[#661] blobovniczatree: Add Rebuild implementation

Signed-off-by: Dmitrii Stepanov <d.stepanov@yadro.com>

pkg/local_object_storage/blobstor/blobovniczatree/manager.go

@@ -1,7 +1,9 @@
 package blobovniczatree
 
 import (
+	"errors"
 	"fmt"
+	"os"
 	"path/filepath"
 	"sync"
 	"sync/atomic"
@@ -12,9 +14,11 @@ import (
 	"go.uber.org/zap"
 )
 
+var errClosingClosedBlobovnicza = errors.New("closing closed blobovnicza is not allowed")
+
 // sharedDB is responsible for opening and closing a file of single blobovnicza.
 type sharedDB struct {
-	guard    *sync.RWMutex
+	cond     *sync.Cond
 	blcza    *blobovnicza.Blobovnicza
 	refCount uint32
 
@@ -31,8 +35,9 @@ func newSharedDB(options []blobovnicza.Option, path string, readOnly bool,
 	metrics blobovnicza.Metrics, openDBCounter *openDBCounter, closedFlag *atomic.Bool, log *logger.Logger,
 ) *sharedDB {
 	return &sharedDB{
-		guard: &sync.RWMutex{},
-
+		cond: &sync.Cond{
+			L: &sync.RWMutex{},
+		},
 		options:       options,
 		path:          path,
 		readOnly:      readOnly,
@@ -48,8 +53,8 @@ func (b *sharedDB) Open() (*blobovnicza.Blobovnicza, error) {
 		return nil, errClosed
 	}
 
-	b.guard.Lock()
-	defer b.guard.Unlock()
+	b.cond.L.Lock()
+	defer b.cond.L.Unlock()
 
 	if b.refCount > 0 {
 		b.refCount++
@@ -77,11 +82,12 @@ func (b *sharedDB) Open() (*blobovnicza.Blobovnicza, error) {
 }
 
 func (b *sharedDB) Close() {
-	b.guard.Lock()
-	defer b.guard.Unlock()
+	b.cond.L.Lock()
+	defer b.cond.L.Unlock()
 
 	if b.refCount == 0 {
 		b.log.Error(logs.AttemtToCloseAlreadyClosedBlobovnicza, zap.String("id", b.path))
+		b.cond.Broadcast()
 		return
 	}
 
@@ -99,9 +105,38 @@ func (b *sharedDB) Close() {
 	}
 
 	b.refCount--
+	if b.refCount == 1 {
+		b.cond.Broadcast()
+	}
 }
 
-func (b *sharedDB) Path() string {
+func (b *sharedDB) CloseAndRemoveFile() error {
+	b.cond.L.Lock()
+	if b.refCount > 1 {
+		b.cond.Wait()
+	}
+	defer b.cond.L.Unlock()
+
+	if b.refCount == 0 {
+		return errClosingClosedBlobovnicza
+	}
+
+	if err := b.blcza.Close(); err != nil {
+		b.log.Error(logs.BlobovniczatreeCouldNotCloseBlobovnicza,
+			zap.String("id", b.path),
+			zap.String("error", err.Error()),
+		)
+		return fmt.Errorf("failed to close blobovnicza (path = %s): %w", b.path, err)
+	}
+
+	b.refCount = 0
+	b.blcza = nil
+	b.openDBCounter.Dec()
+
+	return os.Remove(b.path)
+}
+
+func (b *sharedDB) SystemPath() string {
 	return b.path
 }
 
@@ -166,6 +201,13 @@ func (m *levelDbManager) getOrCreateDB(idx uint64) *sharedDB {
 	return db
 }
 
+func (m *levelDbManager) hasAnyDB() bool {
+	m.dbMtx.RLock()
+	defer m.dbMtx.RUnlock()
+
+	return len(m.databases) > 0
+}
+
 // dbManager manages the opening and closing of blobovnicza instances.
 //
 // The blobovnicza opens at the first request, closes after the last request.
@@ -203,6 +245,17 @@ func (m *dbManager) GetByPath(path string) *sharedDB {
 	return levelManager.GetByIndex(curIndex)
 }
 
+func (m *dbManager) CleanResources(path string) {
+	lvlPath := filepath.Dir(path)
+
+	m.levelToManagerGuard.Lock()
+	defer m.levelToManagerGuard.Unlock()
+
+	if result, ok := m.levelToManager[lvlPath]; ok && !result.hasAnyDB() {
+		delete(m.levelToManager, lvlPath)
+	}
+}
+
 func (m *dbManager) Open() {
 	m.closedFlag.Store(false)
 }