diff options
Diffstat (limited to 'src/journal/journald-rate-limit.c')
| -rw-r--r-- | src/journal/journald-rate-limit.c | 256 |
1 files changed, 256 insertions, 0 deletions
diff --git a/src/journal/journald-rate-limit.c b/src/journal/journald-rate-limit.c new file mode 100644 index 0000000..1028e38 --- /dev/null +++ b/src/journal/journald-rate-limit.c @@ -0,0 +1,256 @@ +/* SPDX-License-Identifier: LGPL-2.1-or-later */ + +#include <errno.h> + +#include "alloc-util.h" +#include "hashmap.h" +#include "journald-rate-limit.h" +#include "list.h" +#include "logarithm.h" +#include "random-util.h" +#include "string-util.h" +#include "time-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; + + /* Interval is stored to keep track of when the group expires */ + usec_t interval; + + JournalRateLimitPool pools[POOLS_MAX]; + uint64_t hash; + + LIST_FIELDS(JournalRateLimitGroup, bucket); + LIST_FIELDS(JournalRateLimitGroup, lru); +}; + +struct JournalRateLimit { + + JournalRateLimitGroup* buckets[BUCKETS_MAX]; + JournalRateLimitGroup *lru, *lru_tail; + + unsigned n_groups; + + uint8_t hash_key[16]; +}; + +JournalRateLimit *journal_ratelimit_new(void) { + JournalRateLimit *r; + + r = new0(JournalRateLimit, 1); + if (!r) + return NULL; + + random_bytes(r->hash_key, sizeof(r->hash_key)); + + return r; +} + +static void journal_ratelimit_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_ratelimit_free(JournalRateLimit *r) { + assert(r); + + while (r->lru) + journal_ratelimit_group_free(r->lru); + + free(r); +} + +static bool journal_ratelimit_group_expired(JournalRateLimitGroup *g, usec_t ts) { + unsigned i; + + assert(g); + + for (i = 0; i < POOLS_MAX; i++) + if (g->pools[i].begin + g->interval >= ts) + return false; + + return true; +} + +static void journal_ratelimit_vacuum(JournalRateLimit *r, usec_t ts) { + assert(r); + + /* Makes room for at least one new item, but drop all expired items too. */ + + while (r->n_groups >= GROUPS_MAX || + (r->lru_tail && journal_ratelimit_group_expired(r->lru_tail, ts))) + journal_ratelimit_group_free(r->lru_tail); +} + +static JournalRateLimitGroup* journal_ratelimit_group_new(JournalRateLimit *r, const char *id, usec_t interval, 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; + + g->hash = siphash24_string(g->id, r->hash_key); + + g->interval = interval; + + journal_ratelimit_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_ratelimit_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 = log2u64(available); + + /* 1MB */ + if (k <= 20) + return burst; + + burst = (burst * (k-16)) / 4; + + /* + * Example: + * + * <= 1MB = rate * 1 + * 16MB = rate * 2 + * 256MB = rate * 3 + * 4GB = rate * 4 + * 64GB = rate * 5 + * 1TB = rate * 6 + */ + + return burst; +} + +int journal_ratelimit_test(JournalRateLimit *r, const char *id, usec_t rl_interval, unsigned rl_burst, int priority, uint64_t available) { + JournalRateLimitGroup *g, *found = NULL; + JournalRateLimitPool *p; + unsigned burst; + uint64_t h; + usec_t ts; + + assert(id); + + /* Returns: + * + * 0 → the log message shall be suppressed, + * 1 + n → the log message shall be permitted, and n messages were dropped from the peer before + * < 0 → error + */ + + if (!r) + return 1; + + ts = now(CLOCK_MONOTONIC); + + h = siphash24_string(id, r->hash_key); + g = r->buckets[h % BUCKETS_MAX]; + + LIST_FOREACH(bucket, i, g) + if (streq(i->id, id)) { + found = i; + break; + } + + if (!found) { + found = journal_ratelimit_group_new(r, id, rl_interval, ts); + if (!found) + return -ENOMEM; + } else + found->interval = rl_interval; + + if (rl_interval == 0 || rl_burst == 0) + return 1; + + burst = burst_modulate(rl_burst, available); + + p = &found->pools[priority_map[priority]]; + + if (p->begin <= 0) { + p->suppressed = 0; + p->num = 1; + p->begin = ts; + return 1; + } + + if (p->begin + rl_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; +} |