Support periodic kernel timers through shared event queue deadlines

src/kernel/eventQueue.cpp

@@ -138,7 +138,13 @@ int KernelEqueuePrivate::GetTriggeredEvents(KernelEvent* ev, int num) {
 
 void KernelEqueuePrivate::TriggerExpiredTimers(uint64_t now_ns) {
 	for (auto& event: m_events) {
-		if (!event.triggered && event.deadline_ns != 0 && event.deadline_ns <= now_ns) {
+		if (event.deadline_ns != 0 && event.deadline_ns <= now_ns) {
+			if (event.event.filter == KERNEL_EVFILT_TIMER) {
+				const auto count = event.interval_ns == 0 ? !event.triggered :
+				    1 + (now_ns - event.deadline_ns) / event.interval_ns;
+				event.event.data += static_cast<intptr_t>(count);
+				event.deadline_ns += count * event.interval_ns;
+			}
 			event.triggered = true;
 		}
 	}
@@ -209,7 +215,9 @@ int KernelEqueuePrivate::AddEvent(const KernelEqueueEvent& event) {
 		                       return e.event.ident == ident && e.event.filter == filter;
 	                       });
 	if (it != m_events.end()) {
+		TriggerExpiredTimers(MonotonicTimeNs());
 		it->deadline_ns = event.deadline_ns;
+		it->interval_ns = event.interval_ns;
 		it->event.udata = event.event.udata;
 		for (auto& pending: it->pending_events) {
 			pending.udata = event.event.udata;
@@ -511,6 +519,22 @@ int KYTY_SYSV_ABI KernelDeleteUserEvent(KernelEqueue eq, int id) {
 	return KernelDeleteEvent(eq, static_cast<uintptr_t>(id), KERNEL_EVFILT_USER);
 }
 
+static int AddTimerEvent(KernelEqueue eq, int id, uint64_t delay_ns, bool periodic, void* udata) {
+	const auto now_ns = MonotonicTimeNs();
+	KernelEqueueEvent event {};
+	event.deadline_ns  = delay_ns <= UINT64_MAX - now_ns ? now_ns + delay_ns : UINT64_MAX;
+	event.interval_ns  = periodic ? delay_ns : 0;
+	event.event.ident  = static_cast<uintptr_t>(id);
+	event.event.filter = periodic ? KERNEL_EVFILT_TIMER : KERNEL_EVFILT_HRTIMER;
+	event.event.flags  = EV_ADD | (periodic ? EV_CLEAR : EV_ONESHOT);
+	event.event.udata  = udata;
+	return KernelAddEvent(eq, event);
+}
+
+int KYTY_SYSV_ABI KernelAddTimerEvent(KernelEqueue eq, int id, KernelUseconds usec, void* udata) {
+	return AddTimerEvent(eq, id, static_cast<uint64_t>(usec) * 1000, true, udata);
+}
+
 int KYTY_SYSV_ABI KernelAddHRTimerEvent(KernelEqueue eq, int id, const KernelTimespec* ts,
                                         void* udata) {
 	if (ts == nullptr) {
@@ -524,17 +548,7 @@ int KYTY_SYSV_ABI KernelAddHRTimerEvent(KernelEqueue eq, int id, const KernelTim
 
 	const auto delay_ns =
 	    static_cast<uint64_t>(ts->tv_sec) * 1000000000ull + static_cast<uint64_t>(ts->tv_nsec);
-	const auto now_ns = MonotonicTimeNs();
+	return AddTimerEvent(eq, id, delay_ns, false, udata);
-
-	KernelEqueueEvent event {};
-	event.deadline_ns  = delay_ns <= UINT64_MAX - now_ns ? now_ns + delay_ns : UINT64_MAX;
-	event.event.ident  = static_cast<uintptr_t>(id);
-	event.event.filter = KERNEL_EVFILT_HRTIMER;
-	event.event.flags  = EV_ADD | EV_ONESHOT;
-	event.event.fflags = 0;
-	event.event.data   = 0;
-	event.event.udata  = udata;
-	return KernelAddEvent(eq, event);
 }
 
