Introduce a new time API

The old time API is based on erlang:now/0. The major issue with
erlang:now/0 is that it was intended to be used for so many
unrelated things. This tied these unrelated operations together
and unnecessarily caused performance, scalability as well as
accuracy, and precision issues for operations that do not need
to have such issues. The new API spreads different functionality
over multiple functions in order to improve on this.

The new API consists of a number of new BIFs:
- erlang:convert_time_unit/3
- erlang:monotonic_time/0
- erlang:monotonic_time/1
- erlang:system_time/0
- erlang:system_time/1
- erlang:time_offset/0
- erlang:time_offset/1
- erlang:timestamp/0
- erlang:unique_integer/0
- erlang:unique_integer/1
- os:system_time/0
- os:system_time/1

and a number of extensions of existing BIFs:
- erlang:monitor(time_offset, clock_service)
- erlang:system_flag(time_offset, finalize)
- erlang:system_info(os_monotonic_time_source)
- erlang:system_info(time_offset)
- erlang:system_info(time_warp_mode)
- erlang:system_info(time_correction)
- erlang:system_info(start_time)

See the "Time and Time Correction in Erlang" chapter of the
ERTS User's Guide for more information.

1 files changed, 155 insertions, 87 deletions

diff --git a/erts/aclocal.m4 b/erts/aclocal.m4
index d78025b0be..989f697201 100644
--- a/erts/aclocal.m4
+++ b/erts/aclocal.m4
@@ -724,6 +724,117 @@ esac
 ])# AC_C_DOUBLE_MIDDLE_ENDIAN
 
 
+AC_DEFUN(ERL_MONOTONIC_CLOCK,
+[
+  AC_CACHE_CHECK([for clock_gettime() with monotonic clock type], erl_cv_clock_gettime_monotonic,
+  [
+     for clock_type in CLOCK_HIGHRES CLOCK_MONOTONIC CLOCK_MONOTONIC_PRECISE; do
+       AC_TRY_COMPILE([
+#include <time.h>
+		      ],
+		      [
+    struct timespec ts;
+    long long result;
+    clock_gettime($clock_type,&ts);
+    result = ((long long) ts.tv_sec) * 1000000000LL + 
+    ((long long) ts.tv_nsec);
+		      ],
+		      erl_cv_clock_gettime_monotonic=$clock_type,
+		      erl_cv_clock_gettime_monotonic=no)
+       test $erl_cv_clock_gettime_monotonic = no || break
+     done
+  ])
+  
+  AC_CHECK_FUNC(clock_getres)
+
+  AC_CHECK_FUNC(gethrtime)
+  
+  AC_CACHE_CHECK([for mach clock_get_time()], erl_cv_mach_clock_get_time,
+  [
+     AC_TRY_COMPILE([
+#include <mach/clock.h>
+#include <mach/mach.h>
+			],
+	 		[
+    kern_return_t res;
+    clock_serv_t clk_srv;
+    mach_timespec_t time_spec;
+
+    host_get_clock_service(mach_host_self(), SYSTEM_CLOCK, &clk_srv);
+    res = clock_get_time(clk_srv, &time_spec);
+    mach_port_deallocate(mach_task_self(), clk_srv);
+    			],
+    			erl_cv_mach_clock_get_time=yes,
+			erl_cv_mach_clock_get_time=no)
+  ])
+  
+  case $erl_cv_clock_gettime_monotonic-$ac_cv_func_gethrtime-$erl_cv_mach_clock_get_time-$host_os in
+    *-*-*-win32)
+      erl_monotonic_clock_func=GetTickCount
+      ;;
+    CLOCK_*-*-*-linux*)
+      if test X$cross_compiling != Xyes; then
+        linux_kernel_vsn_=`uname -r`
+        case $linux_kernel_vsn_ in
+          [[0-1]].*|2.[[0-5]]|2.[[0-5]].*)
+            erl_monotonic_clock_func=times
+	    ;;
+          *)
+            erl_monotonic_clock_func=clock_gettime
+	    ;;
+        esac
+      else
+        case X$erl_xcomp_linux_clock_gettime_correction in
+          X)
+	    AC_MSG_WARN([result clock_gettime guessed because of cross compilation])
+            erl_monotonic_clock_func=clock_gettime
+	    ;;
+          Xyes|Xno)
+            if test $erl_xcomp_linux_clock_gettime_correction = yes; then
+              erl_monotonic_clock_func=clock_gettime
+            else
+              erl_monotonic_clock_func=times
+            fi
+	    ;;
+          *)
+            AC_MSG_ERROR([Bad erl_xcomp_linux_clock_gettime_correction value: $erl_xcomp_linux_clock_gettime_correction])
+	    ;;
+        esac
+      fi
+      ;;
+    no-no-no-linux*)
+      erl_monotonic_clock_func=times
+      ;;
+    CLOCK_*-*-*-*)
+      erl_monotonic_clock_func=clock_gettime
+      ;;
+    no-yes-*-*)
+      erl_monotonic_clock_func=gethrtime
+      ;;
+    no-no-yes-*)
+      erl_monotonic_clock_func=mach_clock_get_time
+      ;;
+    no-no-no-*)
+      erl_monotonic_clock_func=none
+      ;;
+  esac
+
+  erl_monotonic_clock_lib=
+  erl_monotonic_clock_id=
+  case $erl_monotonic_clock_func in
+    clock_gettime)
+      erl_monotonic_clock_id="$erl_cv_clock_gettime_monotonic"
+      AC_CHECK_LIB(rt, clock_gettime, [erl_monotonic_clock_lib="-lrt"])
+      ;;
+    mach_clock_get_time)
+      erl_monotonic_clock_id=SYSTEM_CLOCK
+      ;;
+    *)
+      ;;
+  esac
+ 
+])
+
 dnl ----------------------------------------------------------------------
 dnl
 dnl LM_CHECK_THR_LIB
@@ -1016,12 +1127,32 @@ AC_ARG_WITH(with_sparc_memory_order,
 LM_CHECK_THR_LIB
 ERL_INTERNAL_LIBS
 
