fix: empty data OnProgress by race conditions of AsyncProgressWorker

legendecas · legendecas · commit eb7b4e29796a · 2020-12-11T19:50:05.000+08:00
diff --git a/napi-inl.h b/napi-inl.h
@@ -5390,6 +5390,17 @@ inline void AsyncProgressWorker<T>::OnWorkProgress(void*) {
     this->_asyncsize = 0;
   }
 
+  /**
+   * The callback of ThreadSafeFunction is not been invoked immediately on the
+   * callback of uv_async_t (uv io poll), rather the callback of TSFN is
+   * invoked on the right next uv idle callback. There are chances that during
+   * the deferring the signal of uv_async_t is been sent again, i.e. potential
+   * not coalesced two calls of the TSFN callback.
+   */
+  if (data == nullptr) {
+    return;
+  }
+
   this->OnProgress(data, size);
   delete[] data;
 }
diff --git a/test/asyncprogressworker.cc b/test/asyncprogressworker.cc
@@ -61,11 +61,70 @@ class TestWorker : public AsyncProgressWorker<ProgressData> {
   FunctionReference _progress;
 };
 
+class MalignWorker : public AsyncProgressWorker<ProgressData> {
+ public:
+  static void DoWork(const CallbackInfo& info) {
+    Function cb = info[0].As<Function>();
+    Function progress = info[1].As<Function>();
+
+    MalignWorker* worker =
+        new MalignWorker(cb, progress, "TestResource", Object::New(info.Env()));
+    worker->Queue();
+  }
+
+ protected:
+  void Execute(const ExecutionProgress& progress) override {
+    std::unique_lock<std::mutex> lock(_cvm);
+    // Testing a nullptr send is acceptable.
+    progress.Send(nullptr, 0);
+    _cv.wait(lock);
+    // Testing busy looping on send doesn't trigger unexpected empty data
+    // OnProgress call.
+    for (size_t i = 0; i < 1000000; i++) {
+      ProgressData data{0};
+      progress.Send(&data, 1);
+    }
+    _cv.wait(lock);
+  }
+
+  void OnProgress(const ProgressData* data, size_t count) override {
+    Napi::Env env = Env();
+    _test_case_count++;
+    bool error = false;
+    Napi::String reason = Napi::String::New(env, "No error");
+    if (_test_case_count == 1 && count != 0) {
+      error = true;
+      reason = Napi::String::New(env, "expect 0 count of data on 1st call");
+    }
+    if (_test_case_count > 1 && count != 1) {
+      error = true;
+      reason = Napi::String::New(env, "expect 1 count of data on non-1st call");
+    }
+    _progress.MakeCallback(Receiver().Value(),
+                           {Napi::Boolean::New(env, error), reason});
+    _cv.notify_one();
+  }
+
+ private:
+  MalignWorker(Function cb,
+               Function progress,
+               const char* resource_name,
+               const Object& resource)
+      : AsyncProgressWorker(cb, resource_name, resource) {
+    _progress.Reset(progress, 1);
+  }
+
+  size_t _test_case_count = 0;
+  std::condition_variable _cv;
+  std::mutex _cvm;
+  FunctionReference _progress;
+};
 }
 
 Object InitAsyncProgressWorker(Env env) {
   Object exports = Object::New(env);
   exports["doWork"] = Function::New(env, TestWorker::DoWork);
+  exports["doMalignTest"] = Function::New(env, MalignWorker::DoWork);
   return exports;
 }
 
diff --git a/test/asyncprogressworker.js b/test/asyncprogressworker.js
@@ -9,6 +9,7 @@ module.exports = test(require(`./build/${buildType}/binding.node`))
 async function test({ asyncprogressworker }) {
   await success(asyncprogressworker);
   await fail(asyncprogressworker);
+  await malignTest(asyncprogressworker);
 }
 
 function success(binding) {
@@ -43,3 +44,17 @@ function fail(binding) {
     );
   });
 }
+
+function malignTest(binding) {
+  return new Promise((resolve, reject) => {
+    binding.doMalignTest(
+      common.mustCall((err) => {
+        assert.throws(() => { throw err }, /test error/);
+        resolve();
+      }),
+      common.mustCallAtLeast((error, reason) => {
+        assert(!error, reason);
+      }, 1)
+    );
+  });
+}
diff --git a/test/common/index.js b/test/common/index.js
@@ -33,6 +33,9 @@ function runCallChecks(exitCode) {
 exports.mustCall = function(fn, exact) {
   return _mustCallInner(fn, exact, 'exact');
 };
+exports.mustCallAtLeast = function(fn, minimum) {
+  return _mustCallInner(fn, minimum, 'minimum');
+};
 
 function _mustCallInner(fn, criteria, field) {
   if (typeof fn === 'number') {
