src: minor refactoring to StreamBase writes

Instead of having per-request callbacks, always call a callback
on the `StreamBase` instance itself for `WriteWrap` and `ShutdownWrap`.

This makes `WriteWrap` cleanup consistent for all stream classes,
since the after-write callback is always the same now.

If special handling is needed for writes that happen to a sub-class,
`AfterWrite` can be overridden by that class, rather than that
class providing its own callback (e.g. updating the write
queue size for libuv streams).

If special handling is needed for writes that happen on another
stream instance, the existing `after_write_cb()` callback
is used for that (e.g. custom code after writing to the
transport from a TLS stream).

As a nice bonus, this also makes `WriteWrap` and `ShutdownWrap`
instances slightly smaller.

PR-URL: https://github.com/nodejs/node/pull/17564
Reviewed-By: Anatoli Papirovski <apapirovski@mac.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

9 files changed, 73 insertions, 87 deletions

diff --git a/src/js_stream.cc b/src/js_stream.cc
index da719c357d..22d267f549 100644
--- a/src/js_stream.cc
+++ b/src/js_stream.cc
@@ -176,7 +176,7 @@ void JSStream::DoAfterWrite(const FunctionCallbackInfo<Value>& args) {
   ASSIGN_OR_RETURN_UNWRAP(&wrap, args.Holder());
   ASSIGN_OR_RETURN_UNWRAP(&w, args[0].As<Object>());
 
-  wrap->OnAfterWrite(w);
+  w->Done(0);
 }
 
 
diff --git a/src/node_http2.cc b/src/node_http2.cc
index b763ff0dbe..f8b530c20a 100644
--- a/src/node_http2.cc
+++ b/src/node_http2.cc
@@ -987,9 +987,6 @@ inline void Http2Session::SetChunksSinceLastWrite(size_t n) {
 
 WriteWrap* Http2Session::AllocateSend() {
   HandleScope scope(env()->isolate());
-  auto AfterWrite = [](WriteWrap* req, int status) {
-    req->Dispose();
-  };
   Local<Object> obj =
       env()->write_wrap_constructor_function()
           ->NewInstance(env()->context()).ToLocalChecked();
@@ -999,7 +996,7 @@ WriteWrap* Http2Session::AllocateSend() {
           session(),
           NGHTTP2_SETTINGS_MAX_FRAME_SIZE);
   // Max frame size + 9 bytes for the header
-  return WriteWrap::New(env(), obj, stream_, AfterWrite, size + 9);
+  return WriteWrap::New(env(), obj, stream_, size + 9);
 }
 
 void Http2Session::Send(WriteWrap* req, char* buf, size_t length) {
diff --git a/src/stream_base-inl.h b/src/stream_base-inl.h
index 807e138ef7..29739011c6 100644
--- a/src/stream_base-inl.h
+++ b/src/stream_base-inl.h
@@ -143,15 +143,19 @@ void StreamBase::JSMethod(const FunctionCallbackInfo<Value>& args) {
 }
 
 
+inline void ShutdownWrap::OnDone(int status) {
+  stream()->AfterShutdown(this, status);
+}
+
+
 WriteWrap* WriteWrap::New(Environment* env,
                           Local<Object> obj,
                           StreamBase* wrap,
-                          DoneCb cb,
                           size_t extra) {
   size_t storage_size = ROUND_UP(sizeof(WriteWrap), kAlignSize) + extra;
   char* storage = new char[storage_size];
 
-  return new(storage) WriteWrap(env, obj, wrap, cb, storage_size);
+  return new(storage) WriteWrap(env, obj, wrap, storage_size);
 }
 
 
@@ -171,6 +175,10 @@ size_t WriteWrap::ExtraSize() const {
   return storage_size_ - ROUND_UP(sizeof(*this), kAlignSize);
 }
 
+inline void WriteWrap::OnDone(int status) {
+  stream()->AfterWrite(this, status);
+}
+
 }  // namespace node
 