+ERL_MONOTONIC_CLOCK
+
+case $erl_monotonic_clock_func in
+  clock_gettime)
+    AC_DEFINE(ETHR_HAVE_CLOCK_GETTIME_MONOTONIC, [1], [Define if you have a clock_gettime() with a monotonic clock])
+    ;;
+  mach_clock_get_time)
+    AC_DEFINE(ETHR_HAVE_MACH_CLOCK_GET_TIME, [1], [Define if you have a mach clock_get_time() with a monotonic clock])
+    ;;
+  gethrtime)
+    AC_DEFINE(ETHR_HAVE_GETHRTIME, [1], [Define if you have a monotonic gethrtime()])
+    ;;
+  *)
+    ;;
+esac
+
+if test "x$erl_monotonic_clock_id" != "x"; then
+    AC_DEFINE_UNQUOTED(ETHR_MONOTONIC_CLOCK_ID, [$erl_monotonic_clock_id], [Define to the monotonic clock id to use])
+fi
+
 ethr_have_native_atomics=no
 ethr_have_native_spinlock=no
 ETHR_THR_LIB_BASE="$THR_LIB_NAME"
 ETHR_THR_LIB_BASE_TYPE="$THR_LIB_TYPE"
 ETHR_DEFS="$THR_DEFS"
-ETHR_X_LIBS="$THR_LIBS $ERTS_INTERNAL_X_LIBS"
+ETHR_X_LIBS="$THR_LIBS $ERTS_INTERNAL_X_LIBS $erl_monotonic_clock_lib"
 ETHR_LIBS=
 ETHR_LIB_NAME=
 
@@ -1660,7 +1791,6 @@ AC_SUBST(ETHR_X86_SSE2_ASM)
 ])
 
 
-
 dnl ----------------------------------------------------------------------
 dnl
 dnl ERL_TIME_CORRECTION
@@ -1676,93 +1806,33 @@ dnl work...
 dnl
 
 AC_DEFUN(ERL_TIME_CORRECTION,
-[if test x$ac_cv_func_gethrtime = x; then
-  AC_CHECK_FUNC(gethrtime)
-fi
-if test x$clock_gettime_correction = xunknown; then
-	AC_TRY_COMPILE([#include <time.h>],
-			[struct timespec ts;
-     			 long long result;
-			 clock_gettime(CLOCK_MONOTONIC,&ts);
-                         result = ((long long) ts.tv_sec) * 1000000000LL + 
-			 ((long long) ts.tv_nsec);],
-			clock_gettime_compiles=yes,
-			clock_gettime_compiles=no)
-else
-	clock_gettime_compiles=no
-fi
-			
-
-AC_CACHE_CHECK([how to correct for time adjustments], erl_cv_time_correction,
 [
-case $clock_gettime_correction in
-    yes)
-	erl_cv_time_correction=clock_gettime;;	
-    no|unknown)
-	case $ac_cv_func_gethrtime in
-  	    yes)
-    		erl_cv_time_correction=hrtime ;;
-  	    no)
-    		case $host_os in
-        	    linux*)
-			case $clock_gettime_correction in
-			    unknown)
-				if test x$clock_gettime_compiles = xyes; then
-				    if test X$cross_compiling != Xyes; then
-				    	linux_kernel_vsn_=`uname -r`
-				    	case $linux_kernel_vsn_ in
-					    [[0-1]].*|2.[[0-5]]|2.[[0-5]].*)
-					    	erl_cv_time_correction=times ;;
-					    *)
-					    	erl_cv_time_correction=clock_gettime;;
-				    	esac
-				    else
-					case X$erl_xcomp_linux_clock_gettime_correction in
-					    X)
-						erl_cv_time_correction=cross;;
-					    Xyes|Xno)
-						if test $erl_xcomp_linux_clock_gettime_correction = yes; then
-						    erl_cv_time_correction=clock_gettime
-						else
-					    	    erl_cv_time_correction=times
-						fi;;
-					    *)
-						AC_MSG_ERROR([Bad erl_xcomp_linux_clock_gettime_correction value: $erl_xcomp_linux_clock_gettime_correction]);;
-					esac
-				    fi
-				else
-				    erl_cv_time_correction=times
-				fi
-				;;
-			     *)				
-        			erl_cv_time_correction=times ;;
-			esac
-			;;
-            	    *)
-        		erl_cv_time_correction=none ;;
-    		esac
-    		;;
-	esac
-	;;
-esac
-])
 
