@CacheEvict(allEntries=true) may delete newly inserted keys when beforeInvocation=false

[FULaBUla]

When using Spring Cache with Redis, we observed a potential issue with @CacheEvict(allEntries=true) in combination with @CachePut that leads to intermittent deletion of newly inserted keys.

Environment:

• Spring Boot: 4.0.6
• Redis: 8.6.2
• Redis: single node, TTL=-1 for all keys, non-clustered, single instance
• CacheWriter: default non-locking RedisCacheWriter
• Method visibility: public
• @CachePut return values are never null
• No transactions involved (@Transactional removed)

Steps to Reproduce:

1. Define an empty @CacheEvict method on a cacheName:

@CacheEvict(cacheNames = "xxx", allEntries = true)
public void clearCache() {}

2. Call clearCache() and then insert multiple items using @CachePut:

clearCache();
putCache(item1);
putCache(item2);

3. Use redis-cli MONITOR to track commands.

Observed Behavior:

• With beforeInvocation=false (default), the command sequence may be:

keys cacheName::*
set cacheName::item1 ...
unlink keys_from_snapshot
set cacheName::item2 ...

• The UNLINK command may asynchronously delete the newly inserted first item, causing it to disappear.

• This behavior occurs intermittently.

• When beforeInvocation=true, the command sequence becomes:

keys cacheName::*
del keys_from_snapshot
set cacheName::item1 ...
set cacheName::item2 ...

• In this case, all newly inserted items are preserved.

Questions:

• Why are the values of beforeInvocation being changed using two different instructions, namely DEL and UNLINK??
• Mechanically speaking, how exactly does UNLINK get inserted into the middle of the SET command for execution?
• Is this behavior documented or expected, and should beforeInvocation=true be recommended whenever using allEntries=true with Redis and non-locking CacheWriter?