fix(napi): Implement napi_threadsafe_function ref and unref (#17304)

Co-authored-by: Bartek Iwańczuk <biwanczuk@gmail.com>

ext/napi/lib.rs

@@ -19,6 +19,8 @@ use std::ffi::CString;
 use std::path::Path;
 use std::path::PathBuf;
 use std::rc::Rc;
+use std::sync::atomic::AtomicUsize;
+use std::sync::Arc;
 use std::task::Poll;
 use std::thread_local;
 
@@ -322,7 +324,7 @@ pub struct napi_node_version {
 }
 
 pub type PendingNapiAsyncWork = Box<dyn FnOnce()>;
-
+pub type ThreadsafeFunctionRefCounters = Vec<(usize, Arc<AtomicUsize>)>;
 pub struct NapiState {
   // Async tasks.
   pub pending_async_work: Vec<PendingNapiAsyncWork>,
@@ -336,6 +338,7 @@ pub struct NapiState {
     mpsc::UnboundedSender<ThreadSafeFunctionStatus>,
   pub env_cleanup_hooks:
     Rc<RefCell<Vec<(extern "C" fn(*const c_void), *const c_void)>>>,
+  pub tsfn_ref_counters: Rc<RefCell<ThreadsafeFunctionRefCounters>>,
 }
 
 impl Drop for NapiState {
@@ -391,6 +394,7 @@ pub struct Env {
     mpsc::UnboundedSender<ThreadSafeFunctionStatus>,
   pub cleanup_hooks:
     Rc<RefCell<Vec<(extern "C" fn(*const c_void), *const c_void)>>>,
+  pub tsfn_ref_counters: Rc<RefCell<ThreadsafeFunctionRefCounters>>,
 }
 
 unsafe impl Send for Env {}
@@ -405,6 +409,7 @@ impl Env {
     cleanup_hooks: Rc<
       RefCell<Vec<(extern "C" fn(*const c_void), *const c_void)>>,
     >,
+    tsfn_ref_counters: Rc<RefCell<ThreadsafeFunctionRefCounters>>,
   ) -> Self {
     let sc = sender.clone();
     ASYNC_WORK_SENDER.with(|s| {
@@ -423,6 +428,7 @@ impl Env {
       async_work_sender: sender,
       threadsafe_function_sender,
       cleanup_hooks,
+      tsfn_ref_counters,
     }
   }
 
@@ -458,6 +464,22 @@ impl Env {
     // using `napi_open_handle_scope`.
     unsafe { v8::CallbackScope::new(context) }
   }
+
+  pub fn add_threadsafe_function_ref_counter(
+    &mut self,
+    id: usize,
+    counter: Arc<AtomicUsize>,
+  ) {
+    let mut counters = self.tsfn_ref_counters.borrow_mut();
+    assert!(!counters.iter().any(|(i, _)| *i == id));
+    counters.push((id, counter));
+  }
+
+  pub fn remove_threadsafe_function_ref_counter(&mut self, id: usize) {
+    let mut counters = self.tsfn_ref_counters.borrow_mut();
+    let index = counters.iter().position(|(i, _)| *i == id).unwrap();
+    counters.remove(index);
+  }
 }
 
 pub fn init<P: NapiPermissions + 'static>(unstable: bool) -> Extension {
@@ -479,22 +501,16 @@ pub fn init<P: NapiPermissions + 'static>(unstable: bool) -> Extension {
           napi_state.pending_async_work.push(async_work_fut);
         }
 
-        while let Poll::Ready(Some(tsfn_status)) =
-          napi_state.threadsafe_function_receiver.poll_next_unpin(cx)
-        {
-          match tsfn_status {
-            ThreadSafeFunctionStatus::Alive => {
-              napi_state.active_threadsafe_functions += 1
-            }
-            ThreadSafeFunctionStatus::Dead => {
-              napi_state.active_threadsafe_functions -= 1
-            }
-          };
-        }
-
         if napi_state.active_threadsafe_functions > 0 {
           maybe_scheduling = true;
         }
+
+        for (_id, counter) in napi_state.tsfn_ref_counters.borrow().iter() {
+          if counter.load(std::sync::atomic::Ordering::SeqCst) > 0 {
+            maybe_scheduling = true;
+            break;
+          }
+        }
       }
 
       loop {
@@ -527,6 +543,7 @@ pub fn init<P: NapiPermissions + 'static>(unstable: bool) -> Extension {
         threadsafe_function_receiver,
         active_threadsafe_functions: 0,
         env_cleanup_hooks: Rc::new(RefCell::new(vec![])),
+        tsfn_ref_counters: Rc::new(RefCell::new(vec![])),
       });
       state.put(Unstable(unstable));
       Ok(())
@@ -563,7 +580,13 @@ where
   let permissions = op_state.borrow_mut::<NP>();
   permissions.check(Some(&PathBuf::from(&path)))?;
 
-  let (async_work_sender, tsfn_sender, isolate_ptr, cleanup_hooks) = {
+  let (
+    async_work_sender,
+    tsfn_sender,
+    isolate_ptr,
+    cleanup_hooks,
+    tsfn_ref_counters,
+  ) = {
     let napi_state = op_state.borrow::<NapiState>();
     let isolate_ptr = op_state.borrow::<*mut v8::OwnedIsolate>();
     (
@@ -571,6 +594,7 @@ where
       napi_state.threadsafe_function_sender.clone(),
       *isolate_ptr,
       napi_state.env_cleanup_hooks.clone(),
+      napi_state.tsfn_ref_counters.clone(),
     )
   };
 
@@ -593,6 +617,7 @@ where
     async_work_sender,
     tsfn_sender,
     cleanup_hooks,
+    tsfn_ref_counters,
   );
   env.shared = Box::into_raw(Box::new(env_shared));
   let env_ptr = Box::into_raw(Box::new(env)) as _;