#if defined(__APPLE__)

mach_task_basic_info_data_t info{};

mach_msg_type_number_t count = MACH_TASK_BASIC_INFO_COUNT;

check(task_info(mach_task_self(), MACH_TASK_BASIC_INFO, reinterpret_cast<task_info_t>(&info), &count) == KERN_SUCCESS,

"process memory measurement unavailable");

return info.resident_size;

#else

std::ifstream stat("/proc/self/statm");

std::size_t total = 0, resident = 0;

check(static_cast<bool>(stat >> total >> resident), "process memory measurement unavailable");

return resident * static_cast<std::size_t>(sysconf(_SC_PAGESIZE));

#endif

int small = 2048;

check(setsockopt(r.pair.local(), SOL_SOCKET, SO_SNDBUF, &small, sizeof small) == 0, "local send buffer");

check(setsockopt(r.pair.peer(), SOL_SOCKET, SO_SNDBUF, &small, sizeof small) == 0, "peer send buffer");

r.config.body.max_staged_bytes = 1024;

r.config.outbox.max_queue_bytes = 1024;

r.config.timeouts.body_idle = 10s; r.config.timeouts.write_idle = 10s;

std::size_t sent = 0;

for (std::size_t n = 0; n < attempts; n += buffer.size()) {

auto result = sys::write_some(r.pair.peer(), buffer.data(), buffer.size());

if (result.status == sys::sys_status::ok) {

sent += result.transferred;

} else {

check(result.status == sys::sys_status::would_block, "input connection failed");

}

}

return sent;

workload(1024 * 1024);

auto first = engine_access::queues(*r.engine);

auto memory = resident_bytes();

workload(8 * 1024 * 1024);

auto second = engine_access::queues(*r.engine);

auto after = resident_bytes();

// Two fixed transport buffers (16KiB read + 4KiB write), queue

// budgets and frame overhead; process slack is separately bounded.

check(first.tail <= 16384 + 1024 && second.tail <= 16384 + 1024, "pending transport tail bound");

check(first.body <= 1024 && second.body <= 1024, "HTTP input budget");

check(first.output <= 2048 && second.output <= 2048, "HTTP outbox bound including fixed head");

check(first.ws_input <= 512 && second.ws_input <= 512, "WebSocket input budget");

check(first.ws_output <= 522 && second.ws_output <= 522, "WebSocket output budget");

// RSS includes kernel-independent allocator slack and sanitizer

// metadata/quarantine. No custom allocation operators are installed.

constexpr std::size_t slack = 1024 * 1024;

check(after <= memory + slack, "retained process memory grew past fixed slack");

std::cout << "PLATEAU " << name << " retained=" << first.total() << '/' << second.total()

<< " RSS=" << memory << '/' << after << " slack=" << slack << '\n';

r.engine->shutdown(); r.engine->shutdown();

check(until([&] { return r.stopped.load(); }), "engine shutdown deadline");

check(r.scope.active() == 0 && r.stop_calls == 1, "drained connection and exactly-once stop");

std::weak_ptr<h::detail::connection_engine> released = r.engine;

r.engine.reset();

check(until([&] { return released.expired(); }), "released connection state and retained allocations");

h::resume_signal resume;

std::atomic<bool> entered{false}, delivered{false};

std::atomic<std::size_t> received{0};

rig r; small_sockets(r);

constexpr std::size_t length = 1024 * 1024;

r.routes.route(h::http::method::known(h::http::method_id::post), "/", [&](h::exchange& x) -> h::task<void> {

x.admit_body({}); entered = true;

co_await resume.wait_for(10s);

std::byte scratch[1024];

for (;;) {

auto read = co_await x.body().read_some(scratch);

if (!read.status.ok()) co_return;

for (std::size_t i = 0; i < read.data.size(); ++i) {

if (scratch[i] != std::byte{'u'}) co_return;

}

received += read.data.size();

if (read.end_of_body) break;

}

delivered = received == length;

h::http::fields fields; fields.append("Content-Length", "0");

x.start_response(h::http::status::from_code(200), fields); co_await x.writer().finish();

