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implemented different algorithms for maxmemory

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This commit is contained in:
antirez 2010-10-14 21:22:21 +02:00
parent ef59a8bc9e
commit 165346ca29
5 changed files with 175 additions and 7 deletions
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19
redis.conf
View File

@ -148,6 +148,25 @@ dir ./
#
# 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

44
src/config.c
View File

@ -123,6 +123,21 @@ void loadServerConfig(char *filename) {
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]);
@ -242,6 +257,20 @@ void configSetCommand(redisClient *c) {
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;
@ -358,6 +387,21 @@ void configGetCommand(redisClient *c) {
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];

5
src/object.c
View File

@ -443,8 +443,9 @@ char *strEncoding(int encoding) {
* 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;
}
}

104
src/redis.c
View File

@ -478,6 +478,10 @@ void activeExpireCycle(void) {
}
}
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++;
@ -491,14 +495,18 @@ int serverCron(struct aeEventLoop *eventLoop, long long id, void *clientData) {
* 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. */
@ -729,6 +737,8 @@ void initServerConfig() {
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 */
@ -742,6 +752,7 @@ void initServerConfig() {
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();
@ -1327,10 +1338,93 @@ int tryFreeOneObjectFromFreelist(void) {
* 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;

10
src/redis.h
View File

@ -198,6 +198,13 @@
#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)
@ -212,6 +219,7 @@ void _redisPanic(char *msg, char *file, int line);
/* 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 */
@ -391,6 +399,8 @@ struct redisServer {
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