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, 556 insertions, 0 deletions

diff --git a/erts/emulator/beam/erl_bif_unique.c b/erts/emulator/beam/erl_bif_unique.c
new file mode 100644
index 0000000000..57b0bab72f
--- /dev/null
+++ b/erts/emulator/beam/erl_bif_unique.c
@@ -0,0 +1,556 @@
+/*
+ * %CopyrightBegin%
+ *
+ * Copyright Ericsson AB 2014. All Rights Reserved.
+ *
+ * The contents of this file are subject to the Erlang Public License,
+ * Version 1.1, (the "License"); you may not use this file except in
+ * compliance with the License. You should have received a copy of the
+ * Erlang Public License along with this software. If not, it can be
+ * retrieved online at http://www.erlang.org/.
+ *
+ * Software distributed under the License is distributed on an "AS IS"
+ * basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
+ * the License for the specific language governing rights and limitations
+ * under the License.
+ *
+ * %CopyrightEnd%
+ */
+
+#ifdef HAVE_CONFIG_H
+#  include "config.h"
+#endif
+
+#include "sys.h"
+#include "erl_vm.h"
+#include "erl_alloc.h"
+#include "export.h"
+#include "bif.h"
+#include "erl_bif_unique.h"
+
+/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *\
+ * Reference                                                         *
+\*                                                                   */
+
+static union {
+    erts_atomic64_t count;
+    char align__[ERTS_CACHE_LINE_SIZE];
+} global_reference erts_align_attribute(ERTS_CACHE_LINE_SIZE);
+
+
+/*
+ * ref[0] indicate thread creating reference as follows:
+ *
+ * - ref[0] == 0 => Non-scheduler thread;
+ * - else; ref[0] <= erts_no_schedulers =>
+ *      ordinary scheduler with id == ref[0];
+ * - else; ref[0] <= erts_no_schedulers
+ *                   + erts_no_dirty_cpu_schedulers =>
+ *      dirty cpu scheduler with id == 'ref[0] - erts_no_schedulers';
+ * - else =>
+ *      dirty io scheduler with id == 'ref[0]
+ *                                     - erts_no_schedulers
+ *                                     - erts_no_dirty_cpu_schedulers'
+ */
+
+#ifdef DEBUG
+static Uint32 max_thr_id;
+#endif
+
+static void
+init_reference(void)
+{
+#ifdef DEBUG
+    max_thr_id = (Uint32) erts_no_schedulers;
+#ifdef ERTS_DIRTY_SCHEDULERS
+    max_thr_id += (Uint32) erts_no_dirty_cpu_schedulers;
+    max_thr_id += (Uint32) erts_no_dirty_io_schedulers;
+#endif
+#endif
+    erts_atomic64_init_nob(&global_reference.count, 0);
+}
+
+static ERTS_INLINE void
+global_make_ref_in_array(Uint32 thr_id, Uint32 ref[ERTS_MAX_REF_NUMBERS])
+{
+    Uint64 value;
+
+    value = (Uint64) erts_atomic64_inc_read_mb(&global_reference.count);
+    
+    erts_set_ref_numbers(ref, thr_id, value);
+}
+
+static ERTS_INLINE void
+make_ref_in_array(Uint32 ref[ERTS_MAX_REF_NUMBERS])
+{
