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, 171 insertions, 50 deletions

diff --git a/erts/emulator/sys/common/erl_poll.c b/erts/emulator/sys/common/erl_poll.c
index aa412a20c8..f4d4a85ca4 100644
--- a/erts/emulator/sys/common/erl_poll.c
+++ b/erts/emulator/sys/common/erl_poll.c
@@ -320,7 +320,7 @@ struct ErtsPollSet_ {
 #if defined(USE_THREADS) || ERTS_POLL_ASYNC_INTERRUPT_SUPPORT
     erts_atomic32_t wakeup_state;
 #endif
-    erts_smp_atomic32_t timeout;
+    erts_atomic64_t timeout_time;
 #ifdef ERTS_POLL_COUNT_AVOIDED_WAKEUPS
     erts_smp_atomic_t no_avoided_wakeups;
     erts_smp_atomic_t no_avoided_interrupts;
@@ -384,6 +384,26 @@ static void check_poll_status(ErtsPollSet ps);
 static void print_misc_debug_info(void);
 #endif
 
+static ERTS_INLINE void
+init_timeout_time(ErtsPollSet ps)
+{
+    erts_atomic64_init_nob(&ps->timeout_time,
+			   (erts_aint64_t) ERTS_MONOTONIC_TIME_MAX);
+}
+
+static ERTS_INLINE void
+set_timeout_time(ErtsPollSet ps, ErtsMonotonicTime time)
+{
+    erts_atomic64_set_relb(&ps->timeout_time,
+			   (erts_aint64_t) time);
+}
+
+static ERTS_INLINE ErtsMonotonicTime
+get_timeout_time(ErtsPollSet ps)
+{
+    return (ErtsMonotonicTime) erts_atomic64_read_acqb(&ps->timeout_time);
+}
+
 #define ERTS_POLL_NOT_WOKEN	0
 #define ERTS_POLL_WOKEN		-1
 #define ERTS_POLL_WOKEN_INTR	1
@@ -1993,44 +2013,153 @@ save_poll_result(ErtsPollSet ps, ErtsPollResFd pr[], int max_res,
     }
 }
 
