quic: improve stream header collection performance

Signed-off-by: James M Snell <jasnell@gmail.com>
Assisted-by: Opencode:Opus 4.6
PR-URL: #63267
Backport-PR-URL: #64675
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>

Author: jasnell

src/quic/http3.cc

@@ -333,9 +333,7 @@ class Http3ApplicationImpl final : public Session::Application {
 // We cannot add the header if we've either reached
 // * the max number of header pairs or
 // * the max number of header bytes (name + value combined)
-// current_count is the number of entries in the headers vector
-// (each pair = name entry + value entry = 2 entries).
-return (current_count / 2 < options_.max_header_pairs) &&
+return (current_count < options_.max_header_pairs) &&
  (current_headers_length + this_header_length) <=
  options_.max_header_length;
  }
@@ -825,12 +823,12 @@ class Http3ApplicationImpl final : public Session::Application {
  stream->BeginHeaders(HeadersKind::INITIAL);
  }
 
-voidOnReceiveHeader(stream_id id, Http3Header&& header) {
+voidOnReceiveHeader(stream_id id, std::unique_ptr<Http3Header> header) {
 auto stream = session().FindStream(id);
 
 if (!stream) [[unlikely]]
 return;
-if (header.name() == ":status" && header.value()[0] == '1') {
+if (header->name() == ":status" && header->value()[0] == '1') {
 Debug(&session(),
 "HTTP/3 application switching to hints headers for stream %" PRIi64,
  stream->id());
@@ -839,8 +837,8 @@ class Http3ApplicationImpl final : public Session::Application {
 IF_QUIC_DEBUG(env()) {
 Debug(&session(),
 "Received header \"%s: %s\"",
- header.name(),
- header.value());
+ header->name(),
+ header->value());
  }
  stream->AddHeader(std::move(header));
  }
@@ -874,15 +872,15 @@ class Http3ApplicationImpl final : public Session::Application {
  stream->BeginHeaders(HeadersKind::TRAILING);
  }
 
-voidOnReceiveTrailer(stream_id id, Http3Header&& header) {
+voidOnReceiveTrailer(stream_id id, std::unique_ptr<Http3Header> header) {
 auto stream = session().FindStream(id);
 if (!stream) [[unlikely]]
 return;
 IF_QUIC_DEBUG(env()) {
 Debug(&session(),
 "Received header \"%s: %s\"",
- header.name(),
- header.value());
+ header->name(),
+ header->value());
  }
  stream->AddHeader(std::move(header));
  }
@@ -1239,7 +1237,9 @@ class Http3ApplicationImpl final : public Session::Application {
 returnNGHTTP3_ERR_CALLBACK_FAILURE;
  }
 if (Http3Header::IsZeroLength(token, name, value)) returnNGTCP2_SUCCESS;
- app.OnReceiveHeader(id, Http3Header(app.env(), token, name, value, flags));
+ app.OnReceiveHeader(
+ id,
+ std::make_unique<Http3Header>(app.env(), token, name, value, flags));
 returnNGTCP2_SUCCESS;
  }
 
@@ -1281,7 +1281,9 @@ class Http3ApplicationImpl final : public Session::Application {
 returnNGHTTP3_ERR_CALLBACK_FAILURE;
  }
 if (Http3Header::IsZeroLength(token, name, value)) returnNGTCP2_SUCCESS;
- app.OnReceiveTrailer(id, Http3Header(app.env(), token, name, value, flags));
+ app.OnReceiveTrailer(
+ id,
+ std::make_unique<Http3Header>(app.env(), token, name, value, flags));
 returnNGTCP2_SUCCESS;
  }
 

src/quic/streams.cc

@@ -31,6 +31,7 @@ using v8::HandleScope;
 using v8::Integer;
 using v8::Just;
 using v8::Local;
+using v8::LocalVector;
 using v8::Maybe;
 using v8::Nothing;
 using v8::Object;
@@ -1126,8 +1127,7 @@ Stream::Stream(BaseObjectWeakPtr<Session> session,
  std::shared_ptr<DataQueue> source)
  : AsyncWrap(session->env(), object, PROVIDER_QUIC_STREAM),
  session_(std::move(session)),
- inbound_(DataQueue::Create()),
- headers_(env()->isolate()) {
+ inbound_(DataQueue::Create()) {
 auto& binding = BindingData::Get(env());
  stats_slot_ = GetStreamStatsArena(binding).Allocate(env()->isolate());
  state_slot_ = GetStreamStateArena(binding).Allocate(env()->isolate());
@@ -1185,8 +1185,7 @@ Stream::Stream(BaseObjectWeakPtr<Session> session,
  session_(std::move(session)),
  inbound_(DataQueue::Create()),
  maybe_pending_stream_(
- std::make_unique<PendingStream>(direction, this, session_)),
- headers_(env()->isolate()) {
+ std::make_unique<PendingStream>(direction, this, session_)) {
 auto& binding = BindingData::Get(env());
  stats_slot_ = GetStreamStatsArena(binding).Allocate(env()->isolate());
  state_slot_ = GetStreamStateArena(binding).Allocate(env()->isolate());
@@ -1567,27 +1566,16 @@ void Stream::set_headers_kind(HeadersKind kind) {
  headers_kind_ = kind;
 }
 
-boolStream::AddHeader(constHeader& header) {
-size_t len = header.length();
+boolStream::AddHeader(std::unique_ptr<Header> header) {
+size_t len = header->length();
 if (!session_->application().CanAddHeader(
  headers_.size(), headers_length_, len)) {
 returnfalse;
  }
 
  headers_length_ += len;
-
-auto& state = BindingData::Get(env());
-
-constauto push = [&](auto raw) {
- Local<Value> value;
-if (!raw.ToLocal(&value)) [[unlikely]] {
-returnfalse;
- }
- headers_.push_back(value);
-returntrue;
- };
-
-returnpush(header.GetName(&state)) && push(header.GetValue(&state));
+ headers_.push_back(std::move(header));
+returntrue;
 }
 
 voidStream::Acknowledge(size_t datalen) {
@@ -1899,19 +1887,35 @@ void Stream::EmitHeaders() {
 // state()->wants_headers will be set from the javascript side if the
 // stream object has a handler for the headers event.
 if (!env()->can_call_into_js() || !state()->wants_headers) {
+ headers_.clear();
 return;
  }
  CallbackScope<Stream> cb_scope(this);
 
+auto& binding = BindingData::Get(env());
+size_t count = headers_.size() * 2;
+ LocalVector<Value> values(env()->isolate(), count);
+
+for (size_t i = 0; i < headers_.size(); i++) {
+ Local<Value> name;
+ Local<Value> value;
+if (!headers_[i]->GetName(&binding).ToLocal(&name) ||
+ !headers_[i]->GetValue(&binding).ToLocal(&value)) [[unlikely]] {
+ headers_.clear();
+return;
+ }
+ values[i * 2] = name;
+ values[i * 2 + 1] = value;
+ }
+
+ headers_.clear();
+
  Local<Value> argv[] = {
-Array::New(env()->isolate(), headers_.data(), headers_.size()),
+Array::New(env()->isolate(), values.data(), count),
 Integer::NewFromUnsigned(env()->isolate(),
 static_cast<uint32_t>(headers_kind_))};
 
- headers_.clear();
-
-MakeCallback(
-BindingData::Get(env()).stream_headers_callback(), arraysize(argv), argv);
+MakeCallback(binding.stream_headers_callback(), arraysize(argv), argv);
 }
 
 voidStream::EmitReset(const QuicError& error) {

src/quic/streams.h

@@ -344,7 +344,7 @@ class Stream final : public AsyncWrap,
 // Returns false if the header cannot be added. This will typically happen
 // if the application does not support headers, a maximum number of headers
 // have already been added, or the maximum total header length is reached.
-boolAddHeader(constHeader& header);
+boolAddHeader(std::unique_ptr<Header> header);
 
 // TODO(@jasnell): Implement MemoryInfo to track outbound_, inbound_,
 // reader_, headers_, and pending_headers_queue_.
@@ -455,9 +455,11 @@ class Stream final : public AsyncWrap,
 const StoredPriority& stored_priority() const { return priority_; }
 
 // The headers_ field holds a block of headers that have been received and
-// are being buffered for delivery to the JavaScript side.
-// TODO(@jasnell): Use v8::Global instead of v8::Local here.
- v8::LocalVector<v8::Value> headers_;
+// are being buffered for delivery to the JavaScript side. Headers are
+// stored as C++ objects during collection (AddHeader) and converted to
+// V8 strings only when emitted (EmitHeaders), avoiding StrongRootAllocator
+// mutex contention on the per-header hot path.
+ std::vector<std::unique_ptr<Header>> headers_;
 