+    ErtsSchedulerData *esdp = erts_get_scheduler_data();
+    if (esdp)
+	erts_sched_make_ref_in_array(esdp, ref);
+    else
+	global_make_ref_in_array(0, ref);
+}
+
+void
+erts_make_ref_in_array(Uint32 ref[ERTS_MAX_REF_NUMBERS])
+{
+    make_ref_in_array(ref);
+}
+
+Eterm erts_make_ref_in_buffer(Eterm buffer[REF_THING_SIZE])
+{
+    Eterm* hp = buffer;
+    Uint32 ref[ERTS_MAX_REF_NUMBERS];
+
+    make_ref_in_array(ref);
+    write_ref_thing(hp, ref[0], ref[1], ref[2]);
+    return make_internal_ref(hp);
+}
+
+Eterm erts_make_ref(Process *c_p)
+{
+    Eterm* hp;
+    Uint32 ref[ERTS_MAX_REF_NUMBERS];
+
+    ERTS_SMP_LC_ASSERT(ERTS_PROC_LOCK_MAIN & erts_proc_lc_my_proc_locks(c_p));
+
+    hp = HAlloc(c_p, REF_THING_SIZE);
+
+    make_ref_in_array(ref);
+    write_ref_thing(hp, ref[0], ref[1], ref[2]);
+
+    return make_internal_ref(hp);
+}
+
+/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *\
+ * Unique Integer                                                    *
+\*                                                                   */
+
+static struct {
+    union {
+	struct {
+	    int left_shift;
+	    int right_shift;
+	    Uint64 mask;
+	    Uint64 val0_max;
+	} o;
+	char align__[ERTS_CACHE_LINE_SIZE];
+    } r;
+    union {
+	erts_atomic64_t val1;
+	char align__[ERTS_CACHE_LINE_SIZE];
+    } w;
+} unique_data erts_align_attribute(ERTS_CACHE_LINE_SIZE);
+
+static void
+init_unique_integer(void)
+{
+    int bits;
+    unique_data.r.o.val0_max = (Uint64) erts_no_schedulers;
+#ifdef ERTS_DIRTY_SCHEDULERS
+    unique_data.r.o.val0_max += (Uint64) erts_no_dirty_cpu_schedulers;
+    unique_data.r.o.val0_max += (Uint64) erts_no_dirty_io_schedulers;
+#endif
+    bits = erts_fit_in_bits_int64(unique_data.r.o.val0_max);
+    unique_data.r.o.left_shift = bits;
+    unique_data.r.o.right_shift = 64 - bits;
+    unique_data.r.o.mask = (((Uint64) 1) << bits) - 1;
+    erts_atomic64_init_nob(&unique_data.w.val1, -1);
+}
+
+#define ERTS_MAX_UNIQUE_INT_HEAP_SIZE ERTS_UINT64_ARRAY_TO_BIG_MAX_HEAP_SZ(2)
+
+static ERTS_INLINE Eterm
+bld_unique_integer_term(Eterm **hpp, Uint *szp,
+			Uint64 val0, Uint64 val1,
+			int positive)
+{
+    Uint hsz;
+    Uint64 unique_val[2];
+
+    unique_val[0] = ((Uint64) val0);
+    unique_val[0] |= ((Uint64) val1) << unique_data.r.o.left_shift;
+    unique_val[1] = ((Uint64) val1) >> unique_data.r.o.right_shift;
+    unique_val[1] &= unique_data.r.o.mask;
+
+    if (positive) {
+	unique_val[0]++;
+	if (unique_val[0] == 0)
+	    unique_val[1]++;
+    }
+    else {
+	ASSERT(MIN_SMALL < 0);
+	if (unique_val[1] == 0
+	    && unique_val[0] < ((Uint64) -1*((Sint64) MIN_SMALL))) {
+	    Sint64 s_unique_val = (Sint64) unique_val[0];
+	    s_unique_val += MIN_SMALL;
+	    ASSERT(MIN_SMALL <= s_unique_val && s_unique_val < 0);
+	    if (szp)
+		*szp = 0;
+	    if (!hpp)
+		return THE_NON_VALUE;
