#
# maxmemory <bytes>
+# MAXMEMORY POLICY: how Redis will select what to remove when maxmemory
+# is reached? You can select among five behavior:
+#
+# volatile-lru -> remove the key with an expire set using an LRU algorithm
+# allkeys-lru -> remove any key accordingly to the LRU algorithm
+# volatile-random -> remove a random key with an expire set
+# allkeys->random -> remove a random key, any key
+# volatile-ttl -> remove the key with the nearest expire time (minor TTL)
+#
+# maxmemory-policy volatile-lru
+
+# LRU and minimal TTL algorithms are not precise algorithms but approximated
+# algorithms (in order to save memory), so you can select as well the sample
+# size to check. For instance for default Redis will check three keys and
+# pick the one that was used less recently, you can change the sample size
+# using the following configuration directive.
+#
+# maxmemory-sample 3
+
############################## APPEND ONLY MODE ###############################
# By default Redis asynchronously dumps the dataset on disk. If you can live
server.maxclients = atoi(argv[1]);
} else if (!strcasecmp(argv[0],"maxmemory") && argc == 2) {
server.maxmemory = memtoll(argv[1],NULL);
+ } else if (!strcasecmp(argv[0],"maxmemory-policy") && argc == 2) {
+ if (!strcasecmp(argv[1],"volatile-lru")) {
+ server.maxmemory_policy = REDIS_MAXMEMORY_VOLATILE_LRU;
+ } else if (!strcasecmp(argv[1],"volatile-random")) {
+ server.maxmemory_policy = REDIS_MAXMEMORY_VOLATILE_RANDOM;
+ } else if (!strcasecmp(argv[1],"volatile-ttl")) {
+ server.maxmemory_policy = REDIS_MAXMEMORY_VOLATILE_TTL;
+ } else if (!strcasecmp(argv[1],"allkeys-lru")) {
+ server.maxmemory_policy = REDIS_MAXMEMORY_ALLKEYS_LRU;
+ } else if (!strcasecmp(argv[1],"allkeys-random")) {
+ server.maxmemory_policy = REDIS_MAXMEMORY_ALLKEYS_RANDOM;
+ } else {
+ err = "Invalid maxmemory policy";
+ goto loaderr;
+ }
} else if (!strcasecmp(argv[0],"slaveof") && argc == 3) {
server.masterhost = sdsnew(argv[1]);
server.masterport = atoi(argv[2]);
ll < 0) goto badfmt;
server.maxmemory = ll;
if (server.maxmemory) freeMemoryIfNeeded();
+ } else if (!strcasecmp(c->argv[2]->ptr,"maxmemory-policy")) {
+ if (!strcasecmp(o->ptr,"volatile-lru")) {
+ server.maxmemory_policy = REDIS_MAXMEMORY_VOLATILE_LRU;
+ } else if (!strcasecmp(o->ptr,"volatile-random")) {
+ server.maxmemory_policy = REDIS_MAXMEMORY_VOLATILE_RANDOM;
+ } else if (!strcasecmp(o->ptr,"volatile-ttl")) {
+ server.maxmemory_policy = REDIS_MAXMEMORY_VOLATILE_TTL;
+ } else if (!strcasecmp(o->ptr,"allkeys-lru")) {
+ server.maxmemory_policy = REDIS_MAXMEMORY_ALLKEYS_LRU;
+ } else if (!strcasecmp(o->ptr,"allkeys-random")) {
+ server.maxmemory_policy = REDIS_MAXMEMORY_ALLKEYS_RANDOM;
+ } else {
+ goto badfmt;
+ }
} else if (!strcasecmp(c->argv[2]->ptr,"timeout")) {
if (getLongLongFromObject(o,&ll) == REDIS_ERR ||
ll < 0 || ll > LONG_MAX) goto badfmt;
