// 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"
"errors"
"net/http"
"sync"
"time"
"github.com/ethereum/go-ethereum/log"
"github.com/ethereum/go-ethereum/node"
"github.com/ethereum/go-ethereum/p2p/enode"
"github.com/ethereum/go-ethereum/p2p/simulations"
"github.com/ethereum/go-ethereum/p2p/simulations/adapters"
"github.com/ethereum/go-ethereum/swarm/network"
)
// Common errors that are returned by functions in this package.
var (
ErrNodeNotFound = errors.New("node not found")
)
// Simulation provides methods on network, nodes and services
// to manage them.
type Simulation struct {
// Net is exposed as a way to access lower level functionalities
// of p2p/simulations.Network.
Net *simulations.Network
serviceNames []string
cleanupFuncs []func()
buckets map[enode.ID]*sync.Map
shutdownWG sync.WaitGroup
done chan struct{}
mu sync.RWMutex
neighbourhoodSize int
httpSrv *http.Server //attach a HTTP server via SimulationOptions
handler *simulations.Server //HTTP handler for the server
runC chan struct{} //channel where frontend signals it is ready
}
// ServiceFunc is used in New to declare new service constructor.
// The first argument provides ServiceContext from the adapters package
// giving for example the access to NodeID. Second argument is the sync.Map
// where all "global" state related to the service should be kept.
// All cleanups needed for constructed service and any other constructed
// objects should ne provided in a single returned cleanup function.
// Returned cleanup function will be called by Close function
// after network shutdown.
type ServiceFunc func(ctx *adapters.ServiceContext, bucket *sync.Map) (s node.Service, cleanup func(), err error)
// New creates a new simulation instance
// Services map must have unique keys as service names and
// every ServiceFunc must return a node.Service of the unique type.
// This restriction is required by node.Node.Start() function
// which is used to start node.Service returned by ServiceFunc.
func New(services map[string]ServiceFunc) (s *Simulation) {
s = &Simulation{
buckets: make(map[enode.ID]*sync.Map),
done: make(chan struct{}),
neighbourhoodSize: network.NewKadParams().NeighbourhoodSize,
}
adapterServices := make(map[string]adapters.ServiceFunc, len(services))
for name, serviceFunc := range services {
// Scope this variables correctly
// as they will be in the adapterServices[name] function accessed later.
name, serviceFunc := name, serviceFunc
s.serviceNames = append(s.serviceNames, name)
adapterServices[name] = func(ctx *adapters.ServiceContext) (node.Service, error) {
b := new(sync.Map)
service, cleanup, err := serviceFunc(ctx, b)
if err != nil {
return nil, err
}
s.mu.Lock()
defer s.mu.Unlock()
if cleanup != nil {
s.cleanupFuncs = append(s.cleanupFuncs, cleanup)
}
s.buckets[ctx.Config.ID] = b
return service, nil
}
}
s.Net = simulations.NewNetwork(
adapters.NewTCPAdapter(adapterServices),
&simulations.NetworkConfig{ID: "0"},
)
return s
}
// RunFunc is the function that will be called
// on Simulation.Run method call.
type RunFunc func(context.Context, *Simulation) error
// Result is the returned value of Simulation.Run method.
type Result struct {
Duration time.Duration
Error error
}
// Run calls the RunFunc function while taking care of
// cancellation provided through the Context.
func (s *Simulation) Run(ctx context.Context, f RunFunc) (r Result) {
//if the option is set to run a HTTP server with the simulation,
//init the server and start it
start := time.Now()
if s.httpSrv != nil {
log.Info("Waiting for frontend to be ready...(send POST /runsim to HTTP server)")
//wait for the frontend to connect
select {
case <-s.runC:
case <-ctx.Done():
return Result{
Duration: time.Since(start),
Error: ctx.Err(),
}
}
log.Info("Received signal from frontend - starting simulation run.")
}
errc := make(chan error)
quit := make(chan struct{})
defer close(quit)
go func() {
select {
case errc <- f(ctx, s):
case <-quit:
}
}()
var err error
select {
case <-ctx.Done():
err = ctx.Err()
case err = <-errc:
}
return Result{
Duration: time.Since(start),
Error: err,
}
}
// Maximal number of parallel calls to cleanup functions on
// Simulation.Close.
var maxParallelCleanups = 10
// Close calls all cleanup functions that are returned by
// ServiceFunc, waits for all of them to finish and other
// functions that explicitly block shutdownWG
// (like Simulation.PeerEvents) and shuts down the network
// at the end. It is used to clean all resources from the
// simulation.
func (s *Simulation) Close() {
close(s.done)
sem := make(chan struct{}, maxParallelCleanups)
s.mu.RLock()
cleanupFuncs := make([]func(), len(s.cleanupFuncs))
for i, f := range s.cleanupFuncs {
if f != nil {
cleanupFuncs[i] = f
}
}
s.mu.RUnlock()
var cleanupWG sync.WaitGroup
for _, cleanup := range cleanupFuncs {
cleanupWG.Add(1)
sem <- struct{}{}
go func(cleanup func()) {
defer cleanupWG.Done()
defer func() { <-sem }()
cleanup()
}(cleanup)
}
cleanupWG.Wait()
if s.httpSrv != nil {
ctx, cancel := context.WithTimeout(context.Background(), 2*time.Second)
defer cancel()
err := s.httpSrv.Shutdown(ctx)
if err != nil {
log.Error("Error shutting down HTTP server!", "err", err)
}
close(s.runC)
}
s.shutdownWG.Wait()
s.Net.Shutdown()
}
// Done returns a channel that is closed when the simulation
// is closed by Close method. It is useful for signaling termination
// of all possible goroutines that are created within the test.
func (s *Simulation) Done() <-chan struct{} {
return s.done
}
