src: refactor stream callbacks and ownership

Instead of setting individual callbacks on streams and tracking
stream ownership through a boolean `consume_` flag, always have
one specific listener object in charge of a stream, and call
methods on that object rather than generic C-style callbacks.

PR-URL: https://github.com/nodejs/node/pull/18334
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Anatoli Papirovski <apapirovski@mac.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>

1 files changed, 83 insertions, 2 deletions

diff --git a/src/stream_base-inl.h b/src/stream_base-inl.h
index cdcff67cc5..287978a870 100644
--- a/src/stream_base-inl.h
+++ b/src/stream_base-inl.h
@@ -25,6 +25,87 @@ using v8::Value;
 
 using AsyncHooks = Environment::AsyncHooks;
 
+
+inline StreamListener::~StreamListener() {
+  if (stream_ != nullptr)
+    stream_->RemoveStreamListener(this);
+}
+
+inline void StreamListener::PassReadErrorToPreviousListener(ssize_t nread) {
+  CHECK_NE(previous_listener_, nullptr);
+  previous_listener_->OnStreamRead(nread,
+                                   uv_buf_init(nullptr, 0),
+                                   UV_UNKNOWN_HANDLE);
+}
+
+
+inline StreamResource::~StreamResource() {
+  while (listener_ != nullptr) {
+    listener_->OnStreamDestroy();
+    RemoveStreamListener(listener_);
+  }
+}
+
+inline void StreamResource::PushStreamListener(StreamListener* listener) {
+  CHECK_NE(listener, nullptr);
+  CHECK_EQ(listener->stream_, nullptr);
+
+  listener->previous_listener_ = listener_;
+  listener->stream_ = this;
+
+  listener_ = listener;
+}
+
+inline void StreamResource::RemoveStreamListener(StreamListener* listener) {
+  CHECK_NE(listener, nullptr);
+
+  StreamListener* previous;
+  StreamListener* current;
+
+  // Remove from the linked list.
+  for (current = listener_, previous = nullptr;
+       /* No loop condition because we want a crash if listener is not found */
+       ; previous = current, current = current->previous_listener_) {
+    CHECK_NE(current, nullptr);
+    if (current == listener) {
+      if (previous != nullptr)
+        previous->previous_listener_ = current->previous_listener_;
+      else
+        listener_ = listener->previous_listener_;
+      break;
+    }
+  }
+
+  listener->stream_ = nullptr;
+  listener->previous_listener_ = nullptr;
+}
+
+
+inline uv_buf_t StreamResource::EmitAlloc(size_t suggested_size) {
+  return listener_->OnStreamAlloc(suggested_size);
+}
+
+inline void StreamResource::EmitRead(ssize_t nread,
+                                     const uv_buf_t& buf,
+                                     uv_handle_type pending) {
+  if (nread > 0)
+    bytes_read_ += static_cast<uint64_t>(nread);
+  listener_->OnStreamRead(nread, buf, pending);
+}
+
+inline void StreamResource::EmitAfterWrite(WriteWrap* w, int status) {
+  listener_->OnStreamAfterWrite(w, status);
+}
+
+
+inline StreamBase::StreamBase(Environment* env) : env_(env) {
+  PushStreamListener(&default_listener_);
+}
+
+inline Environment* StreamBase::stream_env() const {
+  return env_;
+}
+
 template <class Base>
 void StreamBase::AddMethods(Environment* env,
                             Local<FunctionTemplate> t,
@@ -70,8 +151,8 @@ void StreamBase::AddMethods(Environment* env,
                                               Local<FunctionTemplate>(),
                                               attributes);
 
-  env->SetProtoMethod(t, "readStart", JSMethod<Base, &StreamBase::ReadStart>);
-  env->SetProtoMethod(t, "readStop", JSMethod<Base, &StreamBase::ReadStop>);
+  env->SetProtoMethod(t, "readStart", JSMethod<Base, &StreamBase::ReadStartJS>);
+  env->SetProtoMethod(t, "readStop", JSMethod<Base, &StreamBase::ReadStopJS>);
   if ((flags & kFlagNoShutdown) == 0)
     env->SetProtoMethod(t, "shutdown", JSMethod<Base, &StreamBase::Shutdown>);
   if ((flags & kFlagHasWritev) != 0)