win: high-resolution poll timeouts via waitable timer + IOCP

src/uv-common.h

@@ -437,6 +437,10 @@ struct uv__loop_internal_fields_s {
   struct uv__iou iou;
   void* inv;  /* used by uv__platform_invalidate_fd() */
 #endif  /* __linux__ */
+#ifdef _WIN32
+  void* hrtimer;       /* CREATE_WAITABLE_TIMER_HIGH_RESOLUTION or NULL */
+  void* hrtimer_pkt;   /* NtCreateWaitCompletionPacket handle or NULL */
+#endif  /* _WIN32 */
 };
 
 #if defined(_WIN32)

src/win/core.c

@@ -224,6 +224,45 @@ static void uv__init(void) {
 }
 
 
+/* Per-loop: create a high-res waitable timer + wait-completion packet so
+ * uv__poll can wake at sub-ms precision (see the hrtimer arm there). On
+ * pre-Win10-1803 either the Nt* pointers or the HIGH_RESOLUTION flag are
+ * absent; hrtimer stays NULL and uv__poll keeps its plain GQCS ms wait. */
+static void uv__hrtimer_init(uv__loop_internal_fields_t* lfields) {
+  HANDLE pkt;
+  if (pNtCreateWaitCompletionPacket == NULL ||
+      pNtAssociateWaitCompletionPacket == NULL ||
+      pNtCancelWaitCompletionPacket == NULL)
+    return;
+  lfields->hrtimer = CreateWaitableTimerExW(
+      NULL,
+      NULL,
+      CREATE_WAITABLE_TIMER_MANUAL_RESET |
+          CREATE_WAITABLE_TIMER_HIGH_RESOLUTION,
+      SYNCHRONIZE | TIMER_QUERY_STATE | TIMER_MODIFY_STATE);
+  if (lfields->hrtimer == NULL)
+    return;
+  pkt = NULL;
+  if (!NT_SUCCESS(pNtCreateWaitCompletionPacket(&pkt, GENERIC_ALL, NULL)) ||
+      pkt == NULL) {
+    CloseHandle(lfields->hrtimer);
+    lfields->hrtimer = NULL;
+    return;
+  }
+  lfields->hrtimer_pkt = pkt;
+}
+
+
+static void uv__hrtimer_close(uv__loop_internal_fields_t* lfields) {
+  if (lfields->hrtimer_pkt != NULL) {
+    pNtCancelWaitCompletionPacket(lfields->hrtimer_pkt, FALSE);
+    CloseHandle(lfields->hrtimer_pkt);
+  }
+  if (lfields->hrtimer != NULL)
+    CloseHandle(lfields->hrtimer);
+}
+
+
 int uv_loop_init(uv_loop_t* loop) {
   uv__loop_internal_fields_t* lfields;
   struct heap* timer_heap;
@@ -300,6 +339,8 @@ int uv_loop_init(uv_loop_t* loop) {
   if (err)
     goto fail_async_init;
 
+  uv__hrtimer_init(lfields);
+
   return 0;
 
 fail_async_init:
@@ -367,6 +408,7 @@ void uv__loop_close(uv_loop_t* loop) {
   loop->timer_heap = NULL;
 
   lfields = uv__get_internal_fields(loop);
+  uv__hrtimer_close(lfields);
   uv_mutex_destroy(&lfields->loop_metrics.lock);
   uv__free(lfields);
   loop->internal_fields = NULL;
@@ -463,6 +505,33 @@ static void uv__poll(uv_loop_t* loop, DWORD timeout) {
      */
     lfields->current_timeout = timeout;
 
+    /* Arm the high-res waitable timer and associate it with this loop's IOCP;
+     * it posts a NULL-overlapped completion (already treated as a pure wakeup
+     * below) so GQCS can block with INFINITE and skip its ~15.6ms-tick ms wait. */
+    if (timeout != 0 && timeout != INFINITE && lfields->hrtimer != NULL) {
+      LARGE_INTEGER due;
+      BOOLEAN signaled;
+      due.QuadPart = -(LONGLONG) timeout * 10000;  /* relative, 100ns units */
+      signaled = FALSE;
+      /* STATUS_PENDING => packet is mid-delivery; re-associate would fail,
+       * so skip the arm this round and let the GQCS ms timeout apply. */
+      if (pNtCancelWaitCompletionPacket(lfields->hrtimer_pkt, TRUE)
+              != STATUS_PENDING &&
+          SetWaitableTimer(lfields->hrtimer, &due, 0, NULL, NULL, FALSE) &&
+          NT_SUCCESS(pNtAssociateWaitCompletionPacket(lfields->hrtimer_pkt,
+                                                      loop->iocp,
+                                                      lfields->hrtimer,
+                                                      NULL,
+                                                      NULL,
+                                                      0,
+                                                      0,
+                                                      &signaled))) {
+        /* AlreadySignaled => timer fired between SetWaitableTimer and the
+         * associate; the packet is already queued so GQCS won't block. */
+        timeout = signaled ? 0 : INFINITE;
+      }
+    }
+
     success = GetQueuedCompletionStatusEx(loop->iocp,
                                           overlappeds,
                                           ARRAY_SIZE(overlappeds),

src/win/winapi.c

@@ -35,6 +35,9 @@ sNtQueryVolumeInformationFile pNtQueryVolumeInformationFile;
 sNtQueryDirectoryFile pNtQueryDirectoryFile;
 sNtQuerySystemInformation pNtQuerySystemInformation;
 sNtQueryInformationProcess pNtQueryInformationProcess;
+sNtCreateWaitCompletionPacket pNtCreateWaitCompletionPacket;
+sNtAssociateWaitCompletionPacket pNtAssociateWaitCompletionPacket;
+sNtCancelWaitCompletionPacket pNtCancelWaitCompletionPacket;
 
