Return stale values if there's an exception thrown

[jonaspero]

Hi,

I use Caffeine combined with Spring Boot.
My current code looks like this:

    @Bean("tenMinuteCache")
    fun shortCache(): CacheManager =
        object : ConcurrentMapCacheManager() {
            override fun createConcurrentMapCache(name: String): Cache {
                val concurrentMap =
                    Caffeine
                        .newBuilder()
                        .maximumSize(1000)
                        .expireAfterWrite(10, TimeUnit.MINUTES)
                        .recordStats()
                        .build<Any, Any>()
                        .asMap()
                return ConcurrentMapCache(name, concurrentMap, true)
            }
        }


    @Cacheable("alle-country", cacheManager = "tenMinuteCache")
    fun retrieveCountry(): CountryDto {
        val uri = URI.create("$uri/countries")

        return getCountry {
            getForEntity(uri)
        }
    }

The issue is that sometimes retrieveCountry will throw an exception.
Is there a way to return stale, last value from the cache if this happens?

[ben-manes]

It sounds like you want to also use refreshAfterWrite. This allows the entry to be reloaded asynchronously and return the stale value, while using expiration to evict if inactive and beyond a usability threshold. Unfortunately this is not supported by Spring (spring-projects/spring-boot#41762), so you would need to use our APIs directly.