 #endif  // defined(NODE_WANT_INTERNALS) && NODE_WANT_INTERNALS
diff --git a/src/stream_base.cc b/src/stream_base.cc
index 922b277c58..46d2ff5faf 100644
--- a/src/stream_base.cc
+++ b/src/stream_base.cc
@@ -55,8 +55,7 @@ int StreamBase::Shutdown(const FunctionCallbackInfo<Value>& args) {
   env->set_init_trigger_async_id(wrap->get_async_id());
   ShutdownWrap* req_wrap = new ShutdownWrap(env,
                                             req_wrap_obj,
-                                            this,
-                                            AfterShutdown);
+                                            this);
 
   int err = DoShutdown(req_wrap);
   if (err)
@@ -66,7 +65,6 @@ int StreamBase::Shutdown(const FunctionCallbackInfo<Value>& args) {
 
 
 void StreamBase::AfterShutdown(ShutdownWrap* req_wrap, int status) {
-  StreamBase* wrap = req_wrap->wrap();
   Environment* env = req_wrap->env();
 
   // The wrap and request objects should still be there.
@@ -78,7 +76,7 @@ void StreamBase::AfterShutdown(ShutdownWrap* req_wrap, int status) {
   Local<Object> req_wrap_obj = req_wrap->object();
   Local<Value> argv[3] = {
     Integer::New(env->isolate(), status),
-    wrap->GetObject(),
+    GetObject(),
     req_wrap_obj
   };
 
@@ -158,7 +156,7 @@ int StreamBase::Writev(const FunctionCallbackInfo<Value>& args) {
   wrap = GetAsyncWrap();
   CHECK_NE(wrap, nullptr);
   env->set_init_trigger_async_id(wrap->get_async_id());
-  req_wrap = WriteWrap::New(env, req_wrap_obj, this, AfterWrite, storage_size);
+  req_wrap = WriteWrap::New(env, req_wrap_obj, this, storage_size);
 
   offset = 0;
   if (!all_buffers) {
@@ -248,7 +246,7 @@ int StreamBase::WriteBuffer(const FunctionCallbackInfo<Value>& args) {
   if (wrap != nullptr)
     env->set_init_trigger_async_id(wrap->get_async_id());
   // Allocate, or write rest
-  req_wrap = WriteWrap::New(env, req_wrap_obj, this, AfterWrite);
+  req_wrap = WriteWrap::New(env, req_wrap_obj, this);
 
   err = DoWrite(req_wrap, bufs, count, nullptr);
   req_wrap_obj->Set(env->async(), True(env->isolate()));
@@ -332,7 +330,7 @@ int StreamBase::WriteString(const FunctionCallbackInfo<Value>& args) {
   wrap = GetAsyncWrap();
   if (wrap != nullptr)
     env->set_init_trigger_async_id(wrap->get_async_id());
-  req_wrap = WriteWrap::New(env, req_wrap_obj, this, AfterWrite, storage_size);
+  req_wrap = WriteWrap::New(env, req_wrap_obj, this, storage_size);
 
   data = req_wrap->Extra();
 
@@ -393,7 +391,6 @@ int StreamBase::WriteString(const FunctionCallbackInfo<Value>& args) {
 
 
 void StreamBase::AfterWrite(WriteWrap* req_wrap, int status) {
-  StreamBase* wrap = req_wrap->wrap();
   Environment* env = req_wrap->env();
 
   HandleScope handle_scope(env->isolate());
@@ -405,19 +402,19 @@ void StreamBase::AfterWrite(WriteWrap* req_wrap, int status) {
   // Unref handle property
   Local<Object> req_wrap_obj = req_wrap->object();
   req_wrap_obj->Delete(env->context(), env->handle_string()).FromJust();
-  wrap->OnAfterWrite(req_wrap);
+  OnAfterWrite(req_wrap, status);
 
