Fix deadlocks in event listener system; closes pterodactyl/panel#2298

Fixes deadlocks that occurred when events were registered while other events were being unsubscribed and data was being flooded to these listeners. A complete mess, I hate this code, it is going to break again, but jesus I'm so tired.
This commit is contained in:
Dane Everitt 2020-09-11 23:01:54 -07:00 committed by GitHub
parent 45bcb9cd68
commit b2eebcaf6d
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
7 changed files with 57 additions and 32 deletions

View File

@ -2,8 +2,8 @@ package events
import (
"encoding/json"
"github.com/sasha-s/go-deadlock"
"strings"
"sync"
)
type Event struct {
@ -12,7 +12,7 @@ type Event struct {
}
type EventBus struct {
sync.RWMutex
deadlock.RWMutex
subscribers map[string]map[chan Event]struct{}
}
@ -47,8 +47,12 @@ func (e *EventBus) Publish(topic string, data string) {
defer e.RUnlock()
if ch, ok := e.subscribers[t]; ok {
e := Event{Data: data, Topic: topic}
for channel := range ch {
channel <- Event{Data: data, Topic: topic}
go func(channel chan Event, e Event) {
channel <- e
}(channel, e)
}
}
}()
@ -66,29 +70,33 @@ func (e *EventBus) PublishJson(topic string, data interface{}) error {
}
// Subscribe to an emitter topic using a channel.
func (e *EventBus) Subscribe(topic string, ch chan Event) {
func (e *EventBus) Subscribe(topics []string, ch chan Event) {
e.Lock()
defer e.Unlock()
if _, exists := e.subscribers[topic]; !exists {
e.subscribers[topic] = make(map[chan Event]struct{})
}
for _, topic := range topics {
if _, exists := e.subscribers[topic]; !exists {
e.subscribers[topic] = make(map[chan Event]struct{})
}
// Only set the channel if there is not currently a matching one for this topic. This
// avoids registering two identical listeners for the same topic and causing pain in
// the unsubscribe functionality as well.
if _, exists := e.subscribers[topic][ch]; !exists {
e.subscribers[topic][ch] = struct{}{}
// Only set the channel if there is not currently a matching one for this topic. This
// avoids registering two identical listeners for the same topic and causing pain in
// the unsubscribe functionality as well.
if _, exists := e.subscribers[topic][ch]; !exists {
e.subscribers[topic][ch] = struct{}{}
}
}
}
// Unsubscribe a channel from a given topic.
func (e *EventBus) Unsubscribe(topic string, ch chan Event) {
func (e *EventBus) Unsubscribe(topics []string, ch chan Event) {
e.Lock()
defer e.Unlock()
if _, exists := e.subscribers[topic][ch]; exists {
delete(e.subscribers[topic], ch)
for _, topic := range topics {
if _, exists := e.subscribers[topic][ch]; exists {
delete(e.subscribers[topic], ch)
}
}
}

2
go.mod
View File

@ -55,6 +55,7 @@ require (
github.com/opencontainers/go-digest v1.0.0 // indirect
github.com/opencontainers/image-spec v1.0.1 // indirect
github.com/patrickmn/go-cache v2.1.0+incompatible
github.com/petermattis/goid v0.0.0-20180202154549-b0b1615b78e5 // indirect
github.com/pierrec/lz4 v2.5.2+incompatible // indirect
github.com/pkg/errors v0.9.1
github.com/pkg/profile v1.5.0
@ -62,6 +63,7 @@ require (
github.com/prometheus/common v0.11.1 // indirect
github.com/remeh/sizedwaitgroup v1.0.0
github.com/sabhiram/go-gitignore v0.0.0-20180611051255-d3107576ba94
github.com/sasha-s/go-deadlock v0.2.0
github.com/spf13/cobra v1.0.0
github.com/spf13/pflag v1.0.5 // indirect
github.com/ulikunitz/xz v0.5.7 // indirect

