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watcher.go
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watcher.go
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package rediswatcher
import (
"context"
"fmt"
"runtime"
"sync"
"time"
"github.com/casbin/casbin/v2/persist"
"github.com/go-redis/redis/v8"
"github.com/google/uuid"
"github.com/gotomicro/ego/core/elog"
)
type Watcher struct {
ctx context.Context
options WatcherOptions
pubConn *redis.Client
subConn *redis.Client
callback func(string)
closed chan struct{}
messagesIn chan *redis.Message
once sync.Once
}
type WatcherMetrics struct {
Name string
LatencyMs float64
LocalID string
Channel string
Protocol string
Error error
MessageSize int64
}
const (
RedisCloseMetric = "RedisClose"
RedisDialMetric = "RedisDial"
PubSubPublishMetric = "PubSubPublish"
PubSubReceiveMetric = "PubSubReceive"
PubSubSubscribeMetric = "PubSubSubscribe"
PubSubUnsubscribeMetric = "PubSubUnsubscribe"
)
const (
defaultShortMessageInTimeout = 1 * time.Millisecond
defaultLongMessageInTimeout = 1 * time.Minute
)
// NewWatcher creates a new Watcher to be used with a Casbin enforcer
// addr is a redis target string in the format "host:port"
// setters allows for inline WatcherOptions
func NewWatcher(ctx context.Context, addr string, setters ...WatcherOption) (persist.Watcher, error) {
w := &Watcher{
ctx: ctx,
closed: make(chan struct{}),
messagesIn: make(chan *redis.Message),
}
w.options = WatcherOptions{
Channel: "/casbin",
Protocol: "tcp",
LocalID: uuid.New().String(),
SquashTimeoutShort: defaultShortMessageInTimeout,
SquashTimeoutLong: defaultLongMessageInTimeout,
}
for _, setter := range setters {
setter(&w.options)
}
if err := w.connect(addr); err != nil {
return nil, err
}
// call destructor when the object is released
runtime.SetFinalizer(w, finalizer)
w.messageInProcessor()
go func() {
for {
select {
case <-w.closed:
return
default:
err := w.connect(addr)
if err == nil {
err = w.subscribe()
}
if err != nil {
fmt.Printf("Failure from Redis subscription: %v\n", err)
}
time.Sleep(2 * time.Second)
}
}
}()
return w, nil
}
// NewPublishWatcher return a Watcher only publish but not subscribe
func NewPublishWatcher(ctx context.Context, addr string, setters ...WatcherOption) (persist.Watcher, error) {
w := &Watcher{
ctx: ctx,
closed: make(chan struct{}),
}
w.options = WatcherOptions{
Channel: "/casbin",
Protocol: "tcp",
LocalID: uuid.New().String(),
SquashTimeoutShort: defaultShortMessageInTimeout,
SquashTimeoutLong: defaultLongMessageInTimeout,
}
for _, setter := range setters {
setter(&w.options)
}
if err := w.connect(addr); err != nil {
return nil, err
}
// call destructor when the object is released
runtime.SetFinalizer(w, finalizer)
return w, nil
}
// SetUpdateCallback sets the update callback function invoked by the watcher
// when the policy is updated. Defaults to Enforcer.LoadPolicy()
func (w *Watcher) SetUpdateCallback(callback func(string)) error {
w.callback = callback
return nil
}
// Update publishes a message to all other casbin instances telling them to
// invoke their update callback
func (w *Watcher) Update() error {
startTime := time.Now()
elog.Info("Casbin update", elog.String("channel", w.options.Channel), elog.String("LocalID", w.options.LocalID))
if _, err := w.pubConn.Publish(w.ctx, w.options.Channel, w.options.LocalID).Result(); err != nil {
if w.options.RecordMetrics != nil {
w.options.RecordMetrics(w.createMetrics(PubSubPublishMetric, startTime, err))
}
return err
}
if w.options.RecordMetrics != nil {
w.options.RecordMetrics(w.createMetrics(PubSubPublishMetric, startTime, nil))
}
return nil
}
// Close disconnects the watcher from redis
func (w *Watcher) Close() {
finalizer(w)
}
func (w *Watcher) connect(addr string) error {
if w.pubConn == nil {
if err := w.connectPub(addr); err != nil {
return err
}
}
if w.subConn == nil {
