journald-rate-limit.c 6.31 KB
Newer Older
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
/*-*- 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"

#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];
59
        unsigned long hash;
60 61 62 63 64 65 66 67 68 69 70 71 72

        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;
73 74

        uint8_t hash_key[16];
75 76 77 78 79 80 81 82 83 84 85 86 87 88
};

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;

89 90
        random_bytes(r->hash_key, sizeof(r->hash_key));

91 92 93 94 95 96 97 98 99 100 101 102
        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;

103 104
                LIST_REMOVE(lru, g->parent->lru, g);
                LIST_REMOVE(bucket, g->parent->buckets[g->hash % BUCKETS_MAX], g);
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

                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;

        assert(r);
        assert(id);

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

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

159
        g->hash = string_hash_func(g->id, r->hash_key);
160 161 162

        journal_rate_limit_vacuum(r, ts);

163 164
        LIST_PREPEND(bucket, r->buckets[g->hash % BUCKETS_MAX], g);
        LIST_PREPEND(lru, r->lru, g);
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
        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) {
206
        unsigned long h;
207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223
        JournalRateLimitGroup *g;
        JournalRateLimitPool *p;
        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);

224
        h = string_hash_func(id, r->hash_key);
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
        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;
}