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507 lines
12 KiB
507 lines
12 KiB
package redis3
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import (
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"bytes"
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"context"
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"fmt"
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"github.com/chrislusf/seaweedfs/weed/util/skiplist"
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"github.com/go-redis/redis/v8"
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)
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type ItemList struct {
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skipList *skiplist.SkipList
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batchSize int
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client redis.UniversalClient
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prefix string
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}
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func newItemList(client redis.UniversalClient, prefix string, store skiplist.ListStore, batchSize int) *ItemList {
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return &ItemList{
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skipList: skiplist.New(store),
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batchSize: batchSize,
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client: client,
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prefix: prefix,
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}
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}
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/*
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Be reluctant to create new nodes. Try to fit into either previous node or next node.
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Prefer to add to previous node.
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There are multiple cases after finding the name for greater or equal node
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1. found and node.Key == name
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The node contains a batch with leading key the same as the name
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nothing to do
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2. no such node found or node.Key > name
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if no such node found
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prevNode = list.LargestNode
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// case 2.1
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if previousNode contains name
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nothing to do
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// prefer to add to previous node
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if prevNode != nil {
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// case 2.2
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if prevNode has capacity
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prevNode.add name, and save
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return
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// case 2.3
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split prevNode by name
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}
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// case 2.4
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// merge into next node. Avoid too many nodes if adding data in reverse order.
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if nextNode is not nil and nextNode has capacity
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delete nextNode.Key
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nextNode.Key = name
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nextNode.batch.add name
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insert nodeNode.Key
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return
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// case 2.5
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if prevNode is nil
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insert new node with key = name, value = batch{name}
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return
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*/
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func (nl *ItemList) canAddMember(node *skiplist.SkipListElementReference, name string) (alreadyContains bool, nodeSize int, err error) {
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ctx := context.Background()
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pipe := nl.client.TxPipeline()
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key := fmt.Sprintf("%s%dm", nl.prefix, node.ElementPointer)
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countOperation := pipe.ZLexCount(ctx, key, "-", "+")
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scoreOperationt := pipe.ZScore(ctx, key, name)
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if _, err = pipe.Exec(ctx); err != nil && err != redis.Nil {
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return false, 0, err
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}
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if err == redis.Nil {
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err = nil
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}
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alreadyContains = scoreOperationt.Err() == nil
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nodeSize = int(countOperation.Val())
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return
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}
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func (nl *ItemList) WriteName(name string) error {
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lookupKey := []byte(name)
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prevNode, nextNode, found, err := nl.skipList.FindGreaterOrEqual(lookupKey)
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if err != nil {
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return err
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}
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// case 1: the name already exists as one leading key in the batch
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if found && bytes.Compare(nextNode.Key, lookupKey) == 0 {
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return nil
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}
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var prevNodeReference *skiplist.SkipListElementReference
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if !found {
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prevNodeReference = nl.skipList.GetLargestNodeReference()
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}
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if nextNode != nil && prevNode == nil {
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prevNodeReference = nextNode.Prev
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}
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if prevNodeReference != nil {
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alreadyContains, nodeSize, err := nl.canAddMember(prevNodeReference, name)
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if err != nil {
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return err
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}
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if alreadyContains {
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// case 2.1
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return nil
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}
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// case 2.2
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if nodeSize < nl.batchSize {
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return nl.NodeAddMember(prevNodeReference, name)
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}
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// case 2.3
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x := nl.NodeInnerPosition(prevNodeReference, name)
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y := nodeSize - x
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addToX := x <= y
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// add to a new node
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if x == 0 || y == 0 {
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if err := nl.ItemAdd(lookupKey, 0, name); err != nil {
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return err
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}
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return nil
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}
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if addToX {
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// collect names before name, add them to X
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namesToX, err := nl.NodeRangeBeforeExclusive(prevNodeReference, name)
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if err != nil {
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return nil
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}
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// delete skiplist reference to old node
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if _, err := nl.skipList.DeleteByKey(prevNodeReference.Key); err != nil {
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return err
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}
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// add namesToY and name to a new X
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namesToX = append(namesToX, name)
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if err := nl.ItemAdd([]byte(namesToX[0]), 0, namesToX...); err != nil {
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return nil
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}
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// remove names less than name from current Y
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if err := nl.NodeDeleteBeforeExclusive(prevNodeReference, name); err != nil {
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return nil
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}
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// point skip list to current Y
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if err := nl.ItemAdd(lookupKey, prevNodeReference.ElementPointer); err != nil {
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return nil
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}
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return nil
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} else {
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// collect names after name, add them to Y
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namesToY, err := nl.NodeRangeAfterExclusive(prevNodeReference, name)
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if err != nil {
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return nil
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}
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// add namesToY and name to a new Y
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namesToY = append(namesToY, name)
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if err := nl.ItemAdd(lookupKey, 0, namesToY...); err != nil {
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return nil
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}
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// remove names after name from current X
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if err := nl.NodeDeleteAfterExclusive(prevNodeReference, name); err != nil {
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return nil
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}
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return nil
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}
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}
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// case 2.4
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if nextNode != nil {
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nodeSize := nl.NodeSize(nextNode.Reference())
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if nodeSize < nl.batchSize {
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if id, err := nl.skipList.DeleteByKey(nextNode.Key); err != nil {
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return err
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} else {
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if err := nl.ItemAdd(lookupKey, id, name); err != nil {
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return err
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}
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}
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return nil
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}
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}
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// case 2.5
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// now prevNode is nil
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return nl.ItemAdd(lookupKey, 0, name)
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}
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/*
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// case 1: exists in nextNode
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if nextNode != nil && nextNode.Key == name {
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remove from nextNode, update nextNode
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// TODO: merge with prevNode if possible?
