[#472] blobstor: implement write-cache

Signed-off-by: Evgenii Stratonikov <evgeniy@nspcc.ru>

pkg/local_object_storage/writecache/put.go

@@ -0,0 +1,44 @@
+package writecache
+
+import (
+	"errors"
+
+	"github.com/nspcc-dev/neofs-node/pkg/core/object"
+)
+
+// ErrBigObject is returned when object is too big to be placed in cache.
+var ErrBigObject = errors.New("too big object")
+
+// Put puts object to write-cache.
+func (c *cache) Put(o *object.Object) error {
+	sz := uint64(o.ToV2().StableSize())
+	if sz > c.maxObjectSize {
+		return ErrBigObject
+	}
+
+	data, err := o.Marshal(nil)
+	if err != nil {
+		return err
+	}
+
+	oi := objectInfo{
+		addr: o.Address().String(),
+		obj:  o,
+		data: data,
+	}
+
+	c.mtx.Lock()
+
+	if sz < c.smallObjectSize && c.curMemSize+sz <= c.maxMemSize {
+		c.curMemSize += sz
+		c.mem = append(c.mem, oi)
+
+		c.mtx.Unlock()
+		return nil
+	}
+
+	c.mtx.Unlock()
+
+	c.persistObjects([]objectInfo{oi})
+	return nil
+}