Update basics/state to v4. (#479)

basics/state/Cargo.toml

@@ -2,8 +2,8 @@
 name = "state"
 version = "2.0.0"
 authors = ["Nikolay Kim <fafhrd91@gmail.com>"]
-edition = "2018"
+edition = "2021"
 
 [dependencies]
-actix-web = "3"
+actix-web = "4.0.0-beta.21"
-env_logger = "0.8"
+env_logger = "0.9.0"

basics/state/src/main.rs

@@ -1,19 +1,19 @@
 //! Application may have multiple data objects that are shared across
 //! all handlers within same Application.
 //!
-//! For global shared state, we wrap our state in a `actix_web::web::Data` and move it into
+//! For global shared state, we wrap our state in a [`actix_web::web::Data`] and move it into
 //! the factory closure. The closure is called once-per-thread, and we clone our state
-//! and attach to each instance of the `App` with `.app_data(state.clone())`.
+//! and attach to each instance of the [`App`] with `.app_data(state.clone())`.
 //!
 //! For thread-local state, we construct our state within the factory closure and attach to
-//! the app with `.data(state)`.
+//! the app with `.app_data(Data::new(state))`.
 //!
 //! We retrieve our app state within our handlers with a `state: Data<...>` argument.
 //!
-//! By default, `actix-web` runs one `App` per logical cpu core.
+//! By default, `actix-web` runs one [`App`] per logical cpu core.
-//! When running on <N> cores, we see that the example will increment `counter1` (global state via
+//! When running on `<N>` cores, we see that the example will increment `counter_mutex` (global state via
-//! Mutex) and `counter3` (global state via Atomic variable) each time the endpoint is called,
+//! Mutex) and `counter_atomic` (global state via Atomic variable) each time the endpoint is called,
-//! but only appear to increment `counter2` every Nth time on average (thread-local state). This
+//! but only appear to increment `counter_cell` every Nth time on average (thread-local state). This
 //! is because the workload is being shared equally among cores.
 //!
 //! Check [user guide](https://actix.rs/docs/application/#state) for more info.
@@ -23,27 +23,31 @@ use std::io;
 use std::sync::atomic::{AtomicUsize, Ordering};
 use std::sync::Mutex;
 
-use actix_web::{middleware, web, App, HttpRequest, HttpResponse, HttpServer};
+use actix_web::{
+    middleware,
+    web::{self, Data},
+    App, HttpRequest, HttpResponse, HttpServer,
+};
 
 /// simple handle
 async fn index(
-    counter1: web::Data<Mutex<usize>>,
+    counter_mutex: Data<Mutex<usize>>,
-    counter2: web::Data<Cell<u32>>,
+    counter_cell: Data<Cell<u32>>,
-    counter3: web::Data<AtomicUsize>,
+    counter_atomic: Data<AtomicUsize>,
     req: HttpRequest,
 ) -> HttpResponse {
     println!("{:?}", req);
 
     // Increment the counters
-    *counter1.lock().unwrap() += 1;
+    *counter_mutex.lock().unwrap() += 1;
-    counter2.set(counter2.get() + 1);
+    counter_cell.set(counter_cell.get() + 1);
-    counter3.fetch_add(1, Ordering::SeqCst);
+    counter_atomic.fetch_add(1, Ordering::SeqCst);
 
     let body = format!(
         "global mutex counter: {}, local counter: {}, global atomic counter: {}",
-        *counter1.lock().unwrap(),
+        *counter_mutex.lock().unwrap(),
-        counter2.get(),
+        counter_cell.get(),
-        counter3.load(Ordering::SeqCst),
+        counter_atomic.load(Ordering::SeqCst),
     );
     HttpResponse::Ok().body(body)
 }
@@ -55,18 +59,18 @@ async fn main() -> io::Result<()> {
 
     // Create some global state prior to building the server
     #[allow(clippy::mutex_atomic)] // it's intentional.
-    let counter1 = web::Data::new(Mutex::new(0usize));
+    let counter_mutex = Data::new(Mutex::new(0usize));
-    let counter3 = web::Data::new(AtomicUsize::new(0usize));
+    let counter_atomic = Data::new(AtomicUsize::new(0usize));
 
     // move is necessary to give closure below ownership of counter1
     HttpServer::new(move || {
         // Create some thread-local state
-        let counter2 = Cell::new(0u32);
+        let counter_cell = Cell::new(0u32);
 
         App::new()
-            .app_data(counter1.clone()) // add shared state
+            .app_data(counter_mutex.clone()) // add shared state
-            .app_data(counter3.clone()) // add shared state
+            .app_data(counter_atomic.clone()) // add shared state
-            .data(counter2) // add thread-local state
+            .app_data(Data::new(counter_cell)) // add thread-local state
             // enable logger
             .wrap(middleware::Logger::default())
             // register simple handler