chore(napi): reduce Mutex usage while loading addon

crates/napi/src/bindgen_runtime/js_values/arraybuffer.rs

@@ -7,8 +7,6 @@ use std::sync::{
   Arc,
 };
 
-#[cfg(feature = "napi4")]
-use crate::bindgen_prelude::{CUSTOM_GC_TSFN, CUSTOM_GC_TSFN_CLOSED, MAIN_THREAD_ID};
 pub use crate::js_values::TypedArrayType;
 use crate::{check_status, sys, Error, Result, Status};
 
@@ -66,31 +64,6 @@ macro_rules! impl_typed_array {
       fn drop(&mut self) {
         if Arc::strong_count(&self.drop_in_vm) == 1 {
           if let Some((ref_, env)) = self.raw {
-            #[cfg(feature = "napi4")]
-            {
-              if CUSTOM_GC_TSFN_CLOSED.load(std::sync::atomic::Ordering::SeqCst) {
-                return;
-              }
-              if !MAIN_THREAD_ID
-                .get()
-                .map(|id| &std::thread::current().id() == id)
-                .unwrap_or(false)
-              {
-                let status = unsafe {
-                  sys::napi_call_threadsafe_function(
-                    CUSTOM_GC_TSFN.load(std::sync::atomic::Ordering::SeqCst),
-                    ref_ as *mut c_void,
-                    1,
-                  )
-                };
-                assert!(
-                  status == sys::Status::napi_ok,
-                  "Call custom GC in ArrayBuffer::drop failed {:?}",
-                  Status::from(status)
-                );
-                return;
-              }
-            }
             crate::check_status_or_throw!(
               env,
               unsafe { sys::napi_reference_unref(env, ref_, &mut 0) },

crates/napi/src/bindgen_runtime/js_values/buffer.rs

@@ -1,4 +1,4 @@
-#[cfg(debug_assertions)]
+#[cfg(all(debug_assertions, not(windows)))]
 use std::collections::HashSet;
 use std::ffi::c_void;
 use std::mem;
@@ -6,12 +6,12 @@ use std::ops::{Deref, DerefMut};
 use std::ptr::{self, NonNull};
 use std::slice;
 use std::sync::Arc;
-#[cfg(debug_assertions)]
+#[cfg(all(debug_assertions, not(windows)))]
 use std::sync::Mutex;
 
 use crate::{bindgen_prelude::*, check_status, sys, Result, ValueType};
 
-#[cfg(debug_assertions)]
+#[cfg(all(debug_assertions, not(windows)))]
 thread_local! {
   pub (crate) static BUFFER_DATA: Mutex<HashSet<*mut u8>> = Default::default();
 }
@@ -32,31 +32,6 @@ impl Drop for Buffer {
   fn drop(&mut self) {
     if Arc::strong_count(&self.ref_count) == 1 {
       if let Some((ref_, env)) = self.raw {
-        #[cfg(feature = "napi4")]
-        {
-          if CUSTOM_GC_TSFN_CLOSED.load(std::sync::atomic::Ordering::SeqCst) {
-            return;
-          }
-          if !MAIN_THREAD_ID
-            .get()
-            .map(|id| &std::thread::current().id() == id)
-            .unwrap_or(false)
-          {
-            let status = unsafe {
-              sys::napi_call_threadsafe_function(
-                CUSTOM_GC_TSFN.load(std::sync::atomic::Ordering::SeqCst),
-                ref_ as *mut c_void,
-                1,
-              )
-            };
-            assert!(
-              status == sys::Status::napi_ok,
-              "Call custom GC in Buffer::drop failed {:?}",
-              Status::from(status)
-            );
-            return;
-          }
-        }
         let mut ref_count = 0;
         check_status_or_throw!(
           env,
@@ -94,7 +69,7 @@ impl Clone for Buffer {
 impl From<Vec<u8>> for Buffer {
   fn from(mut data: Vec<u8>) -> Self {
     let inner_ptr = data.as_mut_ptr();
-    #[cfg(debug_assertions)]
+    #[cfg(all(debug_assertions, not(windows)))]
     {
       let is_existed = BUFFER_DATA.with(|buffer_data| {
         let buffer = buffer_data.lock().expect("Unlock buffer data failed");

crates/napi/src/bindgen_runtime/js_values/promise.rs

@@ -77,7 +77,7 @@ impl<T: FromNapiValue> ValidateNapiValue for Promise<T> {
   }
 }
 
