entitycache

A simple entity in-mem synchronised cache with TTL, TTR and LFU policies, based on Ristretto.

Basic usage

// Declares a new entity cache limited to 10000 entries, with a 5 minutes time to refresh and a 10 minutes time to live.// It exposes a Prometheus metric named "entity_cache_hit_total" with the labels "namespace" and "hit".cache, err:=entitycache.New(10000, 5*time.Minute, 10*time.Minute, "entity_cache_hit_total")
iferr!=nil {
panic(err)
}
// Let's say we want to cache the document with the ID 128.documentID:=128document, ok, err:=cache.Get(ctx, "documents", fmt.Sprintf("%d", documentID), func(ctx context.Context) (valueinterface{}, okbool, errerror) {
document, err:=getDocumentByID(ctx, documentID)
iferr!=nil {
iferr==sql.ErrNoRows {
returnnil, false, nil
}
returnnil, false, err
}
returndocument, true, nil
})

Advanced usage

In some (rare) cases, we may want to cache additional keys when caching.

// Declares a new entity cache limited to 10000 entries, with a 5 minutes time to refresh and a 10 minutes time to live.// It exposes a Prometheus metric named "entity_cache_hit_total" with the labels "namespace" and "hit".cache, err:=entitycache.New(10000, 5*time.Minute, 10*time.Minute, "entity_cache_hit_total")
iferr!=nil {
panic(err)
}
// Let's say we want to cache the document with the ID 128.documentID:=128// We also want it localized in french.language:="fr"// Our cache key would then be for example:key:=fmt.Sprintf("%d-%s", documentID, language)
// We additionally cache the document for an "any" key.// All the languages being requested will keep this entry warm.anyKey:=fmt.Sprintf("%d-any", documentID)
// We get the french document from the cache.document, ok, err:=cache.MultiKeyGet(ctx, "documents", key, []string{anyKey}, func(ctx context.Context) (valueinterface{}, okbool, errerror) {
iflanguage=="any" {
// We fallback to english by default.language="en"
}
document, err:=getDocumentByID(ctx, documentID, language)
iferr!=nil {
iferr==sql.ErrNoRows {
returnnil, false, nil
}
returnnil, false, err
}
returndocument, true, nil
})
// A next call asking for an "any" language would opportunistically get a cached document, in whatever language laying in the cache.