 // The headers_kind_ field indicates the kind of headers that are being
 // buffered.

src/quic/http3.cc

@@ -333,9 +333,7 @@ class Http3ApplicationImpl final : public Session::Application {
 // We cannot add the header if we've either reached
 // * the max number of header pairs or
 // * the max number of header bytes (name + value combined)
-// current_count is the number of entries in the headers vector
-// (each pair = name entry + value entry = 2 entries).
-return (current_count / 2 < options_.max_header_pairs) &&
+return (current_count < options_.max_header_pairs) &&
  (current_headers_length + this_header_length) <=
  options_.max_header_length;
  }
@@ -825,12 +823,12 @@ class Http3ApplicationImpl final : public Session::Application {
  stream->BeginHeaders(HeadersKind::INITIAL);
  }
 
-voidOnReceiveHeader(stream_id id, Http3Header&& header) {
+voidOnReceiveHeader(stream_id id, std::unique_ptr<Http3Header> header) {
 auto stream = session().FindStream(id);
 
 if (!stream) [[unlikely]]
 return;
-if (header.name() == ":status" && header.value()[0] == '1') {
+if (header->name() == ":status" && header->value()[0] == '1') {
 Debug(&session(),
 "HTTP/3 application switching to hints headers for stream %" PRIi64,
  stream->id());
@@ -839,8 +837,8 @@ class Http3ApplicationImpl final : public Session::Application {
 IF_QUIC_DEBUG(env()) {
 Debug(&session(),
 "Received header \"%s: %s\"",
- header.name(),
- header.value());
+ header->name(),
+ header->value());
  }
  stream->AddHeader(std::move(header));
  }
@@ -874,15 +872,15 @@ class Http3ApplicationImpl final : public Session::Application {
  stream->BeginHeaders(HeadersKind::TRAILING);
  }
 
-voidOnReceiveTrailer(stream_id id, Http3Header&& header) {
+voidOnReceiveTrailer(stream_id id, std::unique_ptr<Http3Header> header) {
 auto stream = session().FindStream(id);
 if (!stream) [[unlikely]]
 return;
 IF_QUIC_DEBUG(env()) {
 Debug(&session(),
 "Received header \"%s: %s\"",
- header.name(),
- header.value());
+ header->name(),
+ header->value());
  }
  stream->AddHeader(std::move(header));
  }
@@ -1239,7 +1237,9 @@ class Http3ApplicationImpl final : public Session::Application {
 returnNGHTTP3_ERR_CALLBACK_FAILURE;
  }
 if (Http3Header::IsZeroLength(token, name, value)) returnNGTCP2_SUCCESS;
- app.OnReceiveHeader(id, Http3Header(app.env(), token, name, value, flags));
+ app.OnReceiveHeader(
+ id,
+ std::make_unique<Http3Header>(app.env(), token, name, value, flags));
 returnNGTCP2_SUCCESS;
  }
 
@@ -1281,7 +1281,9 @@ class Http3ApplicationImpl final : public Session::Application {
 returnNGHTTP3_ERR_CALLBACK_FAILURE;
  }
 if (Http3Header::IsZeroLength(token, name, value)) returnNGTCP2_SUCCESS;
- app.OnReceiveTrailer(id, Http3Header(app.env(), token, name, value, flags));
+ app.OnReceiveTrailer(
+ id,
+ std::make_unique<Http3Header>(app.env(), token, name, value, flags));
 returnNGTCP2_SUCCESS;
  }
 

src/quic/streams.cc

@@ -31,6 +31,7 @@ using v8::HandleScope;
 using v8::Integer;
 using v8::Just;
 using v8::Local;
+using v8::LocalVector;
 using v8::Maybe;
 using v8::Nothing;
 using v8::Object;
@@ -1126,8 +1127,7 @@ Stream::Stream(BaseObjectWeakPtr<Session> session,
  std::shared_ptr<DataQueue> source)
  : AsyncWrap(session->env(), object, PROVIDER_QUIC_STREAM),
  session_(std::move(session)),
- inbound_(DataQueue::Create()),
- headers_(env()->isolate()) {
+ inbound_(DataQueue::Create()) {
 auto& binding = BindingData::Get(env());
  stats_slot_ = GetStreamStatsArena(binding).Allocate(env()->isolate());
  state_slot_ = GetStreamStateArena(binding).Allocate(env()->isolate());
@@ -1185,8 +1185,7 @@ Stream::Stream(BaseObjectWeakPtr<Session> session,
  session_(std::move(session)),
  inbound_(DataQueue::Create()),
  maybe_pending_stream_(
- std::make_unique<PendingStream>(direction, this, session_)),
- headers_(env()->isolate()) {
+ std::make_unique<PendingStream>(direction, this, session_)) {
 auto& binding = BindingData::Get(env());
  stats_slot_ = GetStreamStatsArena(binding).Allocate(env()->isolate());
  state_slot_ = GetStreamStateArena(binding).Allocate(env()->isolate());
@@ -1567,27 +1566,16 @@ void Stream::set_headers_kind(HeadersKind kind) {
  headers_kind_ = kind;
 }
 
-boolStream::AddHeader(constHeader& header) {
-size_t len = header.length();
+boolStream::AddHeader(std::unique_ptr<Header> header) {
+size_t len = header->length();
 if (!session_->application().CanAddHeader(
  headers_.size(), headers_length_, len)) {
 returnfalse;
  }
 
  headers_length_ += len;
-
-auto& state = BindingData::Get(env());
-
-constauto push = [&](auto raw) {
- Local<Value> value;
-if (!raw.ToLocal(&value)) [[unlikely]] {
-returnfalse;
- }
- headers_.push_back(value);
-returntrue;
- };
-
-returnpush(header.GetName(&state)) && push(header.GetValue(&state));
+ headers_.push_back(std::move(header));
+returntrue;
 }
 
 voidStream::Acknowledge(size_t datalen) {
@@ -1899,19 +1887,35 @@ void Stream::EmitHeaders() {
 // state()->wants_headers will be set from the javascript side if the
 // stream object has a handler for the headers event.
 if (!env()->can_call_into_js() || !state()->wants_headers) {
+ headers_.clear();
 return;
  }
  CallbackScope<Stream> cb_scope(this);
 
+auto& binding = BindingData::Get(env());
+size_t count = headers_.size() * 2;
+ LocalVector<Value> values(env()->isolate(), count);
+
+for (size_t i = 0; i < headers_.size(); i++) {
+ Local<Value> name;
+ Local<Value> value;
+if (!headers_[i]->GetName(&binding).ToLocal(&name) ||
+ !headers_[i]->GetValue(&binding).ToLocal(&value)) [[unlikely]] {
+ headers_.clear();
+return;
+ }
+ values[i * 2] = name;
+ values[i * 2 + 1] = value;
+ }
+
+ headers_.clear();
+
  Local<Value> argv[] = {
-Array::New(env()->isolate(), headers_.data(), headers_.size()),
+Array::New(env()->isolate(), values.data(), count),
 Integer::NewFromUnsigned(env()->isolate(),
 static_cast<uint32_t>(headers_kind_))};
 
- headers_.clear();
-
-MakeCallback(
-BindingData::Get(env()).stream_headers_callback(), arraysize(argv), argv);
+MakeCallback(binding.stream_headers_callback(), arraysize(argv), argv);
 }
 
 voidStream::EmitReset(const QuicError& error) {

src/quic/streams.h

@@ -344,7 +344,7 @@ class Stream final : public AsyncWrap,
 // Returns false if the header cannot be added. This will typically happen
 // if the application does not support headers, a maximum number of headers
 // have already been added, or the maximum total header length is reached.
-boolAddHeader(constHeader& header);
+boolAddHeader(std::unique_ptr<Header> header);
 
 // TODO(@jasnell): Implement MemoryInfo to track outbound_, inbound_,
 // reader_, headers_, and pending_headers_queue_.
@@ -455,9 +455,11 @@ class Stream final : public AsyncWrap,
 const StoredPriority& stored_priority() const { return priority_; }
 
 // The headers_ field holds a block of headers that have been received and
-// are being buffered for delivery to the JavaScript side.
-// TODO(@jasnell): Use v8::Global instead of v8::Local here.
- v8::LocalVector<v8::Value> headers_;
+// are being buffered for delivery to the JavaScript side. Headers are
+// stored as C++ objects during collection (AddHeader) and converted to
+// V8 strings only when emitted (EmitHeaders), avoiding StrongRootAllocator
+// mutex contention on the per-header hot path.
+ std::vector<std::unique_ptr<Header>> headers_;
 
