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/* SPDX-License-Identifier: LGPL-2.1-or-later */
#include "alloc-util.h"
#include "hashmap.h"
#include "journald-rate-limit.h"
#include "logarithm.h"
#include "string-util.h"
#include "time-util.h"
#define POOLS_MAX 5
#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 {
usec_t begin;
unsigned num;
unsigned suppressed;
} JournalRateLimitPool;
typedef struct JournalRateLimitGroup {
OrderedHashmap *groups_by_id;
char *id;
/* Interval is stored to keep track of when the group expires */
usec_t interval;
JournalRateLimitPool pools[POOLS_MAX];
} JournalRateLimitGroup;
static JournalRateLimitGroup* journal_ratelimit_group_free(JournalRateLimitGroup *g) {
if (!g)
return NULL;
if (g->groups_by_id && g->id)
/* The group is already removed from the hashmap when this is called from the
* destructor of the hashmap. Hence, do not check the return value here. */
ordered_hashmap_remove_value(g->groups_by_id, g->id, g);
free(g->id);
return mfree(g);
}
DEFINE_TRIVIAL_CLEANUP_FUNC(JournalRateLimitGroup*, journal_ratelimit_group_free);
DEFINE_PRIVATE_HASH_OPS_WITH_VALUE_DESTRUCTOR(
journal_ratelimit_group_hash_ops,
char,
string_hash_func,
string_compare_func,
JournalRateLimitGroup,
journal_ratelimit_group_free);
static bool journal_ratelimit_group_expired(JournalRateLimitGroup *g, usec_t ts) {
assert(g);
FOREACH_ELEMENT(p, g->pools)
if (usec_add(p->begin, g->interval) >= ts)
return false;
return true;
}
static void journal_ratelimit_vacuum(OrderedHashmap *groups_by_id, usec_t ts) {
/* Makes room for at least one new item, but drop all expired items too. */
while (ordered_hashmap_size(groups_by_id) >= GROUPS_MAX)
journal_ratelimit_group_free(ordered_hashmap_first(groups_by_id));
JournalRateLimitGroup *g;
while ((g = ordered_hashmap_first(groups_by_id)) && journal_ratelimit_group_expired(g, ts))
journal_ratelimit_group_free(g);
}
static int journal_ratelimit_group_new(
OrderedHashmap **groups_by_id,
const char *id,
usec_t interval,
usec_t ts,
JournalRateLimitGroup **ret) {
_cleanup_(journal_ratelimit_group_freep) JournalRateLimitGroup *g = NULL;
int r;
assert(groups_by_id);
assert(id);
assert(ret);
g = new(JournalRateLimitGroup, 1);
if (!g)
return -ENOMEM;
*g = (JournalRateLimitGroup) {
.id = strdup(id),
.interval = interval,
};
if (!g->id)
return -ENOMEM;
journal_ratelimit_vacuum(*groups_by_id, ts);
r = ordered_hashmap_ensure_put(groups_by_id, &journal_ratelimit_group_hash_ops, g->id, g);
if (r < 0)
return r;
assert(r > 0);
g->groups_by_id = *groups_by_id;
*ret = TAKE_PTR(g);
return 0;
}
static int journal_ratelimit_group_acquire(
OrderedHashmap **groups_by_id,
const char *id,
usec_t interval,
usec_t ts,
JournalRateLimitGroup **ret) {
JournalRateLimitGroup *g;
assert(groups_by_id);
assert(id);
assert(ret);
g = ordered_hashmap_get(*groups_by_id, id);
if (!g)
return journal_ratelimit_group_new(groups_by_id, id, interval, ts, ret);
g->interval = interval;
*ret = g;
return 0;
}
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(
OrderedHashmap **groups_by_id,
const char *id,
usec_t rl_interval,
unsigned rl_burst,
int priority,
uint64_t available) {
JournalRateLimitGroup *g;
JournalRateLimitPool *p;
unsigned burst;
usec_t ts;
int r;
assert(groups_by_id);
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
*/
ts = now(CLOCK_MONOTONIC);
r = journal_ratelimit_group_acquire(groups_by_id, id, rl_interval, ts, &g);
if (r < 0)
return r;
if (rl_interval == 0 || rl_burst == 0)
return 1;
burst = burst_modulate(rl_burst, available);
p = &g->pools[priority_map[priority]];
if (p->begin <= 0) {
p->suppressed = 0;
p->num = 1;
p->begin = ts;
return 1;
}
if (usec_add(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;
}
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