-unsafe impl<T: FromNapiValue> Send for Promise<T> {}
+unsafe impl<T: FromNapiValue + Send> Send for Promise<T> {}
 
 impl<T: FromNapiValue> FromNapiValue for Promise<T> {
   unsafe fn from_napi_value(env: sys::napi_env, napi_val: sys::napi_value) -> crate::Result<Self> {

crates/napi/src/bindgen_runtime/js_values/value_ref.rs

@@ -6,7 +6,7 @@ use std::rc::{Rc, Weak};
 use once_cell::sync::Lazy;
 
 use crate::{
-  bindgen_runtime::{PersistedSingleThreadHashMap, ToNapiValue},
+  bindgen_runtime::{PersistedPerInstanceHashMap, ToNapiValue},
   check_status, Env, Error, Result, Status,
 };
 
@@ -16,9 +16,16 @@ type RefInformation = (
   *const Cell<*mut dyn FnOnce()>,
 );
 
-pub(crate) static REFERENCE_MAP: Lazy<PersistedSingleThreadHashMap<*mut c_void, RefInformation>> =
+pub(crate) static REFERENCE_MAP: Lazy<PersistedPerInstanceHashMap<*mut c_void, RefInformation>> =
   Lazy::new(Default::default);
 
+#[ctor::dtor]
+fn de_init() {
+  REFERENCE_MAP.borrow_mut(|reference_map| {
+    std::mem::take(reference_map);
+  });
+}
+
 /// ### Experimental feature
 ///
 /// Create a `reference` from `Class` instance.

crates/napi/src/bindgen_runtime/mod.rs

@@ -76,7 +76,7 @@ pub unsafe extern "C" fn drop_buffer(
   #[allow(unused)] finalize_data: *mut c_void,
   finalize_hint: *mut c_void,
 ) {
-  #[cfg(debug_assertions)]
+  #[cfg(all(debug_assertions, not(windows)))]
   {
     js_values::BUFFER_DATA.with(|buffer_data| {
       let mut buffer = buffer_data.lock().expect("Unlock Buffer data failed");

crates/napi/src/bindgen_runtime/module_register.rs

@@ -1,21 +1,10 @@
 use std::collections::{HashMap, HashSet};
-#[cfg(feature = "napi4")]
+use std::ffi::{c_void, CStr};
-use std::ffi::c_void;
-use std::ffi::CStr;
-use std::mem;
-#[cfg(feature = "napi4")]
-use std::os::raw::c_char;
 use std::ptr;
-use std::sync::{
+use std::sync::atomic::AtomicUsize;
-  atomic::{AtomicBool, AtomicPtr, Ordering},
+use std::sync::atomic::{AtomicBool, AtomicPtr, Ordering};
-  Mutex,
-};
-#[cfg(feature = "napi4")]
-use std::thread::ThreadId;
 
 use once_cell::sync::Lazy;
-#[cfg(feature = "napi4")]
-use once_cell::sync::OnceCell;
 
 use crate::{
   check_status, check_status_or_throw, sys, Env, JsError, JsFunction, Property, Result, Value,
@@ -26,97 +15,118 @@ pub type ExportRegisterCallback = unsafe fn(sys::napi_env) -> Result<sys::napi_v
 pub type ModuleExportsCallback =
   unsafe fn(env: sys::napi_env, exports: sys::napi_value) -> Result<()>;
 
-#[cfg(feature = "napi4")]
+struct PersistedPerInstanceVec<T> {
-pub(crate) static CUSTOM_GC_TSFN: AtomicPtr<sys::napi_threadsafe_function__> =
+  inner: AtomicPtr<T>,
-  AtomicPtr::new(ptr::null_mut());
+  length: AtomicUsize,
-#[cfg(feature = "napi4")]
-// CustomGC ThreadsafeFunction may be deleted during the process exit.
-// And there may still some Buffer alive after that.
-pub(crate) static CUSTOM_GC_TSFN_CLOSED: AtomicBool = AtomicBool::new(false);
-#[cfg(feature = "napi4")]
-pub(crate) static MAIN_THREAD_ID: OnceCell<ThreadId> = OnceCell::new();
-
-struct PersistedSingleThreadVec<T> {
-  inner: Mutex<Vec<T>>,
 }
 
