forked from TrueCloudLab/frostfs-node
[#80] services/object: Implement iterators over split-tree leaves
Signed-off-by: Leonard Lyubich <leonard@nspcc.ru>
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1 changed files with 163 additions and 0 deletions
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@ -1,6 +1,7 @@
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package util
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import (
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"errors"
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"fmt"
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objectSDK "github.com/nspcc-dev/neofs-api-go/pkg/object"
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@ -26,6 +27,168 @@ type rangeChain struct {
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id *objectSDK.ID
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}
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// HeadReceiver is an interface of entity that can receive
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// object header or the information about the object relations.
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type HeadReceiver interface {
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// Head must return one of:
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// * object header (*object.Object);
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// * structured information about split-chain (*objectSDK.SplitInfo).
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Head(*objectSDK.Address) (interface{}, error)
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}
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// SplitMemberHandler is a handler of next split-chain element.
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//
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// If reverseDirection arg is true, then the traversal is done in reverse order.
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// Stop boolean result provides the ability to interrupt the traversal.
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type SplitMemberHandler func(member *object.Object, reverseDirection bool) (stop bool)
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// IterateAllSplitLeaves is an iterator over all object split-tree leaves in direct order.
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func IterateAllSplitLeaves(r HeadReceiver, addr *objectSDK.Address, h func(*object.Object)) error {
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return IterateSplitLeaves(r, addr, func(leaf *object.Object) bool {
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h(leaf)
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return false
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})
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}
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// IterateSplitLeaves is an iterator over object split-tree leaves in direct order.
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//
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// If member handler returns true, then the iterator aborts without error.
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func IterateSplitLeaves(r HeadReceiver, addr *objectSDK.Address, h func(*object.Object) bool) error {
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var (
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reverse bool
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leaves []*object.Object
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)
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if err := TraverseSplitChain(r, addr, func(member *object.Object, reverseDirection bool) (stop bool) {
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reverse = reverseDirection
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if reverse {
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leaves = append(leaves, member)
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return false
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}
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return h(member)
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}); err != nil {
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return err
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}
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for i := len(leaves) - 1; i >= 0; i-- {
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if h(leaves[i]) {
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break
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}
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}
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return nil
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}
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// TraverseSplitChain is an iterator over object split-tree leaves.
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//
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// Traversal occurs in one of two directions, which depends on what pslit info was received:
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// * in direct order for link part;
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// * in reverse order for last part.
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func TraverseSplitChain(r HeadReceiver, addr *objectSDK.Address, h SplitMemberHandler) error {
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_, err := traverseSplitChain(r, addr, h)
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return err
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}
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func traverseSplitChain(r HeadReceiver, addr *objectSDK.Address, h SplitMemberHandler) (bool, error) {
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v, err := r.Head(addr)
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if err != nil {
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return false, err
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}
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cid := addr.ContainerID()
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switch res := v.(type) {
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default:
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panic(fmt.Sprintf("unexpected result of %T: %T", r, v))
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case *object.Object:
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return h(res, false), nil
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case *objectSDK.SplitInfo:
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switch {
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default:
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return false, errors.New("lack of split information")
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case res.Link() != nil:
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addr := objectSDK.NewAddress()
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addr.SetContainerID(cid)
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addr.SetObjectID(res.Link())
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chain := make([]*objectSDK.ID, 0)
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if _, err := traverseSplitChain(r, addr, func(member *object.Object, reverseDirection bool) (stop bool) {
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children := member.Children()
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if reverseDirection {
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chain = append(children, chain...)
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} else {
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chain = append(chain, children...)
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}
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return false
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}); err != nil {
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return false, err
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}
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var reverseChain []*object.Object
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for i := range chain {
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addr.SetObjectID(chain[i])
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if stop, err := traverseSplitChain(r, addr, func(member *object.Object, reverseDirection bool) (stop bool) {
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if !reverseDirection {
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return h(member, false)
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} else {
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reverseChain = append(reverseChain, member)
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return false
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}
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}); err != nil || stop {
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return stop, err
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}
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}
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for i := len(reverseChain) - 1; i >= 0; i-- {
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if h(reverseChain[i], false) {
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return true, nil
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}
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}
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case res.LastPart() != nil:
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addr := objectSDK.NewAddress()
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addr.SetContainerID(cid)
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for prev := res.LastPart(); prev != nil; {
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addr.SetObjectID(prev)
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var directChain []*object.Object
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if _, err := traverseSplitChain(r, addr, func(member *object.Object, reverseDirection bool) (stop bool) {
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if reverseDirection {
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prev = member.PreviousID()
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return h(member, true)
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}
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directChain = append(directChain, member)
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return false
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}); err != nil {
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return false, err
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}
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for i := len(directChain) - 1; i >= 0; i-- {
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if h(directChain[i], true) {
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return true, nil
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}
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}
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if len(directChain) > 0 {
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prev = directChain[len(directChain)-1].PreviousID()
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}
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}
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}
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}
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return false, nil
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}
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func NewRangeTraverser(originSize uint64, rightElement *object.Object, rngSeek *objectSDK.Range) *RangeTraverser {
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right := &rangeChain{
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bounds: &rangeBounds{
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