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return
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}
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if nextNode is nil
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prevNode = list.Largestnode
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if prevNode == nil and nextNode.Prev != nil
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prevNode = load(nextNode.Prev)
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// case 2: does not exist
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// case 2.1
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if prevNode == nil {
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return
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}
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// case 2.2
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if prevNameBatch does not contain name {
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return
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}
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// case 3
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delete from prevNameBatch
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if prevNameBatch + nextNode < capacityList
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// case 3.1
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merge
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else
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// case 3.2
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update prevNode
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*/
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func (nl *ItemList) DeleteName(name string) error {
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lookupKey := []byte(name)
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prevNode, nextNode, found, err := nl.skipList.FindGreaterOrEqual(lookupKey)
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if err != nil {
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return err
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}
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// case 1
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if found && bytes.Compare(nextNode.Key, lookupKey) == 0 {
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if _, err := nl.skipList.DeleteByKey(nextNode.Key); err != nil {
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return err
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}
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if err := nl.NodeDeleteMember(nextNode.Reference(), name); err != nil {
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return err
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}
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minName := nl.NodeMin(nextNode.Reference())
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if minName == "" {
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return nl.NodeDelete(nextNode.Reference())
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}
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return nl.ItemAdd([]byte(minName), nextNode.Id)
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}
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if !found {
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prevNode, err = nl.skipList.GetLargestNode()
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if err != nil {
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return err
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}
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}
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if nextNode != nil && prevNode == nil {
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prevNode, err = nl.skipList.LoadElement(nextNode.Prev)
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if err != nil {
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return err
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}
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}
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// case 2
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if prevNode == nil {
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// case 2.1
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return nil
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}
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if !nl.NodeContainsItem(prevNode.Reference(), name) {
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return nil
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}
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// case 3
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if err := nl.NodeDeleteMember(prevNode.Reference(), name); err != nil {
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return err
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}
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prevSize := nl.NodeSize(prevNode.Reference())
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if prevSize == 0 {
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if _, err := nl.skipList.DeleteByKey(prevNode.Key); err != nil {
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return err
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}
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return nil
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}
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nextSize := nl.NodeSize(nextNode.Reference())
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if nextSize > 0 && prevSize+nextSize < nl.batchSize {
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// case 3.1 merge nextNode and prevNode
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if _, err := nl.skipList.DeleteByKey(nextNode.Key); err != nil {
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return err
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}
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nextNames, err := nl.NodeRangeBeforeExclusive(nextNode.Reference(), "")
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if err != nil {
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return err
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}
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if err := nl.NodeAddMember(prevNode.Reference(), nextNames...); err != nil {
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return err
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}
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return nl.NodeDelete(nextNode.Reference())
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} else {
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// case 3.2 update prevNode
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// no action to take
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return nil
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}
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return nil
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}
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func (nl *ItemList) ListNames(startFrom string, visitNamesFn func(name string) bool) error {
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lookupKey := []byte(startFrom)
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prevNode, nextNode, found, err := nl.skipList.FindGreaterOrEqual(lookupKey)
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if err != nil {
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return err
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}
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if found && bytes.Compare(nextNode.Key, lookupKey) == 0 {
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prevNode = nil
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}
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if !found {
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prevNode, err = nl.skipList.GetLargestNode()
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if err != nil {
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return err
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}
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}
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if prevNode != nil {
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if !nl.NodeScanIncluseiveAfter(prevNode.Reference(), startFrom, visitNamesFn) {
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return nil
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}
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}
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for nextNode != nil {
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if !nl.NodeScanIncluseiveAfter(nextNode.Reference(), startFrom, visitNamesFn) {
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return nil
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}
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nextNode, err = nl.skipList.LoadElement(nextNode.Next[0])
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if err != nil {
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return err
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}
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}
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return nil
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}
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func (nl *ItemList) RemoteAllListElement() error {
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t := nl.skipList
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nodeRef := t.StartLevels[0]
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for nodeRef != nil {
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node, err := t.LoadElement(nodeRef)
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if err != nil {
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return err
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}
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if node == nil {
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return nil
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}
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if err := t.DeleteElement(node); err != nil {
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return err
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}
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if err := nl.NodeDelete(node.Reference()); err != nil {
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return err
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}
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nodeRef = node.Next[0]
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}
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return nil
