quic: Use weak pointer in blob reader pull

Author: martenrichter

src/node_blob.cc

@@ -347,7 +347,7 @@ void Blob::Reader::Pull(const FunctionCallbackInfo<Value>& args) {
   }
 
   struct Impl {
-    BaseObjectPtr<Blob::Reader> reader;
+    BaseObjectWeakPtr<Blob::Reader> reader;
     Global<Function> callback;
     Environment* env;
     std::vector<DataQueue::Vec> vecs;
@@ -361,15 +361,18 @@ void Blob::Reader::Pull(const FunctionCallbackInfo<Value>& args) {
   // EDIT(martenrichter) We use a shared_ptr instead, as the previous
   // implementation, with am ommrt unique_ptr did not allow to call next twice
   // as impl is gone after the first call.
+  // Also the reference to reader should be a weak pointer, as if it is
+  // collected we should not be interested in the result of a call to next
   std::shared_ptr<Impl> impl = std::make_shared<Impl>();
-  impl->reader = BaseObjectPtr<Blob::Reader>(reader);
+  impl->reader = BaseObjectWeakPtr<Blob::Reader>(reader);
   impl->callback.Reset(env->isolate(), fn);
   impl->env = env;
 
   auto next = [impl](int status,
                      const DataQueue::Vec* vecs,
                      size_t count,
                      bob::Done doneCb) mutable {
+    assert(!impl->reader);
     Environment* env = impl->env;
     HandleScope handleScope(env->isolate());
     Local<Function> fn = impl->callback.Get(env->isolate());
@@ -403,6 +406,7 @@ void Blob::Reader::Pull(const FunctionCallbackInfo<Value>& args) {
             for (size_t n = 0; n < count; n++) impl->byte_count += vecs[n].len;
           }
         };
+        assert(!impl->reader);
         status = impl->reader->inner_->Pull(
             std::move(snext), node::bob::OPTIONS_SYNC, nullptr, 0);
       }
@@ -429,12 +433,14 @@ void Blob::Reader::Pull(const FunctionCallbackInfo<Value>& args) {
                     impl->dones.end(),
                     [](bob::Done& done) { std::move(done)(0); });
       impl->dones.clear();
+      assert(!impl->reader);
       Local<Value> argv[2] = {Uint32::New(env->isolate(), bob::STATUS_CONTINUE),
                               ArrayBuffer::New(env->isolate(), store)};
       impl->reader->MakeCallback(fn, arraysize(argv), argv);
       return;
     }
     impl->dones.clear();  // should not be necessary?
+    assert(!impl->reader);
 
     Local<Value> argv[2] = {
         Int32::New(env->isolate(), status),