Add ddsrt_hrtime_t / ddsrt_time_highres

Some platforms (QNX is an example) have low-resolution clocks that one can use for
timeouts, and high-resolution clocks that cannot be used for that. This introduces a
separate "high resolution" time that can be used only for computing time elapsed between
two events.

Signed-off-by: Erik Boasson <[email protected]>

Author: eboasson

src/ddsrt/include/dds/ddsrt/time.h

@@ -86,6 +86,10 @@ typedef struct {
   dds_time_t v;
 } ddsrt_etime_t;
 
+typedef struct {
+  uint64_t v;
+} ddsrt_hrtime_t;
+
 #define DDSRT_MTIME_NEVER ((ddsrt_mtime_t) { DDS_NEVER })
 #define DDSRT_WCTIME_NEVER ((ddsrt_wctime_t) { DDS_NEVER })
 #define DDSRT_ETIME_NEVER ((ddsrt_etime_t) { DDS_NEVER })
@@ -145,6 +149,20 @@ DDS_EXPORT ddsrt_mtime_t ddsrt_time_monotonic(void);
  */
 DDS_EXPORT ddsrt_etime_t ddsrt_time_elapsed(void);
 
+/**
+ * @brief Get high resolution, elapsed (and thus monotonic) time since some
+ * fixed unspecified past time.
+ *
+ * The elapsed time clock is a clock with near real-time progression and can be
+ * used when a high-resolution suspend-aware monotonic clock is needed, without
+ * having to deal with the complications of discontinuities if for example the
+ * time is changed. The fixed point from which the elapsed time is returned is
+ * not guaranteed to be fixed over reboots of the system.
+ *
+ * @returns Elapsed time if available, otherwise return monotonic time.
+ */
+DDS_EXPORT ddsrt_hrtime_t ddsrt_time_highres(void);
+
 /**
  * @brief Convert time into a human readable string in RFC 3339 format.
  *

src/ddsrt/src/time/darwin/time.c

@@ -75,3 +75,9 @@ ddsrt_etime_t ddsrt_time_elapsed(void)
   return (ddsrt_etime_t) { mt.v };
 #endif
 }
+
+ddsrt_hrtime_t ddsrt_time_highres(void)
+{
+  ddsrt_mtime_t mt = ddsrt_time_monotonic();
+  return (ddsrt_hrtime_t) { (uint64_t) mt.v };
+}

src/ddsrt/src/time/posix/time.c

@@ -15,6 +15,11 @@
 #include <time.h>
 #include <sys/time.h>
 
+#ifdef __QNXNTO__
+#include <sys/neutrino.h>
+#include <sys/syspage.h>
+#endif
+
 #include "dds/ddsrt/time.h"
 
 dds_time_t dds_time(void)
@@ -45,3 +50,20 @@ ddsrt_etime_t ddsrt_time_elapsed(void)
   (void)clock_gettime(CLOCK_MONOTONIC, &ts);
   return (ddsrt_etime_t) { (ts.tv_sec * DDS_NSECS_IN_SEC) + ts.tv_nsec };
 }
+
+ddsrt_hrtime_t ddsrt_time_highres(void)
+{
+#ifdef __QNXNTO__
+  static uint64_t freq = 0;
+  static uint64_t multiplier = 0;
+  if (freq == 0) {
+    freq = SYSPAGE_ENTRY(qtime)->cycles_per_sec;
+    multiplier = (uint64_t) DDS_NSECS_IN_SEC / freq;
+  }
+  uint64_t cycles = ClockCycles ();
+  return (ddsrt_hrtime_t) { cycles * multiplier };
+#else
+  ddsrt_mtime_t mt = ddsrt_time_monotonic();
+  return (ddsrt_hrtime_t) { (uint64_t) mt.v };
+#endif
+}

src/ddsrt/src/time/solaris2.6/time.c

@@ -39,3 +39,8 @@ ddsrt_etime_t ddsrt_time_elapsed(void)
 {
   return (ddsrt_etime_t) { gethrtime () };
 }
+
+ddsrt_hrtime_t ddsrt_time_highres(void)
+{
+  return (ddsrt_hrtime_t) { gethrtime () };
+}

src/ddsrt/src/time/windows/time.c

@@ -113,9 +113,7 @@ ddsrt_wctime_t ddsrt_time_wallclock(void)
 ddsrt_mtime_t ddsrt_time_monotonic(void)
 {
   ULONGLONG ubit;
-
   (void)QueryUnbiasedInterruptTime(&ubit); /* 100ns ticks */
-
   return (ddsrt_mtime_t) { (dds_time_t)ubit * 100 };
 }
 
@@ -165,6 +163,13 @@ ddsrt_etime_t ddsrt_time_elapsed(void)
   return (ddsrt_etime_t) { qpc.QuadPart * qpc_freq };
 }
 
+ddsrt_hrtime_t ddsrt_time_highres(void)
+{
+  ULONGLONG ubit;
+  (void)QueryUnbiasedInterruptTime(&ubit); /* 100ns ticks */
+  return (ddsrt_hrtime_t) { ubit * 100 };
+}
+
 void dds_sleepfor (dds_duration_t timeout)
 {
   DWORD msecs;