+static ERTS_INLINE ErtsMonotonicTime
+get_timeout(ErtsPollSet ps,
+	    int resolution,
+	    ErtsMonotonicTime timeout_time)
+{
+    ErtsMonotonicTime timeout, save_timeout_time;
+
+    if (timeout_time == ERTS_POLL_NO_TIMEOUT) {
+	save_timeout_time = ERTS_MONOTONIC_TIME_MIN;
+	timeout = 0;
+    }
+    else {
+	ErtsMonotonicTime diff_time, current_time;
+	current_time = erts_get_monotonic_time();
+	diff_time = timeout_time - current_time;
+	if (diff_time <= 0) {
+	    save_timeout_time = ERTS_MONOTONIC_TIME_MIN;
+	    timeout = 0;
+	}
+	else {
+	    save_timeout_time = current_time;
+	    switch (resolution) {
+	    case 1000:
+		/* Round up to nearest even milli second */
+		timeout = ERTS_MONOTONIC_TO_MSEC(diff_time - 1) + 1;
+		if (timeout > (ErtsMonotonicTime) INT_MAX)
+		    timeout = (ErtsMonotonicTime) INT_MAX;
+		save_timeout_time += ERTS_MSEC_TO_MONOTONIC(timeout);
+		break;
+	    case 1000000:
+		/* Round up to nearest even micro second */
+		timeout = ERTS_MONOTONIC_TO_USEC(diff_time - 1) + 1;
+		save_timeout_time += ERTS_USEC_TO_MONOTONIC(timeout);
+		break;
+	    case 1000000000:
+		/* Round up to nearest even nano second */
+		timeout = ERTS_MONOTONIC_TO_NSEC(diff_time - 1) + 1;
+		save_timeout_time += ERTS_NSEC_TO_MONOTONIC(timeout);
+		break;
+	    default:
+		ERTS_INTERNAL_ERROR("Invalid resolution");
+		timeout = 0;
+		save_timeout_time = 0;
+		break;
+	    }
+	}
+    }
+    set_timeout_time(ps, save_timeout_time);
+    return timeout;
+}
+
+#if ERTS_POLL_USE_SELECT
+
 static ERTS_INLINE int
-check_fd_events(ErtsPollSet ps, SysTimeval *tv, int max_res)
+get_timeout_timeval(ErtsPollSet ps,
+		    SysTimeval *tvp,
+		    ErtsMonotonicTime timeout_time)
+{
+    ErtsMonotonicTime timeout = get_timeout(ps,
+					    1000*1000,
+					    timeout_time);
+
+    if (!timeout) {
+	tvp->tv_sec = 0;
+	tvp->tv_usec = 0;
+
+	return 0;
+    }
+    else {
+	ErtsMonotonicTime sec = timeout/(1000*1000);
+	tvp->tv_sec = sec;
+	tvp->tv_usec = timeout - sec*(1000*1000);
+
+	ASSERT(tvp->tv_sec >= 0);
+	ASSERT(tvp->tv_usec >= 0);
+	ASSERT(tvp->tv_usec < 1000*1000);
+
+	return !0;
+    }
+
+}
+
+#endif
+
+#if ERTS_POLL_USE_KQUEUE
+
+static ERTS_INLINE int
+get_timeout_timespec(ErtsPollSet ps,
+		     struct timespec *tsp,
+		     ErtsMonotonicTime timeout_time)
+{
+    ErtsMonotonicTime timeout = get_timeout(ps,
+					    1000*1000*1000,
+					    timeout_time);
+
+    if (!timeout) {
+	tsp->tv_sec = 0;
+	tsp->tv_nsec = 0;
+	return 0;
+    }
+    else {
+	ErtsMonotonicTime sec = timeout/(1000*1000*1000);
+	tsp->tv_sec = sec;
+	tsp->tv_nsec = timeout - sec*(1000*1000*1000);
+
+	ASSERT(tsp->tv_sec >= 0);
+	ASSERT(tsp->tv_nsec >= 0);
+	ASSERT(tsp->tv_nsec < 1000*1000);
+
+	return !0;
+    }
+}
+
+#endif
+
+static ERTS_INLINE int
+check_fd_events(ErtsPollSet ps, ErtsMonotonicTime timeout_time, int max_res)
 {
     int res;
     if (erts_smp_atomic_read_nob(&ps->no_of_user_fds) == 0
-	&& tv->tv_usec == 0 && tv->tv_sec == 0) {
+	&& timeout_time == ERTS_POLL_NO_TIMEOUT) {
 	/* Nothing to poll and zero timeout; done... */
 	return 0;
     }
     else {
-	long timeout = tv->tv_sec*1000 + tv->tv_usec/1000;
-	if (timeout > ERTS_AINT32_T_MAX)
-	    timeout = ERTS_AINT32_T_MAX;
-	ASSERT(timeout >= 0);
-	erts_smp_atomic32_set_relb(&ps->timeout, (erts_aint32_t) timeout);
+	int timeout;
 #if ERTS_POLL_USE_FALLBACK
 	if (!(ps->fallback_used = ERTS_POLL_NEED_FALLBACK(ps))) {
 
