p2p/simulations: add mocker functionality (#15207)

This commit adds mocker functionality to p2p/simulations. A
mocker allows to starting/stopping of nodes via the HTTP API.

5 files changed, 480 insertions, 2 deletions

diff --git a/p2p/simulations/adapters/state.go b/p2p/simulations/adapters/state.go
new file mode 100644
index 000000000..8b1dfef90
--- /dev/null
+++ b/p2p/simulations/adapters/state.go
@@ -0,0 +1,35 @@
+// 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 adapters
+
+type SimStateStore struct {
+	m map[string][]byte
+}
+
+func (self *SimStateStore) Load(s string) ([]byte, error) {
+	return self.m[s], nil
+}
+
+func (self *SimStateStore) Save(s string, data []byte) error {
+	self.m[s] = data
+	return nil
+}
+
+func NewSimStateStore() *SimStateStore {
+	return &SimStateStore{
+		make(map[string][]byte),
+	}
+}
diff --git a/p2p/simulations/http.go b/p2p/simulations/http.go
index 3fa8b9292..97dd742e8 100644
--- a/p2p/simulations/http.go
+++ b/p2p/simulations/http.go
@@ -27,6 +27,7 @@ import (
 	"net/http"
 	"strconv"
 	"strings"
+	"sync"
 
 	"github.com/ethereum/go-ethereum/event"
 	"github.com/ethereum/go-ethereum/p2p"
@@ -263,8 +264,10 @@ func (c *Client) Send(method, path string, in, out interface{}) error {
 
 // Server is an HTTP server providing an API to manage a simulation network
 type Server struct {
-	router  *httprouter.Router
-	network *Network
+	router     *httprouter.Router
+	network    *Network
+	mockerStop chan struct{} // when set, stops the current mocker
+	mockerMtx  sync.Mutex    // synchronises access to the mockerStop field
 }
 
 // NewServer returns a new simulation API server
@@ -278,6 +281,10 @@ func NewServer(network *Network) *Server {
 	s.GET("/", s.GetNetwork)
 	s.POST("/start", s.StartNetwork)
 	s.POST("/stop", s.StopNetwork)
+	s.POST("/mocker/start", s.StartMocker)
+	s.POST("/mocker/stop", s.StopMocker)
+	s.GET("/mocker", s.GetMockers)
+	s.POST("/reset", s.ResetNetwork)
 	s.GET("/events", s.StreamNetworkEvents)
 	s.GET("/snapshot", s.CreateSnapshot)
 	s.POST("/snapshot", s.LoadSnapshot)
@@ -318,6 +325,59 @@ func (s *Server) StopNetwork(w http.ResponseWriter, req *http.Request) {
 	w.WriteHeader(http.StatusOK)
 }
 