-xrtlib=""
-case $erl_cv_time_correction in
+ERL_MONOTONIC_CLOCK
+
+case $erl_monotonic_clock_func in
   times)
-    AC_DEFINE(CORRECT_USING_TIMES,[],
-	[Define if you do not have a high-res. timer & want to use times() instead])
+    AC_DEFINE(OS_MONOTONIC_TIME_USING_TIMES, [1], [Define if you want to implement erts_os_monotonic_time() using times()])
     ;;
-  clock_gettime|cross)
-    if test $erl_cv_time_correction = cross; then
-	erl_cv_time_correction=clock_gettime
-	AC_MSG_WARN([result clock_gettime guessed because of cross compilation])
-    fi
-    xrtlib="-lrt"
-    AC_DEFINE(GETHRTIME_WITH_CLOCK_GETTIME,[1],
-	[Define if you want to use clock_gettime to simulate gethrtime])
+  mach_clock_get_time)
+    AC_DEFINE(OS_MONOTONIC_TIME_USING_MACH_CLOCK_GET_TIME, [1], [Define if you want to implement erts_os_monotonic_time() using mach clock_get_time()])
+    ;;
+  clock_gettime)
+    AC_DEFINE(OS_MONOTONIC_TIME_USING_CLOCK_GETTIME, [1], [Define if you want to implement erts_os_monotonic_time() using clock_gettime()])
+    ;;
+  gethrtime)
+    AC_DEFINE(OS_MONOTONIC_TIME_USING_GETHRTIME,  [1], [Define if you want to implement erts_os_monotonic_time() using gethrtime()])
+    ;;
+  *)
     ;;
 esac
+
+xrtlib="$erl_monotonic_clock_lib"
+if test "x$erl_monotonic_clock_id" != "x"; then
+    AC_DEFINE_UNQUOTED(MONOTONIC_CLOCK_ID_STR, ["$erl_monotonic_clock_id"], [Define as a string of monotonic clock id to use])
+    AC_DEFINE_UNQUOTED(MONOTONIC_CLOCK_ID, [$erl_monotonic_clock_id], [Define to monotonic clock id to use])
+fi
+
 dnl
 dnl Check if gethrvtime is working, and if to use procfs ioctl
 dnl or (yet to be written) write to the procfs ctl file.
@@ -1835,6 +1905,7 @@ case X$erl_xcomp_gethrvtime_procfs_ioctl in
 esac
 ])
 
+LIBRT=$xrtlib
 case $erl_gethrvtime in
   procfs_ioctl)
 	AC_DEFINE(HAVE_GETHRVTIME_PROCFS_IOCTL,[1],
@@ -1894,7 +1965,6 @@ case $erl_gethrvtime in
 	case $host_os in
 		linux*)
 			AC_MSG_RESULT([no; not stable])
-			LIBRT=$xrtlib
 			;;
 		*)
 			AC_MSG_RESULT($erl_clock_gettime)
@@ -1907,17 +1977,15 @@ case $erl_gethrvtime in
 	  			cross)
 					erl_clock_gettime=no
 					AC_MSG_WARN([result no guessed because of cross compilation])
-					LIBRT=$xrtlib
 					;;
 	  			*)
-					LIBRT=$xrtlib
 					;;
 			esac
 			;;
 	esac
-	AC_SUBST(LIBRT)
 	;;
 esac
+AC_SUBST(LIBRT)
 ])dnl
 
 dnl ----------------------------------------------------------------------