-impl<T> Default for PersistedSingleThreadVec<T> {
+impl<T> Default for PersistedPerInstanceVec<T> {
   fn default() -> Self {
-    PersistedSingleThreadVec {
+    let mut vec: Vec<T> = Vec::with_capacity(1);
-      inner: Mutex::new(Vec::new()),
+    let ret = Self {
-    }
+      inner: AtomicPtr::new(vec.as_mut_ptr()),
+      length: AtomicUsize::new(0),
+    };
+    std::mem::forget(vec);
+    ret
   }
 }
 
-impl<T> PersistedSingleThreadVec<T> {
+impl<T> PersistedPerInstanceVec<T> {
   #[allow(clippy::mut_from_ref)]
   fn borrow_mut<F>(&self, f: F)
   where
     F: FnOnce(&mut [T]),
   {
-    let mut locked = self
+    let length = self.length.load(Ordering::Relaxed);
-      .inner
+    if length == 0 {
-      .lock()
+      f(&mut []);
-      .expect("Acquire persisted thread vec lock failed");
+    } else {
-    f(&mut locked);
+      let inner = self.inner.load(Ordering::Relaxed);
+      let mut temp = unsafe { Vec::from_raw_parts(inner, length, length) };
+      f(temp.as_mut_slice());
+      // Inner Vec has been reallocated, so we need to update the pointer
+      if temp.as_mut_ptr() != inner {
+        self.inner.store(temp.as_mut_ptr(), Ordering::Relaxed);
+      }
+      self.length.store(temp.len(), Ordering::Relaxed);
+      std::mem::forget(temp);
+    }
   }
 
   fn push(&self, item: T) {
-    let mut locked = self
+    let length = self.length.load(Ordering::Relaxed);
-      .inner
+    let inner = self.inner.load(Ordering::Relaxed);
-      .lock()
+    let mut temp = unsafe { Vec::from_raw_parts(inner, length, length) };
-      .expect("Acquire persisted thread vec lock failed");
+    temp.push(item);
-    locked.push(item);
+    // Inner Vec has been reallocated, so we need to update the pointer
+    if temp.as_mut_ptr() != inner {
+      self.inner.store(temp.as_mut_ptr(), Ordering::Relaxed);
+    }
+    std::mem::forget(temp);
+
+    self.length.fetch_add(1, Ordering::Relaxed);
   }
 }
 
-unsafe impl<T> Send for PersistedSingleThreadVec<T> {}
+unsafe impl<T: Send> Send for PersistedPerInstanceVec<T> {}
-unsafe impl<T> Sync for PersistedSingleThreadVec<T> {}
+unsafe impl<T: Sync> Sync for PersistedPerInstanceVec<T> {}
 
-pub(crate) struct PersistedSingleThreadHashMap<K, V>(Mutex<HashMap<K, V>>);
+pub(crate) struct PersistedPerInstanceHashMap<K, V>(*mut HashMap<K, V>);
 
-impl<K, V> PersistedSingleThreadHashMap<K, V> {
+impl<K, V> PersistedPerInstanceHashMap<K, V> {
   #[allow(clippy::mut_from_ref)]
   pub(crate) fn borrow_mut<F, R>(&self, f: F) -> R
   where
     F: FnOnce(&mut HashMap<K, V>) -> R,
   {
-    let mut lock = self
+    f(unsafe { Box::leak(Box::from_raw(self.0)) })
-      .0
-      .lock()
-      .expect("Acquire persisted thread hash map lock failed");
-    f(&mut *lock)
   }
 }
 
-impl<K, V> Default for PersistedSingleThreadHashMap<K, V> {
+impl<K, V> Default for PersistedPerInstanceHashMap<K, V> {
   fn default() -> Self {
-    PersistedSingleThreadHashMap(Mutex::new(Default::default()))
+    let map = Default::default();
+    Self(Box::into_raw(Box::new(map)))
   }
 }
 
 type ModuleRegisterCallback =
-  PersistedSingleThreadVec<(Option<&'static str>, (&'static str, ExportRegisterCallback))>;
+  PersistedPerInstanceVec<(Option<&'static str>, (&'static str, ExportRegisterCallback))>;
 
