feat: observe changes in repository to automatically clear cache

internal/store/redis/proxy_observable.go

@@ -0,0 +1,85 @@
+package redis
+
+import (
+	"bytes"
+	"context"
+	"encoding/gob"
+
+	"forge.cadoles.com/cadoles/bouncer/internal/store"
+	"github.com/pkg/errors"
+	"gitlab.com/wpetit/goweb/logger"
+)
+
+func init() {
+	gob.Register(&ProxyChange{})
+}
+
+type ProxyChange struct {
+	Operation ChangeOperation
+	Proxy     store.ProxyName
+}
+
+// Change implements store.Change.
+func (p *ProxyChange) Change() {}
+
+func NewProxyChange(op ChangeOperation, name store.ProxyName) *ProxyChange {
+	return &ProxyChange{
+		Operation: op,
+		Proxy:     name,
+	}
+}
+
+var _ store.Change = &ProxyChange{}
+
+const proxyChangeChannel string = "proxy-changes"
+
+// Changes implements store.Observable.
+func (r *ProxyRepository) Changes(ctx context.Context, fn func(store.Change)) {
+	go func() {
+		sub := r.client.Subscribe(ctx, proxyChangeChannel)
+		defer sub.Close()
+
+		for {
+			var buff bytes.Buffer
+			decoder := gob.NewDecoder(&buff)
+
+			msg, err := sub.ReceiveMessage(ctx)
+			if err != nil {
+				logger.Error(ctx, "could not receive message", logger.E(errors.WithStack(err)))
+				return
+			}
+
+			buff.Reset()
+			buff.WriteString(msg.Payload)
+
+			change := &ProxyChange{}
+			if err := decoder.Decode(change); err != nil {
+				logger.Error(ctx, "could not decode message", logger.E(errors.WithStack(err)))
+				continue
+			}
+
+			fn(change)
+		}
+	}()
+}
+
+func (r *ProxyRepository) notifyChange(op ChangeOperation, name store.ProxyName) {
+	change := NewProxyChange(op, name)
+
+	var buff bytes.Buffer
+	encoder := gob.NewEncoder(&buff)
+
+	ctx := context.Background()
+
+	if err := encoder.Encode(change); err != nil {
+		logger.Error(ctx, "could not encode message", logger.E(errors.WithStack(err)))
+		return
+	}
+
+	if err := r.client.Publish(ctx, proxyChangeChannel, buff.Bytes()).Err(); err != nil {
+		logger.Error(ctx, "could not publish message", logger.E(errors.WithStack(err)))
+		return
+	}
+}
+
+var _ store.Observable = &ProxyRepository{}