 /* Powrprof.dll function pointer */
 sPowerRegisterSuspendResumeNotification pPowerRegisterSuspendResumeNotification;
@@ -70,6 +73,9 @@ void uv__winapi_init(void) {
     sNtQueryDirectoryFile pNtQueryDirectoryFile;
     sNtQuerySystemInformation pNtQuerySystemInformation;
     sNtQueryInformationProcess pNtQueryInformationProcess;
+    sNtCreateWaitCompletionPacket pNtCreateWaitCompletionPacket;
+    sNtAssociateWaitCompletionPacket pNtAssociateWaitCompletionPacket;
+    sNtCancelWaitCompletionPacket pNtCancelWaitCompletionPacket;
     sPowerRegisterSuspendResumeNotification pPowerRegisterSuspendResumeNotification;
     sProcessPrng pProcessPrng;
     sSetWinEventHook pSetWinEventHook;
@@ -133,6 +139,15 @@ void uv__winapi_init(void) {
     uv_fatal_error(GetLastError(), "GetProcAddress");
   }
 
+  u.proc = GetProcAddress(ntdll_module, "NtCreateWaitCompletionPacket");
+  pNtCreateWaitCompletionPacket = u.pNtCreateWaitCompletionPacket;
+
+  u.proc = GetProcAddress(ntdll_module, "NtAssociateWaitCompletionPacket");
+  pNtAssociateWaitCompletionPacket = u.pNtAssociateWaitCompletionPacket;
+
+  u.proc = GetProcAddress(ntdll_module, "NtCancelWaitCompletionPacket");
+  pNtCancelWaitCompletionPacket = u.pNtCancelWaitCompletionPacket;
+
   powrprof_module = LoadLibraryExA("powrprof.dll",
                                    NULL,
                                    LOAD_LIBRARY_SEARCH_SYSTEM32);

src/win/winapi.h

@@ -4657,9 +4657,36 @@ typedef NTSTATUS (NTAPI *sNtQueryInformationProcess)
                   ULONG Length,
                   PULONG ReturnLength);
 
+typedef NTSTATUS (NTAPI *sNtCreateWaitCompletionPacket)
+                 (PHANDLE WaitCompletionPacketHandle,
+                  ACCESS_MASK DesiredAccess,
+                  PVOID ObjectAttributes);
+
+typedef NTSTATUS (NTAPI *sNtAssociateWaitCompletionPacket)
+                 (HANDLE WaitCompletionPacketHandle,
+                  HANDLE IoCompletionHandle,
+                  HANDLE TargetObjectHandle,
+                  PVOID KeyContext,
+                  PVOID ApcContext,
+                  NTSTATUS IoStatus,
+                  ULONG_PTR IoStatusInformation,
+                  PBOOLEAN AlreadySignaled);
+
+typedef NTSTATUS (NTAPI *sNtCancelWaitCompletionPacket)
+                 (HANDLE WaitCompletionPacketHandle,
+                  BOOLEAN RemoveSignaledPacket);
+
 /*
  * Kernel32 headers
  */
+#ifndef CREATE_WAITABLE_TIMER_MANUAL_RESET
+# define CREATE_WAITABLE_TIMER_MANUAL_RESET 0x00000001
+#endif
+
+#ifndef CREATE_WAITABLE_TIMER_HIGH_RESOLUTION
+# define CREATE_WAITABLE_TIMER_HIGH_RESOLUTION 0x00000002
+#endif
+
 #ifndef FILE_SKIP_COMPLETION_PORT_ON_SUCCESS
 # define FILE_SKIP_COMPLETION_PORT_ON_SUCCESS 0x1
 #endif
@@ -4813,6 +4840,9 @@ extern sNtQueryVolumeInformationFile pNtQueryVolumeInformationFile;
 extern sNtQueryDirectoryFile pNtQueryDirectoryFile;
 extern sNtQuerySystemInformation pNtQuerySystemInformation;
 extern sNtQueryInformationProcess pNtQueryInformationProcess;
+extern sNtCreateWaitCompletionPacket pNtCreateWaitCompletionPacket;
+extern sNtAssociateWaitCompletionPacket pNtAssociateWaitCompletionPacket;
+extern sNtCancelWaitCompletionPacket pNtCancelWaitCompletionPacket;
 
 /* Powrprof.dll function pointer */
 extern sPowerRegisterSuspendResumeNotification pPowerRegisterSuspendResumeNotification;