frostfs-node/pkg/local_object_storage/metabase/list.go
Alex Vanin 1f911830a5 [#948] engine: Define EndOfListing error in component packages
Signed-off-by: Alex Vanin <alexey@nspcc.ru>
2021-11-19 16:57:19 +03:00

212 lines
5.5 KiB
Go

package meta
import (
"errors"
"strings"
cid "github.com/nspcc-dev/neofs-sdk-go/container/id"
"github.com/nspcc-dev/neofs-sdk-go/object"
"go.etcd.io/bbolt"
)
// ErrEndOfListing is returned from object listing with cursor
// when storage can't return any more objects after provided
// cursor. Use nil cursor object to start listing again.
var ErrEndOfListing = errors.New("end of object listing")
// Cursor is a type for continuous object listing.
type Cursor struct {
bucketName []byte
inBucketOffset []byte
}
// ListPrm contains parameters for ListWithCursor operation.
type ListPrm struct {
count int
cursor *Cursor
}
// WithCount sets maximum amount of addresses that ListWithCursor should return.
func (l *ListPrm) WithCount(count uint32) *ListPrm {
l.count = int(count)
return l
}
// WithCursor sets cursor for ListWithCursor operation. For initial request
// ignore this param or use nil value. For consecutive requests, use value
// from ListRes.
func (l *ListPrm) WithCursor(cursor *Cursor) *ListPrm {
l.cursor = cursor
return l
}
// ListRes contains values returned from ListWithCursor operation.
type ListRes struct {
addrList []*object.Address
cursor *Cursor
}
// AddressList returns addresses selected by ListWithCursor operation.
func (l ListRes) AddressList() []*object.Address {
return l.addrList
}
// Cursor returns cursor for consecutive listing requests.
func (l ListRes) Cursor() *Cursor {
return l.cursor
}
// ListWithCursor lists physical objects available in metabase starting from
// cursor. Includes regular, tombstone and storage group objects. Does not
// include inhumed objects. Use cursor value from response for consecutive requests.
//
// Returns ErrEndOfListing if there are no more objects to return or count
// parameter set to zero.
func ListWithCursor(db *DB, count uint32, cursor *Cursor) ([]*object.Address, *Cursor, error) {
r, err := db.ListWithCursor(new(ListPrm).WithCount(count).WithCursor(cursor))
if err != nil {
return nil, nil, err
}
return r.AddressList(), r.Cursor(), nil
}
// ListWithCursor lists physical objects available in metabase starting from
// cursor. Includes regular, tombstone and storage group objects. Does not
// include inhumed objects. Use cursor value from response for consecutive requests.
//
// Returns ErrEndOfListing if there are no more objects to return or count
// parameter set to zero.
func (db *DB) ListWithCursor(prm *ListPrm) (res *ListRes, err error) {
err = db.boltDB.View(func(tx *bbolt.Tx) error {
res = new(ListRes)
res.addrList, res.cursor, err = db.listWithCursor(tx, prm.count, prm.cursor)
return err
})
return res, err
}
func (db *DB) listWithCursor(tx *bbolt.Tx, count int, cursor *Cursor) ([]*object.Address, *Cursor, error) {
threshold := cursor == nil // threshold is a flag to ignore cursor
result := make([]*object.Address, 0, count)
var bucketName []byte
c := tx.Cursor()
name, _ := c.First()
if !threshold {
name, _ = c.Seek(cursor.bucketName)
}
loop:
for ; name != nil; name, _ = c.Next() {
containerID, postfix := parseContainerIDWithPostfix(name)
if containerID == nil {
continue
}
switch postfix {
case "", storageGroupPostfix, tombstonePostfix:
default:
continue
}
prefix := containerID.String() + "/"
result, cursor = selectNFromBucket(tx, name, prefix, result, count, cursor, threshold)
bucketName = name
if len(result) >= count {
break loop
}
// set threshold flag after first `selectNFromBucket` invocation
// first invocation must look for cursor object
threshold = true
}
if len(result) == 0 {
return nil, nil, ErrEndOfListing
}
// new slice is much faster but less memory efficient
// we need to copy, because bucketName exists during bbolt tx
cursor.bucketName = make([]byte, len(bucketName))
copy(cursor.bucketName, bucketName)
return result, cursor, nil
}
// selectNFromBucket similar to selectAllFromBucket but uses cursor to find
// object to start selecting from. Ignores inhumed objects.
func selectNFromBucket(tx *bbolt.Tx,
name []byte, // bucket name
prefix string, // string of CID, optimization
to []*object.Address, // listing result
limit int, // stop listing at `limit` items in result
cursor *Cursor, // start from cursor object
threshold bool, // ignore cursor and start immediately
) ([]*object.Address, *Cursor) {
bkt := tx.Bucket(name)
if bkt == nil {
return to, cursor
}
if cursor == nil {
cursor = new(Cursor)
}
count := len(to)
c := bkt.Cursor()
k, _ := c.First()
offset := cursor.inBucketOffset
if !threshold {
c.Seek(offset)
k, _ = c.Next() // we are looking for objects _after_ the cursor
}
for ; k != nil; k, _ = c.Next() {
if count >= limit {
break
}
a := object.NewAddress()
if err := a.Parse(prefix + string(k)); err != nil {
break
}
offset = k
if inGraveyard(tx, a) > 0 {
continue
}
to = append(to, a)
count++
}
// new slice is much faster but less memory efficient
// we need to copy, because offset exists during bbolt tx
cursor.inBucketOffset = make([]byte, len(offset))
copy(cursor.inBucketOffset, offset)
return to, cursor
}
func parseContainerIDWithPostfix(name []byte) (*cid.ID, string) {
var (
containerID = cid.New()
containerIDStr = string(name)
postfix string
)
ind := strings.Index(string(name), invalidBase58String)
if ind > 0 {
postfix = containerIDStr[ind:]
containerIDStr = containerIDStr[:ind]
}
if err := containerID.Parse(containerIDStr); err != nil {
return nil, ""
}
return containerID, postfix
}