client: don't freeze when bot does not produce output

planetwars-client/src/main.rs

@@ -7,12 +7,21 @@ pub mod pb {
 
 use clap::Parser;
 use pb::client_api_service_client::ClientApiServiceClient;
-use planetwars_matchrunner::bot_runner::Bot;
+use planetwars_matchrunner::bot_runner::{Bot, BotProcess};
 use serde::Deserialize;
-use std::{path::PathBuf, time::Duration};
-use tokio::sync::mpsc;
+use std::{
+    collections::VecDeque,
+    path::PathBuf,
+    sync::{Arc, Mutex},
+    time::Duration,
+};
+use tokio::{
+    io::{AsyncWriteExt, BufReader, Lines},
+    process::{ChildStdin, ChildStdout},
+    sync::mpsc::{self, UnboundedSender},
+};
 use tokio_stream::wrappers::UnboundedReceiverStream;
-use tonic::{metadata::MetadataValue, transport::Channel, Request, Status};
+use tonic::{metadata::MetadataValue, transport::Channel, Request, Status, Streaming};
 
 #[derive(clap::Parser)]
 struct PlayMatch {
@@ -124,7 +133,11 @@ async fn run_player(
         Ok(req)
     });
 
-    let mut bot_process = Bot {
+    let BotProcess {
+        child: _child,
+        stdin,
+        stdout,
+    } = Bot {
         working_dir: PathBuf::from(
             bot_config
                 .working_directory
@@ -134,27 +147,57 @@ async fn run_player(
     }
     .spawn_process();
 
+    let state = Arc::new(Mutex::new(BotRunnerState {
+        request_queue: VecDeque::new(),
+    }));
+
     let (tx, rx) = mpsc::unbounded_channel();
-    let mut stream = client
+    let stream = client
         .connect_player(UnboundedReceiverStream::new(rx))
         .await
         .unwrap()
         .into_inner();
+
+    let output_handle = tokio::spawn(handle_bot_output(state.clone(), tx, stdout));
+    let input_handle = tokio::spawn(handle_server_messages(state.clone(), stream, stdin));
+
+    output_handle
+        .await
+        .unwrap()
+        .map_err(RunPlayerError::RunBotError)?;
+    input_handle
+        .await
+        .unwrap()
+        .map_err(RunPlayerError::RunBotError)?;
+
+    Ok(())
+}
+
+struct BotRunnerState {
+    request_queue: VecDeque<i32>,
+}
+
+async fn handle_server_messages(
+    runner_state: Arc<Mutex<BotRunnerState>>,
+    mut stream: Streaming<pb::PlayerApiServerMessage>,
+    mut stdin: ChildStdin,
+) -> io::Result<()> {
     while let Some(message) = stream.message().await.unwrap() {
         match message.server_message {
             Some(pb::PlayerApiServerMessageType::ActionRequest(req)) => {
-                let moves = bot_process
-                    .communicate(&req.content)
-                    .await
-                    .map_err(RunPlayerError::RunBotError)?;
-                let action = pb::PlayerAction {
-                    action_request_id: req.action_request_id,
-                    content: moves.as_bytes().to_vec(),
-                };
-                let msg = pb::PlayerApiClientMessage {
-                    client_message: Some(pb::PlayerApiClientMessageType::Action(action)),
-                };
-                tx.send(msg).unwrap();
+                {
+                    let mut state = runner_state.lock().unwrap();
+                    if !state.request_queue.is_empty() {
+                        eprintln!("[WARN] new turn started before bot output was received");
+                        eprintln!(
+                            "[WARN] this could be due to your bot taking too long, \
+                                    or failing to flush output buffers."
+                        );
+                    }
+                    state.request_queue.push_back(req.action_request_id);
+                }
+                stdin.write_all(&req.content).await?;
+                stdin.write_u8(b'\n').await?;
             }
             _ => {} // pass
         }
@@ -162,3 +205,28 @@ async fn run_player(
 
     Ok(())
 }
+
+use std::io;
+
+async fn handle_bot_output(
+    runner_state: Arc<Mutex<BotRunnerState>>,
+    tx: UnboundedSender<pb::PlayerApiClientMessage>,
+    mut bot_stdout: Lines<BufReader<ChildStdout>>,
+) -> io::Result<()> {
+    while let Some(line) = bot_stdout.next_line().await? {
+        if let Some(request_id) = runner_state.lock().unwrap().request_queue.pop_front() {
+            let action = pb::PlayerAction {
+                action_request_id: request_id,
+                content: line.as_bytes().to_vec(),
+            };
+            let msg = pb::PlayerApiClientMessage {
+                client_message: Some(pb::PlayerApiClientMessageType::Action(action)),
+            };
+            tx.send(msg).unwrap();
+        } else {
+            eprintln!("[WARN] bot issued commands before a gamestate was received");
+        }
+    }
+
+    Ok(())
+}

planetwars-matchrunner/src/bot_runner.rs

@@ -108,9 +108,9 @@ impl Bot {
 
 pub struct BotProcess {
     #[allow(dead_code)]
-    child: process::Child,
-    stdin: process::ChildStdin,
-    stdout: Lines<BufReader<process::ChildStdout>>,
+    pub child: process::Child,
+    pub stdin: process::ChildStdin,
+    pub stdout: Lines<BufReader<process::ChildStdout>>,
 }
 
 impl BotProcess {