addReplyBulkCString(c,buf);
matches++;
}
+ if (stringmatch(pattern,"maxmemory-policy",0)) {
+ char *s;
+
+ switch(server.maxmemory_policy) {
+ case REDIS_MAXMEMORY_VOLATILE_LRU: s = "volatile-lru"; break;
+ case REDIS_MAXMEMORY_VOLATILE_TTL: s = "volatile-ttl"; break;
+ case REDIS_MAXMEMORY_VOLATILE_RANDOM: s = "volatile-random"; break;
+ case REDIS_MAXMEMORY_ALLKEYS_LRU: s = "allkeys-lru"; break;
+ case REDIS_MAXMEMORY_ALLKEYS_RANDOM: s = "allkeys-random"; break;
+ default: s = "unknown"; break; /* too harmless to panic */
+ }
+ addReplyBulkCString(c,"maxmemory-policy");
+ addReplyBulkCString(c,s);
+ matches++;
+ }
if (stringmatch(pattern,"timeout",0)) {
char buf[128];
* requested, using an approximated LRU algorithm. */
unsigned long estimateObjectIdleTime(robj *o) {
if (server.lruclock >= o->lru) {
- return (server.lruclock - o->lru) * 60;
+ return (server.lruclock - o->lru) * REDIS_LRU_CLOCK_RESOLUTION;
} else {
- return ((REDIS_LRU_CLOCK_MAX - o->lru) + server.lruclock) * 60;
+ return ((REDIS_LRU_CLOCK_MAX - o->lru) + server.lruclock) *
+ REDIS_LRU_CLOCK_RESOLUTION;
}
}
}
}
+void updateLRUClock(void) {
+ server.lruclock = (time(NULL)/REDIS_LRU_CLOCK_RESOLUTION) &
+ REDIS_LRU_CLOCK_MAX;
+}
int serverCron(struct aeEventLoop *eventLoop, long long id, void *clientData) {
int j, loops = server.cronloops++;
* To access a global var is faster than calling time(NULL) */
server.unixtime = time(NULL);
/* We have just 22 bits per object for LRU information.
- * So we use an (eventually wrapping) LRU clock with minutes resolution.
- * 2^22 minutes are more than 7 years.
+ * So we use an (eventually wrapping) LRU clock with 10 seconds resolution.
+ * 2^22 bits with 10 seconds resoluton is more or less 1.5 years.
*
- * Note that even if this will wrap after 7 years it's not a problem,
+ * Note that even if this will wrap after 1.5 years it's not a problem,
* everything will still work but just some object will appear younger
- * to Redis :)
+ * to Redis. But for this to happen a given object should never be touched
+ * for 1.5 years.
+ *
+ * Note that you can change the resolution altering the
+ * REDIS_LRU_CLOCK_RESOLUTION define.
*/
- server.lruclock = (time(NULL)/60) & REDIS_LRU_CLOCK_MAX;
+ updateLRUClock();
/* We received a SIGTERM, shutting down here in a safe way, as it is
* not ok doing so inside the signal handler. */
server.maxclients = 0;
server.blpop_blocked_clients = 0;
server.maxmemory = 0;
+ server.maxmemory_policy = REDIS_MAXMEMORY_VOLATILE_LRU;
+ server.maxmemory_samples = 3;
server.vm_enabled = 0;
server.vm_swap_file = zstrdup("/tmp/redis-%p.vm");
server.vm_page_size = 256; /* 256 bytes per page */
server.list_max_ziplist_value = REDIS_LIST_MAX_ZIPLIST_VALUE;
server.set_max_intset_entries = REDIS_SET_MAX_INTSET_ENTRIES;
server.shutdown_asap = 0;
+ updateLRUClock();
resetServerSaveParams();
* memory usage.
