[#996] metabase: Speed up bucket creation

Most of the time it exits, e.g. when it is per-container and use on each
object PUT. Bbolt implementation first tries to create bucket and then
returns it if it exists. Create operation uses cursor and thus is not
very lightweight, we can avoid it.

```
goos: linux
goarch: amd64
pkg: git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/metabase
cpu: 11th Gen Intel(R) Core(TM) i5-1135G7 @ 2.40GHz
                 │     old     │                new                 │
                 │   sec/op    │   sec/op     vs base               │
Put/parallel-8     174.4µ ± 3%   163.3µ ± 3%  -6.39% (p=0.000 n=10)
Put/sequential-8   263.3µ ± 2%   259.0µ ± 1%  -1.64% (p=0.000 n=10)
geomean            214.3µ        205.6µ       -4.05%

                 │     old      │                 new                 │
                 │     B/op     │     B/op      vs base               │
Put/parallel-8     275.3Ki ± 3%   281.1Ki ± 4%       ~ (p=0.063 n=10)
Put/sequential-8   413.0Ki ± 2%   426.6Ki ± 2%  +3.29% (p=0.003 n=10)
geomean            337.2Ki        346.3Ki       +2.70%

                 │     old     │                 new                 │
                 │  allocs/op  │  allocs/op   vs base                │
Put/parallel-8      678.0 ± 1%    524.5 ± 2%  -22.64% (p=0.000 n=10)
Put/sequential-8   1.329k ± 0%   1.183k ± 0%  -10.91% (p=0.000 n=10)
geomean             949.1         787.9       -16.98%
```

Signed-off-by: Evgenii Stratonikov <e.stratonikov@yadro.com>

pkg/local_object_storage/metabase/counter.go

@@ -346,7 +346,7 @@ func (db *DB) incContainerObjectCounter(tx *bbolt.Tx, cnrID cid.ID, isUserObject
 // Does nothing if counters are not empty and force is false. If force is
 // true, updates the counters anyway.
 func syncCounter(tx *bbolt.Tx, force bool) error {
-	shardInfoB, err := tx.CreateBucketIfNotExists(shardInfoBucket)
+	shardInfoB, err := createBucketLikelyExists(tx, shardInfoBucket)
 	if err != nil {
 		return fmt.Errorf("could not get shard info bucket: %w", err)
 	}
@@ -359,7 +359,7 @@ func syncCounter(tx *bbolt.Tx, force bool) error {
 		return nil
 	}
 
-	containerCounterB, err := tx.CreateBucketIfNotExists(containerCounterBucketName)
+	containerCounterB, err := createBucketLikelyExists(tx, containerCounterBucketName)
 	if err != nil {
 		return fmt.Errorf("could not get container counter bucket: %w", err)
 	}

pkg/local_object_storage/metabase/put.go

@@ -356,8 +356,21 @@ func updateFKBTIndexes(tx *bbolt.Tx, obj *objectSDK.Object, f updateIndexItemFun
 	return nil
 }
 
+type bucketContainer interface {
+	Bucket([]byte) *bbolt.Bucket
+	CreateBucket([]byte) (*bbolt.Bucket, error)
+	CreateBucketIfNotExists([]byte) (*bbolt.Bucket, error)
+}
+
+func createBucketLikelyExists[T bucketContainer](tx T, name []byte) (*bbolt.Bucket, error) {
+	if bkt := tx.Bucket(name); bkt != nil {
+		return bkt, nil
+	}
+	return tx.CreateBucket(name)
+}
+
 func putUniqueIndexItem(tx *bbolt.Tx, item namedBucketItem) error {
-	bkt, err := tx.CreateBucketIfNotExists(item.name)
+	bkt, err := createBucketLikelyExists(tx, item.name)
 	if err != nil {
 		return fmt.Errorf("can't create index %v: %w", item.name, err)
 	}
@@ -366,12 +379,12 @@ func putUniqueIndexItem(tx *bbolt.Tx, item namedBucketItem) error {
 }
 
 func putFKBTIndexItem(tx *bbolt.Tx, item namedBucketItem) error {
-	bkt, err := tx.CreateBucketIfNotExists(item.name)
+	bkt, err := createBucketLikelyExists(tx, item.name)
 	if err != nil {
 		return fmt.Errorf("can't create index %v: %w", item.name, err)
 	}
 
-	fkbtRoot, err := bkt.CreateBucketIfNotExists(item.key)
+	fkbtRoot, err := createBucketLikelyExists(bkt, item.key)
 	if err != nil {
 		return fmt.Errorf("can't create fake bucket tree index %v: %w", item.key, err)
 	}
@@ -380,7 +393,7 @@ func putFKBTIndexItem(tx *bbolt.Tx, item namedBucketItem) error {
 }
 
 func putListIndexItem(tx *bbolt.Tx, item namedBucketItem) error {
-	bkt, err := tx.CreateBucketIfNotExists(item.name)
+	bkt, err := createBucketLikelyExists(tx, item.name)
 	if err != nil {
 		return fmt.Errorf("can't create index %v: %w", item.name, err)
 	}
@@ -474,7 +487,7 @@ func getVarUint(data []byte) (uint64, int, error) {
 // storage location to another.
 func updateStorageID(tx *bbolt.Tx, addr oid.Address, id []byte) error {
 	key := make([]byte, bucketKeySize)
-	bkt, err := tx.CreateBucketIfNotExists(smallBucketName(addr.Container(), key))
+	bkt, err := createBucketLikelyExists(tx, smallBucketName(addr.Container(), key))
 	if err != nil {
 		return err
 	}