summaryrefslogtreecommitdiff
path: root/erts/emulator/beam/erl_bif_counters.c
blob: 5c5a5c890f28e6a6cf65b3b8bf81854dfbc54052 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
/*
 * %CopyrightBegin%
 *
 * Copyright Ericsson AB 2018-2021. All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 * %CopyrightEnd%
 */

/*
 * Purpose:  The implementation for 'counters' with 'write_concurrency'.
 */

#ifdef HAVE_CONFIG_H
#  include "config.h"
#endif

#include <stddef.h> /* offsetof */

#include "sys.h"
#include "export.h"
#include "bif.h"
#include "erl_threads.h"
#include "big.h"
#include "erl_binary.h"
#include "erl_bif_unique.h"
#include "erl_map.h"

/*
 * Each logical counter consists of one 64-bit atomic instance per scheduler
 * plus one instance for the "base value".
 *
 * get() reads all atomics for the counter and returns the sum.
 * add() reads and writes only its own scheduler specific atomic instance.
 * put() reads all scheduler specific atomics and writes a new base value.
 */
#define ATOMICS_PER_COUNTER (erts_no_schedulers + 1)

#define ATOMICS_PER_CACHE_LINE (ERTS_CACHE_LINE_SIZE / sizeof(erts_atomic64_t))

typedef struct
{
    UWord arity;
#ifdef DEBUG
    UWord ulen;
#endif
    union {
        erts_atomic64_t v[ATOMICS_PER_CACHE_LINE];
        byte cache_line__[ERTS_CACHE_LINE_SIZE];
    } u[1];
}CountersRef;

static int counters_destructor(Binary *mbin)
{
    return 1;
}


static UWord ERTS_INLINE div_ceil(UWord dividend, UWord divisor)
{
    return (dividend + divisor - 1) / divisor;
}

BIF_RETTYPE erts_internal_counters_new_1(BIF_ALIST_1)
{
    CountersRef* p;
    Binary* mbin;
    UWord ui, vi, cnt;
    Uint bytes, cache_lines;
    Eterm* hp;

    if (!term_to_UWord(BIF_ARG_1, &cnt)) {
        BIF_ERROR(BIF_P, cnt);
    }
    if (cnt == 0) {
        BIF_ERROR(BIF_P, BADARG);
    }

    if (cnt > (ERTS_UWORD_MAX / (sizeof(erts_atomic64_t)*2*ATOMICS_PER_COUNTER)))
        BIF_ERROR(BIF_P, SYSTEM_LIMIT);

    cache_lines = ATOMICS_PER_COUNTER * div_ceil(cnt, ATOMICS_PER_CACHE_LINE);
    bytes = offsetof(CountersRef, u) + cache_lines * ERTS_CACHE_LINE_SIZE;
    mbin = erts_create_magic_binary_x(bytes,
                                      counters_destructor,
                                      ERTS_ALC_T_ATOMICS,
                                      0);
    p = ERTS_MAGIC_BIN_DATA(mbin);
    p->arity = cnt;

#ifdef DEBUG
    p->ulen = cache_lines;
#endif
    ASSERT((byte*)&p->u[cache_lines] <= ((byte*)p + bytes));
    for (ui=0; ui < cache_lines; ui++)
        for (vi=0; vi < ATOMICS_PER_CACHE_LINE; vi++)
            erts_atomic64_init_nob(&p->u[ui].v[vi], 0);
    hp = HAlloc(BIF_P, ERTS_MAGIC_REF_THING_SIZE);
    return erts_mk_magic_ref(&hp, &MSO(BIF_P), mbin);
}

static ERTS_INLINE int get_ref(Eterm ref, CountersRef** pp)
{
    Binary* mbin;
    if (!is_internal_magic_ref(ref))
        return 0;

    mbin = erts_magic_ref2bin(ref);
    if (ERTS_MAGIC_BIN_DESTRUCTOR(mbin) != counters_destructor)
        return 0;
    *pp = ERTS_MAGIC_BIN_DATA(mbin);
    return 1;
}

static ERTS_INLINE int get_ref_cnt(Eterm ref, Eterm index,
                                   CountersRef** pp,
                                   erts_atomic64_t** app,
                                   UWord sched_ix)
{
    CountersRef* p;
    UWord ix, ui, vi;
    if (!get_ref(ref, &p) || !term_to_UWord(index, &ix) || --ix >= p->arity)
        return 0;
    ui = (ix / ATOMICS_PER_CACHE_LINE) * ATOMICS_PER_COUNTER + sched_ix;
    vi = ix % ATOMICS_PER_CACHE_LINE;
    ASSERT(ui < p->ulen);
    *pp = p;
    *app = &p->u[ui].v[vi];
    return 1;
}

