hotfix: enable reading lines split over multiple stdout buffers

Cargo.lock

@@ -1256,9 +1256,9 @@ checksum = "73cbba799671b762df5a175adf59ce145165747bb891505c43d09aefbbf38beb"
 
 [[package]]
 name = "memchr"
-version = "2.4.1"
+version = "2.5.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "308cc39be01b73d0d18f82a0e7b2a3df85245f84af96fdddc5d202d27e47b86a"
+checksum = "2dffe52ecf27772e601905b7522cb4ef790d2cc203488bbd0e2fe85fcb74566d"
 
 [[package]]
 name = "mime"
@@ -1586,6 +1586,7 @@ dependencies = [
  "chrono",
  "futures",
  "futures-core",
+ "memchr",
  "planetwars-rules",
  "rand 0.6.5",
  "serde",

planetwars-matchrunner/Cargo.toml

@@ -18,6 +18,7 @@ chrono = { version = "0.4", features = ["serde"] }
 bollard = { git = "https://github.com/fussybeaver/bollard", rev = "c5d87a4934c70a04f9c649fedb241dbd4943c927" }
 bytes = "1.1"
 async-trait = "0.1"
+memchr = "2.5.0"
 
 [dev-dependencies]
 tempfile = "3"

planetwars-matchrunner/src/docker_runner.rs

@@ -5,7 +5,7 @@ use std::sync::{Arc, Mutex};
 use async_trait::async_trait;
 use bollard::container::{self, AttachContainerOptions, AttachContainerResults, LogOutput};
 use bollard::Docker;
-use bytes::Bytes;
+use bytes::{Bytes, BytesMut};
 use futures::{Stream, StreamExt};
 use tokio::io::{AsyncWrite, AsyncWriteExt};
 use tokio::sync::mpsc;
@@ -168,6 +168,8 @@ fn run_docker_bot(
         event_bus,
         match_logger,
         rx,
+
+        stdout_buf: BytesMut::new(),
     };
 
     let join_handle = tokio::spawn(bot_runner.run());
@@ -198,6 +200,9 @@ pub struct DockerBotRunner {
     rx: mpsc::UnboundedReceiver<RequestMessage>,
     match_logger: MatchLogger,
     player_id: u32,
+
+    stdout_buf: BytesMut,
+    // stderr_buf: BytesMut,
 }
 
 impl DockerBotRunner {
@@ -243,8 +248,11 @@ impl DockerBotRunner {
             let log_output = item.expect("failed to get log output");
             match log_output {
                 LogOutput::StdOut { message } => {
-                    // TODO: this is not correct (buffering and such)
-                    return Ok(message);
+                    self.stdout_buf.extend_from_slice(&message);
+                    if let Some(split_idx) = memchr::memchr(b'\n', &self.stdout_buf) {
+                        let line = self.stdout_buf.split_to(split_idx+1);
+                        return Ok(line.freeze())
+                    }
                 }
                 LogOutput::StdErr { mut message } => {
                     // TODO

planetwars-matchrunner/tests/test_matchrunner.rs

@@ -148,3 +148,20 @@ async fn docker_runner_crash() {
     })
     .await;
 }
+
+#[tokio::test]
+async fn test_long_line() {
+    let bot_spec = simple_python_docker_bot_spec("./bots", "echo_bot.py");
+    let len = 10 * 2_usize.pow(20); // 10 megabytes - hopefully large enough to cause buffering
+    let buf = std::iter::repeat(b'a').take(len).collect::<Vec<u8>>();
+    with_bot_match_ctx(bot_spec, |ctx| {
+        async move {
+            let resp = ctx.request(1, buf, Duration::from_millis(200)).await;
+
+            let resp_bytes = resp.expect("unexpected error");
+            assert_eq!(resp_bytes.len(), len + 1);
+        }
+        .boxed()
+    })
+    .await;
+}