63 lines
1.6 KiB
Go
63 lines
1.6 KiB
Go
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package kbucket
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import (
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"container/list"
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"sort"
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"github.com/libp2p/go-libp2p-core/peer"
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)
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// A helper struct to sort peers by their distance to the local node
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type peerDistance struct {
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p peer.ID
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distance ID
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}
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// peerDistanceSorter implements sort.Interface to sort peers by xor distance
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type peerDistanceSorter struct {
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peers []peerDistance
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target ID
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}
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func (pds *peerDistanceSorter) Len() int { return len(pds.peers) }
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func (pds *peerDistanceSorter) Swap(a, b int) { pds.peers[a], pds.peers[b] = pds.peers[b], pds.peers[a] }
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func (pds *peerDistanceSorter) Less(a, b int) bool {
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return pds.peers[a].distance.less(pds.peers[b].distance)
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}
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// Append the peer.ID to the sorter's slice. It may no longer be sorted.
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func (pds *peerDistanceSorter) appendPeer(p peer.ID) {
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pds.peers = append(pds.peers, peerDistance{
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p: p,
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distance: xor(pds.target, ConvertPeerID(p)),
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})
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}
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// Append the peer.ID values in the list to the sorter's slice. It may no longer be sorted.
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func (pds *peerDistanceSorter) appendPeersFromList(l *list.List) {
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for e := l.Front(); e != nil; e = e.Next() {
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pds.appendPeer(e.Value.(peer.ID))
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}
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}
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func (pds *peerDistanceSorter) sort() {
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sort.Sort(pds)
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}
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// Sort the given peers by their ascending distance from the target. A new slice is returned.
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func SortClosestPeers(peers []peer.ID, target ID) []peer.ID {
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sorter := peerDistanceSorter{
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peers: make([]peerDistance, 0, len(peers)),
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target: target,
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}
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for _, p := range peers {
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sorter.appendPeer(p)
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}
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sorter.sort()
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out := make([]peer.ID, 0, sorter.Len())
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for _, p := range sorter.peers {
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out = append(out, p.p)
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}
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return out
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}
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