   Local<Value> argv[] = {
     Integer::New(env->isolate(), status),
-    wrap->GetObject(),
+    GetObject(),
     req_wrap_obj,
     Undefined(env->isolate())
   };
 
-  const char* msg = wrap->Error();
+  const char* msg = Error();
   if (msg != nullptr) {
     argv[3] = OneByteString(env->isolate(), msg);
-    wrap->ClearError();
+    ClearError();
   }
 
   if (req_wrap_obj->Has(env->context(), env->oncomplete_string()).FromJust())
diff --git a/src/stream_base.h b/src/stream_base.h
index 3eeb71e4c7..5bf5f01394 100644
--- a/src/stream_base.h
+++ b/src/stream_base.h
@@ -16,27 +16,27 @@ namespace node {
 // Forward declarations
 class StreamBase;
 
-template <class Req>
+template<typename Base>
 class StreamReq {
  public:
-  typedef void (*DoneCb)(Req* req, int status);
-
-  explicit StreamReq(DoneCb cb) : cb_(cb) {
+  explicit StreamReq(StreamBase* stream) : stream_(stream) {
   }
 
   inline void Done(int status, const char* error_str = nullptr) {
-    Req* req = static_cast<Req*>(this);
+    Base* req = static_cast<Base*>(this);
     Environment* env = req->env();
     if (error_str != nullptr) {
       req->object()->Set(env->error_string(),
                          OneByteString(env->isolate(), error_str));
     }
 
-    cb_(req, status);
+    req->OnDone(status);
   }
 
+  inline StreamBase* stream() const { return stream_; }
+
  private:
-  DoneCb cb_;
+  StreamBase* const stream_;
 };
 
 class ShutdownWrap : public ReqWrap<uv_shutdown_t>,
@@ -44,11 +44,9 @@ class ShutdownWrap : public ReqWrap<uv_shutdown_t>,
  public:
   ShutdownWrap(Environment* env,
                v8::Local<v8::Object> req_wrap_obj,
-               StreamBase* wrap,
-               DoneCb cb)
+               StreamBase* stream)
       : ReqWrap(env, req_wrap_obj, AsyncWrap::PROVIDER_SHUTDOWNWRAP),
-        StreamReq<ShutdownWrap>(cb),
-        wrap_(wrap) {
+        StreamReq<ShutdownWrap>(stream) {
     Wrap(req_wrap_obj, this);
   }
 
@@ -60,27 +58,22 @@ class ShutdownWrap : public ReqWrap<uv_shutdown_t>,
     return ContainerOf(&ShutdownWrap::req_, req);
   }
 
-  inline StreamBase* wrap() const { return wrap_; }
   size_t self_size() const override { return sizeof(*this); }
 
- private:
-  StreamBase* const wrap_;
+  inline void OnDone(int status);  // Just calls stream()->AfterShutdown()
 };
 
-class WriteWrap: public ReqWrap<uv_write_t>,
-                 public StreamReq<WriteWrap> {
+class WriteWrap : public ReqWrap<uv_write_t>,
+                  public StreamReq<WriteWrap> {
  public:
   static inline WriteWrap* New(Environment* env,
                                v8::Local<v8::Object> obj,
-                               StreamBase* wrap,
-                               DoneCb cb,
+                               StreamBase* stream,
                                size_t extra = 0);
   inline void Dispose();
   inline char* Extra(size_t offset = 0);
   inline size_t ExtraSize() const;
 
-  inline StreamBase* wrap() const { return wrap_; }
-
   size_t self_size() const override { return storage_size_; }
 
   static WriteWrap* from_req(uv_write_t* req) {
@@ -91,24 +84,22 @@ class WriteWrap: public ReqWrap<uv_write_t>,
 
   WriteWrap(Environment* env,
             v8::Local<v8::Object> obj,
-            StreamBase* wrap,
-            DoneCb cb)
+            StreamBase* stream)
       : ReqWrap(env, obj, AsyncWrap::PROVIDER_WRITEWRAP),
-        StreamReq<WriteWrap>(cb),
-        wrap_(wrap),
+        StreamReq<WriteWrap>(stream),
         storage_size_(0) {
     Wrap(obj, this);
   }
 
