Data gets corrupted when incrby happens on a key after TTL expires

[pszabop]

Describe the bug

When a key expires, and then I attempt to increment it with the value of 0 (INCRBY), the key becomes corrupted.

I have a program that increments the key by zero if the key does not exist, and it has events every few seconds that cause this logic chain to execute Here's the output of manually polling that entry while this happens using a redis CLI client:

You can see the TTL count down, the value go to nil and the TTL to -2 as expected, but when the program attemps to incr by zero you can see a garbage value appear. That key is now permanently corrupted, it never recovers unless I flush the database or DEL that key.

garnetlocal:6379> ttl session:ae5d5924-2304-4037-99d2-c546fcf1a22c
(integer) 5
garnetlocal:6379> get session:ae5d5924-2304-4037-99d2-c546fcf1a22c
"0"
garnetlocal:6379> ttl session:ae5d5924-2304-4037-99d2-c546fcf1a22c
(integer) 4
garnetlocal:6379> get session:ae5d5924-2304-4037-99d2-c546fcf1a22c
"0"
garnetlocal:6379> ttl session:ae5d5924-2304-4037-99d2-c546fcf1a22c
(integer) 2
garnetlocal:6379> get session:ae5d5924-2304-4037-99d2-c546fcf1a22c
"0"
garnetlocal:6379> ttl session:ae5d5924-2304-4037-99d2-c546fcf1a22c
(integer) 0
garnetlocal:6379> get session:ae5d5924-2304-4037-99d2-c546fcf1a22c
(nil)
garnetlocal:6379> ttl session:ae5d5924-2304-4037-99d2-c546fcf1a22c
(integer) -2
garnetlocal:6379> get session:ae5d5924-2304-4037-99d2-c546fcf1a22c
(nil)
garnetlocal:6379> get session:ae5d5924-2304-4037-99d2-c546fcf1a22c
(nil)
garnetlocal:6379> get session:ae5d5924-2304-4037-99d2-c546fcf1a22c
"0V\xdcQ\xf3\x1a\xdd\b0"

Steps to reproduce the bug

1. INCRBY some random key by zero and set its TTL to some number (say 30).
2. GET the key every second for its value and TTL and watch as the TTL decrements down to zero
3. After the key times out, INCR it by zero and set its TTL in a manner identical to step (1).
4. You should observe garbage value in the key. Also, there is an error when trying to increment a non-integer value

Expected behavior

At step 4 when incrementing a (nil) entry I should get a value of zero in the key

Screenshots

No response

Release version

GarnetServer --version gives me an error, so here's the docker container info instead

           "Labels": {
                "org.opencontainers.image.created": "2024-09-30T19:25:02.511Z",
                "org.opencontainers.image.description": "Garnet is a remote cache-store from Microsoft Research that offers strong performance (throughput and latency), scalability, storage, recovery, cluster sharding, key migration, and replication features. Garnet can work with existing Redis clients.",
                "org.opencontainers.image.licenses": "MIT",
                "org.opencontainers.image.revision": "64636ce1efd6486b5d9e553bc3f6c364710c1b36",
                "org.opencontainers.image.source": "https://github.com/microsoft/garnet",
                "org.opencontainers.image.title": "garnet",
                "org.opencontainers.image.url": "https://github.com/microsoft/garnet",
                "org.opencontainers.image.version": "main"
            }

IDE

No response

OS version

Docker Engine: 20.10.17 (on OSX)

Additional context

I'm using rust's client API with a pipeline. This bug does not reproduce on redict 7.1.3

[Vijay-Nirmal]

I tried to reproduce it but I am not able to. Below is my attempt to reproduce it. Let me know if I did something wrong

127.0.0.1:6379> SET key 5
OK
127.0.0.1:6379> INCRBY key 0
(integer) 5
127.0.0.1:6379> EXPIRE key 30
(integer) 1
127.0.0.1:6379> GET key
"5"
127.0.0.1:6379> TTL key
(integer) 17
127.0.0.1:6379> GET key
"5"
127.0.0.1:6379> TTL key
(integer) 6
127.0.0.1:6379> TTL key
(integer) 0
127.0.0.1:6379> GET key
(nil)
127.0.0.1:6379> TTL key
(integer) -2
127.0.0.1:6379> INCRBY key 0
(integer) 0
127.0.0.1:6379> EXPIRE key 30
(integer) 1
127.0.0.1:6379> GET key
"0"
127.0.0.1:6379> GET key
"0"

[badrishc]

If you are not able to provide a sequence of redis-cli commands that reproduces this error then:

• Are you able to build Garnet and paste server side logs here? Here is the change to make, then rebuild, and use that as your server to generate the repro: Conflict with Spring Data Redis with spring boot 3.3 #811 (comment)

[pszabop]

Maybe it has something to do with the pipelined commands. When I get a chance I'll try running redis-cli with --pipe

here's the Rust code that shows the pipeline command used

let _: () = redis::pipe().incr(session_key.as_ref().unwrap(), recording_score).expire(session_key.as_ref().unwrap(), self.session_blocking_ttl as i64).query_async(&mut con).await.unwrap();