if err := w.connectSub(addr); err != nil {
return err
}
}
return nil
}
func (w *Watcher) connectPub(addr string) error {
if w.options.PubConn != nil {
w.pubConn = w.options.PubConn
return nil
}
c, err := w.dial(addr)
if err != nil {
return err
}
w.pubConn = c
return nil
}
func (w *Watcher) connectSub(addr string) error {
if w.options.SubConn != nil {
w.subConn = w.options.SubConn
return nil
}
c, err := w.dial(addr)
if err != nil {
return err
}
w.subConn = c
return nil
}
func (w *Watcher) dial(addr string) (*redis.Client, error) {
startTime := time.Now()
opt := redis.Options{
DB: 0,
Addr: addr,
Password: w.options.Password,
}
if w.options.RecordMetrics != nil {
w.options.RecordMetrics(w.createMetrics(RedisDialMetric, startTime, nil))
}
c := redis.NewClient(&opt)
if err := c.Ping(context.Background()).Err(); err != nil {
elog.Panic("start stub redis", elog.FieldErr(err))
}
return c, nil
}
func (w *Watcher) unsubscribe(psc *redis.PubSub) {
startTime := time.Now()
err := psc.PUnsubscribe(w.ctx)
if w.options.RecordMetrics != nil {
w.options.RecordMetrics(w.createMetrics(PubSubUnsubscribeMetric, startTime, err))
}
}
func (w *Watcher) subscribe() error {
psc := w.subConn.PSubscribe(w.ctx, w.options.Channel)
startTime := time.Now()
if w.options.RecordMetrics != nil {
w.options.RecordMetrics(w.createMetrics(PubSubSubscribeMetric, startTime, nil))
}
defer w.unsubscribe(psc)
for {
startTime = time.Now()
msg, err := psc.ReceiveMessage(w.ctx)
if err != nil {
elog.Error("subscribe", elog.String("error", err.Error()))
if w.options.RecordMetrics != nil {
w.options.RecordMetrics(w.createMetrics(PubSubReceiveMetric, startTime, err))
}
return err
}
elog.Info("Casbin subscribe", elog.Any("msg", msg))
if w.options.RecordMetrics != nil {
watcherMetrics := w.createMetrics(PubSubReceiveMetric, startTime, nil)
watcherMetrics.MessageSize = int64(len(msg.Payload))
w.options.RecordMetrics(watcherMetrics)
}
elog.Info("Casbin Message")
w.messagesIn <- msg
}
}
func (w *Watcher) messageInProcessor() {
w.options.callbackPending = false
var data string
timeOut := w.options.SquashTimeoutLong
go func() {
for {
select {
case <-w.closed:
return
case msg := <-w.messagesIn:
if w.callback != nil {
data = msg.Payload
switch {
case !w.options.IgnoreSelf && !w.options.SquashMessages:
w.callback(data)
case w.options.IgnoreSelf && data == w.options.LocalID: // ignore message
case !w.options.IgnoreSelf && w.options.SquashMessages:
w.options.callbackPending = true
case w.options.IgnoreSelf && data != w.options.LocalID && !w.options.SquashMessages:
w.callback(data)
case w.options.IgnoreSelf && data != w.options.LocalID && w.options.SquashMessages:
w.options.callbackPending = true
default:
w.callback(data)
}
}
if w.options.callbackPending { // set short timeout
timeOut = w.options.SquashTimeoutShort
}
case <-time.After(timeOut):
if w.options.callbackPending {
w.options.callbackPending = false
w.callback(data) // data will be last message recieved
timeOut = w.options.SquashTimeoutLong // long timeout
}
}
}
}()
}
func (w *Watcher) createMetrics(metricsName string, startTime time.Time, err error) *WatcherMetrics {
return &WatcherMetrics{
Name: metricsName,
Channel: w.options.Channel,
LocalID: w.options.LocalID,
Protocol: w.options.Protocol,
LatencyMs: float64(time.Since(startTime)) / float64(time.Millisecond),
Error: err,
}
}
// GetWatcherOptions return option settings
func (w *Watcher) GetWatcherOptions() WatcherOptions {
return w.options
}
func finalizer(w *Watcher) {
w.once.Do(func() {
close(w.closed)
startTime := time.Now()
err := w.subConn.Close()
if w.options.RecordMetrics != nil {
w.options.RecordMetrics(w.createMetrics(RedisCloseMetric, startTime, err))
}
startTime = time.Now()
err = w.pubConn.Close()
if w.options.RecordMetrics != nil {
w.options.RecordMetrics(w.createMetrics(RedisCloseMetric, startTime, err))
}
})
}