static ERTS_INLINE int get_ref_my_cnt(Eterm ref, Eterm index,
                                      CountersRef** pp,
                                      erts_atomic64_t** app)
{
    ErtsSchedulerData *esdp = erts_get_scheduler_data();
    ASSERT(esdp && !ERTS_SCHEDULER_IS_DIRTY(esdp));
    ASSERT(esdp->no > 0 && esdp->no < ATOMICS_PER_COUNTER);
    return get_ref_cnt(ref, index, pp, app, esdp->no);
}

static ERTS_INLINE int get_ref_first_cnt(Eterm ref, Eterm index,
                                         CountersRef** pp,
                                         erts_atomic64_t** app)
{
    return get_ref_cnt(ref, index, pp, app, 0);
}

static ERTS_INLINE int get_incr(CountersRef* p, Eterm term, erts_aint64_t *valp)
{
    return (term_to_Sint64(term, (Sint64*)valp)
            || term_to_Uint64(term, (Uint64*)valp));
}

static ERTS_INLINE Eterm bld_counter(Process* proc, CountersRef* p,
                                     erts_aint64_t val)
{
    if (IS_SSMALL(val))
        return make_small((Sint) val);
    else {
        Uint hsz = ERTS_SINT64_HEAP_SIZE(val);
        Eterm* hp = HAlloc(proc, hsz);
        return erts_sint64_to_big(val, &hp);
    }
}

BIF_RETTYPE erts_internal_counters_get_2(BIF_ALIST_2)
{
    CountersRef* p;
    erts_atomic64_t* ap;
    erts_aint64_t acc = 0;
    int j;

    if (!get_ref_first_cnt(BIF_ARG_1, BIF_ARG_2, &p, &ap)) {
        BIF_ERROR(BIF_P, BADARG);
    }
    for (j = ATOMICS_PER_COUNTER; j ; --j) {
        acc += erts_atomic64_read_nob(ap);
        ap = (erts_atomic64_t*) ((byte*)ap + ERTS_CACHE_LINE_SIZE);
    }
    return bld_counter(BIF_P, p, acc);
}

BIF_RETTYPE erts_internal_counters_add_3(BIF_ALIST_3)
{
    CountersRef* p;
    erts_atomic64_t* ap;
    erts_aint64_t incr, sum;

    if (!get_ref_my_cnt(BIF_ARG_1, BIF_ARG_2, &p, &ap)
        || !get_incr(p, BIF_ARG_3, &incr)) {
        BIF_ERROR(BIF_P, BADARG);
    }
    sum = incr + erts_atomic64_read_nob(ap);
    erts_atomic64_set_nob(ap, sum);
    return am_ok;
}

BIF_RETTYPE erts_internal_counters_put_3(BIF_ALIST_3)
{
    CountersRef* p;
    erts_atomic64_t* first_ap;
    erts_atomic64_t* ap;
    erts_aint64_t acc;
    erts_aint64_t val;
    int j;

    if (!get_ref_first_cnt(BIF_ARG_1, BIF_ARG_2, &p, &first_ap)
        || !term_to_Sint64(BIF_ARG_3, &val)) {
        BIF_ERROR(BIF_P, BADARG);
    }

    ap = first_ap;
    acc = 0;
    j = ATOMICS_PER_COUNTER - 1;
    do {
        ap = (erts_atomic64_t*) ((byte*)ap + ERTS_CACHE_LINE_SIZE);
        acc += erts_atomic64_read_nob(ap);
    } while (--j);
    erts_atomic64_set_nob(first_ap, val-acc);

    return am_ok;
}

BIF_RETTYPE erts_internal_counters_info_1(BIF_ALIST_1)
{
    CountersRef* p;
    Uint hsz = MAP2_SZ;
    Eterm *hp;
    UWord memory;
    Eterm sz_val, mem_val;

    if (!get_ref(BIF_ARG_1, &p))
        BIF_ERROR(BIF_P, BADARG);

    memory = erts_magic_ref2bin(BIF_ARG_1)->orig_size;
    erts_bld_uword(NULL, &hsz, p->arity);
    erts_bld_uword(NULL, &hsz, memory);

    hp = HAlloc(BIF_P, hsz);
    sz_val  = erts_bld_uword(&hp, NULL, p->arity);
    mem_val = erts_bld_uword(&hp, NULL, memory);

    return MAP2(hp, am_memory, mem_val,
                am_size, sz_val);
}