Add new commands ZDIFF and ZDIFFSTORE

redis.conf

@@ -891,14 +891,12 @@ acllog-max-len 128
 # Both LRU, LFU and volatile-ttl are implemented using approximated
 # randomized algorithms.
 #
-# Note: with any of the above policies, Redis will return an error on write
-#       operations, when there are no suitable keys for eviction.
-#
-#       At the date of writing these commands are: set setnx setex append
-#       incr decr rpush lpush rpushx lpushx linsert lset rpoplpush sadd
-#       sinter sinterstore sunion sunionstore sdiff sdiffstore zadd zincrby
-#       zunionstore zinterstore hset hsetnx hmset hincrby incrby decrby
-#       getset mset msetnx exec sort
+# Note: with any of the above policies, when there are no suitable keys for
+# eviction, Redis will return an error on write operations that require
+# more memory. These are usually commands that create new keys, add data or
+# modify existing keys. A few examples are: SET, INCR, HSET, LPUSH, SUNIONSTORE,
+# SORT (due to the STORE argument), and EXEC (if the transaction includes any
+# command that requires memory).
 #
 # The default is:
 #

src/db.c

@@ -1441,12 +1441,12 @@ int genericGetKeys(int storeKeyOfs, int keyCountOfs, int firstKeyOfs, int keySte
     return result->numkeys;
 }
 
-int zunionInterStoreGetKeys(struct redisCommand *cmd, robj **argv, int argc, getKeysResult *result) {
+int zunionInterDiffStoreGetKeys(struct redisCommand *cmd, robj **argv, int argc, getKeysResult *result) {
     UNUSED(cmd);
     return genericGetKeys(1, 2, 3, 1, argv, argc, result);
 }
 
-int zunionInterGetKeys(struct redisCommand *cmd, robj **argv, int argc, getKeysResult *result) {
+int zunionInterDiffGetKeys(struct redisCommand *cmd, robj **argv, int argc, getKeysResult *result) {
     UNUSED(cmd);
     return genericGetKeys(0, 1, 2, 1, argv, argc, result);
 }

src/server.c

@@ -436,19 +436,27 @@ struct redisCommand redisCommandTable[] = {
 
     {"zunionstore",zunionstoreCommand,-4,
      "write use-memory @sortedset",
-     0,zunionInterStoreGetKeys,0,0,0,0,0,0},
+     0,zunionInterDiffStoreGetKeys,0,0,0,0,0,0},
 
     {"zinterstore",zinterstoreCommand,-4,
      "write use-memory @sortedset",
-     0,zunionInterStoreGetKeys,0,0,0,0,0,0},
+     0,zunionInterDiffStoreGetKeys,0,0,0,0,0,0},
+
+    {"zdiffstore",zdiffstoreCommand,-4,
+     "write use-memory @sortedset",
+     0,zunionInterDiffStoreGetKeys,0,0,0,0,0,0},
 
     {"zunion",zunionCommand,-3,
      "read-only @sortedset",
-     0,zunionInterGetKeys,0,0,0,0,0,0},
+     0,zunionInterDiffGetKeys,0,0,0,0,0,0},
 
     {"zinter",zinterCommand,-3,
      "read-only @sortedset",
-     0,zunionInterGetKeys,0,0,0,0,0,0},
+     0,zunionInterDiffGetKeys,0,0,0,0,0,0},
+
+    {"zdiff",zdiffCommand,-3,
+     "read-only @sortedset",
+     0,zunionInterDiffGetKeys,0,0,0,0,0,0},
 
     {"zrange",zrangeCommand,-4,
      "read-only @sortedset",

src/server.h

@@ -2197,8 +2197,8 @@ void freeObjAsync(robj *o);
 int *getKeysPrepareResult(getKeysResult *result, int numkeys);
 int getKeysFromCommand(struct redisCommand *cmd, robj **argv, int argc, getKeysResult *result);
 void getKeysFreeResult(getKeysResult *result);
-int zunionInterGetKeys(struct redisCommand *cmd,robj **argv, int argc, getKeysResult *result);
-int zunionInterStoreGetKeys(struct redisCommand *cmd,robj **argv, int argc, getKeysResult *result);
+int zunionInterDiffGetKeys(struct redisCommand *cmd,robj **argv, int argc, getKeysResult *result);
+int zunionInterDiffStoreGetKeys(struct redisCommand *cmd,robj **argv, int argc, getKeysResult *result);
 int evalGetKeys(struct redisCommand *cmd, robj **argv, int argc, getKeysResult *result);
 int sortGetKeys(struct redisCommand *cmd, robj **argv, int argc, getKeysResult *result);
 int migrateGetKeys(struct redisCommand *cmd, robj **argv, int argc, getKeysResult *result);
@@ -2417,8 +2417,10 @@ void hstrlenCommand(client *c);
 void zremrangebyrankCommand(client *c);
 void zunionstoreCommand(client *c);
 void zinterstoreCommand(client *c);
+void zdiffstoreCommand(client *c);
 void zunionCommand(client *c);
 void zinterCommand(client *c);
+void zdiffCommand(client *c);
 void zscanCommand(client *c);
 void hkeysCommand(client *c);
 void hvalsCommand(client *c);