` module. `ServiceConfig`, `ServiceRuntime` public types are removed due to this change. [#349]
 * Remove `ServerBuilder::configure` [#349]
+* Add `io-uring` feature for enabling async file I/O on linux. [#374]
 * Server no long listens to SIGHUP signal.
   It actually did not take any action when receiving SIGHUP, the only thing SIGHUP did was to stop
   the Server from receiving any future signal, because the `Signals` future stops on the first
   signal received [#389]
 
+[#374]: https://github.com/actix/actix-net/pull/374
 [#349]: https://github.com/actix/actix-net/pull/349
 [#389]: https://github.com/actix/actix-net/pull/389
 

actix-server/Cargo.toml

@@ -18,6 +18,7 @@ path = "src/lib.rs"
 
 [features]
 default = []
+io-uring = ["actix-rt/io-uring"]
 
 [dependencies]
 actix-rt = { version = "2.0.0", default-features = false }

actix-server/src/worker.rs

@@ -280,14 +280,24 @@ impl ServerWorker {
         let counter_clone = counter.clone();
         // every worker runs in it's own arbiter.
         // use a custom tokio runtime builder to change the settings of runtime.
-        Arbiter::with_tokio_rt(move || {
+        #[cfg(all(target_os = "linux", feature = "io-uring"))]
+        let arbiter = {
+            // TODO: pass max blocking thread config when tokio-uring enable configuration
+            // on building runtime.
+            let _ = config.max_blocking_threads;
+            Arbiter::new()
+        };
+
+        #[cfg(not(all(target_os = "linux", feature = "io-uring")))]
+        let arbiter = Arbiter::with_tokio_rt(move || {
             tokio::runtime::Builder::new_current_thread()
                 .enable_all()
                 .max_blocking_threads(config.max_blocking_threads)
                 .build()
                 .unwrap()
-        })
-        .spawn(async move {
+        });
+
+        arbiter.spawn(async move {
             let fut = factories
                 .iter()
                 .enumerate()