-type ModuleClassProperty = PersistedSingleThreadHashMap<
+type ModuleClassProperty = PersistedPerInstanceHashMap<
   &'static str,
   HashMap<Option<&'static str>, (&'static str, Vec<Property>)>,
 >;
 
-unsafe impl<K, V> Send for PersistedSingleThreadHashMap<K, V> {}
+unsafe impl<K, V> Send for PersistedPerInstanceHashMap<K, V> {}
-unsafe impl<K, V> Sync for PersistedSingleThreadHashMap<K, V> {}
+unsafe impl<K, V> Sync for PersistedPerInstanceHashMap<K, V> {}
 
 type FnRegisterMap =
-  PersistedSingleThreadHashMap<ExportRegisterCallback, (sys::napi_callback, &'static str)>;
+  PersistedPerInstanceHashMap<ExportRegisterCallback, (sys::napi_callback, &'static str)>;
 
 static MODULE_REGISTER_CALLBACK: Lazy<ModuleRegisterCallback> = Lazy::new(Default::default);
 static MODULE_CLASS_PROPERTIES: Lazy<ModuleClassProperty> = Lazy::new(Default::default);
-static MODULE_REGISTER_LOCK: Lazy<Mutex<()>> = Lazy::new(|| Mutex::new(()));
+static REGISTERED: AtomicBool = AtomicBool::new(false);
-static REGISTERED: Lazy<AtomicBool> = Lazy::new(|| AtomicBool::new(false));
 static REGISTERED_CLASSES: Lazy<thread_local::ThreadLocal<AtomicPtr<RegisteredClasses>>> =
   Lazy::new(thread_local::ThreadLocal::new);
 static FN_REGISTER_MAP: Lazy<FnRegisterMap> = Lazy::new(Default::default);
 
+#[ctor::dtor]
+fn destroy() {
+  {
+    let ptr = MODULE_REGISTER_CALLBACK.inner.load(Ordering::Relaxed);
+    let len = MODULE_REGISTER_CALLBACK.length.load(Ordering::Relaxed);
+    unsafe { Vec::from_raw_parts(ptr, len, len) };
+  }
+  {
+    unsafe { Box::from_raw(MODULE_CLASS_PROPERTIES.0) };
+  }
+  {
+    unsafe { Box::from_raw(FN_REGISTER_MAP.0) };
+  }
+}
+
 #[inline]
 fn wait_first_thread_registered() {
   while !REGISTERED.load(Ordering::SeqCst) {
@@ -130,7 +140,7 @@ type RegisteredClasses =
 #[cfg(feature = "compat-mode")]
 // compatibility for #[module_exports]
 
-static MODULE_EXPORTS: Lazy<PersistedSingleThreadVec<ModuleExportsCallback>> =
+static MODULE_EXPORTS: Lazy<PersistedPerInstanceVec<ModuleExportsCallback>> =
   Lazy::new(Default::default);
 
 #[doc(hidden)]
@@ -271,20 +281,21 @@ pub fn get_c_callback(raw_fn: ExportRegisterCallback) -> Result<crate::Callback>
   })
 }
 
+#[cfg(windows)]
+#[ctor::ctor]
+fn load_host() {
+  unsafe {
+    sys::setup();
+  }
+}
+
 #[no_mangle]
 unsafe extern "C" fn napi_register_module_v1(
   env: sys::napi_env,
   exports: sys::napi_value,
 ) -> sys::napi_value {
-  #[cfg(windows)]
-  unsafe {
-    sys::setup();
-  }
   crate::__private::___CALL_FROM_FACTORY.get_or_default();
   let registered_classes_ptr = REGISTERED_CLASSES.get_or_default();
-  let lock = MODULE_REGISTER_LOCK
-    .lock()
-    .expect("Failed to acquire module register lock");
   let mut exports_objects: HashSet<String> = HashSet::default();
   MODULE_REGISTER_CALLBACK.borrow_mut(|inner| {
     inner
@@ -462,29 +473,27 @@ unsafe extern "C" fn napi_register_module_v1(
     })
   });
 