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}
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func (nl *ItemList) NodeContainsItem(node *skiplist.SkipListElementReference, item string) bool {
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key := fmt.Sprintf("%s%dm", nl.prefix, node.ElementPointer)
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_, err := nl.client.ZScore(context.Background(), key, item).Result()
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if err == redis.Nil {
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return false
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}
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if err == nil {
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return true
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}
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return false
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}
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func (nl *ItemList) NodeSize(node *skiplist.SkipListElementReference) int {
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if node == nil {
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return 0
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}
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key := fmt.Sprintf("%s%dm", nl.prefix, node.ElementPointer)
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return int(nl.client.ZLexCount(context.Background(), key, "-", "+").Val())
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}
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func (nl *ItemList) NodeAddMember(node *skiplist.SkipListElementReference, names ...string) error {
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key := fmt.Sprintf("%s%dm", nl.prefix, node.ElementPointer)
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var members []*redis.Z
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for _, name := range names {
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members = append(members, &redis.Z{
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Score: 0,
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Member: name,
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})
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}
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return nl.client.ZAddNX(context.Background(), key, members...).Err()
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}
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func (nl *ItemList) NodeDeleteMember(node *skiplist.SkipListElementReference, name string) error {
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key := fmt.Sprintf("%s%dm", nl.prefix, node.ElementPointer)
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return nl.client.ZRem(context.Background(), key, name).Err()
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}
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func (nl *ItemList) NodeDelete(node *skiplist.SkipListElementReference) error {
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key := fmt.Sprintf("%s%dm", nl.prefix, node.ElementPointer)
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return nl.client.Del(context.Background(), key).Err()
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}
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func (nl *ItemList) NodeInnerPosition(node *skiplist.SkipListElementReference, name string) int {
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key := fmt.Sprintf("%s%dm", nl.prefix, node.ElementPointer)
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return int(nl.client.ZLexCount(context.Background(), key, "-", "("+name).Val())
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}
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func (nl *ItemList) NodeMin(node *skiplist.SkipListElementReference) string {
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key := fmt.Sprintf("%s%dm", nl.prefix, node.ElementPointer)
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slice := nl.client.ZRangeByLex(context.Background(), key, &redis.ZRangeBy{
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Min: "-",
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Max: "+",
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Offset: 0,
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Count: 1,
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}).Val()
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if len(slice) > 0 {
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s := slice[0]
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return s
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}
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return ""
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}
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func (nl *ItemList) NodeScanIncluseiveAfter(node *skiplist.SkipListElementReference, startFrom string, visitNamesFn func(name string) bool) bool {
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key := fmt.Sprintf("%s%dm", nl.prefix, node.ElementPointer)
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if startFrom == "" {
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startFrom = "-"
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} else {
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startFrom = "[" + startFrom
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}
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names := nl.client.ZRangeByLex(context.Background(), key, &redis.ZRangeBy{
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Min: startFrom,
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Max: "+",
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}).Val()
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for _, n := range names {
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if !visitNamesFn(n) {
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return false
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}
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}
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return true
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}
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func (nl *ItemList) NodeRangeBeforeExclusive(node *skiplist.SkipListElementReference, stopAt string) ([]string, error) {
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key := fmt.Sprintf("%s%dm", nl.prefix, node.ElementPointer)
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if stopAt == "" {
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stopAt = "+"
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} else {
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stopAt = "(" + stopAt
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}
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return nl.client.ZRangeByLex(context.Background(), key, &redis.ZRangeBy{
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Min: "-",
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Max: stopAt,
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}).Result()
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}
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func (nl *ItemList) NodeRangeAfterExclusive(node *skiplist.SkipListElementReference, startFrom string) ([]string, error) {
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key := fmt.Sprintf("%s%dm", nl.prefix, node.ElementPointer)
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if startFrom == "" {
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startFrom = "-"
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} else {
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startFrom = "(" + startFrom
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}
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return nl.client.ZRangeByLex(context.Background(), key, &redis.ZRangeBy{
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Min: startFrom,
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Max: "+",
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}).Result()
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}
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func (nl *ItemList) NodeDeleteBeforeExclusive(node *skiplist.SkipListElementReference, stopAt string) error {
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key := fmt.Sprintf("%s%dm", nl.prefix, node.ElementPointer)
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if stopAt == "" {
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stopAt = "+"
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} else {
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stopAt = "(" + stopAt
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}
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return nl.client.ZRemRangeByLex(context.Background(), key, "-", stopAt).Err()
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}
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func (nl *ItemList) NodeDeleteAfterExclusive(node *skiplist.SkipListElementReference, startFrom string) error {
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key := fmt.Sprintf("%s%dm", nl.prefix, node.ElementPointer)
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if startFrom == "" {
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startFrom = "-"
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} else {
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startFrom = "(" + startFrom
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}
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return nl.client.ZRemRangeByLex(context.Background(), key, startFrom, "+").Err()
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}
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func (nl *ItemList) ItemAdd(lookupKey []byte, idIfKnown int64, names ...string) error {
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if id, err := nl.skipList.InsertByKey(lookupKey, idIfKnown, nil); err != nil {
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return err
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} else {
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if len(names) > 0 {
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return nl.NodeAddMember(&skiplist.SkipListElementReference{
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ElementPointer: id,
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Key: lookupKey,
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}, names...)
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}
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}
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return nil
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}
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