 // The headers_kind_ field indicates the kind of headers that are being
 // buffered.

src/quic/http3.cc

@@ -333,9 +333,7 @@ class Http3ApplicationImpl final : public Session::Application {
 // We cannot add the header if we've either reached
 // * the max number of header pairs or
 // * the max number of header bytes (name + value combined)
-// current_count is the number of entries in the headers vector
-// (each pair = name entry + value entry = 2 entries).
-return (current_count / 2 < options_.max_header_pairs) &&
+return (current_count < options_.max_header_pairs) &&
  (current_headers_length + this_header_length) <=
  options_.max_header_length;
  }
@@ -825,12 +823,12 @@ class Http3ApplicationImpl final : public Session::Application {
  stream->BeginHeaders(HeadersKind::INITIAL);
  }
 
-voidOnReceiveHeader(stream_id id, Http3Header&& header) {
+voidOnReceiveHeader(stream_id id, std::unique_ptr<Http3Header> header) {
 auto stream = session().FindStream(id);
 
 if (!stream) [[unlikely]]
 return;
-if (header.name() == ":status" && header.value()[0] == '1') {
+if (header->name() == ":status" && header->value()[0] == '1') {
 Debug(&session(),
 "HTTP/3 application switching to hints headers for stream %" PRIi64,
  stream->id());
@@ -839,8 +837,8 @@ class Http3ApplicationImpl final : public Session::Application {
 IF_QUIC_DEBUG(env()) {
 Debug(&session(),
 "Received header \"%s: %s\"",
- header.name(),
- header.value());
+ header->name(),
+ header->value());
  }
  stream->AddHeader(std::move(header));
  }
@@ -874,15 +872,15 @@ class Http3ApplicationImpl final : public Session::Application {
  stream->BeginHeaders(HeadersKind::TRAILING);
  }
 
-voidOnReceiveTrailer(stream_id id, Http3Header&& header) {
+voidOnReceiveTrailer(stream_id id, std::unique_ptr<Http3Header> header) {
 auto stream = session().FindStream(id);
 if (!stream) [[unlikely]]
 return;
 IF_QUIC_DEBUG(env()) {
 Debug(&session(),
 "Received header \"%s: %s\"",
- header.name(),
- header.value());
+ header->name(),
+ header->value());
  }
  stream->AddHeader(std::move(header));
  }
@@ -1239,7 +1237,9 @@ class Http3ApplicationImpl final : public Session::Application {
 returnNGHTTP3_ERR_CALLBACK_FAILURE;
  }
 if (Http3Header::IsZeroLength(token, name, value)) returnNGTCP2_SUCCESS;
- app.OnReceiveHeader(id, Http3Header(app.env(), token, name, value, flags));
+ app.OnReceiveHeader(
+ id,
+ std::make_unique<Http3Header>(app.env(), token, name, value, flags));
 returnNGTCP2_SUCCESS;
  }
 
@@ -1281,7 +1281,9 @@ class Http3ApplicationImpl final : public Session::Application {
 returnNGHTTP3_ERR_CALLBACK_FAILURE;
  }
 if (Http3Header::IsZeroLength(token, name, value)) returnNGTCP2_SUCCESS;
- app.OnReceiveTrailer(id, Http3Header(app.env(), token, name, value, flags));
+ app.OnReceiveTrailer(
+ id,
+ std::make_unique<Http3Header>(app.env(), token, name, value, flags));
 returnNGTCP2_SUCCESS;
  }
 

src/quic/streams.cc

@@ -31,6 +31,7 @@ using v8::HandleScope;
 using v8::Integer;
 using v8::Just;
 using v8::Local;
+using v8::LocalVector;
 using v8::Maybe;
 using v8::Nothing;
 using v8::Object;
@@ -1126,8 +1127,7 @@ Stream::Stream(BaseObjectWeakPtr<Session> session,
  std::shared_ptr<DataQueue> source)
  : AsyncWrap(session->env(), object, PROVIDER_QUIC_STREAM),
  session_(std::move(session)),
- inbound_(DataQueue::Create()),
- headers_(env()->isolate()) {
+ inbound_(DataQueue::Create()) {
 auto& binding = BindingData::Get(env());
  stats_slot_ = GetStreamStatsArena(binding).Allocate(env()->isolate());
  state_slot_ = GetStreamStateArena(binding).Allocate(env()->isolate());
@@ -1185,8 +1185,7 @@ Stream::Stream(BaseObjectWeakPtr<Session> session,
  session_(std::move(session)),
  inbound_(DataQueue::Create()),
  maybe_pending_stream_(
- std::make_unique<PendingStream>(direction, this, session_)),
- headers_(env()->isolate()) {
+ std::make_unique<PendingStream>(direction, this, session_)) {
 auto& binding = BindingData::Get(env());
  stats_slot_ = GetStreamStatsArena(binding).Allocate(env()->isolate());
  state_slot_ = GetStreamStateArena(binding).Allocate(env()->isolate());
@@ -1567,27 +1566,16 @@ void Stream::set_headers_kind(HeadersKind kind) {
  headers_kind_ = kind;
 }
 
-boolStream::AddHeader(constHeader& header) {
-size_t len = header.length();
+boolStream::AddHeader(std::unique_ptr<Header> header) {
+size_t len = header->length();
 if (!session_->application().CanAddHeader(
  headers_.size(), headers_length_, len)) {
 returnfalse;
  }
 
  headers_length_ += len;
-
-auto& state = BindingData::Get(env());
-
-constauto push = [&](auto raw) {
- Local<Value> value;
-if (!raw.ToLocal(&value)) [[unlikely]] {
-returnfalse;
- }
- headers_.push_back(value);
-returntrue;
- };
-
-returnpush(header.GetName(&state)) && push(header.GetValue(&state));
+ headers_.push_back(std::move(header));
+returntrue;
 }
 
 voidStream::Acknowledge(size_t datalen) {
@@ -1899,19 +1887,35 @@ void Stream::EmitHeaders() {
 // state()->wants_headers will be set from the javascript side if the
 // stream object has a handler for the headers event.
 if (!env()->can_call_into_js() || !state()->wants_headers) {
+ headers_.clear();
 return;
  }
  CallbackScope<Stream> cb_scope(this);
 
+auto& binding = BindingData::Get(env());
+size_t count = headers_.size() * 2;
+ LocalVector<Value> values(env()->isolate(), count);
+
+for (size_t i = 0; i < headers_.size(); i++) {
+ Local<Value> name;
+ Local<Value> value;
+if (!headers_[i]->GetName(&binding).ToLocal(&name) ||
+ !headers_[i]->GetValue(&binding).ToLocal(&value)) [[unlikely]] {
+ headers_.clear();
+return;
+ }
+ values[i * 2] = name;
+ values[i * 2 + 1] = value;
+ }
+
+ headers_.clear();
+
  Local<Value> argv[] = {
-Array::New(env()->isolate(), headers_.data(), headers_.size()),
+Array::New(env()->isolate(), values.data(), count),
 Integer::NewFromUnsigned(env()->isolate(),
 static_cast<uint32_t>(headers_kind_))};
 
- headers_.clear();
-
-MakeCallback(
-BindingData::Get(env()).stream_headers_callback(), arraysize(argv), argv);
+MakeCallback(binding.stream_headers_callback(), arraysize(argv), argv);
 }
 
 voidStream::EmitReset(const QuicError& error) {

src/quic/streams.h

@@ -344,7 +344,7 @@ class Stream final : public AsyncWrap,
 // Returns false if the header cannot be added. This will typically happen
 // if the application does not support headers, a maximum number of headers
 // have already been added, or the maximum total header length is reached.
-boolAddHeader(constHeader& header);
+boolAddHeader(std::unique_ptr<Header> header);
 
 // TODO(@jasnell): Implement MemoryInfo to track outbound_, inbound_,
 // reader_, headers_, and pending_headers_queue_.
@@ -455,9 +455,11 @@ class Stream final : public AsyncWrap,
 const StoredPriority& stored_priority() const { return priority_; }
 
 // The headers_ field holds a block of headers that have been received and
-// are being buffered for delivery to the JavaScript side.
-// TODO(@jasnell): Use v8::Global instead of v8::Local here.
- v8::LocalVector<v8::Value> headers_;
+// are being buffered for delivery to the JavaScript side. Headers are
+// stored as C++ objects during collection (AddHeader) and converted to
+// V8 strings only when emitted (EmitHeaders), avoiding StrongRootAllocator
+// mutex contention on the per-header hot path.
+ std::vector<std::unique_ptr<Header>> headers_;
 