-  #[cfg(all(feature = "tokio_rt", feature = "napi4"))]
+  #[cfg(feature = "napi3")]
   {
-    let _ = crate::tokio_runtime::RT.clone();
+    unsafe {
-    crate::tokio_runtime::TOKIO_RT_REF_COUNT.fetch_add(1, Ordering::SeqCst);
+      sys::napi_add_env_cleanup_hook(env, Some(remove_registered_classes), env as *mut c_void)
-    assert_eq!(
+    };
-      unsafe {
-        sys::napi_add_env_cleanup_hook(
-          env,
-          Some(crate::shutdown_tokio_rt),
-          env as *mut std::ffi::c_void,
-        )
-      },
-      sys::Status::napi_ok
-    );
   }
-  mem::drop(lock);
-
-  #[cfg(feature = "napi4")]
-  create_custom_gc(env);
   REGISTERED.store(true, Ordering::SeqCst);
   exports
 }
 
+unsafe extern "C" fn remove_registered_classes(env: *mut c_void) {
+  let env = env as sys::napi_env;
+  if let Some(s) = REGISTERED_CLASSES.get() {
+    let registered_classes = unsafe { Box::from_raw(s.load(Ordering::Relaxed)) };
+    registered_classes.iter().for_each(|(_, v)| {
+      unsafe { sys::napi_delete_reference(env, *v) };
+    });
+    s.store(ptr::null_mut(), Ordering::Relaxed);
+  }
+}
+
 pub(crate) unsafe extern "C" fn noop(
   env: sys::napi_env,
   _info: sys::napi_callback_info,
@@ -502,99 +511,3 @@ pub(crate) unsafe extern "C" fn noop(
   }
   ptr::null_mut()
 }
-
-#[cfg(feature = "napi4")]
-fn create_custom_gc(env: sys::napi_env) {
-  let mut custom_gc_fn = ptr::null_mut();
-  check_status_or_throw!(
-    env,
-    unsafe {
-      sys::napi_create_function(
-        env,
-        "custom_gc".as_ptr() as *const c_char,
-        9,
-        Some(empty),
-        ptr::null_mut(),
-        &mut custom_gc_fn,
-      )
-    },
-    "Create Custom GC Function in napi_register_module_v1 failed"
-  );
-  let mut async_resource_name = ptr::null_mut();
-  check_status_or_throw!(
-    env,
-    unsafe {
-      sys::napi_create_string_utf8(
-        env,
-        "CustomGC".as_ptr() as *const c_char,
-        8,
-        &mut async_resource_name,
-      )
-    },
-    "Create async resource string in napi_register_module_v1 napi_register_module_v1"
-  );
-  let mut custom_gc_tsfn = ptr::null_mut();
-  check_status_or_throw!(
-    env,
-    unsafe {
-      sys::napi_create_threadsafe_function(
-        env,
-        custom_gc_fn,
-        ptr::null_mut(),
-        async_resource_name,
-        0,
-        1,
-        ptr::null_mut(),
-        Some(custom_gc_finalize),
-        ptr::null_mut(),
-        Some(custom_gc),
-        &mut custom_gc_tsfn,
-      )
-    },
-    "Create Custom GC ThreadsafeFunction in napi_register_module_v1 failed"
-  );
-  check_status_or_throw!(
-    env,
-    unsafe { sys::napi_unref_threadsafe_function(env, custom_gc_tsfn) },
-    "Unref Custom GC ThreadsafeFunction in napi_register_module_v1 failed"
-  );
-  CUSTOM_GC_TSFN.store(custom_gc_tsfn, Ordering::SeqCst);
-  MAIN_THREAD_ID.get_or_init(|| std::thread::current().id());
-}
-
-#[cfg(feature = "napi4")]
-#[allow(unused)]
-unsafe extern "C" fn empty(env: sys::napi_env, info: sys::napi_callback_info) -> sys::napi_value {
-  ptr::null_mut()
-}
-
-#[cfg(feature = "napi4")]
-#[allow(unused)]
-unsafe extern "C" fn custom_gc_finalize(
-  env: sys::napi_env,
-  finalize_data: *mut c_void,
-  finalize_hint: *mut c_void,
-) {
-  CUSTOM_GC_TSFN_CLOSED.store(true, Ordering::SeqCst);
-}
-
-#[cfg(feature = "napi4")]
-// recycle the ArrayBuffer/Buffer Reference if the ArrayBuffer/Buffer is not dropped on the main thread
-extern "C" fn custom_gc(
-  env: sys::napi_env,
-  _js_callback: sys::napi_value,
-  _context: *mut c_void,
-  data: *mut c_void,
-) {
-  let mut ref_count = 0;
-  check_status_or_throw!(
-    env,
-    unsafe { sys::napi_reference_unref(env, data as sys::napi_ref, &mut ref_count) },
-    "Failed to unref Buffer reference in Custom GC"
-  );
-  check_status_or_throw!(
-    env,
-    unsafe { sys::napi_delete_reference(env, data as sys::napi_ref) },
-    "Failed to delete Buffer reference in Custom GC"
-  );
-}