+  inline void OnDone(int status);  // Just calls stream()->AfterWrite()
+
  protected:
   WriteWrap(Environment* env,
             v8::Local<v8::Object> obj,
-            StreamBase* wrap,
-            DoneCb cb,
+            StreamBase* stream,
             size_t storage_size)
       : ReqWrap(env, obj, AsyncWrap::PROVIDER_WRITEWRAP),
-        StreamReq<WriteWrap>(cb),
-        wrap_(wrap),
+        StreamReq<WriteWrap>(stream),
         storage_size_(storage_size) {
     Wrap(obj, this);
   }
@@ -129,7 +120,6 @@ class WriteWrap: public ReqWrap<uv_write_t>,
   // WriteWrap. Ensure this never happens.
   void operator delete(void* ptr) { UNREACHABLE(); }
 
-  StreamBase* const wrap_;
   const size_t storage_size_;
 };
 
@@ -151,7 +141,7 @@ class StreamResource {
     void* ctx;
   };
 
-  typedef void (*AfterWriteCb)(WriteWrap* w, void* ctx);
+  typedef void (*AfterWriteCb)(WriteWrap* w, int status, void* ctx);
   typedef void (*AllocCb)(size_t size, uv_buf_t* buf, void* ctx);
   typedef void (*ReadCb)(ssize_t nread,
                          const uv_buf_t* buf,
@@ -176,9 +166,9 @@ class StreamResource {
   virtual void ClearError();
 
   // Events
-  inline void OnAfterWrite(WriteWrap* w) {
+  inline void OnAfterWrite(WriteWrap* w, int status) {
     if (!after_write_cb_.is_empty())
-      after_write_cb_.fn(w, after_write_cb_.ctx);
+      after_write_cb_.fn(w, status, after_write_cb_.ctx);
   }
 
   inline void OnAlloc(size_t size, uv_buf_t* buf) {
@@ -208,14 +198,12 @@ class StreamResource {
   inline Callback<ReadCb> read_cb() { return read_cb_; }
   inline Callback<DestructCb> destruct_cb() { return destruct_cb_; }
 
- private:
+ protected:
   Callback<AfterWriteCb> after_write_cb_;
   Callback<AllocCb> alloc_cb_;
   Callback<ReadCb> read_cb_;
   Callback<DestructCb> destruct_cb_;
   uint64_t bytes_read_;
-
-  friend class StreamBase;
 };
 
 class StreamBase : public StreamResource {
@@ -253,6 +241,10 @@ class StreamBase : public StreamResource {
                 v8::Local<v8::Object> buf,
                 v8::Local<v8::Object> handle);
 
+  // These are called by the respective {Write,Shutdown}Wrap class.
+  virtual void AfterShutdown(ShutdownWrap* req, int status);
+  virtual void AfterWrite(WriteWrap* req, int status);
+
  protected:
   explicit StreamBase(Environment* env) : env_(env), consumed_(false) {
   }
@@ -263,10 +255,6 @@ class StreamBase : public StreamResource {
   virtual AsyncWrap* GetAsyncWrap() = 0;
   virtual v8::Local<v8::Object> GetObject();
 
-  // Libuv callbacks
-  static void AfterShutdown(ShutdownWrap* req, int status);
-  static void AfterWrite(WriteWrap* req, int status);
-
   // JS Methods
   int ReadStart(const v8::FunctionCallbackInfo<v8::Value>& args);
   int ReadStop(const v8::FunctionCallbackInfo<v8::Value>& args);
diff --git a/src/stream_wrap.cc b/src/stream_wrap.cc
index 7bd53c58af..3cce3b151c 100644
--- a/src/stream_wrap.cc
+++ b/src/stream_wrap.cc
@@ -91,7 +91,6 @@ LibuvStreamWrap::LibuvStreamWrap(Environment* env,
                  provider),
       StreamBase(env),
       stream_(stream) {
-  set_after_write_cb({ OnAfterWriteImpl, this });
   set_alloc_cb({ OnAllocImpl, this });
   set_read_cb({ OnReadImpl, this });
 }
@@ -293,13 +292,13 @@ void LibuvStreamWrap::SetBlocking(const FunctionCallbackInfo<Value>& args) {
 