 // The headers_kind_ field indicates the kind of headers that are being
 // buffered.

src/quic/http3.cc

@@ -333,9 +333,7 @@ class Http3ApplicationImpl final : public Session::Application {
 // We cannot add the header if we've either reached
 // * the max number of header pairs or
 // * the max number of header bytes (name + value combined)
-// current_count is the number of entries in the headers vector
-// (each pair = name entry + value entry = 2 entries).
-return (current_count / 2 < options_.max_header_pairs) &&
+return (current_count < options_.max_header_pairs) &&
  (current_headers_length + this_header_length) <=
  options_.max_header_length;
  }
@@ -825,12 +823,12 @@ class Http3ApplicationImpl final : public Session::Application {
  stream->BeginHeaders(HeadersKind::INITIAL);
  }
 
-voidOnReceiveHeader(stream_id id, Http3Header&& header) {
+voidOnReceiveHeader(stream_id id, std::unique_ptr<Http3Header> header) {
 auto stream = session().FindStream(id);
 
 if (!stream) [[unlikely]]
 return;
-if (header.name() == ":status" && header.value()[0] == '1') {
+if (header->name() == ":status" && header->value()[0] == '1') {
 Debug(&session(),
 "HTTP/3 application switching to hints headers for stream %" PRIi64,
  stream->id());
@@ -839,8 +837,8 @@ class Http3ApplicationImpl final : public Session::Application {
 IF_QUIC_DEBUG(env()) {
 Debug(&session(),
 "Received header \"%s: %s\"",
- header.name(),
- header.value());
+ header->name(),
+ header->value());
  }
  stream->AddHeader(std::move(header));
  }
@@ -874,15 +872,15 @@ class Http3ApplicationImpl final : public Session::Application {
  stream->BeginHeaders(HeadersKind::TRAILING);
  }
 
-voidOnReceiveTrailer(stream_id id, Http3Header&& header) {
+voidOnReceiveTrailer(stream_id id, std::unique_ptr<Http3Header> header) {
 auto stream = session().FindStream(id);
 if (!stream) [[unlikely]]
 return;
 IF_QUIC_DEBUG(env()) {
 Debug(&session(),
 "Received header \"%s: %s\"",
- header.name(),
- header.value());
+ header->name(),
+ header->value());
  }
  stream->AddHeader(std::move(header));
  }
@@ -1239,7 +1237,9 @@ class Http3ApplicationImpl final : public Session::Application {
 returnNGHTTP3_ERR_CALLBACK_FAILURE;
  }
 if (Http3Header::IsZeroLength(token, name, value)) returnNGTCP2_SUCCESS;
- app.OnReceiveHeader(id, Http3Header(app.env(), token, name, value, flags));
+ app.OnReceiveHeader(
+ id,
+ std::make_unique<Http3Header>(app.env(), token, name, value, flags));
 returnNGTCP2_SUCCESS;
  }
 
@@ -1281,7 +1281,9 @@ class Http3ApplicationImpl final : public Session::Application {
 returnNGHTTP3_ERR_CALLBACK_FAILURE;
  }
 if (Http3Header::IsZeroLength(token, name, value)) returnNGTCP2_SUCCESS;
- app.OnReceiveTrailer(id, Http3Header(app.env(), token, name, value, flags));
+ app.OnReceiveTrailer(
+ id,
+ std::make_unique<Http3Header>(app.env(), token, name, value, flags));
 returnNGTCP2_SUCCESS;
  }
 

src/quic/streams.cc

@@ -31,6 +31,7 @@ using v8::HandleScope;
 using v8::Integer;
 using v8::Just;
 using v8::Local;
+using v8::LocalVector;
 using v8::Maybe;
 using v8::Nothing;
 using v8::Object;
@@ -1126,8 +1127,7 @@ Stream::Stream(BaseObjectWeakPtr<Session> session,
  std::shared_ptr<DataQueue> source)
  : AsyncWrap(session->env(), object, PROVIDER_QUIC_STREAM),
  session_(std::move(session)),
- inbound_(DataQueue::Create()),
- headers_(env()->isolate()) {
+ inbound_(DataQueue::Create()) {
 auto& binding = BindingData::Get(env());
  stats_slot_ = GetStreamStatsArena(binding).Allocate(env()->isolate());
  state_slot_ = GetStreamStateArena(binding).Allocate(env()->isolate());
@@ -1185,8 +1185,7 @@ Stream::Stream(BaseObjectWeakPtr<Session> session,
  session_(std::move(session)),
  inbound_(DataQueue::Create()),
  maybe_pending_stream_(
- std::make_unique<PendingStream>(direction, this, session_)),
- headers_(env()->isolate()) {
+ std::make_unique<PendingStream>(direction, this, session_)) {
 auto& binding = BindingData::Get(env());
  stats_slot_ = GetStreamStatsArena(binding).Allocate(env()->isolate());
  state_slot_ = GetStreamStateArena(binding).Allocate(env()->isolate());
@@ -1567,27 +1566,16 @@ void Stream::set_headers_kind(HeadersKind kind) {
  headers_kind_ = kind;
 }
 
-boolStream::AddHeader(constHeader& header) {
-size_t len = header.length();
+boolStream::AddHeader(std::unique_ptr<Header> header) {
+size_t len = header->length();
 if (!session_->application().CanAddHeader(
  headers_.size(), headers_length_, len)) {
 returnfalse;
  }
 
  headers_length_ += len;
-
-auto& state = BindingData::Get(env());
-
-constauto push = [&](auto raw) {
- Local<Value> value;
-if (!raw.ToLocal(&value)) [[unlikely]] {
-returnfalse;
- }
- headers_.push_back(value);
-returntrue;
- };
-
-returnpush(header.GetName(&state)) && push(header.GetValue(&state));
+ headers_.push_back(std::move(header));
+returntrue;
 }
 
 voidStream::Acknowledge(size_t datalen) {
@@ -1899,19 +1887,35 @@ void Stream::EmitHeaders() {
 // state()->wants_headers will be set from the javascript side if the
 // stream object has a handler for the headers event.
 if (!env()->can_call_into_js() || !state()->wants_headers) {
+ headers_.clear();
 return;
  }
  CallbackScope<Stream> cb_scope(this);
 
+auto& binding = BindingData::Get(env());
+size_t count = headers_.size() * 2;
+ LocalVector<Value> values(env()->isolate(), count);
+
+for (size_t i = 0; i < headers_.size(); i++) {
+ Local<Value> name;
+ Local<Value> value;
+if (!headers_[i]->GetName(&binding).ToLocal(&name) ||
+ !headers_[i]->GetValue(&binding).ToLocal(&value)) [[unlikely]] {
+ headers_.clear();
+return;
+ }
+ values[i * 2] = name;
+ values[i * 2 + 1] = value;
+ }
+
+ headers_.clear();
+
  Local<Value> argv[] = {
-Array::New(env()->isolate(), headers_.data(), headers_.size()),
+Array::New(env()->isolate(), values.data(), count),
 Integer::NewFromUnsigned(env()->isolate(),
 static_cast<uint32_t>(headers_kind_))};
 
- headers_.clear();
-
-MakeCallback(
-BindingData::Get(env()).stream_headers_callback(), arraysize(argv), argv);
+MakeCallback(binding.stream_headers_callback(), arraysize(argv), argv);
 }
 
 voidStream::EmitReset(const QuicError& error) {

src/quic/streams.h

@@ -344,7 +344,7 @@ class Stream final : public AsyncWrap,
 // Returns false if the header cannot be added. This will typically happen
 // if the application does not support headers, a maximum number of headers
 // have already been added, or the maximum total header length is reached.
-boolAddHeader(constHeader& header);
+boolAddHeader(std::unique_ptr<Header> header);
 
 // TODO(@jasnell): Implement MemoryInfo to track outbound_, inbound_,
 // reader_, headers_, and pending_headers_queue_.
@@ -455,9 +455,11 @@ class Stream final : public AsyncWrap,
 const StoredPriority& stored_priority() const { return priority_; }
 
 // The headers_ field holds a block of headers that have been received and
-// are being buffered for delivery to the JavaScript side.
-// TODO(@jasnell): Use v8::Global instead of v8::Local here.
- v8::LocalVector<v8::Value> headers_;
+// are being buffered for delivery to the JavaScript side. Headers are
+// stored as C++ objects during collection (AddHeader) and converted to
+// V8 strings only when emitted (EmitHeaders), avoiding StrongRootAllocator
+// mutex contention on the per-header hot path.
+ std::vector<std::unique_ptr<Header>> headers_;
 