*/
void freeMemoryIfNeeded(void) {
+ /* Remove keys accordingly to the active policy as long as we are
+ * over the memory limit. */
while (server.maxmemory && zmalloc_used_memory() > server.maxmemory) {
int j, k, freed = 0;
+ /* Basic strategy -- remove objects from the free list. */
if (tryFreeOneObjectFromFreelist() == REDIS_OK) continue;
+
+ for (j = 0; j < server.dbnum; j++) {
+ long bestval;
+ sds bestkey = NULL;
+ struct dictEntry *de;
+ redisDb *db = server.db+j;
+ dict *dict;
+
+ if (server.maxmemory_policy == REDIS_MAXMEMORY_ALLKEYS_LRU ||
+ server.maxmemory_policy == REDIS_MAXMEMORY_ALLKEYS_RANDOM)
+ {
+ dict = server.db[j].dict;
+ } else {
+ dict = server.db[j].expires;
+ }
+ if (dictSize(dict) == 0) continue;
+
+ /* volatile-random and allkeys-random policy */
+ if (server.maxmemory_policy == REDIS_MAXMEMORY_ALLKEYS_RANDOM ||
+ server.maxmemory_policy == REDIS_MAXMEMORY_VOLATILE_RANDOM)
+ {
+ de = dictGetRandomKey(dict);
+ bestkey = dictGetEntryKey(de);
+ }
+
+ /* volatile-lru and allkeys-lru policy */
+ else if (server.maxmemory_policy == REDIS_MAXMEMORY_ALLKEYS_LRU ||
+ server.maxmemory_policy == REDIS_MAXMEMORY_VOLATILE_LRU)
+ {
+ for (k = 0; k < server.maxmemory_samples; k++) {
+ sds thiskey;
+ long thisval;
+ robj *o;
+
+ de = dictGetRandomKey(dict);
+ thiskey = dictGetEntryKey(de);
+ o = dictGetEntryVal(de);
+ thisval = estimateObjectIdleTime(o);
+
+ /* Higher idle time is better candidate for deletion */
+ if (bestkey == NULL || thisval > bestval) {
+ bestkey = thiskey;
+ bestval = thisval;
+ }
+ }
+ }
+
+ /* volatile-ttl */
+ else if (server.maxmemory_policy == REDIS_MAXMEMORY_VOLATILE_TTL) {
+ for (k = 0; k < server.maxmemory_samples; k++) {
+ sds thiskey;
+ long thisval;
+
+ de = dictGetRandomKey(dict);
+ thiskey = dictGetEntryKey(de);
+ thisval = (long) dictGetEntryVal(de);
+
+ /* Expire sooner (minor expire unix timestamp) is better
+ * candidate for deletion */
+ if (bestkey == NULL || thisval < bestval) {
+ bestkey = thiskey;
+ bestval = thisval;
+ }
+ }
+ }
+
+ /* Finally remove the selected key. */
+ if (bestkey) {
+ robj *keyobj = createStringObject(bestkey,sdslen(bestkey));
+ dbDelete(db,keyobj);
+ server.stat_expiredkeys++;
+ decrRefCount(keyobj);
+ freed++;
+ }
+ }
+ if (!freed) return; /* nothing to free... */
+ }
+
+ while(0) {
+ int j, k, freed = 0;
for (j = 0; j < server.dbnum; j++) {
int minttl = -1;
sds minkey = NULL;
#define REDIS_OP_DIFF 1
#define REDIS_OP_INTER 2
+/* Redis maxmemory strategies */
+#define REDIS_MAXMEMORY_VOLATILE_LRU 0
+#define REDIS_MAXMEMORY_VOLATILE_TTL 1
+#define REDIS_MAXMEMORY_VOLATILE_RANDOM 2
+#define REDIS_MAXMEMORY_ALLKEYS_LRU 3
+#define REDIS_MAXMEMORY_ALLKEYS_RANDOM 4
+
/* We can print the stacktrace, so our assert is defined this way: */
#define redisAssert(_e) ((_e)?(void)0 : (_redisAssert(#_e,__FILE__,__LINE__),_exit(1)))
#define redisPanic(_e) _redisPanic(#_e,__FILE__,__LINE__),_exit(1)
/* The actual Redis Object */
#define REDIS_LRU_CLOCK_MAX ((1<<21)-1) /* Max value of obj->lru */
+#define REDIS_LRU_CLOCK_RESOLUTION 10 /* LRU clock resolution in seconds */
typedef struct redisObject {
unsigned type:4;
unsigned storage:2; /* REDIS_VM_MEMORY or REDIS_VM_SWAPPING */
int replstate;
unsigned int maxclients;
unsigned long long maxmemory;
+ int maxmemory_policy;
+ int maxmemory_samples;
unsigned int blpop_blocked_clients;
unsigned int vm_blocked_clients;
/* Sort parameters - qsort_r() is only available under BSD so we
projects / redis.git / commitdiff
