mirror of
https://github.com/actix/examples
synced 2024-11-28 00:12:57 +01:00
88 lines
3.0 KiB
Rust
88 lines
3.0 KiB
Rust
//! Application may have multiple data objects that are shared across
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//! all handlers within same Application.
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//!
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//! For global shared state, we wrap our state in a [`actix_web::web::Data`] and move it into
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//! the factory closure. The closure is called once-per-thread, and we clone our state
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//! and attach to each instance of the [`App`] with `.app_data(state.clone())`.
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//!
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//! For thread-local state, we construct our state within the factory closure and attach to
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//! the app with `.app_data(Data::new(state))`.
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//!
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//! We retrieve our app state within our handlers with a `state: Data<...>` argument.
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//!
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//! By default, Actix Web runs one [`App`] per logical cpu core.
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//! When running on `<N>` cores, we see that the example will increment `counter_mutex` (global state via
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//! Mutex) and `counter_atomic` (global state via Atomic variable) each time the endpoint is called,
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//! but only appear to increment `counter_cell` every Nth time on average (thread-local state). This
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//! is because the workload is being shared equally among cores.
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//!
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//! Check [user guide](https://actix.rs/docs/application/#state) for more info.
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use std::{
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cell::Cell,
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io,
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sync::{
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atomic::{AtomicUsize, Ordering},
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Mutex,
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},
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};
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use actix_web::{
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middleware,
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web::{self, Data},
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App, HttpRequest, HttpResponse, HttpServer,
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};
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/// simple handle
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async fn index(
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counter_mutex: Data<Mutex<usize>>,
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counter_cell: Data<Cell<u32>>,
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counter_atomic: Data<AtomicUsize>,
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req: HttpRequest,
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) -> HttpResponse {
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println!("{req:?}");
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// Increment the counters
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*counter_mutex.lock().unwrap() += 1;
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counter_cell.set(counter_cell.get() + 1);
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counter_atomic.fetch_add(1, Ordering::SeqCst);
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let body = format!(
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"global mutex counter: {}, local counter: {}, global atomic counter: {}",
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*counter_mutex.lock().unwrap(),
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counter_cell.get(),
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counter_atomic.load(Ordering::SeqCst),
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);
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HttpResponse::Ok().body(body)
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}
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#[actix_web::main]
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async fn main() -> io::Result<()> {
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env_logger::init_from_env(env_logger::Env::new().default_filter_or("info"));
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// Create some global state prior to building the server
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#[allow(clippy::mutex_atomic)] // it's intentional.
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let counter_mutex = Data::new(Mutex::new(0usize));
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let counter_atomic = Data::new(AtomicUsize::new(0usize));
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log::info!("starting HTTP server at http://localhost:8080");
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// move is necessary to give closure below ownership of counter1
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HttpServer::new(move || {
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// Create some thread-local state
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let counter_cell = Cell::new(0u32);
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App::new()
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.app_data(counter_mutex.clone()) // add shared state
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.app_data(counter_atomic.clone()) // add shared state
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.app_data(Data::new(counter_cell)) // add thread-local state
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// enable logger
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.wrap(middleware::Logger::default())
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// register simple handler
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.service(web::resource("/").to(index))
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})
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.bind(("127.0.0.1", 8080))?
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.run()
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.await
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}
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