mirror of
https://github.com/ProtonMail/proton-bridge.git
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We build too many walls and not enough bridges
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Jakub
180
pkg/listener/listener.go
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180
pkg/listener/listener.go
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// Copyright (c) 2020 Proton Technologies AG
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//
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// This file is part of ProtonMail Bridge.
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//
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// ProtonMail Bridge is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// ProtonMail Bridge is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with ProtonMail Bridge. If not, see <https://www.gnu.org/licenses/>.
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package listener
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import (
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"sync"
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"time"
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"github.com/ProtonMail/proton-bridge/pkg/config"
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)
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var log = config.GetLogEntry("bridgeUtils/listener") //nolint[gochecknoglobals]
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// Listener has a list of channels watching for updates.
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type Listener interface {
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SetLimit(eventName string, limit time.Duration)
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Add(eventName string, channel chan<- string)
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Remove(eventName string, channel chan<- string)
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Emit(eventName string, data string)
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SetBuffer(eventName string)
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RetryEmit(eventName string)
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}
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type listener struct {
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channels map[string][]chan<- string
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limits map[string]time.Duration
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lastEmits map[string]map[string]time.Time
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buffered map[string][]string
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lock *sync.RWMutex
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}
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// New returns a new Listener which initially has no topics.
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func New() Listener {
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return &listener{
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channels: nil,
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limits: make(map[string]time.Duration),
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lastEmits: make(map[string]map[string]time.Time),
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buffered: make(map[string][]string),
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lock: &sync.RWMutex{},
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}
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}
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// SetLimit sets the limit for the `eventName`. When the same event (name and data)
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// is emitted within last time duration (`limit`), event is dropped. Zero limit clears
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// the limit for the specific `eventName`.
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func (l *listener) SetLimit(eventName string, limit time.Duration) {
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if limit == 0 {
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delete(l.limits, eventName)
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return
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}
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l.limits[eventName] = limit
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}
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// Add adds an event listener.
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func (l *listener) Add(eventName string, channel chan<- string) {
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l.lock.Lock()
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defer l.lock.Unlock()
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if l.channels == nil {
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l.channels = make(map[string][]chan<- string)
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}
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if _, ok := l.channels[eventName]; ok {
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l.channels[eventName] = append(l.channels[eventName], channel)
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} else {
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l.channels[eventName] = []chan<- string{channel}
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}
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}
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// Remove removes an event listener.
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func (l *listener) Remove(eventName string, channel chan<- string) {
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l.lock.Lock()
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defer l.lock.Unlock()
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if _, ok := l.channels[eventName]; ok {
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for i := range l.channels[eventName] {
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if l.channels[eventName][i] == channel {
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l.channels[eventName] = append(l.channels[eventName][:i], l.channels[eventName][i+1:]...)
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break
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}
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}
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}
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}
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// Emit emits an event in parallel to all listeners (channels).
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func (l *listener) Emit(eventName string, data string) {
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l.emit(eventName, data, false)
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}
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func (l *listener) emit(eventName, data string, isReEmit bool) {
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l.lock.RLock()
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defer l.lock.RUnlock()
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if !l.shouldEmit(eventName, data) {
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log.Warn("Emit of ", eventName, " with data ", data, " skipped")
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return
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}
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if _, ok := l.channels[eventName]; ok {
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for i, handler := range l.channels[eventName] {
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go func(handler chan<- string, i int) {
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handler <- data
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log.Debugf("emitted %s data %s -> %d", eventName, data, i)
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}(handler, i)
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}
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} else if !isReEmit {
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if bufferedData, ok := l.buffered[eventName]; ok {
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l.buffered[eventName] = append(bufferedData, data)
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log.Debugf("Buffering event %s data %s", eventName, data)
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} else {
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log.Warnf("No channel is listening to %s data %s", eventName, data)
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}
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}
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}
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func (l *listener) shouldEmit(eventName, data string) bool {
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if _, ok := l.limits[eventName]; !ok {
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return true
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}
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l.clearLastEmits()
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if eventLastEmits, ok := l.lastEmits[eventName]; ok {
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if _, ok := eventLastEmits[data]; ok {
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return false
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}
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} else {
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l.lastEmits[eventName] = make(map[string]time.Time)
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}
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l.lastEmits[eventName][data] = time.Now()
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return true
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}
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func (l *listener) clearLastEmits() {
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for eventName, lastEmits := range l.lastEmits {
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limit, ok := l.limits[eventName]
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if !ok { // Limits were disabled.