+// StartMocker starts the mocker node simulation
+func (s *Server) StartMocker(w http.ResponseWriter, req *http.Request) {
+	s.mockerMtx.Lock()
+	defer s.mockerMtx.Unlock()
+	if s.mockerStop != nil {
+		http.Error(w, "mocker already running", http.StatusInternalServerError)
+		return
+	}
+	mockerType := req.FormValue("mocker-type")
+	mockerFn := LookupMocker(mockerType)
+	if mockerFn == nil {
+		http.Error(w, fmt.Sprintf("unknown mocker type %q", mockerType), http.StatusBadRequest)
+		return
+	}
+	nodeCount, err := strconv.Atoi(req.FormValue("node-count"))
+	if err != nil {
+		http.Error(w, "invalid node-count provided", http.StatusBadRequest)
+		return
+	}
+	s.mockerStop = make(chan struct{})
+	go mockerFn(s.network, s.mockerStop, nodeCount)
+
+	w.WriteHeader(http.StatusOK)
+}
+
+// StopMocker stops the mocker node simulation
+func (s *Server) StopMocker(w http.ResponseWriter, req *http.Request) {
+	s.mockerMtx.Lock()
+	defer s.mockerMtx.Unlock()
+	if s.mockerStop == nil {
+		http.Error(w, "stop channel not initialized", http.StatusInternalServerError)
+		return
+	}
+	close(s.mockerStop)
+	s.mockerStop = nil
+
+	w.WriteHeader(http.StatusOK)
+}
+
+// GetMockerList returns a list of available mockers
+func (s *Server) GetMockers(w http.ResponseWriter, req *http.Request) {
+
+	list := GetMockerList()
+	s.JSON(w, http.StatusOK, list)
+}
+
+// ResetNetwork resets all properties of a network to its initial (empty) state
+func (s *Server) ResetNetwork(w http.ResponseWriter, req *http.Request) {
+	s.network.Reset()
+
+	w.WriteHeader(http.StatusOK)
+}
+
 // StreamNetworkEvents streams network events as a server-sent-events stream
 func (s *Server) StreamNetworkEvents(w http.ResponseWriter, req *http.Request) {
 	events := make(chan *Event)
diff --git a/p2p/simulations/mocker.go b/p2p/simulations/mocker.go
new file mode 100644
index 000000000..c38e28855
--- /dev/null
+++ b/p2p/simulations/mocker.go
@@ -0,0 +1,192 @@
+// 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/ethereum/go-ethereum/log"
+	"github.com/ethereum/go-ethereum/p2p/discover"
+)
+
+//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 {
+		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(fmt.Sprintf("Error stopping node %s", nodes[i]))
+				wg.Done()
+				continue
+			}
+			go func(id discover.NodeID) {
+				time.Sleep(randWait)
+				err := net.Start(id)
+				if err != nil {
+					log.Error(fmt.Sprintf("Error starting node %s", id))
+				}
+				wg.Done()
+			}(nodes[i])
+		}
+		wg.Wait()
+	}
+
+}
+
+//connect nodeCount number of nodes in a ring
+func connectNodesInRing(net *Network, nodeCount int) ([]discover.NodeID, error) {
+	ids := make([]discover.NodeID, nodeCount)
+	for i := 0; i < nodeCount; i++ {
+		node, err := net.NewNode()
+		if err != nil {
+			log.Error("Error creating a node! %s", 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! %s", 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! %s", err)
+			return nil, err
+		}
+	}
+
+	return ids, nil
+}
diff --git a/p2p/simulations/mocker_test.go b/p2p/simulations/mocker_test.go
new file mode 100644
index 000000000..6b866fb74
--- /dev/null
+++ b/p2p/simulations/mocker_test.go
@@ -0,0 +1,171 @@
+// 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 mokcer simulates starting and stopping real nodes in a network.
+package simulations
+
+import (
+	"encoding/json"
+	"net/http"
+	"net/url"
+	"strconv"
+	"sync"
+	"testing"
+	"time"
+
+	"github.com/ethereum/go-ethereum/p2p/discover"
+)
+
+func TestMocker(t *testing.T) {
+	//start the simulation HTTP server
+	_, s := testHTTPServer(t)
+	defer s.Close()
+
+	//create a client
+	client := NewClient(s.URL)
+
+	//start the network
+	err := client.StartNetwork()
+	if err != nil {
+		t.Fatalf("Could not start test network: %s", err)
+	}
+	//stop the network to terminate
+	defer func() {
+		err = client.StopNetwork()
+		if err != nil {
+			t.Fatalf("Could not stop test network: %s", err)
+		}
+	}()
+
+	//get the list of available mocker types
+	resp, err := http.Get(s.URL + "/mocker")
+	if err != nil {
+		t.Fatalf("Could not get mocker list: %s", err)
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != 200 {
+		t.Fatalf("Invalid Status Code received, expected 200, got %d", resp.StatusCode)
+	}
+
+	//check the list is at least 1 in size
