asmhatre
a9867c0423
A Spring Boot 4.1.1 module whose test suite is the evidence for the article: 20 tests producing 22 transcripts under docs/output/, plus 12 documentation chapters. Findings the build pins: - @EnableCaching has no exposeProxy attribute; the widely-copied @EnableCaching(exposeProxy = true) does not compile. - Two methods sharing a cache name and an argument type share a key space, and one silently serves the other's answers. - The documented cache-provider detection order does not match CacheType's enum order in 4.1.1: COUCHBASE before INFINISPAN, and CACHE2K before CAFFEINE. - beforeInvocation = true is NOT deferred by TransactionAwareCacheManagerProxy on 7.0.9 - doEvict picks evictIfPresent, which the decorator does not intercept. - Four of five invalid declarations start a clean context and throw at the first call. - Caffeine on the classpath silently displaces the simple provider.
68 lines
2.6 KiB
Markdown
68 lines
2.6 KiB
Markdown
[← transactions](10-transactions.md) · [next: production checklist →](12-production-checklist.md)
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# 11. Seeing what is actually happening
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Most caching bugs stop being mysterious the moment you can see the keys. Four things to reach
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for, in order of how quickly they answer the question.
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## 1. Print the cache
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The diagnostic endpoint in this module walks the `CacheManager` and dumps every entry with the
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runtime class of the key and the value. `docs/output/23-diagnostics.txt`:
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```json
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"shapes": {
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"implementation": "org.springframework.cache.concurrent.ConcurrentMapCache",
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"nativeStore": "java.util.concurrent.ConcurrentHashMap",
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"entries": {
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"SimpleKey [] [SimpleKey]": "zero [String]",
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"SimpleKey [abc, 7] [SimpleKey]": "two:abc:7 [String]",
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"abc [String]": "one:abc [String]"
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}
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}
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```
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A `SimpleKey []` where you expected an id, two methods writing into one key space, or a
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`NullValue` sitting where a record should be — all visible at a glance.
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**Delete it before shipping.** It exposes cached data over HTTP with no authorisation. If you
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want something permanent, put it behind Actuator's security and return key counts rather than
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values.
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## 2. Is the bean even proxied?
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```java
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AopUtils.isAopProxy(bean) // false -> nothing downstream matters
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bean.getClass().getName() // ...$$SpringCGLIB$$0
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AopUtils.getTargetClass(bean)
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```
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If it is proxied and the cache is still empty, the call is not going through the proxy. See
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[chapter 3](03-self-invocation.md).
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## 3. Actuator
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`management.endpoints.web.exposure.include=caches` gives `/actuator/caches`, which lists the
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cache names and their `CacheManager` — enough to confirm which provider is live and whether a
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cache name is a typo. `DELETE /actuator/caches/{name}` clears one, which is a genuinely useful
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operational lever.
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`/actuator/metrics/cache.gets` and friends are populated automatically for providers Micrometer
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can instrument. **Caffeine only reports statistics if the cache was built with `recordStats()`**
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— without it the metrics exist and read zero, which looks exactly like a cache nobody is using.
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## 4. Turn the cache off
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```properties
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spring.cache.type=none
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```
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A `NoOpCacheManager`: every method runs every time, annotations untouched. If the bug survives,
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it was never the cache. This is the fastest bisect available and it takes one property.
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## Logging
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`logging.level.org.springframework.cache=TRACE` logs each operation the interceptor resolves.
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It is noisy enough that it is a debugging tool rather than something to leave on, but it answers
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"did the interceptor see this call at all" definitively.
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