path: root/swarm/network/simulation/kademlia.go

// Copyright 2018 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.

package simulation

import (
    "context"
    "encoding/binary"
    "encoding/hex"
    "time"

    "github.com/ethereum/go-ethereum/common"
    "github.com/ethereum/go-ethereum/log"
    "github.com/ethereum/go-ethereum/p2p/enode"
    "github.com/ethereum/go-ethereum/p2p/simulations"
    "github.com/ethereum/go-ethereum/swarm/network"
)

// BucketKeyKademlia is the key to be used for storing the kademlia
// instance for particular node, usually inside the ServiceFunc function.
var BucketKeyKademlia BucketKey = "kademlia"

// WaitTillHealthy is blocking until the health of all kademlias is true.
// If error is not nil, a map of kademlia that was found not healthy is returned.
// TODO: Check correctness since change in kademlia depth calculation logic
func (s *Simulation) WaitTillHealthy(ctx context.Context) (ill map[enode.ID]*network.Kademlia, err error) {
    // Prepare PeerPot map for checking Kademlia health
    var ppmap map[string]*network.PeerPot
    kademlias := s.kademlias()
    addrs := make([][]byte, 0, len(kademlias))
    // TODO verify that all kademlias have same params
    for _, k := range kademlias {
        addrs = append(addrs, k.BaseAddr())
    }
    ppmap = network.NewPeerPotMap(s.neighbourhoodSize, addrs)

    // Wait for healthy Kademlia on every node before checking files
    ticker := time.NewTicker(200 * time.Millisecond)
    defer ticker.Stop()

    ill = make(map[enode.ID]*network.Kademlia)
    for {
        select {
        case <-ctx.Done():
            return ill, ctx.Err()
        case <-ticker.C:
            for k := range ill {
                delete(ill, k)
            }
            log.Debug("kademlia health check", "addr count", len(addrs), "kad len", len(kademlias))
            for id, k := range kademlias {
                //PeerPot for this node
                addr := common.Bytes2Hex(k.BaseAddr())
                pp := ppmap[addr]
                //call Healthy RPC
                h := k.GetHealthInfo(pp)
                //print info
                log.Debug(k.String())
                log.Debug("kademlia", "connectNN", h.ConnectNN, "knowNN", h.KnowNN)
                log.Debug("kademlia", "health", h.ConnectNN && h.KnowNN, "addr", hex.EncodeToString(k.BaseAddr()), "node", id)
                log.Debug("kademlia", "ill condition", !h.ConnectNN, "addr", hex.EncodeToString(k.BaseAddr()), "node", id)
                if !h.Healthy() {
                    ill[id] = k
                }
            }
            if len(ill) == 0 {
                return nil, nil
            }
        }
    }
}

// kademlias returns all Kademlia instances that are set
// in simulation bucket.
func (s *Simulation) kademlias() (ks map[enode.ID]*network.Kademlia) {
    items := s.UpNodesItems(BucketKeyKademlia)
    log.Debug("kademlia len items", "len", len(items))
    ks = make(map[enode.ID]*network.Kademlia, len(items))
    for id, v := range items {
        k, ok := v.(*network.Kademlia)
        if !ok {
            continue
        }
        ks[id] = k
    }
    return ks
}

// WaitTillSnapshotRecreated is blocking until all the connections specified
// in the snapshot are registered in the kademlia.
// It differs from WaitTillHealthy, which waits only until all the kademlias are
// healthy (it might happen even before all the connections are established).
func (s *Simulation) WaitTillSnapshotRecreated(ctx context.Context, snap *simulations.Snapshot) error {
    expected := getSnapshotConnections(snap.Conns)
    ticker := time.NewTicker(150 * time.Millisecond)
    defer ticker.Stop()

    for {
        select {
        case <-ctx.Done():
            return ctx.Err()
        case <-ticker.C:
            actual := s.getActualConnections()
            if isAllDeployed(expected, actual) {
                return nil
            }
        }
    }
}

func (s *Simulation) getActualConnections() (res []uint64) {
    kademlias := s.kademlias()
    for base, k := range kademlias {
        k.EachConn(base[:], 256, func(p *network.Peer, _ int) bool {
            res = append(res, getConnectionHash(base, p.ID()))
            return true
        })
    }

    // only list those connections that appear twice (both peers should recognize connection as active)
    res = removeDuplicatesAndSingletons(res)
    return res
}

func getSnapshotConnections(conns []simulations.Conn) (res []uint64) {
    for _, c := range conns {
        res = append(res, getConnectionHash(c.One, c.Other))
    }
    return res
}

// returns an integer connection identifier (similar to 8-byte hash)
func getConnectionHash(a, b enode.ID) uint64 {
    var h [8]byte
    for i := 0; i < 8; i++ {
        h[i] = a[i] ^ b[i]
    }
    res := binary.LittleEndian.Uint64(h[:])
    return res
}

// returns true if all connections in expected are listed in actual
func isAllDeployed(expected []uint64, actual []uint64) bool {
    if len(expected) == 0 {
        return true
    }

    exp := make([]uint64, len(expected))
    copy(exp, expected)
    for _, c := range actual {
        // remove value c from exp
        for i := 0; i < len(exp); i++ {
            if exp[i] == c {
                exp = removeListElement(exp, i)
                if len(exp) == 0 {
                    return true
                }
            }
        }
    }
    return len(exp) == 0
}

func removeListElement(arr []uint64, i int) []uint64 {
    last := len(arr) - 1
    arr[i] = arr[last]
    arr = arr[:last]
    return arr
}

func removeDuplicatesAndSingletons(arr []uint64) []uint64 {
    for i := 0; i < len(arr); {
        found := false
        for j := i + 1; j < len(arr); j++ {
            if arr[i] == arr[j] {
                arr = removeListElement(arr, j) // remove duplicate
                found = true
                break
            }
        }

        if found {
            i++
        } else {
            arr = removeListElement(arr, i) // remove singleton
        }
    }

    return arr
}