EXISTS is now variadic.

The new return value is the number of keys existing, among the ones
specified in the command line, counting the same key multiple times if
given multiple times (and if it exists).

See PR #2667.

src/db.c

@@ -318,13 +318,17 @@ void delCommand(redisClient *c) {
     addReplyLongLong(c,deleted);
 }
 
+/* EXISTS key1 key2 ... key_N.
+ * Return value is the number of keys existing. */
 void existsCommand(redisClient *c) {
-    expireIfNeeded(c->db,c->argv[1]);
-    if (dbExists(c->db,c->argv[1])) {
-        addReply(c, shared.cone);
-    } else {
-        addReply(c, shared.czero);
+    long long count = 0;
+    int j;
+
+    for (j = 1; j < c->argc; j++) {
+        expireIfNeeded(c->db,c->argv[j]);
+        if (dbExists(c->db,c->argv[j])) count++;
     }
+    addReplyLongLong(c,count);
 }
 
 void selectCommand(redisClient *c) {

src/redis.c

@@ -132,7 +132,7 @@ struct redisCommand redisCommandTable[] = {
     {"append",appendCommand,3,"wm",0,NULL,1,1,1,0,0},
     {"strlen",strlenCommand,2,"rF",0,NULL,1,1,1,0,0},
     {"del",delCommand,-2,"w",0,NULL,1,-1,1,0,0},
-    {"exists",existsCommand,2,"rF",0,NULL,1,1,1,0,0},
+    {"exists",existsCommand,-2,"rF",0,NULL,1,-1,1,0,0},
     {"setbit",setbitCommand,4,"wm",0,NULL,1,1,1,0,0},
     {"getbit",getbitCommand,3,"rF",0,NULL,1,1,1,0,0},
     {"setrange",setrangeCommand,4,"wm",0,NULL,1,1,1,0,0},