Method Load

go/libkb/burst_cache.go:61–99

Load item key from the burst cache. On a cache miss, load with the given loader function. Return the object as an interface{}, so the caller needs to cast out of this burst cache.

(ctx context.Context, key BurstCacheKey, loader BurstCacheLoader)

// Load item key from the burst cache. On a cache miss, load with the given loader function.
// Return the object as an interface{}, so the caller needs to cast out of this burst cache.
func (b *BurstCache) Load(ctx context.Context, key BurstCacheKey, loader BurstCacheLoader) (ret interface{}, err error) {
	ctx = WithLogTag(ctx, "BC")
	defer b.G().CVTrace(ctx, VLog0, fmt.Sprintf("BurstCache(%s)#Load(%s)", b.cacheName, key.String()), &err)()

	lock := b.locktab.AcquireOnName(ctx, b.G(), key.String())
	defer lock.Release(ctx)

	b.G().VDL.CLogf(ctx, VLog0, "| past single-flight lock")

	found := false
	if val, ok := b.lru.Get(key.String()); ok {
		b.G().VDL.CLogf(ctx, VLog0, "| found in LRU cache")
		if tmp, ok := val.(*burstCacheObj); ok {
			age := b.G().GetClock().Now().Sub(tmp.cachedAt)
			if age < b.cacheLife {
				b.G().VDL.CLogf(ctx, VLog0, "| cached object was fresh (loaded %v ago)", age)
				ret = tmp.obj
				found = true
			} else {
				b.G().VDL.CLogf(ctx, VLog0, "| cached object expired %v ago", (age - b.cacheLife))
				b.lru.Remove(key.String())
			}
		} else {
			b.G().Log.CErrorf(ctx, "| object in LRU was of wrong type")
		}
	} else {
		b.G().VDL.CLogf(ctx, VLog0, "| object cache miss")
	}

	if !found {
		ret, err = loader()
		if err == nil {
			b.G().VDL.CLogf(ctx, VLog0, "| caching object after successful fetch")
			b.lru.Add(key.String(), &burstCacheObj{ret, b.G().GetClock().Now()})
		}
	}

	return ret, err
}