 // The headers_kind_ field indicates the kind of headers that are being
 // buffered.

src/quic/http3.cc

@@ -333,9 +333,7 @@ class Http3ApplicationImpl final : public Session::Application {
 // We cannot add the header if we've either reached
 // * the max number of header pairs or
 // * the max number of header bytes (name + value combined)
-// current_count is the number of entries in the headers vector
-// (each pair = name entry + value entry = 2 entries).
-return (current_count / 2 < options_.max_header_pairs) &&
+return (current_count < options_.max_header_pairs) &&
  (current_headers_length + this_header_length) <=
  options_.max_header_length;
  }
@@ -825,12 +823,12 @@ class Http3ApplicationImpl final : public Session::Application {
  stream->BeginHeaders(HeadersKind::INITIAL);
  }
 
-voidOnReceiveHeader(stream_id id, Http3Header&& header) {
+voidOnReceiveHeader(stream_id id, std::unique_ptr<Http3Header> header) {
 auto stream = session().FindStream(id);
 
 if (!stream) [[unlikely]]
 return;
-if (header.name() == ":status" && header.value()[0] == '1') {
+if (header->name() == ":status" && header->value()[0] == '1') {
 Debug(&session(),
 "HTTP/3 application switching to hints headers for stream %" PRIi64,
  stream->id());
@@ -839,8 +837,8 @@ class Http3ApplicationImpl final : public Session::Application {
 IF_QUIC_DEBUG(env()) {
 Debug(&session(),
 "Received header \"%s: %s\"",
- header.name(),
- header.value());
+ header->name(),
+ header->value());
  }
  stream->AddHeader(std::move(header));
  }
@@ -874,15 +872,15 @@ class Http3ApplicationImpl final : public Session::Application {
  stream->BeginHeaders(HeadersKind::TRAILING);
  }
 
-voidOnReceiveTrailer(stream_id id, Http3Header&& header) {
+voidOnReceiveTrailer(stream_id id, std::unique_ptr<Http3Header> header) {
 auto stream = session().FindStream(id);
 if (!stream) [[unlikely]]
 return;
 IF_QUIC_DEBUG(env()) {
 Debug(&session(),
 "Received header \"%s: %s\"",
- header.name(),
- header.value());
+ header->name(),
+ header->value());
  }
  stream->AddHeader(std::move(header));
  }
@@ -1239,7 +1237,9 @@ class Http3ApplicationImpl final : public Session::Application {
 returnNGHTTP3_ERR_CALLBACK_FAILURE;
  }
 if (Http3Header::IsZeroLength(token, name, value)) returnNGTCP2_SUCCESS;
- app.OnReceiveHeader(id, Http3Header(app.env(), token, name, value, flags));
+ app.OnReceiveHeader(
+ id,
+ std::make_unique<Http3Header>(app.env(), token, name, value, flags));
 returnNGTCP2_SUCCESS;
  }
 
@@ -1281,7 +1281,9 @@ class Http3ApplicationImpl final : public Session::Application {
 returnNGHTTP3_ERR_CALLBACK_FAILURE;
  }
 if (Http3Header::IsZeroLength(token, name, value)) returnNGTCP2_SUCCESS;
- app.OnReceiveTrailer(id, Http3Header(app.env(), token, name, value, flags));
+ app.OnReceiveTrailer(
+ id,
+ std::make_unique<Http3Header>(app.env(), token, name, value, flags));
 returnNGTCP2_SUCCESS;
  }
 

src/quic/streams.cc

@@ -31,6 +31,7 @@ using v8::HandleScope;
 using v8::Integer;
 using v8::Just;
 using v8::Local;
+using v8::LocalVector;
 using v8::Maybe;
 using v8::Nothing;
 using v8::Object;
@@ -1126,8 +1127,7 @@ Stream::Stream(BaseObjectWeakPtr<Session> session,
  std::shared_ptr<DataQueue> source)
  : AsyncWrap(session->env(), object, PROVIDER_QUIC_STREAM),
  session_(std::move(session)),
- inbound_(DataQueue::Create()),
- headers_(env()->isolate()) {
+ inbound_(DataQueue::Create()) {
 auto& binding = BindingData::Get(env());
  stats_slot_ = GetStreamStatsArena(binding).Allocate(env()->isolate());
  state_slot_ = GetStreamStateArena(binding).Allocate(env()->isolate());
@@ -1185,8 +1185,7 @@ Stream::Stream(BaseObjectWeakPtr<Session> session,
  session_(std::move(session)),
  inbound_(DataQueue::Create()),
  maybe_pending_stream_(
- std::make_unique<PendingStream>(direction, this, session_)),
- headers_(env()->isolate()) {
+ std::make_unique<PendingStream>(direction, this, session_)) {
 auto& binding = BindingData::Get(env());
  stats_slot_ = GetStreamStatsArena(binding).Allocate(env()->isolate());
  state_slot_ = GetStreamStateArena(binding).Allocate(env()->isolate());
@@ -1567,27 +1566,16 @@ void Stream::set_headers_kind(HeadersKind kind) {
  headers_kind_ = kind;
 }
 
-boolStream::AddHeader(constHeader& header) {
-size_t len = header.length();
+boolStream::AddHeader(std::unique_ptr<Header> header) {
+size_t len = header->length();
 if (!session_->application().CanAddHeader(
  headers_.size(), headers_length_, len)) {
 returnfalse;
  }
 
  headers_length_ += len;
-
-auto& state = BindingData::Get(env());
-
-constauto push = [&](auto raw) {
- Local<Value> value;
-if (!raw.ToLocal(&value)) [[unlikely]] {
-returnfalse;
- }
- headers_.push_back(value);
-returntrue;
- };
-
-returnpush(header.GetName(&state)) && push(header.GetValue(&state));
+ headers_.push_back(std::move(header));
+returntrue;
 }
 
 voidStream::Acknowledge(size_t datalen) {
@@ -1899,19 +1887,35 @@ void Stream::EmitHeaders() {
 // state()->wants_headers will be set from the javascript side if the
 // stream object has a handler for the headers event.
 if (!env()->can_call_into_js() || !state()->wants_headers) {
+ headers_.clear();
 return;
  }
  CallbackScope<Stream> cb_scope(this);
 
+auto& binding = BindingData::Get(env());
+size_t count = headers_.size() * 2;
+ LocalVector<Value> values(env()->isolate(), count);
+
+for (size_t i = 0; i < headers_.size(); i++) {
+ Local<Value> name;
+ Local<Value> value;
+if (!headers_[i]->GetName(&binding).ToLocal(&name) ||
+ !headers_[i]->GetValue(&binding).ToLocal(&value)) [[unlikely]] {
+ headers_.clear();
+return;
+ }
+ values[i * 2] = name;
+ values[i * 2 + 1] = value;
+ }
+
+ headers_.clear();
+
  Local<Value> argv[] = {
-Array::New(env()->isolate(), headers_.data(), headers_.size()),
+Array::New(env()->isolate(), values.data(), count),
 Integer::NewFromUnsigned(env()->isolate(),
 static_cast<uint32_t>(headers_kind_))};
 
- headers_.clear();
-
-MakeCallback(
-BindingData::Get(env()).stream_headers_callback(), arraysize(argv), argv);
+MakeCallback(binding.stream_headers_callback(), arraysize(argv), argv);
 }
 
 voidStream::EmitReset(const QuicError& error) {

src/quic/streams.h

@@ -344,7 +344,7 @@ class Stream final : public AsyncWrap,
 // Returns false if the header cannot be added. This will typically happen
 // if the application does not support headers, a maximum number of headers
 // have already been added, or the maximum total header length is reached.
-boolAddHeader(constHeader& header);
+boolAddHeader(std::unique_ptr<Header> header);
 
 // TODO(@jasnell): Implement MemoryInfo to track outbound_, inbound_,
 // reader_, headers_, and pending_headers_queue_.
@@ -455,9 +455,11 @@ class Stream final : public AsyncWrap,
 const StoredPriority& stored_priority() const { return priority_; }
 
 // The headers_ field holds a block of headers that have been received and
-// are being buffered for delivery to the JavaScript side.
-// TODO(@jasnell): Use v8::Global instead of v8::Local here.
- v8::LocalVector<v8::Value> headers_;
+// are being buffered for delivery to the JavaScript side. Headers are
+// stored as C++ objects during collection (AddHeader) and converted to
+// V8 strings only when emitted (EmitHeaders), avoiding StrongRootAllocator
+// mutex contention on the per-header hot path.
+ std::vector<std::unique_ptr<Header>> headers_;
 