 int LibuvStreamWrap::DoShutdown(ShutdownWrap* req_wrap) {
   int err;
-  err = uv_shutdown(req_wrap->req(), stream(), AfterShutdown);
+  err = uv_shutdown(req_wrap->req(), stream(), AfterUvShutdown);
   req_wrap->Dispatched();
   return err;
 }
 
 
-void LibuvStreamWrap::AfterShutdown(uv_shutdown_t* req, int status) {
+void LibuvStreamWrap::AfterUvShutdown(uv_shutdown_t* req, int status) {
   ShutdownWrap* req_wrap = ShutdownWrap::from_req(req);
   CHECK_NE(req_wrap, nullptr);
   HandleScope scope(req_wrap->env()->isolate());
@@ -354,9 +353,9 @@ int LibuvStreamWrap::DoWrite(WriteWrap* w,
                         uv_stream_t* send_handle) {
   int r;
   if (send_handle == nullptr) {
-    r = uv_write(w->req(), stream(), bufs, count, AfterWrite);
+    r = uv_write(w->req(), stream(), bufs, count, AfterUvWrite);
   } else {
-    r = uv_write2(w->req(), stream(), bufs, count, send_handle, AfterWrite);
+    r = uv_write2(w->req(), stream(), bufs, count, send_handle, AfterUvWrite);
   }
 
   if (!r) {
@@ -377,7 +376,7 @@ int LibuvStreamWrap::DoWrite(WriteWrap* w,
 }
 
 
-void LibuvStreamWrap::AfterWrite(uv_write_t* req, int status) {
+void LibuvStreamWrap::AfterUvWrite(uv_write_t* req, int status) {
   WriteWrap* req_wrap = WriteWrap::from_req(req);
   CHECK_NE(req_wrap, nullptr);
   HandleScope scope(req_wrap->env()->isolate());
@@ -386,9 +385,9 @@ void LibuvStreamWrap::AfterWrite(uv_write_t* req, int status) {
 }
 
 
-void LibuvStreamWrap::OnAfterWriteImpl(WriteWrap* w, void* ctx) {
-  LibuvStreamWrap* wrap = static_cast<LibuvStreamWrap*>(ctx);
-  wrap->UpdateWriteQueueSize();
+void LibuvStreamWrap::AfterWrite(WriteWrap* w, int status) {
+  StreamBase::AfterWrite(w, status);
+  UpdateWriteQueueSize();
 }
 
 }  // namespace node
diff --git a/src/stream_wrap.h b/src/stream_wrap.h
index 91fe642cd9..414bad393f 100644
--- a/src/stream_wrap.h
+++ b/src/stream_wrap.h
@@ -102,17 +102,18 @@ class LibuvStreamWrap : public HandleWrap, public StreamBase {
   static void OnRead(uv_stream_t* handle,
                      ssize_t nread,
                      const uv_buf_t* buf);
-  static void AfterWrite(uv_write_t* req, int status);
-  static void AfterShutdown(uv_shutdown_t* req, int status);
+  static void AfterUvWrite(uv_write_t* req, int status);
+  static void AfterUvShutdown(uv_shutdown_t* req, int status);
 
   // Resource interface implementation
-  static void OnAfterWriteImpl(WriteWrap* w, void* ctx);
   static void OnAllocImpl(size_t size, uv_buf_t* buf, void* ctx);
   static void OnReadImpl(ssize_t nread,
                          const uv_buf_t* buf,
                          uv_handle_type pending,
                          void* ctx);
 