crates/napi/src/lib.rs

@@ -109,8 +109,6 @@ pub use error::*;
 pub use js_values::*;
 pub use status::Status;
 pub use task::Task;
-#[cfg(all(feature = "tokio_rt", feature = "napi4"))]
-pub use tokio_runtime::shutdown_tokio_rt;
 pub use value_type::*;
 pub use version::NodeVersion;
 #[cfg(feature = "serde-json")]

crates/napi/src/tokio_runtime.rs

@@ -1,7 +1,5 @@
-use std::ffi::c_void;
 use std::future::Future;
 use std::ptr;
-use std::sync::atomic::{AtomicUsize, Ordering};
 
 use once_cell::sync::Lazy;
 use tokio::{
@@ -29,27 +27,17 @@ pub(crate) static RT: Lazy<(Handle, mpsc::Sender<()>)> = Lazy::new(|| {
     .expect("Create tokio runtime failed")
 });
 
-pub(crate) static TOKIO_RT_REF_COUNT: AtomicUsize = AtomicUsize::new(0);
+#[ctor::dtor]
-
+fn shutdown_tokio() {
-#[doc(hidden)]
+  let sender = &RT.1;
-#[inline(never)]
+  if let Err(e) = sender.clone().try_send(()) {
-pub unsafe extern "C" fn shutdown_tokio_rt(arg: *mut c_void) {
+    match e {
-  if TOKIO_RT_REF_COUNT.fetch_sub(1, Ordering::SeqCst) == 0 {
+      TrySendError::Closed(_) => {}
-    let sender = &RT.1;
+      TrySendError::Full(_) => {
-    if let Err(e) = sender.clone().try_send(()) {
+        panic!("Send shutdown signal to tokio runtime failed, queue is full");
-      match e {
-        TrySendError::Closed(_) => {}
-        TrySendError::Full(_) => {
-          panic!("Send shutdown signal to tokio runtime failed, queue is full");
-        }
       }
     }
   }
-
-  unsafe {
-    let env: sys::napi_env = arg as *mut sys::napi_env__;
-    sys::napi_remove_env_cleanup_hook(env, Some(shutdown_tokio_rt), arg);
-  }
 }
 
 /// Spawns a future onto the Tokio runtime.

crates/sys/src/functions.rs

@@ -738,7 +738,7 @@ pub use napi7::*;
 pub use napi8::*;
 
 #[cfg(windows)]
-pub(super) unsafe fn load() -> Result<(), libloading::Error> {
+pub(super) unsafe fn load() -> Result<libloading::Library, libloading::Error> {
   let host = match libloading::os::windows::Library::this() {
     Ok(lib) => lib.into(),
     Err(err) => {
@@ -764,5 +764,5 @@ pub(super) unsafe fn load() -> Result<(), libloading::Error> {
   napi8::load(&host)?;
   #[cfg(feature = "experimental")]
   experimental::load(&host)?;
-  Ok(())
+  Ok(host)
 }

crates/sys/src/lib.rs

@@ -77,28 +77,21 @@ macro_rules! generate {
   };
 }
 
-#[cfg(windows)]
-use std::sync::Once;
-
 mod functions;
 mod types;
 
 pub use functions::*;
 pub use types::*;
 
-#[cfg(windows)]
-static SETUP: Once = Once::new();
-
 /// Loads N-API symbols from host process.
 /// Must be called at least once before using any functions in bindings or
 /// they will panic.
 /// Safety: `env` must be a valid `napi_env` for the current thread
 #[cfg(windows)]
 #[allow(clippy::missing_safety_doc)]
-pub unsafe fn setup() {
+pub unsafe fn setup() -> libloading::Library {
-  SETUP.call_once(|| {
+  match load() {
-    if let Err(err) = load() {
+    Err(err) => panic!("{}", err),
-      panic!("{}", err);
+    Ok(l) => l,
-    }
+  }
-  });
 }