4
go.sum
View File

@ -412,6 +412,8 @@ github.com/patrickmn/go-cache v2.1.0+incompatible/go.mod h1:3Qf8kWWT7OJRJbdiICTK
github.com/pborman/uuid v1.2.0/go.mod h1:X/NO0urCmaxf9VXbdlT7C2Yzkj2IKimNn4k+gtPdI/k=
github.com/pelletier/go-toml v1.2.0/go.mod h1:5z9KED0ma1S8pY6P1sdut58dfprrGBbd/94hg7ilaic=
github.com/performancecopilot/speed v3.0.0+incompatible/go.mod h1:/CLtqpZ5gBg1M9iaPbIdPPGyKcA8hKdoy6hAWba7Yac=
github.com/petermattis/goid v0.0.0-20180202154549-b0b1615b78e5 h1:q2e307iGHPdTGp0hoxKjt1H5pDo6utceo3dQVK3I5XQ=
github.com/petermattis/goid v0.0.0-20180202154549-b0b1615b78e5/go.mod h1:jvVRKCrJTQWu0XVbaOlby/2lO20uSCHEMzzplHXte1o=
github.com/pierrec/lz4 v1.0.2-0.20190131084431-473cd7ce01a1/go.mod h1:3/3N9NVKO0jef7pBehbT1qWhCMrIgbYNnFAZCqQ5LRc=
github.com/pierrec/lz4 v2.0.5+incompatible h1:2xWsjqPFWcplujydGg4WmhC/6fZqK42wMM8aXeqhl0I=
github.com/pierrec/lz4 v2.0.5+incompatible/go.mod h1:pdkljMzZIN41W+lC3N2tnIh5sFi+IEE17M5jbnwPHcY=
@ -479,6 +481,8 @@ github.com/ryanuber/columnize v0.0.0-20160712163229-9b3edd62028f/go.mod h1:sm1tb
github.com/sabhiram/go-gitignore v0.0.0-20180611051255-d3107576ba94 h1:G04eS0JkAIVZfaJLjla9dNxkJCPiKIGZlw9AfOhzOD0=
github.com/sabhiram/go-gitignore v0.0.0-20180611051255-d3107576ba94/go.mod h1:b18R55ulyQ/h3RaWyloPyER7fWQVZvimKKhnI5OfrJQ=
github.com/samuel/go-zookeeper v0.0.0-20190923202752-2cc03de413da/go.mod h1:gi+0XIa01GRL2eRQVjQkKGqKF3SF9vZR/HnPullcV2E=
github.com/sasha-s/go-deadlock v0.2.0 h1:lMqc+fUb7RrFS3gQLtoQsJ7/6TV/pAIFvBsqX73DK8Y=
github.com/sasha-s/go-deadlock v0.2.0/go.mod h1:StQn567HiB1fF2yJ44N9au7wOhrPS3iZqiDbRupzT10=
github.com/sean-/seed v0.0.0-20170313163322-e2103e2c3529/go.mod h1:DxrIzT+xaE7yg65j358z/aeFdxmN0P9QXhEzd20vsDc=
github.com/sergi/go-diff v1.0.0/go.mod h1:0CfEIISq7TuYL3j771MWULgwwjU+GofnZX9QAmXWZgo=
github.com/shurcooL/sanitized_anchor_name v1.0.0/go.mod h1:1NzhyTcUVG4SuEtjjoZeVRXNmyL/1OwPU0+IJeTBvfc=

View File

@ -50,24 +50,26 @@ var e = []string{
// Listens for different events happening on a server and sends them along
// to the connected websocket.
func (h *Handler) ListenForServerEvents(ctx context.Context) {
eventChannel := make(chan events.Event)
for _, event := range e {
h.server.Events().Subscribe(event, eventChannel)
}
h.server.Log().Debug("listening for server events over websocket")
for d := range eventChannel {
eventChannel := make(chan events.Event)
h.server.Events().Subscribe(e, eventChannel)
go func(ctx context.Context) {
select {
case <-ctx.Done():
for _, event := range e {
h.server.Events().Unsubscribe(event, eventChannel)
if h.jwt != nil {
h.server.Log().WithField("jwt_subject", h.jwt.Subject).Debug("unsubscribing server from event listeners")
}
h.server.Events().Unsubscribe(e, eventChannel)
close(eventChannel)
default:
_ = h.SendJson(&Message{
Event: d.Topic,
Args: []string{d.Data},
})
}
}(ctx)
for d := range eventChannel {
if err := h.SendJson(&Message{Event: d.Topic, Args: []string{d.Data}}); err != nil {
h.server.Log().WithField("error", err).Warn("error while sending server data over websocket")
}
}
}

View File

@ -95,6 +95,8 @@ func (h *Handler) SendJson(v *Message) error {
// Do not send JSON down the line if the JWT on the connection is not
// valid!
if err := h.TokenValid(); err != nil {
h.server.Log().WithField("error", err).Warn("invalid JWT detected for server websocket!")
return nil
}

View File

@ -17,10 +17,6 @@ func (s *Server) StartEventListeners() {
state := make(chan events.Event)
stats := make(chan events.Event)
s.Environment.Events().Subscribe(environment.ConsoleOutputEvent, console)
s.Environment.Events().Subscribe(environment.StateChangeEvent, state)
s.Environment.Events().Subscribe(environment.ResourceEvent, stats)
go func(console chan events.Event) {
for data := range console {
// Immediately emit this event back over the server event stream since it is
@ -31,12 +27,16 @@ func (s *Server) StartEventListeners() {
// Also pass the data along to the console output channel.
s.onConsoleOutput(data.Data)
}
s.Log().Fatal("unexpected end-of-range for server console channel")
}(console)
go func(state chan events.Event) {
for data := range state {
s.SetState(data.Data)
}
s.Log().Fatal("unexpected end-of-range for server state channel")
}(state)
go func(stats chan events.Event) {
@ -56,7 +56,14 @@ func (s *Server) StartEventListeners() {
s.emitProcUsage()
}
s.Log().Fatal("unexpected end-of-range for server stats channel")
}(stats)
s.Log().Info("registering event listeners: console, state, resources...")
s.Environment.Events().Subscribe([]string{environment.ConsoleOutputEvent}, console)
s.Environment.Events().Subscribe([]string{environment.StateChangeEvent}, state)
s.Environment.Events().Subscribe([]string{environment.ResourceEvent}, stats)
}
var stripAnsiRegex = regexp.MustCompile("[\u001B\u009B][[\\]()#;?]*(?:(?:(?:[a-zA-Z\\d]*(?:;[a-zA-Z\\d]*)*)?\u0007)|(?:(?:\\d{1,4}(?:;\\d{0,4})*)?[\\dA-PRZcf-ntqry=><~]))")

View File

@ -118,7 +118,7 @@ func FromConfiguration(data *api.ServerConfigurationResponse) (*Server, error) {
return nil, err
} else {
s.Environment = env
go s.StartEventListeners()
s.StartEventListeners()
}
// Forces the configuration to be synced with the panel.