[#472] blobstor: implement write-cache

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

pkg/local_object_storage/writecache/writecache.go

@@ -0,0 +1,109 @@
+package writecache
+
+import (
+	"sync"
+
+	objectSDK "github.com/nspcc-dev/neofs-api-go/pkg/object"
+	"github.com/nspcc-dev/neofs-node/pkg/core/object"
+	"github.com/nspcc-dev/neofs-node/pkg/local_object_storage/blobstor/fstree"
+	"go.uber.org/atomic"
+	"go.uber.org/zap"
+)
+
+// Cache represents write-cache for objects.
+type Cache interface {
+	Get(*objectSDK.Address) (*object.Object, error)
+	Delete(*objectSDK.Address) error
+	Put(*object.Object) error
+
+	Init() error
+	Open() error
+	Close() error
+}
+
+type cache struct {
+	options
+
+	// mtx protects mem field, statistics and counters.
+	mtx sync.RWMutex
+	mem []objectInfo
+
+	// curMemSize is the current size of all objects cached in memory.
+	curMemSize uint64
+
+	// flushCh is a channel with objects to flush.
+	flushCh chan *object.Object
+	// directCh is a channel with objects to put directly to the main storage.
+	// it is prioritized over flushCh.
+	directCh chan *object.Object
+	// metaCh is a channel with objects for which only metadata needs to be written.
+	metaCh chan *object.Object
+	// closeCh is close channel.
+	closeCh chan struct{}
+	evictCh chan []byte
+	// store contains underlying database.
+	store
+	// dbSize stores approximate database size. It is updated every flush/persist cycle.
+	dbSize atomic.Uint64
+	// fsTree contains big files stored directly on file-system.
+	fsTree *fstree.FSTree
+}
+
+type objectInfo struct {
+	addr string
+	data []byte
+	obj  *object.Object
+}
+
+const (
+	maxInMemorySizeBytes = 1024 * 1024 * 1024 // 1 GiB
+	maxObjectSize        = 64 * 1024 * 1024   // 64 MiB
+	smallObjectSize      = 32 * 1024          // 32 KiB
+)
+
+var (
+	defaultBucket = []byte{0}
+)
+
+// New creates new writecache instance.
+func New(opts ...Option) Cache {
+	c := &cache{
+		flushCh:  make(chan *object.Object),
+		directCh: make(chan *object.Object),
+		metaCh:   make(chan *object.Object),
+		closeCh:  make(chan struct{}),
+		evictCh:  make(chan []byte),
+
+		options: options{
+			log:             zap.NewNop(),
+			maxMemSize:      maxInMemorySizeBytes,
+			maxObjectSize:   maxObjectSize,
+			smallObjectSize: smallObjectSize,
+			workersCount:    flushWorkersCount,
+		},
+	}
+
+	for i := range opts {
+		opts[i](&c.options)
+	}
+
+	return c
+}
+
+// Open opens and initializes database.
+func (c *cache) Open() error {
+	return c.openStore()
+}
+
+// Init runs necessary services.
+func (c *cache) Init() error {
+	go c.persistLoop()
+	go c.flushLoop()
+	return nil
+}
+
+// Close closes db connection and stops services.
+func (c *cache) Close() error {
+	close(c.closeCh)
+	return c.db.Close()
+}