+	    return make_small((Sint) s_unique_val);
+	}
+	if (unique_val[0] < ((Uint64) -1*((Sint64) MIN_SMALL))) {
+	    ASSERT(unique_val[1] != 0);
+	    unique_val[1] -= 1;
+	}
+	unique_val[0] += MIN_SMALL;
+    }
+
+    if (!unique_val[1]) {
+	if (unique_val[0] <= MAX_SMALL) {
+	    if (szp)
+		*szp = 0;
+	    if (!hpp)
+		return THE_NON_VALUE;
+	    return make_small((Uint) unique_val[0]);
+	}
+
+	if (szp)
+	    *szp = ERTS_UINT64_HEAP_SIZE(unique_val[0]);
+	if (!hpp)
+	    return THE_NON_VALUE;
+	return erts_uint64_to_big(unique_val[0], hpp);
+    }
+    else {
+	Eterm tmp, *tmp_hp, res;
+	DeclareTmpHeapNoproc(local_heap, 2*ERTS_MAX_UNIQUE_INT_HEAP_SIZE);
+
+	UseTmpHeapNoproc(2*ERTS_MAX_UNIQUE_INT_HEAP_SIZE);
+
+	tmp_hp = local_heap;
+
+	tmp = erts_uint64_array_to_big(&tmp_hp, 0, 2, unique_val);
+	ASSERT(is_big(tmp));
+
+	hsz = big_arity(tmp) + 1;
+
+	ASSERT(hsz <= ERTS_MAX_UNIQUE_INT_HEAP_SIZE);
+
+	if (szp)
+	    *szp = hsz;
+
+	if (!hpp)
+	    res = THE_NON_VALUE;
+	else {
+	    int hix;
+	    Eterm *hp = *hpp;
+	    tmp_hp = big_val(tmp);
+	    for (hix = 0; hix < hsz; hix++)
+		hp[hix] = tmp_hp[hix];
+
+	    *hpp = hp + hsz;
+	    res = make_big(hp);
+	}
+
+	UnUseTmpHeapNoproc(2*ERTS_MAX_UNIQUE_INT_HEAP_SIZE);
+
+	return res;
+    }
+}
+
+static ERTS_INLINE Eterm unique_integer_bif(Process *c_p, int positive)
+{
+    ErtsSchedulerData *esdp;
+    Uint64 thr_id, unique;
+    Uint hsz;
+    Eterm *hp;
+
+    esdp = ERTS_PROC_GET_SCHDATA(c_p);
+    thr_id = (Uint64) esdp->thr_id;
+    unique = esdp->unique++;
+    bld_unique_integer_term(NULL, &hsz, thr_id, unique, positive);
+    hp = hsz ? HAlloc(c_p, hsz) : NULL;
+    return bld_unique_integer_term(&hp, NULL, thr_id, unique, positive);
+}
+
+Uint
+erts_raw_unique_integer_heap_size(Uint64 val[ERTS_UNIQUE_INT_RAW_VALUES])
+{
+    Uint sz;
+    bld_unique_integer_term(NULL, &sz, val[0], val[1], 0);
+    return sz;
+}
+
+Eterm
+erts_raw_make_unique_integer(Eterm **hpp, Uint64 val[ERTS_UNIQUE_INT_RAW_VALUES])
+{
+    return bld_unique_integer_term(hpp, NULL, val[0], val[1], 0);
+}
+
+void
+erts_raw_get_unique_integer(Uint64 val[ERTS_UNIQUE_INT_RAW_VALUES])
+{
+    ErtsSchedulerData *esdp = erts_get_scheduler_data();
+    if (esdp) {
+	val[0] = (Uint64) esdp->thr_id;
+	val[1] = esdp->unique++;
+    }
+    else {
+	val[0] = (Uint64) 0;
+	val[1] = (Uint64) erts_atomic64_inc_read_nob(&unique_data.w.val1);
+    }
+}
+
+
+Sint64
+erts_get_min_unique_integer(void)
+{
+    return (Sint64) MIN_SMALL;
+}
+
+/* --- Debug --- */
+
+Eterm
+erts_debug_make_unique_integer(Process *c_p, Eterm etval0, Eterm etval1)
+{
+    Uint64 val0, val1;
+    Uint hsz;
+    Eterm res, *hp, *end_hp;
+
+    if (!term_to_Uint64(etval0, &val0))
+	return THE_NON_VALUE;
+
+    if (!term_to_Uint64(etval1, &val1))
+	return THE_NON_VALUE;
+
