[#236] api: Refactor caches: ObjectsList, Objects

Move ObjectsList from layer to cache package
Rename object_cache.go to objects.go

Signed-off-by: Angira Kekteeva <kira@nspcc.ru>

api/cache/objects.go

@@ -0,0 +1,62 @@
+package cache
+
+import (
+	"time"
+
+	"github.com/bluele/gcache"
+	"github.com/nspcc-dev/neofs-api-go/pkg/object"
+)
+
+// ObjectsCache provides interface for lru cache for objects.
+type ObjectsCache interface {
+	Get(address *object.Address) *object.Object
+	Put(obj object.Object) error
+	Delete(address *object.Address) bool
+}
+
+const (
+	// DefaultObjectsCacheLifetime is a default lifetime of entries in objects' cache.
+	DefaultObjectsCacheLifetime = time.Minute * 5
+	// DefaultObjectsCacheSize is a default maximum number of entries in objects' in cache.
+	DefaultObjectsCacheSize = 1e6
+)
+
+type (
+	// ObjectHeadersCache contains cache with objects and lifetime of cache entries.
+	ObjectHeadersCache struct {
+		cache    gcache.Cache
+		lifetime time.Duration
+	}
+)
+
+// New creates an object of ObjectHeadersCache.
+func New(cacheSize int, lifetime time.Duration) *ObjectHeadersCache {
+	gc := gcache.New(cacheSize).LRU().Build()
+
+	return &ObjectHeadersCache{cache: gc, lifetime: lifetime}
+}
+
+// Get returns cached object.
+func (o *ObjectHeadersCache) Get(address *object.Address) *object.Object {
+	entry, err := o.cache.Get(address.String())
+	if err != nil {
+		return nil
+	}
+
+	result, ok := entry.(object.Object)
+	if !ok {
+		return nil
+	}
+
+	return &result
+}
+
+// Put puts an object to cache.
+func (o *ObjectHeadersCache) Put(obj object.Object) error {
+	return o.cache.SetWithExpire(obj.ContainerID().String()+"/"+obj.ID().String(), obj, o.lifetime)
+}
+
+// Delete deletes an object from cache.
+func (o *ObjectHeadersCache) Delete(address *object.Address) bool {
+	return o.cache.Remove(address.String())
+}