remove race from asyncprogressqueueworker

Author: Gabriel Schulhof

test/asyncprogressqueueworker.cc

@@ -40,8 +40,6 @@ class TestWorker : public AsyncProgressQueueWorker<ProgressData> {
   static void CancelWork(const CallbackInfo& info) {
     auto wrap = info[0].As<Napi::External<TestWorker>>();
     auto worker = wrap.Data();
-    // We cannot cancel a worker if it got started. So we have to do a quick cancel.
-    worker->Queue();
     worker->Cancel();
   }
 

test/asyncprogressqueueworker.js

@@ -10,7 +10,7 @@ module.exports = test(require(`./build/${buildType}/binding.node`))
 async function test({ asyncprogressqueueworker }) {
   await success(asyncprogressqueueworker);
   await fail(asyncprogressqueueworker);
-  await cancel(asyncprogressqueueworker);
+  cancel(asyncprogressqueueworker);
 }
 
 function success(binding) {
@@ -49,22 +49,17 @@ function fail(binding) {
 }
 
 function cancel(binding) {
-  return new Promise((resolve, reject) => {
-    // make sure the work we are going to cancel will not be
-    // able to start by using all the threads in the pool.
-    for (let i = 0; i < os.cpus().length; ++i) {
-      const worker = binding.createWork(-1, () => {}, () => {});
-      binding.queueWork(worker);
-    }
-    const worker = binding.createWork(-1,
-      () => {
-        assert.fail('unexpected callback');
-      },
-      () => {
-        assert.fail('unexpected progress report');
-      }
-    );
-    binding.cancelWork(worker);
-    resolve();
-  });
+  // We cannot cancel work once it gets started, so we have no choice here but
+  // to create the work and then cancel it without queueing it. Thus we cannot
+  // reliably test create -> queue -> cancel.
+  //
+  // We could queue it and immediately cancel, and we could even attempt to
+  // saturate the thread pool with work before we do that but that would still
+  // be racy and, on some platforms and under certain circumstances the work
+  // might still get queued and therefore be unable to be cancelled, resulting
+  // in this test being flaky.
+  const worker = binding.createWork(-1,
+                         () => reject(new Error('unexpected callback')),
+                         () => reject(new Error('unexpected progress report')));
+  binding.cancelWork(worker);
 }