TTL API change: TTL returns -2 for non existing keys.

The previous behavior was to return -1 if:

1) Existing key but without an expire set.
2) Non existing key.

Now the second case is handled in a different, and TTL will return -2
if the key does not exist at all.

PTTL follows the same behavior as well.

1 files changed, 7 insertions, 0 deletions

diff --git a/src/db.c b/src/db.c
index 9fe9a003c..a73d1fbf5 100644
--- a/src/db.c
+++ b/src/db.c
@@ -614,6 +614,13 @@ void ttlGenericCommand(redisClient *c, int output_ms) {
     long long expire, ttl = -1;
 
     expire = getExpire(c->db,c->argv[1]);
+    /* If the key does not exist at all, return -2 */
+    if (expire == -1 && lookupKeyRead(c->db,c->argv[1]) == NULL) {
+        addReplyLongLong(c,-2);
+        return;
+    }
+    /* The key exists. Return -1 if it has no expire, or the actual
+     * TTL value otherwise. */
     if (expire != -1) {
         ttl = expire-mstime();
         if (ttl < 0) ttl = -1;