Expire cycle: introduce the new state needed for the new algo.

src/db.c

@@ -1077,10 +1077,12 @@ int dbSwapDatabases(long id1, long id2) {
     db1->dict = db2->dict;
     db1->expires = db2->expires;
     db1->avg_ttl = db2->avg_ttl;
+    db1->expires_cursor = db2->expires_cursor;
 
     db2->dict = aux.dict;
     db2->expires = aux.expires;
     db2->avg_ttl = aux.avg_ttl;
+    db2->expires_cursor = aux.expires_cursor;
 
     /* Now we need to handle clients blocked on lists: as an effect
      * of swapping the two DBs, a client that was waiting for list

src/expire.c

@@ -95,6 +95,10 @@ int activeExpireCycleTryExpire(redisDb *db, dictEntry *de, long long now) {
  * executed, where the time limit is a percentage of the REDIS_HZ period
  * as specified by the ACTIVE_EXPIRE_CYCLE_SLOW_TIME_PERC define. */
 
+#define ACTIVE_EXPIRE_CYCLE_LOOKUPS_PER_LOOP 20 /* Loopkups per loop. */
+#define ACTIVE_EXPIRE_CYCLE_FAST_DURATION 1000 /* Microseconds. */
+#define ACTIVE_EXPIRE_CYCLE_SLOW_TIME_PERC 25 /* Percentage of CPU to use. */
+
 void activeExpireCycle(int type) {
     /* This function has some global state in order to continue the work
      * incrementally across calls. */
@@ -231,6 +235,7 @@ void activeExpireCycle(int type) {
     }
 
     elapsed = ustime()-start;
+    server.stat_expire_cycle_time_used += elapsed;
     latencyAddSampleIfNeeded("expire-cycle",elapsed/1000);
 
     /* Update our estimate of keys existing but yet to be expired.

src/server.c

@@ -2745,6 +2745,7 @@ void resetServerStats(void) {
     server.stat_expiredkeys = 0;
     server.stat_expired_stale_perc = 0;
     server.stat_expired_time_cap_reached_count = 0;
+    server.stat_expire_cycle_time_used = 0;
     server.stat_evictedkeys = 0;
     server.stat_keyspace_misses = 0;
     server.stat_keyspace_hits = 0;
@@ -2848,6 +2849,7 @@ void initServer(void) {
     for (j = 0; j < server.dbnum; j++) {
         server.db[j].dict = dictCreate(&dbDictType,NULL);
         server.db[j].expires = dictCreate(&keyptrDictType,NULL);
+        server.db[j].expires_cursor = 0;
         server.db[j].blocking_keys = dictCreate(&keylistDictType,NULL);
         server.db[j].ready_keys = dictCreate(&objectKeyPointerValueDictType,NULL);
         server.db[j].watched_keys = dictCreate(&keylistDictType,NULL);

src/server.h

@@ -180,9 +180,6 @@ typedef long long ustime_t; /* microsecond time type. */
 #define CONFIG_DEFAULT_PROTO_MAX_BULK_LEN (512ll*1024*1024) /* Bulk request max size */
 #define CONFIG_DEFAULT_TRACKING_TABLE_MAX_FILL 10 /* 10% tracking table max fill. */
 
-#define ACTIVE_EXPIRE_CYCLE_LOOKUPS_PER_LOOP 20 /* Loopkups per loop. */
-#define ACTIVE_EXPIRE_CYCLE_FAST_DURATION 1000 /* Microseconds */
-#define ACTIVE_EXPIRE_CYCLE_SLOW_TIME_PERC 25 /* CPU max % for keys collection */
 #define ACTIVE_EXPIRE_CYCLE_SLOW 0
 #define ACTIVE_EXPIRE_CYCLE_FAST 1
 
@@ -721,6 +718,7 @@ typedef struct redisDb {
     dict *watched_keys;         /* WATCHED keys for MULTI/EXEC CAS */
     int id;                     /* Database ID */
     long long avg_ttl;          /* Average TTL, just for stats */
+    unsigned long expires_cursor; /* Cursor of the active expire cycle. */
     list *defrag_later;         /* List of key names to attempt to defrag one by one, gradually. */
 } redisDb;
 
@@ -1167,6 +1165,7 @@ struct redisServer {
     long long stat_expiredkeys;     /* Number of expired keys */
     double stat_expired_stale_perc; /* Percentage of keys probably expired */
     long long stat_expired_time_cap_reached_count; /* Early expire cylce stops.*/
+    long long stat_expire_cycle_time_used; /* Cumulative microseconds used. */
     long long stat_evictedkeys;     /* Number of evicted keys (maxmemory) */
     long long stat_keyspace_hits;   /* Number of successful lookups of keys */
     long long stat_keyspace_misses; /* Number of failed lookups of keys */