 // The headers_kind_ field indicates the kind of headers that are being
 // buffered.

src/quic/http3.cc

@@ -333,9 +333,7 @@ class Http3ApplicationImpl final : public Session::Application {
 // We cannot add the header if we've either reached
 // * the max number of header pairs or
 // * the max number of header bytes (name + value combined)
-// current_count is the number of entries in the headers vector
-// (each pair = name entry + value entry = 2 entries).
-return (current_count / 2 < options_.max_header_pairs) &&
+return (current_count < options_.max_header_pairs) &&
  (current_headers_length + this_header_length) <=
  options_.max_header_length;
  }
@@ -825,12 +823,12 @@ class Http3ApplicationImpl final : public Session::Application {
  stream->BeginHeaders(HeadersKind::INITIAL);
  }
 
-voidOnReceiveHeader(stream_id id, Http3Header&& header) {
+voidOnReceiveHeader(stream_id id, std::unique_ptr<Http3Header> header) {
 auto stream = session().FindStream(id);
 
 if (!stream) [[unlikely]]
 return;
-if (header.name() == ":status" && header.value()[0] == '1') {
+if (header->name() == ":status" && header->value()[0] == '1') {
 Debug(&session(),
 "HTTP/3 application switching to hints headers for stream %" PRIi64,
  stream->id());
@@ -839,8 +837,8 @@ class Http3ApplicationImpl final : public Session::Application {
 IF_QUIC_DEBUG(env()) {
 Debug(&session(),
 "Received header \"%s: %s\"",
- header.name(),
- header.value());
+ header->name(),
+ header->value());
  }
  stream->AddHeader(std::move(header));
  }
@@ -874,15 +872,15 @@ class Http3ApplicationImpl final : public Session::Application {
  stream->BeginHeaders(HeadersKind::TRAILING);
  }
 
-voidOnReceiveTrailer(stream_id id, Http3Header&& header) {
+voidOnReceiveTrailer(stream_id id, std::unique_ptr<Http3Header> header) {
 auto stream = session().FindStream(id);
 if (!stream) [[unlikely]]
 return;
 IF_QUIC_DEBUG(env()) {
 Debug(&session(),
 "Received header \"%s: %s\"",
- header.name(),
- header.value());
+ header->name(),
+ header->value());
  }
  stream->AddHeader(std::move(header));
  }
@@ -1239,7 +1237,9 @@ class Http3ApplicationImpl final : public Session::Application {
 returnNGHTTP3_ERR_CALLBACK_FAILURE;
  }
 if (Http3Header::IsZeroLength(token, name, value)) returnNGTCP2_SUCCESS;
- app.OnReceiveHeader(id, Http3Header(app.env(), token, name, value, flags));
+ app.OnReceiveHeader(
+ id,
+ std::make_unique<Http3Header>(app.env(), token, name, value, flags));
 returnNGTCP2_SUCCESS;
  }
 
@@ -1281,7 +1281,9 @@ class Http3ApplicationImpl final : public Session::Application {
 returnNGHTTP3_ERR_CALLBACK_FAILURE;
  }
 if (Http3Header::IsZeroLength(token, name, value)) returnNGTCP2_SUCCESS;
- app.OnReceiveTrailer(id, Http3Header(app.env(), token, name, value, flags));
+ app.OnReceiveTrailer(
+ id,
+ std::make_unique<Http3Header>(app.env(), token, name, value, flags));
 returnNGTCP2_SUCCESS;
  }
 

src/quic/streams.cc

@@ -31,6 +31,7 @@ using v8::HandleScope;
 using v8::Integer;
 using v8::Just;
 using v8::Local;
+using v8::LocalVector;
 using v8::Maybe;
 using v8::Nothing;
 using v8::Object;
@@ -1126,8 +1127,7 @@ Stream::Stream(BaseObjectWeakPtr<Session> session,
  std::shared_ptr<DataQueue> source)
  : AsyncWrap(session->env(), object, PROVIDER_QUIC_STREAM),
  session_(std::move(session)),
- inbound_(DataQueue::Create()),
- headers_(env()->isolate()) {
+ inbound_(DataQueue::Create()) {
 auto& binding = BindingData::Get(env());
  stats_slot_ = GetStreamStatsArena(binding).Allocate(env()->isolate());
  state_slot_ = GetStreamStateArena(binding).Allocate(env()->isolate());
@@ -1185,8 +1185,7 @@ Stream::Stream(BaseObjectWeakPtr<Session> session,
  session_(std::move(session)),
  inbound_(DataQueue::Create()),
  maybe_pending_stream_(
- std::make_unique<PendingStream>(direction, this, session_)),
- headers_(env()->isolate()) {
+ std::make_unique<PendingStream>(direction, this, session_)) {
 auto& binding = BindingData::Get(env());
  stats_slot_ = GetStreamStatsArena(binding).Allocate(env()->isolate());
  state_slot_ = GetStreamStateArena(binding).Allocate(env()->isolate());
@@ -1567,27 +1566,16 @@ void Stream::set_headers_kind(HeadersKind kind) {
  headers_kind_ = kind;
 }
 
-boolStream::AddHeader(constHeader& header) {
-size_t len = header.length();
+boolStream::AddHeader(std::unique_ptr<Header> header) {
+size_t len = header->length();
 if (!session_->application().CanAddHeader(
  headers_.size(), headers_length_, len)) {
 returnfalse;
  }
 
  headers_length_ += len;
-
-auto& state = BindingData::Get(env());
-
-constauto push = [&](auto raw) {
- Local<Value> value;
-if (!raw.ToLocal(&value)) [[unlikely]] {
-returnfalse;
- }
- headers_.push_back(value);
-returntrue;
- };
-
-returnpush(header.GetName(&state)) && push(header.GetValue(&state));
+ headers_.push_back(std::move(header));
+returntrue;
 }
 
 voidStream::Acknowledge(size_t datalen) {
@@ -1899,19 +1887,35 @@ void Stream::EmitHeaders() {
 // state()->wants_headers will be set from the javascript side if the
 // stream object has a handler for the headers event.
 if (!env()->can_call_into_js() || !state()->wants_headers) {
+ headers_.clear();
 return;
  }
  CallbackScope<Stream> cb_scope(this);
 
+auto& binding = BindingData::Get(env());
+size_t count = headers_.size() * 2;
+ LocalVector<Value> values(env()->isolate(), count);
+
+for (size_t i = 0; i < headers_.size(); i++) {
+ Local<Value> name;
+ Local<Value> value;
+if (!headers_[i]->GetName(&binding).ToLocal(&name) ||
+ !headers_[i]->GetValue(&binding).ToLocal(&value)) [[unlikely]] {
+ headers_.clear();
+return;
+ }
+ values[i * 2] = name;
+ values[i * 2 + 1] = value;
+ }
+
+ headers_.clear();
+
  Local<Value> argv[] = {
-Array::New(env()->isolate(), headers_.data(), headers_.size()),
+Array::New(env()->isolate(), values.data(), count),
 Integer::NewFromUnsigned(env()->isolate(),
 static_cast<uint32_t>(headers_kind_))};
 
- headers_.clear();
-
-MakeCallback(
-BindingData::Get(env()).stream_headers_callback(), arraysize(argv), argv);
+MakeCallback(binding.stream_headers_callback(), arraysize(argv), argv);
 }
 
 voidStream::EmitReset(const QuicError& error) {

src/quic/streams.h

@@ -344,7 +344,7 @@ class Stream final : public AsyncWrap,
 // Returns false if the header cannot be added. This will typically happen
 // if the application does not support headers, a maximum number of headers
 // have already been added, or the maximum total header length is reached.
-boolAddHeader(constHeader& header);
+boolAddHeader(std::unique_ptr<Header> header);
 
 // TODO(@jasnell): Implement MemoryInfo to track outbound_, inbound_,
 // reader_, headers_, and pending_headers_queue_.
@@ -455,9 +455,11 @@ class Stream final : public AsyncWrap,
 const StoredPriority& stored_priority() const { return priority_; }
 
 // The headers_ field holds a block of headers that have been received and
-// are being buffered for delivery to the JavaScript side.
-// TODO(@jasnell): Use v8::Global instead of v8::Local here.
- v8::LocalVector<v8::Value> headers_;
+// are being buffered for delivery to the JavaScript side. Headers are
+// stored as C++ objects during collection (AddHeader) and converted to
+// V8 strings only when emitted (EmitHeaders), avoiding StrongRootAllocator
+// mutex contention on the per-header hot path.
+ std::vector<std::unique_ptr<Header>> headers_;
 
