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Implemented a much better lazy expiring algorithm for EXPIRE

This commit is contained in:
antirez 2009-11-10 17:48:01 +01:00
parent 060f6be6bf
commit f232429386
1 changed files with 12 additions and 4 deletions
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16
redis.c
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@ -940,14 +940,21 @@ static int serverCron(struct aeEventLoop *eventLoop, long long id, void *clientD
}
}
/* Try to expire a few timed out keys */
/* Try to expire a few timed out keys. The algorithm used is adaptive and
* will use few CPU cycles if there are few expiring keys, otherwise
* it will get more aggressive to avoid that too much memory is used by
* keys that can be removed from the keyspace. */
for (j = 0; j < server.dbnum; j++) {
int expired;
redisDb *db = server.db+j;
int num = dictSize(db->expires);
if (num) {
/* Continue to expire if at the end of the cycle more than 25%
* of the keys were expired. */
do {
int num = dictSize(db->expires);
time_t now = time(NULL);
expired = 0;
if (num > REDIS_EXPIRELOOKUPS_PER_CRON)
num = REDIS_EXPIRELOOKUPS_PER_CRON;
while (num--) {
@ -958,9 +965,10 @@ static int serverCron(struct aeEventLoop *eventLoop, long long id, void *clientD
t = (time_t) dictGetEntryVal(de);
if (now > t) {
deleteKey(db,dictGetEntryKey(de));
expired++;
}
}
}
} while (expired > REDIS_EXPIRELOOKUPS_PER_CRON/4);
}
/* Check if we should connect to a MASTER */