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delete(l.lastEmits, eventName)
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continue
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}
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for key, lastEmit := range lastEmits {
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if time.Since(lastEmit) > limit {
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delete(lastEmits, key)
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}
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}
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}
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}
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func (l *listener) SetBuffer(eventName string) {
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if _, ok := l.buffered[eventName]; !ok {
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l.buffered[eventName] = []string{}
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}
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}
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func (l *listener) RetryEmit(eventName string) {
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if _, ok := l.channels[eventName]; !ok || len(l.channels[eventName]) == 0 {
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return
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}
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if bufferedData, ok := l.buffered[eventName]; ok {
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for _, data := range bufferedData {
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l.emit(eventName, data, true)
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}
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l.buffered[eventName] = []string{}
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}
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}
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172
pkg/listener/listener_test.go
Normal file
172
pkg/listener/listener_test.go
Normal file
@ -0,0 +1,172 @@
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// Copyright (c) 2020 Proton Technologies AG
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//
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// This file is part of ProtonMail Bridge.
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//
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// ProtonMail Bridge is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// ProtonMail Bridge is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with ProtonMail Bridge. If not, see <https://www.gnu.org/licenses/>.
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package listener
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import (
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"fmt"
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"testing"
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"time"
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"github.com/sirupsen/logrus"
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"github.com/stretchr/testify/require"
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)
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func Example() {
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eventListener := New()
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ch := make(chan string)
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eventListener.Add("eventname", ch)
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for eventdata := range ch {
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fmt.Println(eventdata + " world")
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}
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eventListener.Emit("eventname", "hello")
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}
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func TestAddAndEmitSameEvent(t *testing.T) {
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listener, channel := newListener()
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listener.Emit("event", "hello!")
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checkChannelEmitted(t, channel, "hello!")
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}
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func TestAddAndEmitDifferentEvent(t *testing.T) {
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listener, channel := newListener()
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listener.Emit("other", "hello!")
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checkChannelNotEmitted(t, channel)
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}
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func TestAddAndRemove(t *testing.T) {
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listener := New()
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channel := make(chan string)
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listener.Add("event", channel)
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listener.Remove("event", channel)
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listener.Emit("event", "hello!")
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checkChannelNotEmitted(t, channel)
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}
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func TestNoLimit(t *testing.T) {
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listener, channel := newListener()
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listener.Emit("event", "hello!")
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checkChannelEmitted(t, channel, "hello!")
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listener.Emit("event", "hello!")
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checkChannelEmitted(t, channel, "hello!")
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}
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func TestLimit(t *testing.T) {
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listener, channel := newListener()
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listener.SetLimit("event", 1*time.Second)
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channel2 := make(chan string)
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listener.Add("event", channel2)
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listener.Emit("event", "hello!")
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checkChannelEmitted(t, channel, "hello!")
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checkChannelEmitted(t, channel2, "hello!")
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listener.Emit("event", "hello!")
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checkChannelNotEmitted(t, channel)
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checkChannelNotEmitted(t, channel2)
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time.Sleep(1 * time.Second)
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listener.Emit("event", "hello!")
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checkChannelEmitted(t, channel, "hello!")
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checkChannelEmitted(t, channel2, "hello!")
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}
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func TestLimitDifferentData(t *testing.T) {
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listener, channel := newListener()
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listener.SetLimit("event", 1*time.Second)
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listener.Emit("event", "hello!")
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checkChannelEmitted(t, channel, "hello!")
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listener.Emit("event", "hello?")
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checkChannelEmitted(t, channel, "hello?")
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}
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func TestReEmit(t *testing.T) {
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logrus.SetLevel(logrus.DebugLevel)
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listener := New()
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listener.Emit("event", "hello?")
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listener.SetBuffer("event")
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listener.SetBuffer("other")
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listener.Emit("event", "hello1")
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listener.Emit("event", "hello2")
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listener.Emit("other", "hello!")
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listener.Emit("event", "hello3")
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listener.Emit("other", "hello!")
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eventCH := make(chan string, 3)
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listener.Add("event", eventCH)
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otherCH := make(chan string)
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listener.Add("other", otherCH)
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listener.RetryEmit("event")
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listener.RetryEmit("other")
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time.Sleep(time.Millisecond)
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receivedEvents := map[string]int{}
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for i := 0; i < 5; i++ {
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select {
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case res := <-eventCH:
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receivedEvents[res]++
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case res := <-otherCH:
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receivedEvents[res+":other"]++
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case <-time.After(10 * time.Millisecond):
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t.Fatalf("Channel not emitted %d times", i+1)
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}
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}
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expectedEvents := map[string]int{"hello1": 1, "hello2": 1, "hello3": 1, "hello!:other": 2}
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require.Equal(t, expectedEvents, receivedEvents)
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}
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func newListener() (Listener, chan string) {
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listener := New()
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channel := make(chan string)
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listener.Add("event", channel)
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return listener, channel
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}
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func checkChannelEmitted(t testing.TB, channel chan string, expectedData string) {
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select {
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case res := <-channel:
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require.Equal(t, expectedData, res)
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case <-time.After(10 * time.Millisecond):
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t.Fatalf("Channel not emitted with expected data: %s", expectedData)
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}
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}
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func checkChannelNotEmitted(t testing.TB, channel chan string) {
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select {
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case res := <-channel:
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t.Fatalf("Channel emitted with a unexpected response: %s", res)
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case <-time.After(10 * time.Millisecond):
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}
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}
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