 // The headers_kind_ field indicates the kind of headers that are being
 // buffered.

src/quic/http3.cc

@@ -333,9 +333,7 @@ class Http3ApplicationImpl final : public Session::Application {
 // We cannot add the header if we've either reached
 // * the max number of header pairs or
 // * the max number of header bytes (name + value combined)
-// current_count is the number of entries in the headers vector
-// (each pair = name entry + value entry = 2 entries).
-return (current_count / 2 < options_.max_header_pairs) &&
+return (current_count < options_.max_header_pairs) &&
  (current_headers_length + this_header_length) <=
  options_.max_header_length;
  }
@@ -825,12 +823,12 @@ class Http3ApplicationImpl final : public Session::Application {
  stream->BeginHeaders(HeadersKind::INITIAL);
  }
 
-voidOnReceiveHeader(stream_id id, Http3Header&& header) {
+voidOnReceiveHeader(stream_id id, std::unique_ptr<Http3Header> header) {
 auto stream = session().FindStream(id);
 
 if (!stream) [[unlikely]]
 return;
-if (header.name() == ":status" && header.value()[0] == '1') {
+if (header->name() == ":status" && header->value()[0] == '1') {
 Debug(&session(),
 "HTTP/3 application switching to hints headers for stream %" PRIi64,
  stream->id());
@@ -839,8 +837,8 @@ class Http3ApplicationImpl final : public Session::Application {
 IF_QUIC_DEBUG(env()) {
 Debug(&session(),
 "Received header \"%s: %s\"",
- header.name(),
- header.value());
+ header->name(),
+ header->value());
  }
  stream->AddHeader(std::move(header));
  }
@@ -874,15 +872,15 @@ class Http3ApplicationImpl final : public Session::Application {
  stream->BeginHeaders(HeadersKind::TRAILING);
  }
 
-voidOnReceiveTrailer(stream_id id, Http3Header&& header) {
+voidOnReceiveTrailer(stream_id id, std::unique_ptr<Http3Header> header) {
 auto stream = session().FindStream(id);
 if (!stream) [[unlikely]]
 return;
 IF_QUIC_DEBUG(env()) {
 Debug(&session(),
 "Received header \"%s: %s\"",
- header.name(),
- header.value());
+ header->name(),
+ header->value());
  }
  stream->AddHeader(std::move(header));
  }
@@ -1239,7 +1237,9 @@ class Http3ApplicationImpl final : public Session::Application {
 returnNGHTTP3_ERR_CALLBACK_FAILURE;
  }
 if (Http3Header::IsZeroLength(token, name, value)) returnNGTCP2_SUCCESS;
- app.OnReceiveHeader(id, Http3Header(app.env(), token, name, value, flags));
+ app.OnReceiveHeader(
+ id,
+ std::make_unique<Http3Header>(app.env(), token, name, value, flags));
 returnNGTCP2_SUCCESS;
  }
 
@@ -1281,7 +1281,9 @@ class Http3ApplicationImpl final : public Session::Application {
 returnNGHTTP3_ERR_CALLBACK_FAILURE;
  }
 if (Http3Header::IsZeroLength(token, name, value)) returnNGTCP2_SUCCESS;
- app.OnReceiveTrailer(id, Http3Header(app.env(), token, name, value, flags));
+ app.OnReceiveTrailer(
+ id,
+ std::make_unique<Http3Header>(app.env(), token, name, value, flags));
 returnNGTCP2_SUCCESS;
  }
 

src/quic/streams.cc

@@ -31,6 +31,7 @@ using v8::HandleScope;
 using v8::Integer;
 using v8::Just;
 using v8::Local;
+using v8::LocalVector;
 using v8::Maybe;
 using v8::Nothing;
 using v8::Object;
@@ -1126,8 +1127,7 @@ Stream::Stream(BaseObjectWeakPtr<Session> session,
  std::shared_ptr<DataQueue> source)
  : AsyncWrap(session->env(), object, PROVIDER_QUIC_STREAM),
  session_(std::move(session)),
- inbound_(DataQueue::Create()),
- headers_(env()->isolate()) {
+ inbound_(DataQueue::Create()) {
 auto& binding = BindingData::Get(env());
  stats_slot_ = GetStreamStatsArena(binding).Allocate(env()->isolate());
  state_slot_ = GetStreamStateArena(binding).Allocate(env()->isolate());
@@ -1185,8 +1185,7 @@ Stream::Stream(BaseObjectWeakPtr<Session> session,
  session_(std::move(session)),
  inbound_(DataQueue::Create()),
  maybe_pending_stream_(
- std::make_unique<PendingStream>(direction, this, session_)),
- headers_(env()->isolate()) {
+ std::make_unique<PendingStream>(direction, this, session_)) {
 auto& binding = BindingData::Get(env());
  stats_slot_ = GetStreamStatsArena(binding).Allocate(env()->isolate());
  state_slot_ = GetStreamStateArena(binding).Allocate(env()->isolate());
@@ -1567,27 +1566,16 @@ void Stream::set_headers_kind(HeadersKind kind) {
  headers_kind_ = kind;
 }
 
-boolStream::AddHeader(constHeader& header) {
-size_t len = header.length();
+boolStream::AddHeader(std::unique_ptr<Header> header) {
+size_t len = header->length();
 if (!session_->application().CanAddHeader(
  headers_.size(), headers_length_, len)) {
 returnfalse;
  }
 
  headers_length_ += len;
-
-auto& state = BindingData::Get(env());
-
-constauto push = [&](auto raw) {
- Local<Value> value;
-if (!raw.ToLocal(&value)) [[unlikely]] {
-returnfalse;
- }
- headers_.push_back(value);
-returntrue;
- };
-
-returnpush(header.GetName(&state)) && push(header.GetValue(&state));
+ headers_.push_back(std::move(header));
+returntrue;
 }
 
 voidStream::Acknowledge(size_t datalen) {
@@ -1899,19 +1887,35 @@ void Stream::EmitHeaders() {
 // state()->wants_headers will be set from the javascript side if the
 // stream object has a handler for the headers event.
 if (!env()->can_call_into_js() || !state()->wants_headers) {
+ headers_.clear();
 return;
  }
  CallbackScope<Stream> cb_scope(this);
 
+auto& binding = BindingData::Get(env());
+size_t count = headers_.size() * 2;
+ LocalVector<Value> values(env()->isolate(), count);
+
+for (size_t i = 0; i < headers_.size(); i++) {
+ Local<Value> name;
+ Local<Value> value;
+if (!headers_[i]->GetName(&binding).ToLocal(&name) ||
+ !headers_[i]->GetValue(&binding).ToLocal(&value)) [[unlikely]] {
+ headers_.clear();
+return;
+ }
+ values[i * 2] = name;
+ values[i * 2 + 1] = value;
+ }
+
+ headers_.clear();
+
  Local<Value> argv[] = {
-Array::New(env()->isolate(), headers_.data(), headers_.size()),
+Array::New(env()->isolate(), values.data(), count),
 Integer::NewFromUnsigned(env()->isolate(),
 static_cast<uint32_t>(headers_kind_))};
 
- headers_.clear();
-
-MakeCallback(
-BindingData::Get(env()).stream_headers_callback(), arraysize(argv), argv);
+MakeCallback(binding.stream_headers_callback(), arraysize(argv), argv);
 }
 
 voidStream::EmitReset(const QuicError& error) {

src/quic/streams.h

@@ -344,7 +344,7 @@ class Stream final : public AsyncWrap,
 // Returns false if the header cannot be added. This will typically happen
 // if the application does not support headers, a maximum number of headers
 // have already been added, or the maximum total header length is reached.
-boolAddHeader(constHeader& header);
+boolAddHeader(std::unique_ptr<Header> header);
 
 // TODO(@jasnell): Implement MemoryInfo to track outbound_, inbound_,
 // reader_, headers_, and pending_headers_queue_.
@@ -455,9 +455,11 @@ class Stream final : public AsyncWrap,
 const StoredPriority& stored_priority() const { return priority_; }
 
 // The headers_ field holds a block of headers that have been received and
-// are being buffered for delivery to the JavaScript side.
-// TODO(@jasnell): Use v8::Global instead of v8::Local here.
- v8::LocalVector<v8::Value> headers_;
+// are being buffered for delivery to the JavaScript side. Headers are
+// stored as C++ objects during collection (AddHeader) and converted to
+// V8 strings only when emitted (EmitHeaders), avoiding StrongRootAllocator
+// mutex contention on the per-header hot path.
+ std::vector<std::unique_ptr<Header>> headers_;
 
 // The headers_kind_ field indicates the kind of headers that are being
 // buffered.

