Skip to content

Keep onData, onDataV2 and onWritable callbacks in MoveOnlyFunction inline storage #1325

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
uNetworkingAB merged 1 commit into from
Sep 28, 2026
Merged

Keep onData, onDataV2 and onWritable callbacks in MoveOnlyFunction inline storage #1325

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
18 changes: 9 additions & 9 deletions src/HttpResponseWrapper.h
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -94,16 +94,16 @@ struct HttpResponseWrapper {
Isolate *isolate = args.GetIsolate();
auto *res = getHttpResponse<SSL>(args);
if (res) {
/* This thing perfectly fits in with unique_function, and will Reset on destructor */
UniquePersistent<Function> p(isolate, Local<Function>::Cast(args[0]));
/* Noexcept move keeps the 16 byte capture in MoveOnlyFunction's inline storage */
NoexceptPersistent<Function> p(isolate, Local<Function>::Cast(args[0]));

res->onData([p = std::move(p), isolate](std::string_view data, bool last) {
HandleScope hs(isolate);

Local<ArrayBuffer> dataArrayBuffer = ArrayBuffer_New(isolate, (void *) data.data(), data.length());

Local<Value> argv[] = {dataArrayBuffer, Boolean::New(isolate, last)};
CallJS(isolate, Local<Function>::New(isolate, p), 2, argv);
CallJS(isolate, Local<Function>::New(isolate, p.p), 2, argv);

dataArrayBuffer->Detach();
});
Expand Down Expand Up @@ -197,8 +197,8 @@ struct HttpResponseWrapper {
Isolate *isolate = args.GetIsolate();
auto *res = getHttpResponse<SSL>(args);
if (res) {
/* This thing perfectly fits in with unique_function, and will Reset on destructor */
UniquePersistent<Function> p(isolate, Local<Function>::Cast(args[0]));
/* Noexcept move keeps the 16 byte capture in MoveOnlyFunction's inline storage */
NoexceptPersistent<Function> p(isolate, Local<Function>::Cast(args[0]));

res->onDataV2([p = std::move(p), isolate](std::string_view data, uint64_t maxRemainingBodyLength) {
HandleScope hs(isolate);
Expand All @@ -207,7 +207,7 @@ struct HttpResponseWrapper {

/* Pass maxRemainingBodyLength so user can preallocate; 0 signals the last chunk */
Local<Value> argv[] = {dataArrayBuffer, BigInt::NewFromUnsigned(isolate, maxRemainingBodyLength)};
CallJS(isolate, Local<Function>::New(isolate, p), 2, argv);
CallJS(isolate, Local<Function>::New(isolate, p.p), 2, argv);

dataArrayBuffer->Detach();
});
Expand Down Expand Up @@ -341,16 +341,16 @@ struct HttpResponseWrapper {
Isolate *isolate = args.GetIsolate();
auto *res = getHttpResponse<SSL>(args);
if (res) {
/* This thing perfectly fits in with unique_function, and will Reset on destructor */
UniquePersistent<Function> p(isolate, Local<Function>::Cast(args[0]));
/* Noexcept move keeps the 16 byte capture in MoveOnlyFunction's inline storage */
NoexceptPersistent<Function> p(isolate, Local<Function>::Cast(args[0]));

res->onWritable([p = std::move(p), isolate](size_t offset) -> bool {
HandleScope hs(isolate);

Local<Value> argv[] = {Number::New(isolate, offset)};

/* We should check if this is really here! */
MaybeLocal<Value> maybeBoolean = CallJS(isolate, Local<Function>::New(isolate, p), 1, argv);
MaybeLocal<Value> maybeBoolean = CallJS(isolate, Local<Function>::New(isolate, p.p), 1, argv);
if (maybeBoolean.IsEmpty()) {
std::cerr << "Warning: uWS.HttpResponse.onWritable callback should return Boolean. See documentation for uWS.HttpResponse.onWritable and consult the user manual." << std::endl;
/* The default should be true, as it only adds a potential extra send, rather than erroneously avoid it */
Expand Down
11 changes: 11 additions & 0 deletions src/Utilities.h
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -112,6 +112,17 @@ static inline bool missingArguments(int length, const FunctionCallbackInfo<Value
return false;
}

/* v8::Global's move constructor is not noexcept, so a lambda capturing one fails
* MoveOnlyFunction's small-object test and heap-allocates. The underlying move is
* a pointer swap and cannot throw, this wrapper only restores the noexcept */
template <class T>
struct NoexceptPersistent {
UniquePersistent<T> p;
NoexceptPersistent(Isolate *isolate, const Local<T> &v) : p(isolate, v) {}
NoexceptPersistent(NoexceptPersistent &&other) noexcept : p(std::move(other.p)) {}
};
static_assert(std::is_nothrow_move_constructible<NoexceptPersistent<Function>>::value, "NoexceptPersistent must be nothrow movable");

struct Callback {
bool invalid = false;
UniquePersistent<Function> f;
Expand Down