[← transactions](10-transactions.md) · [next: production checklist →](12-production-checklist.md)

# 11. Seeing what is actually happening

Most caching bugs stop being mysterious the moment you can see the keys. Four things to reach
for, in order of how quickly they answer the question.

## 1. Print the cache

The diagnostic endpoint in this module walks the `CacheManager` and dumps every entry with the
runtime class of the key and the value. `docs/output/23-diagnostics.txt`:

```json
"shapes": {
    "implementation": "org.springframework.cache.concurrent.ConcurrentMapCache",
    "nativeStore": "java.util.concurrent.ConcurrentHashMap",
    "entries": {
        "SimpleKey []   [SimpleKey]": "zero   [String]",
        "SimpleKey [abc, 7]   [SimpleKey]": "two:abc:7   [String]",
        "abc   [String]": "one:abc   [String]"
    }
}
```

A `SimpleKey []` where you expected an id, two methods writing into one key space, or a
`NullValue` sitting where a record should be — all visible at a glance.

**Delete it before shipping.** It exposes cached data over HTTP with no authorisation. If you
want something permanent, put it behind Actuator's security and return key counts rather than
values.

## 2. Is the bean even proxied?

```java
AopUtils.isAopProxy(bean)          // false -> nothing downstream matters
bean.getClass().getName()          // ...$$SpringCGLIB$$0
AopUtils.getTargetClass(bean)
```

If it is proxied and the cache is still empty, the call is not going through the proxy. See
[chapter 3](03-self-invocation.md).

## 3. Actuator

`management.endpoints.web.exposure.include=caches` gives `/actuator/caches`, which lists the
cache names and their `CacheManager` — enough to confirm which provider is live and whether a
cache name is a typo. `DELETE /actuator/caches/{name}` clears one, which is a genuinely useful
operational lever.

`/actuator/metrics/cache.gets` and friends are populated automatically for providers Micrometer
can instrument. **Caffeine only reports statistics if the cache was built with `recordStats()`**
— without it the metrics exist and read zero, which looks exactly like a cache nobody is using.

## 4. Turn the cache off

```properties
spring.cache.type=none
```

A `NoOpCacheManager`: every method runs every time, annotations untouched. If the bug survives,
it was never the cache. This is the fastest bisect available and it takes one property.

## Logging

`logging.level.org.springframework.cache=TRACE` logs each operation the interceptor resolves.
It is noisy enough that it is a debugging tool rather than something to leave on, but it answers
"did the interceptor see this call at all" definitively.