From c4fe58d8df51e8f07142803ec0522f862fd30a3f Mon Sep 17 00:00:00 2001
From: Yiyu Lin <linyiyu1992@gmail.com>
Date: Sun, 17 May 2020 12:50:38 +0800
Subject: [PATCH] Return error if more than one listener calls
 `WorkerHandle::get_event()` (#5461)

---
 cli/ops/worker_host.rs |  2 +-
 cli/tsc.rs             |  2 +-
 cli/web_worker.rs      |  8 ++++----
 cli/worker.rs          | 10 +++++-----
 4 files changed, 11 insertions(+), 11 deletions(-)

diff --git a/cli/ops/worker_host.rs b/cli/ops/worker_host.rs
index 479fcceafc..d1b4bb80f1 100644
--- a/cli/ops/worker_host.rs
+++ b/cli/ops/worker_host.rs
@@ -306,7 +306,7 @@ fn op_host_get_message(
   };
   let state_ = state.clone();
   let op = async move {
-    let response = match worker_handle.get_event().await {
+    let response = match worker_handle.get_event().await? {
       Some(event) => {
         // Terminal error means that worker should be removed from worker table.
         if let WorkerEvent::TerminalError(_) = &event {
diff --git a/cli/tsc.rs b/cli/tsc.rs
index 483d849632..4d1d2368cd 100644
--- a/cli/tsc.rs
+++ b/cli/tsc.rs
@@ -794,7 +794,7 @@ async fn execute_in_thread(
   })?;
   let handle = handle_receiver.recv().unwrap()?;
   handle.post_message(req)?;
-  let event = handle.get_event().await.expect("Compiler didn't respond");
+  let event = handle.get_event().await?.expect("Compiler didn't respond");
   let buf = match event {
     WorkerEvent::Message(buf) => Ok(buf),
     WorkerEvent::Error(error) => Err(error),
diff --git a/cli/web_worker.rs b/cli/web_worker.rs
index 490d9a5f32..46f03da363 100644
--- a/cli/web_worker.rs
+++ b/cli/web_worker.rs
@@ -300,13 +300,13 @@ mod tests {
       let r = handle.post_message(msg.clone());
       assert!(r.is_ok());
 
-      let maybe_msg = handle.get_event().await;
+      let maybe_msg = handle.get_event().await.unwrap();
       assert!(maybe_msg.is_some());
 
       let r = handle.post_message(msg.clone());
       assert!(r.is_ok());
 
-      let maybe_msg = handle.get_event().await;
+      let maybe_msg = handle.get_event().await.unwrap();
       assert!(maybe_msg.is_some());
       match maybe_msg {
         Some(WorkerEvent::Message(buf)) => {
@@ -321,7 +321,7 @@ mod tests {
         .into_boxed_bytes();
       let r = handle.post_message(msg);
       assert!(r.is_ok());
-      let event = handle.get_event().await;
+      let event = handle.get_event().await.unwrap();
       assert!(event.is_none());
       handle.sender.close_channel();
     });
@@ -348,7 +348,7 @@ mod tests {
       let msg = json!("hi").to_string().into_boxed_str().into_boxed_bytes();
       let r = handle.post_message(msg.clone());
       assert!(r.is_ok());
-      let event = handle.get_event().await;
+      let event = handle.get_event().await.unwrap();
       assert!(event.is_none());
       handle.sender.close_channel();
     });
diff --git a/cli/worker.rs b/cli/worker.rs
index d52d965944..b66c1cb06b 100644
--- a/cli/worker.rs
+++ b/cli/worker.rs
@@ -51,11 +51,11 @@ impl WorkerHandle {
     sender.try_send(buf).map_err(ErrBox::from)
   }
 
-  // TODO: should use `try_lock` and return error if
-  // more than one listener tries to get event
-  pub async fn get_event(&self) -> Option<WorkerEvent> {
-    let mut receiver = self.receiver.lock().await;
-    receiver.next().await
+  /// Get the event with lock.
+  /// Return error if more than one listener tries to get event
+  pub async fn get_event(&self) -> Result<Option<WorkerEvent>, ErrBox> {
+    let mut receiver = self.receiver.try_lock()?;
+    Ok(receiver.next().await)
   }
 }