summaryrefslogtreecommitdiff
path: root/src/journal/journald-rate-limit.c
blob: 8afd493b50f6d60917515568949ea54082fe2a58 (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
258
259
260
261
262
263
264
265
266
267
268
269
270
271
/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/

/***
  This file is part of systemd.

  Copyright 2011 Lennart Poettering

  systemd is free software; you can redistribute it and/or modify it
  under the terms of the GNU Lesser General Public License as published by
  the Free Software Foundation; either version 2.1 of the License, or
  (at your option) any later version.

  systemd is distributed in the hope that it will be useful, but
  WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  Lesser General Public License for more details.

  You should have received a copy of the GNU Lesser General Public License
  along with systemd; If not, see <http://www.gnu.org/licenses/>.
***/

#include <string.h>
#include <errno.h>

#include "journald-rate-limit.h"
#include "list.h"
#include "util.h"
#include "hashmap.h"
#include "random-util.h"

#define POOLS_MAX 5
#define BUCKETS_MAX 127
#define GROUPS_MAX 2047

static const int priority_map[] = {
        [LOG_EMERG]   = 0,
        [LOG_ALERT]   = 0,
        [LOG_CRIT]    = 0,
        [LOG_ERR]     = 1,
        [LOG_WARNING] = 2,
        [LOG_NOTICE]  = 3,
        [LOG_INFO]    = 3,
        [LOG_DEBUG]   = 4
};

typedef struct JournalRateLimitPool JournalRateLimitPool;
typedef struct JournalRateLimitGroup JournalRateLimitGroup;

struct JournalRateLimitPool {
        usec_t begin;
        unsigned num;
        unsigned suppressed;
};

struct JournalRateLimitGroup {
        JournalRateLimit *parent;

        char *id;
        JournalRateLimitPool pools[POOLS_MAX];
        uint64_t hash;

        LIST_FIELDS(JournalRateLimitGroup, bucket);
        LIST_FIELDS(JournalRateLimitGroup, lru);
};

struct JournalRateLimit {
        usec_t interval;
        unsigned burst;

        JournalRateLimitGroup* buckets[BUCKETS_MAX];
        JournalRateLimitGroup *lru, *lru_tail;

        unsigned n_groups;

        uint8_t hash_key[16];
};

JournalRateLimit *journal_rate_limit_new(usec_t interval, unsigned burst) {
        JournalRateLimit *r;

        assert(interval > 0 || burst == 0);

        r = new0(JournalRateLimit, 1);
        if (!r)
                return NULL;

        r->interval = interval;
        r->burst = burst;

        random_bytes(r->hash_key, sizeof(r->hash_key));

        return r;
}

static void journal_rate_limit_group_free(JournalRateLimitGroup *g) {
        assert(g);

        if (g->parent) {
                assert(g->parent->n_groups > 0);

                if (g->parent->lru_tail == g)
                        g->parent->lru_tail = g->lru_prev;

                LIST_REMOVE(lru, g->parent->lru, g);
                LIST_REMOVE(bucket, g->parent->buckets[g->hash % BUCKETS_MAX], g);

                g->parent->n_groups --;
        }

        free(g->id);
        free(g);
}

void journal_rate_limit_free(JournalRateLimit *r) {
        assert(r);

        while (r->lru)
                journal_rate_limit_group_free(r->lru);

        free(r);
}

_pure_ static bool journal_rate_limit_group_expired(JournalRateLimitGroup *g, usec_t ts) {
        unsigned i;

        assert(g);

        for (i = 0; i < POOLS_MAX; i++)
                if (g->pools[i].begin + g->parent->interval >= ts)
                        return false;

        return true;
}

static void journal_rate_limit_vacuum(JournalRateLimit *r, usec_t ts) {
        assert(r);

        /* Makes room for at least one new item, but drop all
         * expored items too. */

        while (r->n_groups >= GROUPS_MAX ||
               (r->lru_tail && journal_rate_limit_group_expired(r->lru_tail, ts)))
                journal_rate_limit_group_free(r->lru_tail);
}

static JournalRateLimitGroup* journal_rate_limit_group_new(JournalRateLimit *r, const char *id, usec_t ts) {
        JournalRateLimitGroup *g;
        struct siphash state;

        assert(r);
        assert(id);

        g = new0(JournalRateLimitGroup, 1);
        if (!g)
                return NULL;

        g->id = strdup(id);
        if (!g->id)
                goto fail;

        siphash24_init(&state, r->hash_key);
        string_hash_func(g->id, &state);
        siphash24_finalize((uint8_t*)&g->hash, &state);

        journal_rate_limit_vacuum(r, ts);

        LIST_PREPEND(bucket, r->buckets[g->hash % BUCKETS_MAX], g);
        LIST_PREPEND(lru, r->lru, g);
        if (!g->lru_next)
                r->lru_tail = g;
        r->n_groups ++;

        g->parent = r;
        return g;

fail:
        journal_rate_limit_group_free(g);
        return NULL;
}

static unsigned burst_modulate(unsigned burst, uint64_t available) {
        unsigned k;

        /* Modulates the burst rate a bit with the amount of available
         * disk space */

        k = u64log2(available);

        /* 1MB */
        if (k <= 20)
                return burst;

        burst = (burst * (k-20)) / 4;

        /*
         * Example:
         *
         *      <= 1MB = rate * 1
         *        16MB = rate * 2
         *       256MB = rate * 3
         *         4GB = rate * 4
         *        64GB = rate * 5
         *         1TB = rate * 6
         */

        return burst;
}

int journal_rate_limit_test(JournalRateLimit *r, const char *id, int priority, uint64_t available) {
        uint64_t h;
        JournalRateLimitGroup *g;
        JournalRateLimitPool *p;
        struct siphash state;
        unsigned burst;
        usec_t ts;

        assert(id);

        if (!r)
                return 1;

        if (r->interval == 0 || r->burst == 0)
                return 1;

        burst = burst_modulate(r->burst, available);

        ts = now(CLOCK_MONOTONIC);

        siphash24_init(&state, r->hash_key);
        string_hash_func(id, &state);
        siphash24_finalize((uint8_t*)&h, &state);
        g = r->buckets[h % BUCKETS_MAX];

        LIST_FOREACH(bucket, g, g)
                if (streq(g->id, id))
                        break;

        if (!g) {
                g = journal_rate_limit_group_new(r, id, ts);
                if (!g)
                        return -ENOMEM;
        }

        p = &g->pools[priority_map[priority]];

        if (p->begin <= 0) {
                p->suppressed = 0;
                p->num = 1;
                p->begin = ts;
                return 1;
        }

        if (p->begin + r->interval < ts) {
                unsigned s;

                s = p->suppressed;
                p->suppressed = 0;
                p->num = 1;
                p->begin = ts;

                return 1 + s;
        }

        if (p->num <= burst) {
                p->num++;
                return 1;
        }

        p->suppressed++;
        return 0;
}