validation: parallel request processing

validation/src/main.rs

@@ -28,6 +28,8 @@ pub type MapsServiceClient=rust_grpc::maps::maps_service_client::MapsServiceClie
 
 pub const GROUP_STRAFESNET:u64=6980477;
 
+pub const PARALLEL_REQUESTS:usize=16;
+
 #[tokio::main]
 async fn main()->Result<(),StartupError>{
 	// talk to roblox through STRAFESNET_CI2 account
@@ -67,17 +69,30 @@ async fn main()->Result<(),StartupError>{
 	// run futures
 	let (mut messages,message_handler)=tokio::try_join!(nats_fut,message_handler_fut)?;
 
-	// nats consumer thread
-	tokio::spawn(async move{
-		while let Some(message_result)=messages.next().await{
-			match message_handler.handle_message_result(message_result).await{
-				Ok(())=>println!("[Validation] Success, hooray!"),
-				Err(e)=>println!("[Validation] There was an error, oopsie! {e}"),
-			}
+	// process up to PARALLEL_REQUESTS in parallel
+	let main_loop=async move{
+		static SEM:tokio::sync::Semaphore=tokio::sync::Semaphore::const_new(PARALLEL_REQUESTS);
+		// use memory leak to make static lifetime
+		let message_handler=Box::leak(Box::new(message_handler));
+		// acquire a permit before attempting to receive a message, exit if either fails
+		while let (Ok(permit),Some(message_result))=(SEM.acquire().await,messages.next().await){
+			// handle the message on a new thread (mainly to decode the model file)
+			tokio::spawn(async{
+				match message_handler.handle_message_result(message_result).await{
+					Ok(())=>println!("[Validation] Success, hooray!"),
+					Err(e)=>println!("[Validation] There was an error, oopsie! {e}"),
+				}
+				// explicitly call drop to make the move semantics and permit release more obvious
+				core::mem::drop(permit);
+			});
 		}
-	});
+	};
 
-	sig_term.recv().await;
+	// race sigkill and main loop termination and then die
+	tokio::select!{
+		_=sig_term.recv()=>(),
+		_=main_loop=>(),
+	};
 
 	Ok(())
 }