From 3506d115583282bc22c025818603a53dc7970659 Mon Sep 17 00:00:00 2001
From: Andrew Johnson <anj@anl.gov>
Date: Mon, 3 Aug 2020 11:37:19 -0500
Subject: [PATCH] Speed up osdTimeGetCurrent() on recent macOS

Fixes https://github.com/epics-base/epics-base/issues/83
---
 modules/libcom/src/osi/os/Darwin/osdTime.cpp | 39 +++++++++++++++-----
 1 file changed, 29 insertions(+), 10 deletions(-)

diff --git a/modules/libcom/src/osi/os/Darwin/osdTime.cpp b/modules/libcom/src/osi/os/Darwin/osdTime.cpp
index 88abd00d6..cb0c070d9 100644
--- a/modules/libcom/src/osi/os/Darwin/osdTime.cpp
+++ b/modules/libcom/src/osi/os/Darwin/osdTime.cpp
@@ -12,8 +12,25 @@
 #include <stdio.h>
 #include <string.h>
 #include <errno.h>
-#include <mach/mach.h>
-#include <mach/clock.h>
+#include <sys/time.h>
+
+#ifndef CLOCK_REALTIME
+  #include <mach/mach.h>
+  #include <mach/clock.h>
+
+  static clock_serv_t host_clock;
+
+  #define HOST_GETCLOCK host_get_clock_service(mach_host_self(), \
+              CALENDAR_CLOCK, &host_clock)
+  #define TIMESPEC mach_timespec_t
+  #define CLOCK_GETTIME(ts) clock_get_time(host_clock, ts)
+  #define TP_NAME "MachTime"
+#else
+  #define HOST_GETCLOCK
+  #define TIMESPEC struct timespec
+  #define CLOCK_GETTIME(ts) clock_gettime(CLOCK_REALTIME, ts)
+  #define TP_NAME "OS Clock"
+#endif
 
 #define EPICS_EXPOSE_LIBCOM_MONOTONIC_PRIVATE
 #include "osiSock.h"
@@ -22,17 +39,19 @@
 #include "epicsTime.h"
 #include "generalTimeSup.h"
 
-static clock_serv_t host_clock;
-
 extern "C" {
 int osdTimeGetCurrent (epicsTimeStamp *pDest)
 {
-    mach_timespec_t mts;
     struct timespec ts;
 
-    clock_get_time(host_clock, &mts);
+#ifndef CLOCK_REALTIME
+    TIMESPEC mts;
+    CLOCK_GETTIME(&mts);
     ts.tv_sec = mts.tv_sec;
     ts.tv_nsec = mts.tv_nsec;
+#else
+    CLOCK_GETTIME(&ts);
+#endif
     *pDest = epicsTime(ts);
     return epicsTimeOK;
 }
@@ -41,9 +60,9 @@ int osdTimeGetCurrent (epicsTimeStamp *pDest)
 
 static int timeRegister(void)
 {
-    host_get_clock_service(mach_host_self(), CALENDAR_CLOCK, &host_clock);
+    HOST_GETCLOCK;
 
-    generalTimeCurrentTpRegister("MachTime", \
+    generalTimeCurrentTpRegister(TP_NAME, \
         LAST_RESORT_PRIORITY, osdTimeGetCurrent);
 
     osdMonotonicInit();
@@ -67,7 +86,7 @@ int epicsTime_localtime(const time_t *clock, struct tm *result)
 extern "C" LIBCOM_API void
 convertDoubleToWakeTime(double timeout, struct timespec *wakeTime)
 {
-    mach_timespec_t now;
+    TIMESPEC now;
     struct timespec wait;
 
     if (timeout < 0.0)
@@ -75,7 +94,7 @@ convertDoubleToWakeTime(double timeout, struct timespec *wakeTime)
     else if (timeout > 60 * 60 * 24 * 3652.5)
         timeout = 60 * 60 * 24 * 3652.5;    /* 10 years */
 
-    clock_get_time(host_clock, &now);
+    CLOCK_GETTIME(&now);
 
     wait.tv_sec  = static_cast< time_t >(timeout);
     wait.tv_nsec = static_cast< long >((timeout - (double)wait.tv_sec) * 1e9);