+	var mockerlist []string
+	err = json.NewDecoder(resp.Body).Decode(&mockerlist)
+	if err != nil {
+		t.Fatalf("Error decoding JSON mockerlist: %s", err)
+	}
+
+	if len(mockerlist) < 1 {
+		t.Fatalf("No mockers available")
+	}
+
+	nodeCount := 10
+	var wg sync.WaitGroup
+
+	events := make(chan *Event, 10)
+	var opts SubscribeOpts
+	sub, err := client.SubscribeNetwork(events, opts)
+	defer sub.Unsubscribe()
+	//wait until all nodes are started and connected
+	//store every node up event in a map (value is irrelevant, mimic Set datatype)
+	nodemap := make(map[discover.NodeID]bool)
+	wg.Add(1)
+	nodesComplete := false
+	connCount := 0
+	go func() {
+		for {
+			select {
+			case event := <-events:
+				//if the event is a node Up event only
+				if event.Node != nil && event.Node.Up == true {
+					//add the correspondent node ID to the map
+					nodemap[event.Node.Config.ID] = true
+					//this means all nodes got a nodeUp event, so we can continue the test
+					if len(nodemap) == nodeCount {
+						nodesComplete = true
+						//wait for 3s as the mocker will need time to connect the nodes
+						//time.Sleep( 3 *time.Second)
+					}
+				} else if event.Conn != nil && nodesComplete {
+					connCount += 1
+					if connCount == (nodeCount-1)*2 {
+						wg.Done()
+						return
+					}
+				}
+			case <-time.After(30 * time.Second):
+				wg.Done()
+				t.Fatalf("Timeout waiting for nodes being started up!")
+			}
+		}
+	}()
+
+	//take the last element of the mockerlist as the default mocker-type to ensure one is enabled
+	mockertype := mockerlist[len(mockerlist)-1]
+	//still, use hardcoded "probabilistic" one if available ;)
+	for _, m := range mockerlist {
+		if m == "probabilistic" {
+			mockertype = m
+			break
+		}
+	}
+	//start the mocker with nodeCount number of nodes
+	resp, err = http.PostForm(s.URL+"/mocker/start", url.Values{"mocker-type": {mockertype}, "node-count": {strconv.Itoa(nodeCount)}})
+	if err != nil {
+		t.Fatalf("Could not start mocker: %s", err)
+	}
+	if resp.StatusCode != 200 {
+		t.Fatalf("Invalid Status Code received for starting mocker, expected 200, got %d", resp.StatusCode)
+	}
+
+	wg.Wait()
+
+	//check there are nodeCount number of nodes in the network
+	nodes_info, err := client.GetNodes()
+	if err != nil {
+		t.Fatalf("Could not get nodes list: %s", err)
+	}
+
+	if len(nodes_info) != nodeCount {
+		t.Fatalf("Expected %d number of nodes, got: %d", nodeCount, len(nodes_info))
+	}
+
+	//stop the mocker
+	resp, err = http.Post(s.URL+"/mocker/stop", "", nil)
+	if err != nil {
+		t.Fatalf("Could not stop mocker: %s", err)
+	}
+	if resp.StatusCode != 200 {
+		t.Fatalf("Invalid Status Code received for stopping mocker, expected 200, got %d", resp.StatusCode)
+	}
+
+	//reset the network
+	_, err = http.Post(s.URL+"/reset", "", nil)
+	if err != nil {
+		t.Fatalf("Could not reset network: %s", err)
+	}
+
+	//now the number of nodes in the network should be zero
+	nodes_info, err = client.GetNodes()
+	if err != nil {
+		t.Fatalf("Could not get nodes list: %s", err)
+	}
+
+	if len(nodes_info) != 0 {
+		t.Fatalf("Expected empty list of nodes, got: %d", len(nodes_info))
+	}
+}
diff --git a/p2p/simulations/network.go b/p2p/simulations/network.go
index f3dda2e44..caf428ece 100644
--- a/p2p/simulations/network.go
+++ b/p2p/simulations/network.go
@@ -501,6 +501,20 @@ func (self *Network) Shutdown() {
 	close(self.quitc)
 }
 
+//Reset resets all network properties:
+//emtpies the nodes and the connection list
+func (self *Network) Reset() {
+	self.lock.Lock()
+	defer self.lock.Unlock()
+
+	//re-initialize the maps
+	self.connMap = make(map[string]int)
+	self.nodeMap = make(map[discover.NodeID]int)
+
+	self.Nodes = nil
+	self.Conns = nil
+}
+
 // Node is a wrapper around adapters.Node which is used to track the status
 // of a node in the network
 type Node struct {
@@ -664,6 +678,12 @@ func (self *Network) Load(snap *Snapshot) error {
 		}
 	}
 	for _, conn := range snap.Conns {
+
+		if !self.GetNode(conn.One).Up || !self.GetNode(conn.Other).Up {
+			//in this case, at least one of the nodes of a connection is not up,
+			//so it would result in the snapshot `Load` to fail
+			continue
+		}
 		if err := self.Connect(conn.One, conn.Other); err != nil {
 			return err
 		}