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, 97 insertions, 23 deletions

diff --git a/erts/emulator/sys/unix/erl_unix_sys.h b/erts/emulator/sys/unix/erl_unix_sys.h
index 26ed2fb558..5417bb2687 100644
--- a/erts/emulator/sys/unix/erl_unix_sys.h
+++ b/erts/emulator/sys/unix/erl_unix_sys.h
@@ -114,11 +114,6 @@
 /*
  * Make sure that MAXPATHLEN is defined.
  */
-#ifdef GETHRTIME_WITH_CLOCK_GETTIME
-#undef HAVE_GETHRTIME
-#define HAVE_GETHRTIME 1
-#endif
-
 #ifndef MAXPATHLEN
 #   ifdef PATH_MAX
 #       define MAXPATHLEN PATH_MAX
@@ -160,33 +155,112 @@ typedef struct timeval SysTimeval;
 
 typedef struct tms SysTimes;
 
-extern int erts_ticks_per_sec;
-
-#define SYS_CLK_TCK (erts_ticks_per_sec)
+#define SYS_CLK_TCK (erts_sys_time_data__.r.o.ticks_per_sec)
 
 #define sys_times(Arg) times(Arg)
 
-#define ERTS_WRAP_SYS_TIMES 1
-extern int erts_ticks_per_sec_wrap;
-#define SYS_CLK_TCK_WRAP (erts_ticks_per_sec_wrap)
-extern clock_t sys_times_wrap(void);
+#if SIZEOF_LONG == 8
+typedef long ErtsMonotonicTime;
+#elif SIZEOF_LONG_LONG == 8
+typedef long long ErtsMonotonicTime;
+#else
+#error No signed 64-bit type found...
+#endif
+
+#define ERTS_MONOTONIC_TIME_MIN (((ErtsMonotonicTime) 1) << 63)
+#define ERTS_MONOTONIC_TIME_MAX (~ERTS_MONOTONIC_TIME_MIN)
+
+/*
+ * OS monotonic time
+ */
+
+/*
+ * Most common with os monotonic time using nano second
+ * time unit. These defines are modified below if this
+ * isn't the case...
+ */
+#define ERTS_HAVE_OS_MONOTONIC_TIME_SUPPORT 1
+#define ERTS_COMPILE_TIME_MONOTONIC_TIME_UNIT (1000*1000*1000)
+
+#undef ERTS_OS_MONOTONIC_INLINE_FUNC_PTR_CALL__
+#undef ERTS_HAVE_CORRECTED_OS_MONOTONIC
+
+#if defined(OS_MONOTONIC_TIME_USING_CLOCK_GETTIME)
+
+#if defined(__linux__)
 
-#ifdef HAVE_GETHRTIME
-#ifdef GETHRTIME_WITH_CLOCK_GETTIME
-typedef long long SysHrTime;
+#define ERTS_HAVE_CORRECTED_OS_MONOTONIC 1
+#define ERTS_OS_MONOTONIC_INLINE_FUNC_PTR_CALL__ 1
 
-extern SysHrTime sys_gethrtime(void);
-#define sys_init_hrtime() /* Nothing */
+#else /* !defined(__linux__) */
 
-#else /* Real gethrtime (Solaris) */
+ErtsMonotonicTime erts_os_monotonic_time(void);
 
-typedef hrtime_t SysHrTime;
+#endif /* !defined(__linux__) */
+
+#elif defined(OS_MONOTONIC_TIME_USING_GETHRTIME)
+
+#define erts_os_monotonic() ((ErtsMonotonicTime) gethrtime())
+
+#elif defined(OS_MONOTONIC_TIME_USING_MACH_CLOCK_GET_TIME) \
+    || defined(OS_MONOTONIC_TIME_USING_TIMES)
+
+#if defined(OS_MONOTONIC_TIME_USING_TIMES)
+#  undef ERTS_COMPILE_TIME_MONOTONIC_TIME_UNIT
+#  define ERTS_COMPILE_TIME_MONOTONIC_TIME_UNIT (1000*1000)
+#  define ERTS_HAVE_ERTS_OS_TIME_OFFSET_FINALIZE 1
+void erts_os_time_offset_finalize(void);
+#  define ERTS_HAVE_ERTS_OS_MONOTONIC_TIME_INIT
+void erts_os_monotonic_time_init(void);
+#endif
 
-#define sys_gethrtime() gethrtime()
-#define sys_init_hrtime() /* Nothing */
+ErtsMonotonicTime erts_os_monotonic_time(void);
 
-#endif /* GETHRTIME_WITH_CLOCK_GETTIME */
-#endif /* HAVE_GETHRTIME */
+#else /* No OS monotonic available... */
+
+#undef ERTS_HAVE_OS_MONOTONIC_TIME_SUPPORT
+#undef ERTS_COMPILE_TIME_MONOTONIC_TIME_UNIT
+#define ERTS_COMPILE_TIME_MONOTONIC_TIME_UNIT (1000*1000)
+
+#endif
+
+struct erts_sys_time_read_only_data__ {
+#ifdef ERTS_OS_MONOTONIC_INLINE_FUNC_PTR_CALL__
+    ErtsMonotonicTime (*os_monotonic_time)(void);
+#endif
+    int ticks_per_sec;
+};
+
+typedef struct {
+    union {
+	struct erts_sys_time_read_only_data__ o;
+	char align__[(((sizeof(struct erts_sys_time_read_only_data__) - 1)
+		       / ASSUMED_CACHE_LINE_SIZE) + 1)
+		     * ASSUMED_CACHE_LINE_SIZE];
+    } r;
+} ErtsSysTimeData__;
+
+extern ErtsSysTimeData__ erts_sys_time_data__;
+
+#ifdef ERTS_OS_MONOTONIC_INLINE_FUNC_PTR_CALL__
+
+ERTS_GLB_INLINE ErtsMonotonicTime erts_os_monotonic_time(void);
+
+#if ERTS_GLB_INLINE_INCL_FUNC_DEF
+
+ERTS_GLB_INLINE ErtsMonotonicTime
+erts_os_monotonic_time(void)
+{
+    return (*erts_sys_time_data__.r.o.os_monotonic_time)();
+}
+
+#endif /* ERTS_GLB_INLINE_INCL_FUNC_DEF */
+
+#endif /* ERTS_OS_MONOTONIC_INLINE_FUNC_PTR_CALL__ */
+
+/*
+ *
+ */
 
 #if (defined(HAVE_GETHRVTIME) || defined(HAVE_CLOCK_GETTIME))
 typedef long long SysCpuTime;