make number of compute threads configurable

battlesnake/src/main.rs

@@ -1,4 +1,7 @@
-use std::env;
+use std::{
+    env,
+    sync::atomic::{AtomicUsize, Ordering},
+};
 
 use axum::{
     Router,
@@ -21,6 +24,8 @@ use tokio::{
     time::{Duration, Instant},
 };
 
+static THREADS: AtomicUsize = AtomicUsize::new(1);
+
 #[tokio::main]
 async fn main() {
     env_logger::init();
@@ -32,6 +37,17 @@ async fn main() {
         .route("/move", post(get_move))
         .route("/end", post(end));
 
+    let threads = env::var("THREADS")
+        .ok()
+        .and_then(|threads| {
+            threads
+                .parse()
+                .inspect_err(|err| error!("Unable to parse number of threads: {err}"))
+                .ok()
+        })
+        .unwrap_or(1);
+    THREADS.store(threads, Ordering::Relaxed);
+
     debug!("Creating listener");
     let port = env::var("PORT").unwrap_or_else(|_| "8000".into());
     let listener = TcpListener::bind(format!("0.0.0.0:{port}")).await.unwrap();
@@ -104,7 +120,7 @@ async fn get_move(request: Json<Request>) -> response::Json<Response> {
         _ => score_standard,
     };
 
-    let action_futures = (0..3).map(|_| {
+    let action_futures = (0..THREADS.load(Ordering::Relaxed)).map(|_| {
         let request = request.clone();
         let board = board.clone();
         let mut rng = SmallRng::from_os_rng();