});

check(r.start(), "upload start");

std::string head = "POST / HTTP/1.1\r\nHost: h\r\nContent-Length: 1048576\r\n\r\n";

io_loopback::write_all(r.pair.peer(), head.data(), head.size());

check(until([&] { return entered.load(); }), "upload admission");

std::array<std::byte, 1024> data; data.fill(std::byte{'u'});

std::size_t sent = 0;

check(until([&] { sent += attempt_input(r, data, data.size()); return engine_access::queues(*r.engine).body == 1024; }), "upload staging full");

check(until([&] { auto progress = attempt_input(r, data, data.size()); sent += progress; return progress == 0; }), "upload transport backpressure");

plateau(r, "HTTP upload", [&](std::size_t n) { sent += attempt_input(r, data, n); });

check(sent < length && received == 0, "application stall stopped progress");

resume.signal();

while (sent < length) {

auto part = std::span(data).first(std::min(data.size(), length - sent));

auto result = sys::write_some(r.pair.peer(), part.data(), part.size());

if (result.transferred) {

sent += result.transferred;

} else {

bool resumed = until([&] { auto result = sys::write_some(r.pair.peer(), part.data(), part.size()); sent += result.transferred; return result.transferred > 0; });

check(resumed, "upload resume");

}

}

check(until([&] { return delivered.load(); }), "ordered upload delivery");

check(until([&] { return engine_access::http_idle(*r.engine); }), "upload exchange settled before abort");

terminal(r);

release_engine(r);

rig r; small_sockets(r); check(r.start(), "output start");

auto& sink = engine_access::output_slot(*r.engine);

h::http::request_head request; request.request_protocol = h::http::protocol::http_1_1;

h::http::fields fields; fields.append("Content-Length", "1048576");

check(sink.start(request, h::http::status::from_code(200), fields).ok(), "output head");

std::array<std::byte, 1024> data; data.fill(std::byte{'o'});

std::size_t accepted = 0;

auto produce = [&](std::size_t attempts) {

for (std::size_t n = 0; n < attempts; n += data.size()) {

auto result = sink.push(data); accepted += result.copied;

check(result.kind != h::detail::body_push::failed, "output push");

}

engine_access::notify(*r.engine);

};

auto steady = std::chrono::steady_clock::now();

check(until([&] {

auto before = accepted; produce(1024);

if (accepted != before) steady = std::chrono::steady_clock::now();

std::this_thread::sleep_for(1ms);

return engine_access::queues(*r.engine).output == 1024 && std::chrono::steady_clock::now() - steady >= 20ms;

}), "stalled peer stops outbox admission");

plateau(r, "HTTP output", produce);

check(sink.push(data).kind == h::detail::body_push::full, "output admission stopped");

std::string wire;

std::array<std::byte, 4096> scratch;

check(until([&] {

auto result = sys::read_some(r.pair.peer(), scratch.data(), scratch.size());

if (result.transferred) wire.append(reinterpret_cast<const char*>(scratch.data()), result.transferred);

auto end = wire.find("\r\n\r\n");

return end != std::string::npos && wire.size() - end - 4 == accepted;

}), "output resumes");

// Retain only the small admitted prefix, never the attempted windows.

auto end = wire.find("\r\n\r\n");

check(end != std::string::npos, "response head delivered");

check(wire.size() - end - 4 == accepted && wire.substr(end + 4) == std::string(wire.size() - end - 4, 'o'), "ordered output bytes");

check(accepted < 1048576, "bounded output admission");

terminal(r);

check(engine_access::queues(*r.engine).output == 0, "outbox release");

release_engine(r);

h::resume_signal resume, closed;

std::atomic<bool> entered{false}, invalid{false}, clean{false}; std::atomic<int> closes{0};

std::atomic<std::size_t> received{0};

rig r; small_sockets(r);

r.config.websocket_limits.max_message_bytes = 64; r.config.websocket_limits.incoming_bytes = 512;

r.config.websocket_limits.incoming_messages = 8;

r.routes.route(h::http::method::known(h::http::method_id::get), "/", [&](h::exchange& x) -> h::task<void> {

auto upgraded = co_await x.upgrade({});

if (!upgraded.session) co_return;

upgraded.session->on_close([&](auto info) { clean = info.clean; ++closes; closed.signal(); }); entered = true;

co_await resume.wait_for(10s);

for (;;) {

auto result = co_await upgraded.session->receive();

if (!result.value) break;

if (result.value->data != std::vector<std::byte>(64, std::byte{'w'})) invalid = true;

received += result.value->data.size();

}

co_await closed.wait_for(5s);

});

check(r.start(), "WebSocket input start"); auto head = opening();

io_loopback::write_all(r.pair.peer(), head.data(), head.size());

check(until([&] { return entered.load(); }), "WebSocket upgrade");

std::string handshake;

std::array<std::byte, 512> head_bytes;

check(until([&] {

auto result = sys::read_some(r.pair.peer(), head_bytes.data(), head_bytes.size());

handshake.append(reinterpret_cast<const char*>(head_bytes.data()), result.transferred);

check(handshake.size() <= 1024, "bounded upgrade response");

return handshake.find("\r\n\r\n") != std::string::npos;