 #if ERTS_POLL_USE_EPOLL		/* --- epoll ------------------------------- */
-	    if (timeout > INT_MAX)
-		timeout = INT_MAX;
 	    if (max_res > ps->res_events_len)
 		grow_res_events(ps, max_res);
+	    timeout = (int) get_timeout(ps, 1000, timeout_time);
 #ifdef ERTS_SMP
 	    if (timeout)
 		erts_thr_progress_prepare_wait(NULL);
 #endif
-	    res = epoll_wait(ps->kp_fd, ps->res_events, max_res, (int)timeout);
+	    res = epoll_wait(ps->kp_fd, ps->res_events, max_res, timeout);
 #elif ERTS_POLL_USE_KQUEUE	/* --- kqueue ------------------------------ */
 	    struct timespec ts;
 	    if (max_res > ps->res_events_len)
 		grow_res_events(ps, max_res);
+	    timeout = get_timeout_timespec(ps, &ts, timeout_time);
 #ifdef ERTS_SMP
 	    if (timeout)
 		erts_thr_progress_prepare_wait(NULL);
 #endif
-	    ts.tv_sec = tv->tv_sec;
-	    ts.tv_nsec = tv->tv_usec*1000;
 	    res = kevent(ps->kp_fd, NULL, 0, ps->res_events, max_res, &ts);
 #endif				/* ----------------------------------------- */
 	}
@@ -2049,8 +2178,7 @@ check_fd_events(ErtsPollSet ps, SysTimeval *tv, int max_res)
 #if ERTS_POLL_USE_WAKEUP_PIPE
 	    nfds++; /* Wakeup pipe */
 #endif
-	    if (timeout > INT_MAX)
-		timeout = INT_MAX;
+	    timeout = (int) get_timeout(ps, 1000, timeout_time);
 	    poll_res.dp_nfds = nfds < max_res ? nfds : max_res;
 	    if (poll_res.dp_nfds > ps->res_events_len)
 		grow_res_events(ps, poll_res.dp_nfds);
@@ -2059,33 +2187,33 @@ check_fd_events(ErtsPollSet ps, SysTimeval *tv, int max_res)
 	    if (timeout)
 		erts_thr_progress_prepare_wait(NULL);
 #endif
-	    poll_res.dp_timeout = (int) timeout;
+	    poll_res.dp_timeout = timeout;
 	    res = ioctl(ps->kp_fd, DP_POLL, &poll_res);
 #elif ERTS_POLL_USE_POLL	/* --- poll -------------------------------- */
-	    if (timeout > INT_MAX)
-		timeout = INT_MAX;
+	    timeout = (int) get_timeout(ps, 1000, timeout_time);
 #ifdef ERTS_SMP
 	    if (timeout)
 		erts_thr_progress_prepare_wait(NULL);
 #endif
-	    res = poll(ps->poll_fds, ps->no_poll_fds, (int) timeout);
+	    res = poll(ps->poll_fds, ps->no_poll_fds, timeout);
 #elif ERTS_POLL_USE_SELECT	/* --- select ------------------------------ */
-	    SysTimeval to = *tv;
+	    SysTimeval to;
+	    timeout = get_timeout_timeval(ps, &to, timeout_time);
 
 	    ERTS_FD_COPY(&ps->input_fds, &ps->res_input_fds);
 	    ERTS_FD_COPY(&ps->output_fds, &ps->res_output_fds);
 	    
 #ifdef ERTS_SMP
-	    if (to.tv_sec || to.tv_usec)
+	    if (timeout)
 		erts_thr_progress_prepare_wait(NULL);
 #endif
 	    res = ERTS_SELECT(ps->max_fd + 1,
-			 &ps->res_input_fds,
-			 &ps->res_output_fds,
-			 NULL,
-			 &to);
+			      &ps->res_input_fds,
+			      &ps->res_output_fds,
+			      NULL,
+			      &to);
 #ifdef ERTS_SMP
-	    if (to.tv_sec || to.tv_usec)
+	    if (timeout)
 		erts_thr_progress_finalize_wait(NULL);
 	    if (res < 0
 		&& errno == EBADF
@@ -2108,10 +2236,10 @@ check_fd_events(ErtsPollSet ps, SysTimeval *tv, int max_res)
 		handle_update_requests(ps);
 		ERTS_POLLSET_UNLOCK(ps);
 		res = ERTS_SELECT(ps->max_fd + 1,
-			     &ps->res_input_fds,
-			     &ps->res_output_fds,
-			     NULL,
-			     &to);
+				  &ps->res_input_fds,
+				  &ps->res_output_fds,
+				  NULL,
+				  &to);
 		if (res == 0) {
 		    errno = EAGAIN;
 		    res = -1;
@@ -2133,15 +2261,14 @@ int
 ERTS_POLL_EXPORT(erts_poll_wait)(ErtsPollSet ps,
 				 ErtsPollResFd pr[],
 				 int *len,
-				 SysTimeval *utvp)
+				 ErtsMonotonicTime timeout_time)
 {
+    ErtsMonotonicTime to;
     int res, no_fds;
     int ebadf = 0;
 #ifdef ERTS_SMP
     int ps_locked = 0;
 #endif
-    SysTimeval *tvp;
-    SysTimeval itv;
 
     no_fds = *len;
 #ifdef ERTS_POLL_MAX_RES
@@ -2151,13 +2278,9 @@ ERTS_POLL_EXPORT(erts_poll_wait)(ErtsPollSet ps,
 
