take a hashslot -> keys index, will be used for cluster rehasing

src/cluster.c

@@ -202,6 +202,7 @@ void clusterInit(void) {
     }
     if (aeCreateFileEvent(server.el, server.cfd, AE_READABLE,
         clusterAcceptHandler, NULL) == AE_ERR) oom("creating file event");
+    server.cluster.slots_to_keys = zslCreate();
 }
 
 /* -----------------------------------------------------------------------------

src/db.c

@@ -2,6 +2,9 @@
 
 #include <signal.h>
 
+void SlotToKeyAdd(robj *key);
+void SlotToKeyDel(robj *key);
+
 /*-----------------------------------------------------------------------------
  * C-level DB API
  *----------------------------------------------------------------------------*/
@@ -131,6 +134,7 @@ int dbAdd(redisDb *db, robj *key, robj *val) {
         sds copy = sdsdup(key->ptr);
         dictAdd(db->dict, copy, val);
         if (server.ds_enabled) cacheSetKeyMayExist(db,key);
+        if (server.cluster_enabled) SlotToKeyAdd(key);
         return REDIS_OK;
     }
 }
@@ -146,6 +150,7 @@ int dbReplace(redisDb *db, robj *key, robj *val) {
     if ((oldval = dictFetchValue(db->dict,key->ptr)) == NULL) {
         sds copy = sdsdup(key->ptr);
         dictAdd(db->dict, copy, val);
+        if (server.cluster_enabled) SlotToKeyAdd(key);
         retval = 1;
     } else {
         dictReplace(db->dict, key->ptr, val);
@@ -198,7 +203,12 @@ int dbDelete(redisDb *db, robj *key) {
     /* Deleting an entry from the expires dict will not free the sds of
      * the key, because it is shared with the main dictionary. */
     if (dictSize(db->expires) > 0) dictDelete(db->expires,key->ptr);
-    return dictDelete(db->dict,key->ptr) == DICT_OK;
+    if (dictDelete(db->dict,key->ptr) == DICT_OK) {
+        if (server.cluster_enabled) SlotToKeyDel(key);
+        return 1;
+    } else {
+        return 0;
+    }
 }
 
 /* Empty the whole database.
@@ -698,3 +708,31 @@ int *zunionInterGetKeys(struct redisCommand *cmd,robj **argv, int argc, int *num
     *numkeys = num;
     return keys;
 }
+
+/* Slot to Key API. This is used by Redis Cluster in order to obtain in
+ * a fast way a key that belongs to a specified hash slot. This is useful
+ * while rehashing the cluster. */
+void SlotToKeyAdd(robj *key) {
+    unsigned int hashslot = keyHashSlot(key->ptr,sdslen(key->ptr));
+
+    zslInsert(server.cluster.slots_to_keys,hashslot,key);
+    incrRefCount(key);
+}
+
+void SlotToKeyDel(robj *key) {
+    unsigned int hashslot = keyHashSlot(key->ptr,sdslen(key->ptr));
+
+    zslDelete(server.cluster.slots_to_keys,hashslot,key);
+}
+
+robj *GetKeyInSlot(unsigned int hashslot) {
+    zskiplistNode *n;
+    zrangespec range;
+
+    range.min = range.max = hashslot;
+    range.minex = range.maxex = 0;
+    
+    n = zslFirstInRange(server.cluster.slots_to_keys, range);
+    if (!n) return NULL;
+    return n->obj;
+}

src/redis.h

@@ -367,6 +367,28 @@ struct sharedObjectsStruct {
     *integers[REDIS_SHARED_INTEGERS];
 };
 
+/* ZSETs use a specialized version of Skiplists */
+typedef struct zskiplistNode {
+    robj *obj;
+    double score;
+    struct zskiplistNode *backward;
+    struct zskiplistLevel {
+        struct zskiplistNode *forward;
+        unsigned int span;
+    } level[];
+} zskiplistNode;
+
+typedef struct zskiplist {
+    struct zskiplistNode *header, *tail;
+    unsigned long length;
+    int level;
+} zskiplist;
+
+typedef struct zset {
+    dict *dict;
+    zskiplist *zsl;
+} zset;
+
 /*-----------------------------------------------------------------------------
  * Redis cluster data structures
  *----------------------------------------------------------------------------*/
@@ -425,6 +447,7 @@ typedef struct {
     clusterNode *migrating_slots_to[REDIS_CLUSTER_SLOTS];
     clusterNode *importing_slots_from[REDIS_CLUSTER_SLOTS];
     clusterNode *slots[REDIS_CLUSTER_SLOTS];
+    zskiplist *slots_to_keys;
 } clusterState;
 
 /* Redis cluster messages header */
@@ -627,6 +650,7 @@ struct redisServer {
     /* Misc */
     unsigned lruclock:22;        /* clock incrementing every minute, for LRU */
     unsigned lruclock_padding:10;
+    /* Cluster */
     int cluster_enabled;
     clusterState cluster;
 };
@@ -671,28 +695,6 @@ typedef struct _redisSortOperation {
     robj *pattern;
 } redisSortOperation;
 
-/* ZSETs use a specialized version of Skiplists */
-typedef struct zskiplistNode {
-    robj *obj;
-    double score;
-    struct zskiplistNode *backward;
-    struct zskiplistLevel {
-        struct zskiplistNode *forward;
-        unsigned int span;
-    } level[];
-} zskiplistNode;
-
-typedef struct zskiplist {
-    struct zskiplistNode *header, *tail;
-    unsigned long length;
-    int level;
-} zskiplist;
-
-typedef struct zset {
-    dict *dict;
-    zskiplist *zsl;
-} zset;
-
 /* DIsk store threaded I/O request message */
 #define REDIS_IOJOB_LOAD 0
 #define REDIS_IOJOB_SAVE 1
@@ -921,10 +923,19 @@ int startAppendOnly(void);
 void backgroundRewriteDoneHandler(int exitcode, int bysignal);
 
 /* Sorted sets data type */
+
+/* Struct to hold a inclusive/exclusive range spec. */
+typedef struct {
+    double min, max;
+    int minex, maxex; /* are min or max exclusive? */
+} zrangespec;
+
 zskiplist *zslCreate(void);
 void zslFree(zskiplist *zsl);
 zskiplistNode *zslInsert(zskiplist *zsl, double score, robj *obj);
 unsigned char *zzlInsert(unsigned char *zl, robj *ele, double score);
+int zslDelete(zskiplist *zsl, double score, robj *obj);
+zskiplistNode *zslFirstInRange(zskiplist *zsl, zrangespec range);
 double zzlGetScore(unsigned char *sptr);
 void zzlNext(unsigned char *zl, unsigned char **eptr, unsigned char **sptr);
 void zzlPrev(unsigned char *zl, unsigned char **eptr, unsigned char **sptr);

src/t_zset.c

@@ -174,12 +174,6 @@ int zslDelete(zskiplist *zsl, double score, robj *obj) {
     return 0; /* not found */
 }
 
-/* Struct to hold a inclusive/exclusive range spec. */
-typedef struct {
-    double min, max;
-    int minex, maxex; /* are min or max exclusive? */
-} zrangespec;
-
 static int zslValueGteMin(double value, zrangespec *spec) {
     return spec->minex ? (value > spec->min) : (value >= spec->min);
 }