+    bld_unique_integer_term(NULL, &hsz, val0, val1, 0);
+
+    hp = HAlloc(c_p, hsz);
+    end_hp = hp + hsz;
+
+    res = bld_unique_integer_term(&hp, NULL, val0, val1, 0);
+    if (hp != end_hp)
+	ERTS_INTERNAL_ERROR("Heap allocation error");
+
+    return res;
+}
+
+/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *\
+ * Strict Monotonic Counter                                          *
+\*                                                                   */
+
+static struct {
+    union {
+	erts_atomic64_t value;
+	char align__[ERTS_CACHE_LINE_SIZE];
+    } w;
+} raw_unique_monotonic_integer erts_align_attribute(ERTS_CACHE_LINE_SIZE);
+
+#if defined(ARCH_32) || HALFWORD_HEAP
+#  define ERTS_UNIQUE_MONOTONIC_OFFSET ERTS_SINT64_MIN
+#else
+#  define ERTS_UNIQUE_MONOTONIC_OFFSET MIN_SMALL
+#endif
+
+static void
+init_unique_monotonic_integer(void)
+{
+    erts_atomic64_init_nob(&raw_unique_monotonic_integer.w.value,
+			   (erts_aint64_t) -1);
+}
+
+static ERTS_INLINE Uint64
+get_raw_unique_monotonic_integer(void)
+{
+    return (Uint64) erts_atomic64_inc_read_mb(&raw_unique_monotonic_integer.w.value);
+}
+
+static ERTS_INLINE Uint
+get_unique_monotonic_integer_heap_size(Uint64 raw, int positive)
+{
+    if (positive) {
+	Uint64 value = raw+1;
+	return ERTS_UINT64_HEAP_SIZE(value);
+    }
+    else {
+	Sint64 value = ((Sint64) raw) + ERTS_UNIQUE_MONOTONIC_OFFSET;
+	if (IS_SSMALL(value))
+	    return 0;
+#if defined(ARCH_32) || HALFWORD_HEAP
+	return ERTS_SINT64_HEAP_SIZE(value);
+#else
+	return ERTS_UINT64_HEAP_SIZE((Uint64) value);
+#endif
+    }
+}
+
+static ERTS_INLINE Eterm
+make_unique_monotonic_integer_value(Eterm *hp, Uint hsz, Uint64 raw, int positive)
+{
+    Eterm res;
+#ifdef DEBUG
+    Eterm *end_hp = hp + hsz;
+#endif
+
+    if (positive) {
+	Uint64 value = raw+1;
+	res = hsz ? erts_uint64_to_big(value, &hp) : make_small(value);
+    }
+    else {
+	Sint64 value = ((Sint64) raw) + ERTS_UNIQUE_MONOTONIC_OFFSET;
+	if (hsz == 0)
+	    res = make_small(value);
+	else {
+#if defined(ARCH_32) || HALFWORD_HEAP
+	    res = erts_sint64_to_big(value, &hp);
+#else 
+	    res = erts_uint64_to_big((Uint64) value, &hp);
+#endif
+	}
+    }
+
+    ASSERT(end_hp == hp);
+
+    return res;
+}
+
+static ERTS_INLINE Eterm
+unique_monotonic_integer_bif(Process *c_p, int positive)
+{
+    Uint64 raw;
+    Uint hsz;
+    Eterm *hp;
+
+    raw = get_raw_unique_monotonic_integer();
+    hsz = get_unique_monotonic_integer_heap_size(raw, positive);
+    hp = hsz ? HAlloc(c_p, hsz) : NULL;
+    return make_unique_monotonic_integer_value(hp, hsz, raw, positive);
+}
+
+Sint64
+erts_raw_get_unique_monotonic_integer(void)
+{
+    return get_raw_unique_monotonic_integer();
+}
+
+Uint
+erts_raw_unique_monotonic_integer_heap_size(Sint64 raw)
+{
+    return get_unique_monotonic_integer_heap_size(raw, 0);
+}
+
+Eterm