     *len = 0;
 
-    ASSERT(utvp);
-
-    tvp = utvp;
-
 #ifdef ERTS_POLL_DEBUG_PRINT
-    erts_printf("Entering erts_poll_wait(), timeout=%d\n",
-		 (int) tvp->tv_sec*1000 + tvp->tv_usec/1000);
+    erts_printf("Entering erts_poll_wait(), timeout_time=%bps\n",
+		timeout_time);
 #endif
 
     if (ERTS_POLLSET_SET_POLLED_CHK(ps)) {
@@ -2166,12 +2289,9 @@ ERTS_POLL_EXPORT(erts_poll_wait)(ErtsPollSet ps,
 	goto done;
     }
 
-    if (is_woken(ps)) {
-	/* Use zero timeout */
-	itv.tv_sec = 0;
-	itv.tv_usec = 0;
-	tvp = &itv;
-    }
+    to = (is_woken(ps)
+	  ? ERTS_POLL_NO_TIMEOUT /* Use zero timeout */
+	  : timeout_time);
 
 #if ERTS_POLL_USE_UPDATE_REQUESTS_QUEUE
     if (ERTS_POLLSET_HAVE_UPDATE_REQUESTS(ps)) {
@@ -2181,7 +2301,7 @@ ERTS_POLL_EXPORT(erts_poll_wait)(ErtsPollSet ps,
     }
 #endif
 
-    res = check_fd_events(ps, tvp, no_fds);
+    res = check_fd_events(ps, to, no_fds);
 
     woke_up(ps);
 
@@ -2224,7 +2344,7 @@ ERTS_POLL_EXPORT(erts_poll_wait)(ErtsPollSet ps,
 #endif
 
  done:
-    erts_smp_atomic32_set_relb(&ps->timeout, ERTS_AINT32_T_MAX);
+    set_timeout_time(ps, ERTS_MONOTONIC_TIME_MAX);
 #ifdef ERTS_POLL_DEBUG_PRINT
     erts_printf("Leaving %s = erts_poll_wait()\n",
 		 res == 0 ? "0" : erl_errno_id(res));
@@ -2268,13 +2388,14 @@ ERTS_POLL_EXPORT(erts_poll_async_sig_interrupt)(ErtsPollSet ps)
 void
 ERTS_POLL_EXPORT(erts_poll_interrupt_timed)(ErtsPollSet ps,
 					    int set,
-					    erts_short_time_t msec)
+					    ErtsMonotonicTime timeout_time)
 {
 #if ERTS_POLL_ASYNC_INTERRUPT_SUPPORT || defined(ERTS_SMP)
     if (!set)
 	reset_wakeup_state(ps);
     else {
-	if (erts_smp_atomic32_read_acqb(&ps->timeout) > (erts_aint32_t) msec)
+	ErtsMonotonicTime max_wait_time = get_timeout_time(ps);
+	if (max_wait_time > timeout_time)
 	    wake_poller(ps, 1, 0);
 #ifdef ERTS_POLL_COUNT_AVOIDED_WAKEUPS
 	else {
@@ -2431,7 +2552,7 @@ ERTS_POLL_EXPORT(erts_poll_create_pollset)(void)
 	ps->internal_fd_limit = kp_fd + 1;
     ps->kp_fd = kp_fd;
 #endif
-    erts_smp_atomic32_init_nob(&ps->timeout, ERTS_AINT32_T_MAX);
+    init_timeout_time(ps);
 #ifdef ERTS_POLL_COUNT_AVOIDED_WAKEUPS
     erts_smp_atomic_init_nob(&ps->no_avoided_wakeups, 0);
     erts_smp_atomic_init_nob(&ps->no_avoided_interrupts, 0);