Add an additional case for clocks to sleep with a wallclock deadline (swiftlang#79139)

This only modifies the runtime function `swift_task_enqueueGlobalWithDeadline` to take new clock primitive to
interoperate with existing dispatch wall clock values.

Author: phausler

include/swift/Runtime/Concurrency.h

@@ -1074,7 +1074,8 @@ void swift_task_donateThreadToGlobalExecutorUntil(bool (*condition)(void*),
 
 enum swift_clock_id : int {
   swift_clock_id_continuous = 1,
-  swift_clock_id_suspending = 2
+  swift_clock_id_suspending = 2,
+  swift_clock_id_wall = 3
 };
 
 SWIFT_EXPORT_FROM(swift_Concurrency) SWIFT_CC(swift)

stdlib/public/Concurrency/Clock.cpp

@@ -33,6 +33,10 @@
 
 #include "Error.h"
 
+#ifndef NSEC_PER_SEC
+#define NSEC_PER_SEC 1000000000ull
+#endif
+
 using namespace swift;
 
 SWIFT_EXPORT_FROM(swift_Concurrency)
@@ -109,6 +113,29 @@ void swift_get_time(
       *seconds = suspending.tv_sec;
       *nanoseconds = suspending.tv_nsec;
       return;
+    case swift_clock_id_wall:
+      struct timespec wall;
+#if defined(__linux__) || defined(__APPLE__) || defined(__wasi__) || defined(__OpenBSD__) || defined(__FreeBSD__)
+      clock_gettime(CLOCK_REALTIME, &wall);
+#elif defined(_WIN32)
+      // This needs to match what swift-corelibs-libdispatch does
+
+      static const uint64_t kNTToUNIXBiasAdjustment = 11644473600 * NSEC_PER_SEC;
+      // FILETIME is 100-nanosecond intervals since January 1, 1601 (UTC).
+      FILETIME ft;
+      ULARGE_INTEGER li;
+      GetSystemTimePreciseAsFileTime(&ft);
+      li.LowPart = ft.dwLowDateTime;
+      li.HighPart = ft.dwHighDateTime;
+      ULONGLONG ns = li.QuadPart * 100ull - kNTToUNIXBiasAdjustment;
+      wall.tv_sec = ns / 1000000000ull;
+      wall.tv_nsec = ns % 1000000000ull;
+#else
+#error Missing platform wall time definition
+#endif
+      *seconds = wall.tv_sec;
+      *nanoseconds = wall.tv_nsec;
+      return;
     }
   }
   swift_Concurrency_fatalError(0, "Fatal error: invalid clock ID %d\n",
@@ -170,6 +197,20 @@ switch (clock_id) {
       *nanoseconds = suspending.tv_nsec;
       return;
     }
+    case swift_clock_id_wall: {
+      struct timespec wall;
+#if defined(__linux__) || defined(__APPLE__) || defined(__OpenBSD__) || defined(__FreeBSD__) || defined(__wasi__)
+      clock_getres(CLOCK_REALTIME, &wall);
+#elif defined(_WIN32)
+      wall.tv_sec = 0;
+      wall.tv_nsec = 100;
+#else
+#error Missing platform wall time definition
+#endif
+      *seconds = wall.tv_sec;
+      *nanoseconds = wall.tv_nsec;
+      return;
+    }
   }
   swift_Concurrency_fatalError(0, "Fatal error: invalid clock ID %d\n",
                                clock_id);

stdlib/public/Concurrency/DispatchGlobalExecutor.cpp

@@ -55,6 +55,10 @@
 #include "ExecutorImpl.h"
 #include "TaskPrivate.h"
 
+#ifndef NSEC_PER_SEC
+#define NSEC_PER_SEC 1000000000ull
+#endif
+
 using namespace swift;
 
 /// The function passed to dispatch_async_f to execute a job.
@@ -294,7 +298,12 @@ platform_time(uint64_t nsec) {
 #endif
 
 static inline dispatch_time_t
-clock_and_value_to_time(int clock, long long deadline) {
+clock_and_value_to_time(int clock, long long sec, long long nsec) {
+  uint64_t deadline;
+  if (__builtin_mul_overflow(sec, NSEC_PER_SEC, &deadline)
+      || __builtin_add_overflow(nsec, deadline, &deadline)) {
+    deadline = UINT64_MAX;
+  }
   uint64_t value = platform_time((uint64_t)deadline);
   if (value >= DISPATCH_TIME_MAX_VALUE) {
     return DISPATCH_TIME_FOREVER;
@@ -304,6 +313,20 @@ clock_and_value_to_time(int clock, long long deadline) {
     return value;
   case swift_clock_id_continuous:
     return value | DISPATCH_UP_OR_MONOTONIC_TIME_MASK;
+  case swift_clock_id_wall: {
+#if defined(_WIN32)
+    struct timespec ts = { 
+      .tv_sec = sec,
+      .tv_nsec = static_cast<long>(nsec)
+    };
+#else
+    struct timespec ts = { 
+      .tv_sec = sec,
+      .tv_nsec = nsec
+    };
+#endif
+    return dispatch_walltime(&ts, 0);
+  }
   }
   __builtin_unreachable();
 }
@@ -332,13 +355,7 @@ void swift_dispatchEnqueueWithDeadline(bool global,
     job->schedulerPrivate[SwiftJobDispatchQueueIndex] = queue;
   }
 
-  uint64_t deadline;
-  if (__builtin_mul_overflow(sec, NSEC_PER_SEC, &deadline)
-      || __builtin_add_overflow(nsec, deadline, &deadline)) {
-    deadline = UINT64_MAX;
-  }
-
-  dispatch_time_t when = clock_and_value_to_time(clock, deadline);
+  dispatch_time_t when = clock_and_value_to_time(clock, sec, nsec);
 
   if (tnsec != -1) {
     uint64_t leeway;