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// Copyright 2017 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 simulations simulates p2p networks.
// A mocker simulates starting and stopping real nodes in a network.
package simulations
import (
"fmt"
"math/rand"
"sync"
"time"
"github.com/dexon-foundation/dexon/log"
"github.com/dexon-foundation/dexon/p2p/enode"
"github.com/dexon-foundation/dexon/p2p/simulations/adapters"
)
//a map of mocker names to its function
var mockerList = map[string]func(net *Network, quit chan struct{}, nodeCount int){
"startStop": startStop,
"probabilistic": probabilistic,
"boot": boot,
}
//Lookup a mocker by its name, returns the mockerFn
func LookupMocker(mockerType string) func(net *Network, quit chan struct{}, nodeCount int) {
return mockerList[mockerType]
}
//Get a list of mockers (keys of the map)
//Useful for frontend to build available mocker selection
func GetMockerList() []string {
list := make([]string, 0, len(mockerList))
for k := range mockerList {
list = append(list, k)
}
return list
}
//The boot mockerFn only connects the node in a ring and doesn't do anything else
func boot(net *Network, quit chan struct{}, nodeCount int) {
_, err := connectNodesInRing(net, nodeCount)
if err != nil {
panic("Could not startup node network for mocker")
}
}
//The startStop mockerFn stops and starts nodes in a defined period (ticker)
func startStop(net *Network, quit chan struct{}, nodeCount int) {
nodes, err := connectNodesInRing(net, nodeCount)
if err != nil {
panic("Could not startup node network for mocker")
}
tick := time.NewTicker(10 * time.Second)
defer tick.Stop()
for {
select {
case <-quit:
log.Info("Terminating simulation loop")
return
case <-tick.C:
id := nodes[rand.Intn(len(nodes))]
log.Info("stopping node", "id", id)
if err := net.Stop(id); err != nil {
log.Error("error stopping node", "id", id, "err", err)
return
}
select {
case <-quit:
log.Info("Terminating simulation loop")
return
case <-time.After(3 * time.Second):
}
log.Debug("starting node", "id", id)
if err := net.Start(id); err != nil {
log.Error("error starting node", "id", id, "err", err)
return
}
}
}
}
//The probabilistic mocker func has a more probabilistic pattern
//(the implementation could probably be improved):
//nodes are connected in a ring, then a varying number of random nodes is selected,
//mocker then stops and starts them in random intervals, and continues the loop
func probabilistic(net *Network, quit chan struct{}, nodeCount int) {
nodes, err := connectNodesInRing(net, nodeCount)
if err != nil {
select {
case <-quit:
//error may be due to abortion of mocking; so the quit channel is closed
return
default:
panic("Could not startup node network for mocker")
}
}
for {
select {
case <-quit:
log.Info("Terminating simulation loop")
return
default:
}
var lowid, highid int
var wg sync.WaitGroup
randWait := time.Duration(rand.Intn(5000)+1000) * time.Millisecond
rand1 := rand.Intn(nodeCount - 1)
rand2 := rand.Intn(nodeCount - 1)
if rand1 < rand2 {
lowid = rand1
highid = rand2
} else if rand1 > rand2 {
highid = rand1
lowid = rand2
} else {
if rand1 == 0 {
rand2 = 9
} else if rand1 == 9 {
rand1 = 0
}
lowid = rand1
highid = rand2
}
var steps = highid - lowid
wg.Add(steps)
for i := lowid; i < highid; i++ {
select {
case <-quit:
log.Info("Terminating simulation loop")
return
case <-time.After(randWait):
}
log.Debug(fmt.Sprintf("node %v shutting down", nodes[i]))
err := net.Stop(nodes[i])
if err != nil {
log.Error("Error stopping node", "node", nodes[i])
wg.Done()
continue
}
go func(id enode.ID) {
time.Sleep(randWait)
err := net.Start(id)
if err != nil {
log.Error("Error starting node", "node", id)
}
wg.Done()
}(nodes[i])
}
wg.Wait()
}
}
//connect nodeCount number of nodes in a ring
func connectNodesInRing(net *Network, nodeCount int) ([]enode.ID, error) {
ids := make([]enode.ID, nodeCount)
for i := 0; i < nodeCount; i++ {
conf := adapters.RandomNodeConfig()
node, err := net.NewNodeWithConfig(conf)
if err != nil {
log.Error("Error creating a node!", "err", err)
return nil, err
}
ids[i] = node.ID()
}
for _, id := range ids {
if err := net.Start(id); err != nil {
log.Error("Error starting a node!", "err", err)
return nil, err
}
log.Debug(fmt.Sprintf("node %v starting up", id))
}
for i, id := range ids {
peerID := ids[(i+1)%len(ids)]
if err := net.Connect(id, peerID); err != nil {
log.Error("Error connecting a node to a peer!", "err", err)
return nil, err
}
}
return ids, nil
}
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