 int KYTY_SYSV_ABI KernelDeleteHRTimerEvent(KernelEqueue eq, int id) {

src/kernel/eventQueue.h

@@ -51,6 +51,7 @@ struct KernelFilter {
 struct KernelEqueueEvent {
 	bool                    triggered   = false;
 	uint64_t                deadline_ns = 0;
+	uint64_t                interval_ns = 0;
 	KernelEvent             event;
 	KernelFilter            filter;
 	std::deque<KernelEvent> pending_events;
@@ -72,6 +73,8 @@ int KYTY_SYSV_ABI KernelAddUserEventEdge(KernelEqueue eq, int id);
 int KYTY_SYSV_ABI KernelTriggerUserEvent(KernelEqueue eq, int id, void* udata);
 int KYTY_SYSV_ABI KernelTriggerUserEventForAll(int id, void* udata);
 int KYTY_SYSV_ABI KernelDeleteUserEvent(KernelEqueue eq, int id);
+int KYTY_SYSV_ABI KernelAddTimerEvent(KernelEqueue eq, int id, KernelUseconds usec,
+                                      void* udata);
 int KYTY_SYSV_ABI KernelAddHRTimerEvent(KernelEqueue eq, int id, const KernelTimespec* ts,
                                         void* udata);
 int KYTY_SYSV_ABI KernelDeleteHRTimerEvent(KernelEqueue eq, int id);

src/libs/libKernel.cpp

@@ -3148,6 +3148,7 @@ LIB_DEFINE(InitLibKernel_1_Equeue) {
 	LIB_FUNC("WDszmSbWuDk", EventQueue::KernelAddUserEventEdge);
 	LIB_FUNC("F6e0kwo4cnk", EventQueue::KernelTriggerUserEvent);
 	LIB_FUNC("LJDwdSNTnDg", EventQueue::KernelDeleteUserEvent);
+	LIB_FUNC("57ZK+ODEXWY", EventQueue::KernelAddTimerEvent);
 	LIB_FUNC("R74tt43xP6k", EventQueue::KernelAddHRTimerEvent);
 	LIB_FUNC("J+LF6LwObXU", EventQueue::KernelDeleteHRTimerEvent);
 	LIB_FUNC("bBfz7kMF2Ho", EventQueue::KernelAddAmprEvent);

tests/EventQueueLifetimeTests.cpp

@@ -3,6 +3,7 @@
 
 #include <algorithm>
 #include <atomic>
+#include <chrono>
 #include <cstdio>
 #include <cstdlib>
 #include <memory>
@@ -27,6 +28,69 @@ void CheckConcurrentResult(int result, const char* text) {
 	Check(result == OK || result == KERNEL_ERROR_EBADF || result == KERNEL_ERROR_ENOENT, text);
 }
 
