package main import ( "sync" "time" lru "github.com/hashicorp/golang-lru" containerSDK "github.com/nspcc-dev/neofs-api-go/pkg/container" "github.com/nspcc-dev/neofs-node/pkg/core/container" ) type netValueReader func(interface{}) (interface{}, error) type valueWithTime struct { v interface{} t time.Time } // entity that provides TTL cache interface. type ttlNetCache struct { mtx sync.Mutex ttl time.Duration sz int cache *lru.Cache netRdr netValueReader } // complicates netValueReader with TTL caching mechanism. func newNetworkTTLCache(sz int, ttl time.Duration, netRdr netValueReader) *ttlNetCache { cache, err := lru.New(sz) fatalOnErr(err) return &ttlNetCache{ ttl: ttl, sz: sz, cache: cache, netRdr: netRdr, } } // reads value by the key. // // updates the value from the network on cache miss or by TTL. // // returned value should not be modified. func (c *ttlNetCache) get(key interface{}) (interface{}, error) { c.mtx.Lock() defer c.mtx.Unlock() val, ok := c.cache.Peek(key) if ok { valWithTime := val.(*valueWithTime) if time.Since(valWithTime.t) < c.ttl { valWithTime.t = time.Now() return valWithTime.v, nil } c.cache.Remove(key) } val, err := c.netRdr(key) if err != nil { return nil, err } c.cache.Add(key, &valueWithTime{ v: val, t: time.Now(), }) return val, nil } // wrapper over TTL cache of values read from the network // that implements container storage. type ttlContainerStorage ttlNetCache func newCachedContainerStorage(v container.Source) container.Source { const ( containerCacheSize = 100 containerCacheTTL = 30 * time.Second ) lruCnrCache := newNetworkTTLCache(containerCacheSize, containerCacheTTL, func(key interface{}) (interface{}, error) { cid := containerSDK.NewID() err := cid.Parse(key.(string)) if err != nil { return nil, err } return v.Get(cid) }) return (*ttlContainerStorage)(lruCnrCache) } func (s *ttlContainerStorage) Get(cid *containerSDK.ID) (*containerSDK.Container, error) { val, err := (*ttlNetCache)(s).get(cid.String()) if err != nil { return nil, err } return val.(*containerSDK.Container), nil }