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pubsub.go
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pubsub.go
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// The event system is used to propegate events from different yagpdb instances
// For example when you change the streamer settings, and event gets fired
// Telling the streamer plugin to recheck everyones streaming status
package pubsub
import (
"encoding/json"
"fmt"
"reflect"
"runtime/debug"
"strconv"
"strings"
"sync"
"time"
"github.com/botlabs-gg/yagpdb/v2/common"
"github.com/botlabs-gg/yagpdb/v2/lib/discordgo"
"github.com/mediocregopher/radix/v3"
"github.com/prometheus/client_golang/prometheus"
"github.com/prometheus/client_golang/prometheus/promauto"
)
type Event struct {
TargetGuild string // The guild this event was meant for, or * for all
TargetGuildInt int64
EventName string
Data interface{}
}
type eventHandler struct {
evt string
handler func(*Event)
}
var (
eventHandlers = make([]*eventHandler, 0)
handlersMU sync.RWMutex
eventTypes = make(map[string]reflect.Type)
// if set, return true to handle the event, false to ignore it
FilterFunc func(guildID int64) (handle bool)
logger = common.GetFixedPrefixLogger("pubsub")
)
// AddEventHandler adds a event handler
// For the specified event, should only be done during startup
func AddHandler(evt string, cb func(*Event), t interface{}) {
handlersMU.Lock()
defer handlersMU.Unlock()
handler := &eventHandler{
evt: evt,
handler: cb,
}
if t != nil {
eventTypes[evt] = reflect.TypeOf(t)
}
eventHandlers = append(eventHandlers, handler)
logger.WithField("evt", evt).Debug("Added event handler")
}
// PublishEvent publishes the specified event
// set target to -1 to handle on all nodes
func Publish(evt string, target int64, data interface{}) error {
dataStr := ""
if data != nil {
encoded, err := json.Marshal(data)
if err != nil {
return err
}
dataStr = string(encoded)
}
value := fmt.Sprintf("%d,%s,%s", target, evt, dataStr)
metricsPubsubSent.With(prometheus.Labels{"event": evt}).Inc()
return common.RedisPool.Do(radix.Cmd(nil, "PUBLISH", "events", value))
}
func PublishLogErr(evt string, target int64, data interface{}) {
err := Publish(evt, target, data)
if err != nil {
logger.WithError(err).WithField("target", target).WithField("evt", evt).Error("failed sending pubsub")
}
}
func PollEvents() {
AddHandler("global_ratelimit", handleGlobalRatelimtPusub, globalRatelimitTriggeredEventData{})
AddHandler("evict_core_config_cache", handleEvictCoreConfigCache, nil)
AddHandler("evict_cache_set", handleEvictCacheSet, evictCacheSetData{})
common.BotSession.AddHandler(func(s *discordgo.Session, r *discordgo.RateLimit) {
if r.Global {
PublishRatelimit(r)
}
})
for {
err := runPollEvents()
logger.WithError(err).Error("subscription for events ended, starting a new one...")
time.Sleep(time.Second)
}
}
var metricsPubsubEvents = promauto.NewCounterVec(prometheus.CounterOpts{
Name: "yagpdb_pubsub_events_handled_total",
Help: "Number of pubsub events handled",
}, []string{"event"})
var metricsPubsubSent = promauto.NewCounterVec(prometheus.CounterOpts{
Name: "yagpdb_pubsub_events_sent_total",
Help: "YAGPDB pubsub sent events",
}, []string{"event"})
var metricsPubsubSkipped = promauto.NewCounterVec(prometheus.CounterOpts{
Name: "yagpdb_pubsub_events_skipped__total",
Help: "YAGPDB pubsub skipped events (unmatched target, unknown evt etc)",
}, []string{"event"})
func runPollEvents() error {
logger.Info("Listening for pubsub events")
conn, err := radix.PersistentPubSubWithOpts("tcp", common.RedisAddr)
if err != nil {
return err
}
msgChan := make(chan radix.PubSubMessage, 100)
if err := conn.Subscribe(msgChan, "events"); err != nil {
return err
}
for msg := range msgChan {
if len(msg.Message) < 1 {
continue
}
handlersMU.RLock()
handleEvent(string(msg.Message))
handlersMU.RUnlock()
}
logger.Error("Stopped listening for pubsub events")
return nil
}
func handleEvent(evt string) {
split := strings.SplitN(evt, ",", 3)
if len(split) < 3 {
logger.WithField("evt", evt).Error("Invalid event")
return
}
target := split[0]
name := split[1]
data := split[2]
parsedTarget, _ := strconv.ParseInt(target, 10, 64)
if FilterFunc != nil {
if !FilterFunc(parsedTarget) {
metricsPubsubSkipped.With(prometheus.Labels{"event": name}).Inc()
return
}
}
t, ok := eventTypes[name]
if !ok && data != "" {
// No handler for this event
logger.WithField("evt", name).Debug("No handler for pubsub event")
metricsPubsubSkipped.With(prometheus.Labels{"event": name}).Inc()
return
}
var decoded interface{}
if data != "" && t != nil {
decoded = reflect.New(t).Interface()
err := json.Unmarshal([]byte(data), decoded)
if err != nil {
logger.WithError(err).Error("Failed unmarshaling event")
return
}
} else if t != nil {
logger.Error("No data provided for event that requires data")
return
}
event := &Event{
TargetGuild: target,
EventName: name,
Data: decoded,
}
event.TargetGuildInt = parsedTarget
defer func() {
if r := recover(); r != nil {
stack := string(debug.Stack())
logger.Error("Recovered from panic in pubsub event handler", r, "\n", stack)
}
}()
metricsPubsubEvents.With(prometheus.Labels{"event": name}).Inc()
for _, handler := range eventHandlers {
if handler.evt != name {
continue
}
handler.handler(event)
}
}