From e97bbd085572b4b43e23914123e8e10b0991c212 Mon Sep 17 00:00:00 2001
From: Fedor Indutny <fedor@indutny.com>
Date: Sat, 22 May 2021 12:35:24 -0700
Subject: [PATCH] more locks

---
 crates/neon-runtime/src/napi/tsfn.rs | 20 ++++++++++++++++++--
 1 file changed, 18 insertions(+), 2 deletions(-)

diff --git a/crates/neon-runtime/src/napi/tsfn.rs b/crates/neon-runtime/src/napi/tsfn.rs
index bdb118fd9..f76f5136c 100644
--- a/crates/neon-runtime/src/napi/tsfn.rs
+++ b/crates/neon-runtime/src/napi/tsfn.rs
@@ -119,12 +119,28 @@ impl<T: Send + 'static> ThreadsafeFunction<T> {
             data,
         }));
 
-        let status =
-            unsafe { napi::call_threadsafe_function(self.tsfn.0, callback as *mut _, is_blocking) };
+        let status = {
+            // Hold the lock before entering `call_threadsafe_function` so that
+            // `finalize_cb` would never complete.
+            let is_finalized = self.is_finalized.lock().unwrap();
+
+            if *is_finalized {
+                napi::Status::Closing
+            } else {
+                unsafe {
+                    napi::call_threadsafe_function(self.tsfn.0, callback as *mut _, is_blocking)
+                }
+            }
+        };
 
         if status == napi::Status::Ok {
             Ok(())
         } else {
+            // Prevent further calls to `call_threadsafe_function`
+            if status == napi::Status::Closing {
+                *self.is_finalized.lock().unwrap() = true;
+            }
+
             // If the call failed, the callback won't execute
             let callback = unsafe { Box::from_raw(callback) };