+erts_raw_make_unique_monotonic_integer_value(Eterm **hpp, Sint64 raw)
+{
+    Uint hsz = get_unique_monotonic_integer_heap_size(raw, 0);
+    Eterm res = make_unique_monotonic_integer_value(*hpp, hsz, raw, 0);
+    *hpp += hsz;
+    return res;
+}
+
+Sint64
+erts_get_min_unique_monotonic_integer(void)
+{
+    return ERTS_UNIQUE_MONOTONIC_OFFSET;
+}
+
+/* --- Debug --- */
+
+int
+erts_debug_set_unique_monotonic_integer_state(Eterm et_value)
+{
+    Sint64 value;
+
+    if (!term_to_Sint64(et_value, &value)) {
+	Uint64 uvalue;
+	if (!term_to_Uint64(et_value, &uvalue))
+	    return 0;
+	value = (Sint64) uvalue;
+    }
+
+    erts_atomic64_set_mb(&raw_unique_monotonic_integer.w.value,
+			 (erts_aint64_t) value);
+    return 1;
+}
+
+Eterm
+erts_debug_get_unique_monotonic_integer_state(Process *c_p)
+{
+    Uint64 value;
+    Eterm hsz, *hp;
+
+    value = (Uint64) erts_atomic64_read_mb(&raw_unique_monotonic_integer.w.value);
+
+    if (IS_USMALL(0, value))
+	return make_small(value);
+    hsz = ERTS_UINT64_HEAP_SIZE(value);
+    hp = HAlloc(c_p, hsz);
+    return erts_uint64_to_big(value, &hp);
+}
+
+/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *\
+ * Initilazation                                                     *
+\*                                                                   */
+
+void
+erts_bif_unique_init(void)
+{
+    init_reference();
+    init_unique_monotonic_integer();
+    init_unique_integer();
+}
+
+void
+erts_sched_bif_unique_init(ErtsSchedulerData *esdp)
+{
+    esdp->unique = (Uint64) 0;
+    esdp->ref = (Uint64) 0;
+}
+
+/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *\
+ * The BIFs                                                          *
+\*                                                                   */
+
+
+BIF_RETTYPE make_ref_0(BIF_ALIST_0)
+{
+    BIF_RETTYPE res;
+    Eterm* hp;
+
+    ERTS_SMP_LC_ASSERT(ERTS_PROC_LOCK_MAIN & erts_proc_lc_my_proc_locks(BIF_P));
+
+    hp = HAlloc(BIF_P, REF_THING_SIZE);
+
+    res = erts_sched_make_ref_in_buffer(ERTS_PROC_GET_SCHDATA(BIF_P), hp);
+
+    BIF_RET(res);
+}
+
+BIF_RETTYPE unique_integer_0(BIF_ALIST_0)
+{
+    BIF_RET(unique_integer_bif(BIF_P, 0));
+}
+
+BIF_RETTYPE unique_integer_1(BIF_ALIST_1)
+{
+    Eterm modlist = BIF_ARG_1;
+    int monotonic = 0;
+    int positive = 0;
+    BIF_RETTYPE res;
+
+    while (is_list(modlist)) {
+	Eterm *consp = list_val(modlist);
+	switch (CAR(consp)) {
+	case am_monotonic:
+	    monotonic = 1;
+	    break;
+	case am_positive:
+	    positive = 1;
+	    break;
+	default:
+	    BIF_ERROR(BIF_P, BADARG);
+	}
+	modlist = CDR(consp);
+    }
+
+    if (is_not_nil(modlist))
+	BIF_ERROR(BIF_P, BADARG);
+
+    if (monotonic)
+	res = unique_monotonic_integer_bif(BIF_P, positive);
+    else
+	res = unique_integer_bif(BIF_P, positive);
+
+    BIF_RET(res);
+}