src/quic/http3.cc

@@ -333,9 +333,7 @@ class Http3ApplicationImpl final : public Session::Application {
 // We cannot add the header if we've either reached
 // * the max number of header pairs or
 // * the max number of header bytes (name + value combined)
-// current_count is the number of entries in the headers vector
-// (each pair = name entry + value entry = 2 entries).
-return (current_count / 2 < options_.max_header_pairs) &&
+return (current_count < options_.max_header_pairs) &&
  (current_headers_length + this_header_length) <=
  options_.max_header_length;
  }
@@ -825,12 +823,12 @@ class Http3ApplicationImpl final : public Session::Application {
  stream->BeginHeaders(HeadersKind::INITIAL);
  }
 
-voidOnReceiveHeader(stream_id id, Http3Header&& header) {
+voidOnReceiveHeader(stream_id id, std::unique_ptr<Http3Header> header) {
 auto stream = session().FindStream(id);
 
 if (!stream) [[unlikely]]
 return;
-if (header.name() == ":status" && header.value()[0] == '1') {
+if (header->name() == ":status" && header->value()[0] == '1') {
 Debug(&session(),
 "HTTP/3 application switching to hints headers for stream %" PRIi64,
  stream->id());
@@ -839,8 +837,8 @@ class Http3ApplicationImpl final : public Session::Application {
 IF_QUIC_DEBUG(env()) {
 Debug(&session(),
 "Received header \"%s: %s\"",
- header.name(),
- header.value());
+ header->name(),
+ header->value());
  }
  stream->AddHeader(std::move(header));
  }
@@ -874,15 +872,15 @@ class Http3ApplicationImpl final : public Session::Application {
  stream->BeginHeaders(HeadersKind::TRAILING);
  }
 
-voidOnReceiveTrailer(stream_id id, Http3Header&& header) {
+voidOnReceiveTrailer(stream_id id, std::unique_ptr<Http3Header> header) {
 auto stream = session().FindStream(id);
 if (!stream) [[unlikely]]
 return;
 IF_QUIC_DEBUG(env()) {
 Debug(&session(),
 "Received header \"%s: %s\"",
- header.name(),
- header.value());
+ header->name(),
+ header->value());
  }
  stream->AddHeader(std::move(header));
  }
@@ -1239,7 +1237,9 @@ class Http3ApplicationImpl final : public Session::Application {
 returnNGHTTP3_ERR_CALLBACK_FAILURE;
  }
 if (Http3Header::IsZeroLength(token, name, value)) returnNGTCP2_SUCCESS;
- app.OnReceiveHeader(id, Http3Header(app.env(), token, name, value, flags));
+ app.OnReceiveHeader(
+ id,
+ std::make_unique<Http3Header>(app.env(), token, name, value, flags));
 returnNGTCP2_SUCCESS;
  }
 
@@ -1281,7 +1281,9 @@ class Http3ApplicationImpl final : public Session::Application {
 returnNGHTTP3_ERR_CALLBACK_FAILURE;
  }
 if (Http3Header::IsZeroLength(token, name, value)) returnNGTCP2_SUCCESS;
- app.OnReceiveTrailer(id, Http3Header(app.env(), token, name, value, flags));
+ app.OnReceiveTrailer(
+ id,
+ std::make_unique<Http3Header>(app.env(), token, name, value, flags));
 returnNGTCP2_SUCCESS;
  }
 

src/quic/streams.cc

@@ -31,6 +31,7 @@ using v8::HandleScope;
 using v8::Integer;
 using v8::Just;
 using v8::Local;
+using v8::LocalVector;
 using v8::Maybe;
 using v8::Nothing;
 using v8::Object;
@@ -1126,8 +1127,7 @@ Stream::Stream(BaseObjectWeakPtr<Session> session,
  std::shared_ptr<DataQueue> source)
  : AsyncWrap(session->env(), object, PROVIDER_QUIC_STREAM),
  session_(std::move(session)),
- inbound_(DataQueue::Create()),
- headers_(env()->isolate()) {
+ inbound_(DataQueue::Create()) {
 auto& binding = BindingData::Get(env());
  stats_slot_ = GetStreamStatsArena(binding).Allocate(env()->isolate());
  state_slot_ = GetStreamStateArena(binding).Allocate(env()->isolate());
@@ -1185,8 +1185,7 @@ Stream::Stream(BaseObjectWeakPtr<Session> session,
  session_(std::move(session)),
  inbound_(DataQueue::Create()),
  maybe_pending_stream_(
- std::make_unique<PendingStream>(direction, this, session_)),
- headers_(env()->isolate()) {
+ std::make_unique<PendingStream>(direction, this, session_)) {
 auto& binding = BindingData::Get(env());
  stats_slot_ = GetStreamStatsArena(binding).Allocate(env()->isolate());
  state_slot_ = GetStreamStateArena(binding).Allocate(env()->isolate());
@@ -1567,27 +1566,16 @@ void Stream::set_headers_kind(HeadersKind kind) {
  headers_kind_ = kind;
 }
 
-boolStream::AddHeader(constHeader& header) {
-size_t len = header.length();
+boolStream::AddHeader(std::unique_ptr<Header> header) {
+size_t len = header->length();
 if (!session_->application().CanAddHeader(
  headers_.size(), headers_length_, len)) {
 returnfalse;
  }
 
  headers_length_ += len;
-
-auto& state = BindingData::Get(env());
-
-constauto push = [&](auto raw) {
- Local<Value> value;
-if (!raw.ToLocal(&value)) [[unlikely]] {
-returnfalse;
- }
- headers_.push_back(value);
-returntrue;
- };
-
-returnpush(header.GetName(&state)) && push(header.GetValue(&state));
+ headers_.push_back(std::move(header));
+returntrue;
 }
 
 voidStream::Acknowledge(size_t datalen) {
@@ -1899,19 +1887,35 @@ void Stream::EmitHeaders() {
 // state()->wants_headers will be set from the javascript side if the
 // stream object has a handler for the headers event.
 if (!env()->can_call_into_js() || !state()->wants_headers) {
+ headers_.clear();
 return;
  }
  CallbackScope<Stream> cb_scope(this);
 
+auto& binding = BindingData::Get(env());
+size_t count = headers_.size() * 2;
+ LocalVector<Value> values(env()->isolate(), count);
+
+for (size_t i = 0; i < headers_.size(); i++) {
+ Local<Value> name;
+ Local<Value> value;
+if (!headers_[i]->GetName(&binding).ToLocal(&name) ||
+ !headers_[i]->GetValue(&binding).ToLocal(&value)) [[unlikely]] {
+ headers_.clear();
+return;
+ }
+ values[i * 2] = name;
+ values[i * 2 + 1] = value;
+ }
+
+ headers_.clear();
+
  Local<Value> argv[] = {
-Array::New(env()->isolate(), headers_.data(), headers_.size()),
+Array::New(env()->isolate(), values.data(), count),
 Integer::NewFromUnsigned(env()->isolate(),
 static_cast<uint32_t>(headers_kind_))};
 
- headers_.clear();
-
-MakeCallback(
-BindingData::Get(env()).stream_headers_callback(), arraysize(argv), argv);
+MakeCallback(binding.stream_headers_callback(), arraysize(argv), argv);
 }
 
 voidStream::EmitReset(const QuicError& error) {

src/quic/streams.h

@@ -344,7 +344,7 @@ class Stream final : public AsyncWrap,
 // Returns false if the header cannot be added. This will typically happen
 // if the application does not support headers, a maximum number of headers
 // have already been added, or the maximum total header length is reached.
-boolAddHeader(constHeader& header);
+boolAddHeader(std::unique_ptr<Header> header);
 
 // TODO(@jasnell): Implement MemoryInfo to track outbound_, inbound_,
 // reader_, headers_, and pending_headers_queue_.
@@ -455,9 +455,11 @@ class Stream final : public AsyncWrap,
 const StoredPriority& stored_priority() const { return priority_; }
 
 // The headers_ field holds a block of headers that have been received and
-// are being buffered for delivery to the JavaScript side.
-// TODO(@jasnell): Use v8::Global instead of v8::Local here.
- v8::LocalVector<v8::Value> headers_;
+// are being buffered for delivery to the JavaScript side. Headers are
+// stored as C++ objects during collection (AddHeader) and converted to
+// V8 strings only when emitted (EmitHeaders), avoiding StrongRootAllocator
+// mutex contention on the per-header hot path.
+ std::vector<std::unique_ptr<Header>> headers_;
 
 // The headers_kind_ field indicates the kind of headers that are being
 // buffered.