I’m using the spring-boot spring-data-redis 1.8.9.RELEASE RedisCacheManager implementation of CacheManager for caching. One metric that I want visibility into is the cache hit/miss ratio. To get that, I’m extracting the keyspace_hits and keyspace_misses exposed via the redis server which can also be viewed via the redis_cli with INFO STATS. The problem is that RedisCacheManager never registers cache misses, i.e. keyspace_misses never increments even if there is a cache "miss".
Debugging the code, I see that spring-data-redis actually checks to see if the key EXISTS in redis before retrieving it. I see the sense with this approach however when EXISTS is executed against the redis server, it does not register a cache miss.
Is there any way to use RedisCacheManager and register cache misses? I know I can use other redis objects to accomplish this but I was wondering if it could be done with the standard CacheManager implementation?
Edit
The ideal solution won't add a great deal of overhead and I am unable to edit the configuration of the redis server.
Code that RedisCacheManager uses when retrieving an element from cache. Notice Boolean exists:
public RedisCacheElement get(final RedisCacheKey cacheKey) { Assert.notNull(cacheKey, "CacheKey must not be null!"); Boolean exists = (Boolean)this.redisOperations.execute(new RedisCallback<Boolean>() { public Boolean doInRedis(RedisConnection connection) throws DataAccessException { return connection.exists(cacheKey.getKeyBytes()); } }); return !exists ? null : new RedisCacheElement(cacheKey, this.fromStoreValue(this.lookup(cacheKey))); } The above code will execute these commands on redis viewable via MONITOR on a cache miss. Notice again that EXISTS is executed as per the code:
After the above commands are executed, keyspace_misses is not incremented even though there was a cache miss:
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