+void TestPeriodicTimerEvents() {
+	using namespace std::chrono_literals;
+	using Libs::LibKernel::KERNEL_ERROR_ETIMEDOUT;
+	Check(EventQueue::KernelAddTimerEvent(EventQueue::KERNEL_EQUEUE_INVALID, 10, 1000, nullptr) ==
+	          KERNEL_ERROR_EBADF,
+	      "timer rejects invalid queue");
+	EventQueue::KernelEqueue queue = EventQueue::KERNEL_EQUEUE_INVALID;
+	Check(EventQueue::KernelCreateEqueue(&queue, "periodic-timer") == OK, "create timer queue");
+	auto* user_data = reinterpret_cast<void*>(0x1234);
+	Check(EventQueue::KernelAddTimerEvent(queue, 10, 1000, user_data) == OK, "add periodic timer");
+	std::this_thread::sleep_for(5ms);
+	EventQueue::KernelEvent events[2] {};
+	int out = 0;
+	Libs::LibKernel::KernelUseconds timeout = 0;
+	Check(EventQueue::KernelWaitEqueue(queue, events, 2, &out, &timeout) == OK && out == 1,
+	      "periodic occurrences are aggregated into one event");
+	Check(events[0].ident == 10 && events[0].filter == EventQueue::KERNEL_EVFILT_TIMER &&
+	          events[0].data >= 5 && events[0].udata == user_data,
+	      "timer reports identity, userdata and elapsed occurrence count");
+	timeout = 100000;
+	Check(EventQueue::KernelWaitEqueue(queue, events, 2, &out, &timeout) == OK && out == 1 &&
+	          events[0].data >= 1,
+	      "periodic timer remains registered after delivery");
+
+	std::this_thread::sleep_for(5ms);
+	user_data = reinterpret_cast<void*>(0x5678);
+	Check(EventQueue::KernelAddTimerEvent(queue, 10, 3000000000u, user_data) == OK,
+	      "update periodic timer interval");
+	timeout = 0;
+	Check(EventQueue::KernelWaitEqueue(queue, events, 2, &out, &timeout) == OK && out == 1 &&
+	          events[0].data >= 5 && events[0].udata == user_data,
+	      "timer update preserves accumulated occurrences and updates userdata");
+	Check(EventQueue::KernelWaitEqueue(queue, events, 2, &out, &timeout) == KERNEL_ERROR_ETIMEDOUT,
+	      "timer update replaces the repeating interval");
+	Check(EventQueue::KernelDeleteEvent(queue, 10, EventQueue::KERNEL_EVFILT_TIMER) == OK,
+	      "delete periodic timer");
+
+	Check(EventQueue::KernelAddTimerEvent(queue, 10, 0, user_data) == OK,
+	      "add immediate periodic timer");
+	for (int i = 0; i < 2; ++i) {
+		Check(EventQueue::KernelAddTimerEvent(queue, 10, 0, user_data) == OK,
+		      "update pending immediate timer");
+	}
+	for (int i = 0; i < 2; ++i) {
+		Check(EventQueue::KernelWaitEqueue(queue, events, 2, &out, &timeout) == OK && out == 1 &&
+		          events[0].data == 1,
+		      "zero interval remains immediately ready after delivery");
+	}
+	Check(EventQueue::KernelDeleteEvent(queue, 10, EventQueue::KERNEL_EVFILT_TIMER) == OK,
+	      "delete immediate timer");
+
+	const Libs::LibKernel::KernelTimespec delay {0, 1000000};
+	Check(EventQueue::KernelAddHRTimerEvent(queue, 10, &delay, user_data) == OK,
+	      "add high resolution timer");
+	timeout = 100000;
+	Check(EventQueue::KernelWaitEqueue(queue, events, 2, &out, &timeout) == OK && out == 1 &&
+	          events[0].filter == EventQueue::KERNEL_EVFILT_HRTIMER && events[0].udata == user_data,
+	      "shared timer scheduling delivers high resolution event");
+	Check(EventQueue::KernelDeleteHRTimerEvent(queue, 10) == KERNEL_ERROR_ENOENT,
+	      "high resolution timer is removed after one delivery");
+	Check(EventQueue::KernelDeleteEqueue(queue) == OK, "delete timer queue");
+}
+
 void CountDeletedEvent(EventQueue::KernelEqueue, EventQueue::KernelEqueueEvent* event) {
 	auto* count = static_cast<std::atomic_uint32_t*>(event->filter.data);
 	count->fetch_add(1, std::memory_order_relaxed);
@@ -431,6 +495,7 @@ void TestConcurrentDelete() {
 } // namespace
 
 int main() {
+	TestPeriodicTimerEvents();
 	TestDuplicateAddPreservesEventState();
 	TestCallbackStateOutlivesPort();
 	TestCallbackOwnsPayload();