+  void AfterWrite(WriteWrap* req_wrap, int status) override;
+
   uv_stream_t* const stream_;
 };
 
diff --git a/src/tls_wrap.cc b/src/tls_wrap.cc
index 62d3fd06fe..616771b389 100644
--- a/src/tls_wrap.cc
+++ b/src/tls_wrap.cc
@@ -328,8 +328,7 @@ void TLSWrap::EncOut() {
           ->NewInstance(env()->context()).ToLocalChecked();
   WriteWrap* write_req = WriteWrap::New(env(),
                                         req_wrap_obj,
-                                        this,
-                                        EncOutCb);
+                                        stream_);
 
   uv_buf_t buf[arraysize(data)];
   for (size_t i = 0; i < count; i++)
@@ -346,34 +345,31 @@ void TLSWrap::EncOut() {
 }
 
 
-void TLSWrap::EncOutCb(WriteWrap* req_wrap, int status) {
-  TLSWrap* wrap = static_cast<TLSWrap*>(req_wrap->wrap());
-  req_wrap->Dispose();
-
+void TLSWrap::EncOutAfterWrite(WriteWrap* req_wrap, int status) {
   // We should not be getting here after `DestroySSL`, because all queued writes
   // must be invoked with UV_ECANCELED
-  CHECK_NE(wrap->ssl_, nullptr);
+  CHECK_NE(ssl_, nullptr);
 
   // Handle error
   if (status) {
     // Ignore errors after shutdown
-    if (wrap->shutdown_)
+    if (shutdown_)
       return;
 
     // Notify about error
-    wrap->InvokeQueued(status);
+    InvokeQueued(status);
     return;
   }
 
   // Commit
-  crypto::NodeBIO::FromBIO(wrap->enc_out_)->Read(nullptr, wrap->write_size_);
+  crypto::NodeBIO::FromBIO(enc_out_)->Read(nullptr, write_size_);
 
   // Ensure that the progress will be made and `InvokeQueued` will be called.
-  wrap->ClearIn();
+  ClearIn();
 
   // Try writing more data
-  wrap->write_size_ = 0;
-  wrap->EncOut();
+  write_size_ = 0;
+  EncOut();
 }
 
 
@@ -676,9 +672,9 @@ int TLSWrap::DoWrite(WriteWrap* w,
 }
 
 
-void TLSWrap::OnAfterWriteImpl(WriteWrap* w, void* ctx) {
+void TLSWrap::OnAfterWriteImpl(WriteWrap* w, int status, void* ctx) {
   TLSWrap* wrap = static_cast<TLSWrap*>(ctx);
-  wrap->UpdateWriteQueueSize();
+  wrap->EncOutAfterWrite(w, status);
 }
 
 
diff --git a/src/tls_wrap.h b/src/tls_wrap.h
index edd21cf1cf..87eac75779 100644
--- a/src/tls_wrap.h
+++ b/src/tls_wrap.h
@@ -111,7 +111,7 @@ class TLSWrap : public AsyncWrap,
   static void SSLInfoCallback(const SSL* ssl_, int where, int ret);
   void InitSSL();
   void EncOut();
-  static void EncOutCb(WriteWrap* req_wrap, int status);
+  void EncOutAfterWrite(WriteWrap* req_wrap, int status);
   bool ClearIn();
   void ClearOut();
   void MakePending();
@@ -134,7 +134,7 @@ class TLSWrap : public AsyncWrap,
   uint32_t UpdateWriteQueueSize(uint32_t write_queue_size = 0);
 
   // Resource implementation
-  static void OnAfterWriteImpl(WriteWrap* w, void* ctx);
+  static void OnAfterWriteImpl(WriteWrap* w, int status, void* ctx);
   static void OnAllocImpl(size_t size, uv_buf_t* buf, void* ctx);
   static void OnReadImpl(ssize_t nread,
                          const uv_buf_t* buf,