}), "upgrade response drained before input stall");

check(handshake.starts_with("HTTP/1.1 101 "), "wire upgrade status");

auto wire = ws_test::frame(2, std::vector<std::byte>(64, std::byte{'w'}));

std::size_t sent = 0, partial = 0;

auto produce = [&](std::size_t attempts) {

for (std::size_t n = 0; n < attempts; n += wire.size()) {

auto result = sys::write_some(r.pair.peer(), wire.data() + partial, wire.size() - partial);

sent += result.transferred; partial = (partial + result.transferred) % wire.size();

check(result.status == sys::sys_status::ok || result.status == sys::sys_status::would_block, "WebSocket input write");

}

};

check(until([&] { produce(1024); return engine_access::queues(*r.engine).ws_input == 512; }), "WebSocket receiver stall");

plateau(r, "WebSocket input", produce);

check(received == 0, "stalled application receives nothing");

resume.signal();

if (partial) {

io_loopback::write_all(r.pair.peer(), wire.data() + partial, wire.size() - partial); sent += wire.size() - partial; }

check(until([&] { return received == sent / wire.size() * 64; }), "ordered WebSocket input resume");

auto close = ws_test::frame(8, ws_test::bytes("\x03\xe8"));

io_loopback::write_all(r.pair.peer(), close.data(), close.size());

check(until([&] { return r.stopped.load(); }), "WebSocket clean close");

check(!invalid && clean && closes == 1 && r.stop_calls == 1 && r.scope.active() == 0, "WebSocket terminal notification once");

check(engine_access::queues(*r.engine).ws_input == 0, "WebSocket input released");

release_engine(r);

rig r; small_sockets(r);

auto limits = ws_test::small(); limits.max_message_bytes = 64; limits.incoming_bytes = 512; limits.output_bytes = 522; limits.outgoing_messages = 8;

auto driver = std::make_shared<h::detail::websocket_driver>(limits);

auto session = driver->take_session(); std::atomic<int> closes{0}; session.on_close([&](auto) { ++closes; });

r.create_engine(); engine_access::install(*r.engine, driver);

sys::set_nonblocking(r.pair.peer(), true); r.backend.adopt_connection(1, r.pair.detach_local());

r.engine->start(); r.started = true;

std::array<std::byte, 64> data; data.fill(std::byte{'s'});

std::size_t messages = 0;

auto produce = [&](std::size_t attempts) {

for (std::size_t n = 0; n < attempts; n += data.size()) {

auto result = session.try_send(h::websocket::message_kind::binary, data);

if (result.disposition == h::websocket::send_disposition::accepted) {

++messages;

} else {

check(result.disposition == h::websocket::send_disposition::backpressured, "WebSocket output send");

}

}

};

auto steady = std::chrono::steady_clock::now();

check(until([&] {

auto before = messages; produce(1024);

if (messages != before) steady = std::chrono::steady_clock::now();

std::this_thread::sleep_for(1ms);

return driver->usage().output_bytes >= 462 && std::chrono::steady_clock::now() - steady >= 20ms;

}), "stalled peer stops WebSocket output admission");

plateau(r, "WebSocket output", produce);

check(session.try_send(h::websocket::message_kind::binary, data).disposition == h::websocket::send_disposition::backpressured,

"WebSocket output admission stopped");

std::string wire;

std::array<std::byte, 4096> scratch;

check(messages * 66 <= 1024 * 1024, "bounded receiver buffer");

check(until([&] {

auto result = sys::read_some(r.pair.peer(), scratch.data(), scratch.size());

wire.append(reinterpret_cast<const char*>(scratch.data()), result.transferred);

return wire.size() == messages * 66;

}), "WebSocket output resumes");

for (std::size_t n = 0; n < messages; ++n) {

check(static_cast<unsigned char>(wire[n * 66]) == 0x82 && wire[n * 66 + 1] == 64,

"ordered WebSocket frame header");

check(wire.substr(n * 66 + 2, 64) == std::string(64, 's'), "ordered WebSocket frame payload");

}

terminal(r); check(closes == 1 && driver->usage().output_bytes == 0, "WebSocket output released once");

release_engine(r);

try {

http_upload(); http_output(); websocket_input(); websocket_output();

}

catch (const std::exception& error) { std::cerr << error.what() << '\n'; return 1; }