feat: can use existing Redis client in the watcher (#59)

Author: hsluoyz

README.md

@@ -78,6 +78,97 @@ func main() {
 
 ```
 
+## Using Existing Redis Client
+
+If you already have an existing Redis client instance (e.g., due to restricted access to connection details or centralized Redis setup), you can reuse it to create a watcher.
+
+### With Regular Redis Client
+
+```go
+package main
+
+import (
+	"fmt"
+
+	"github.com/casbin/casbin/v3"
+	rediswatcher "github.com/casbin/redis-watcher/v2"
+	"github.com/redis/go-redis/v9"
+)
+
+func main() {
+	// Create your own Redis client
+	redisClient := redis.NewClient(&redis.Options{
+		Addr:     "localhost:6379",
+		Password: "",
+		DB:       0,
+	})
+
+	// Initialize the watcher with existing client
+	// Pass empty string for addr since the SubClient and PubClient are already provided
+	w, _ := rediswatcher.NewWatcher("", rediswatcher.WatcherOptions{
+		SubClient: redisClient,
+		PubClient: redisClient,
+		Channel:   "/casbin",
+	})
+
+	// Initialize the enforcer.
+	e, _ := casbin.NewEnforcer("examples/rbac_model.conf", "examples/rbac_policy.csv")
+
+	// Set the watcher for the enforcer.
+	_ = e.SetWatcher(w)
+
+	// Set callback
+	_ = w.SetUpdateCallback(rediswatcher.DefaultUpdateCallback(e))
+
+	// Update the policy to test the effect.
+	_ = e.SavePolicy()
+	fmt.Scanln()
+}
+```
+
+### With Redis Cluster Client
+
+```go
+package main
+
+import (
+	"fmt"
+
+	"github.com/casbin/casbin/v3"
+	rediswatcher "github.com/casbin/redis-watcher/v2"
+	"github.com/redis/go-redis/v9"
+)
+
+func main() {
+	// Create your own Redis cluster client
+	clusterClient := redis.NewClusterClient(&redis.ClusterOptions{
+		Addrs:    []string{"localhost:7000", "localhost:7001", "localhost:7002"},
+		Password: "",
+	})
+
+	// Initialize the watcher with existing cluster client
+	// Pass empty string for addrs since the SubClient and PubClient are already provided
+	w, _ := rediswatcher.NewWatcherWithCluster("", rediswatcher.WatcherOptions{
+		SubClient: clusterClient,
+		PubClient: clusterClient,
+		Channel:   "/casbin",
+	})
+
+	// Initialize the enforcer.
+	e, _ := casbin.NewEnforcer("examples/rbac_model.conf", "examples/rbac_policy.csv")
+
+	// Set the watcher for the enforcer.
+	_ = e.SetWatcher(w)
+
+	// Set callback
+	_ = w.SetUpdateCallback(rediswatcher.DefaultUpdateCallback(e))
+
+	// Update the policy to test the effect.
+	_ = e.SavePolicy()
+	fmt.Scanln()
+}
+```
+
 ## Getting Help
 
 - [Casbin](https://github.com/casbin/casbin)

options.go

@@ -8,8 +8,8 @@ import (
 type WatcherOptions struct {
 	Options                rds.Options
 	ClusterOptions         rds.ClusterOptions
-	SubClient              *rds.Client
-	PubClient              *rds.Client
+	SubClient              rds.UniversalClient
+	PubClient              rds.UniversalClient
 	Channel                string
 	IgnoreSelf             bool
 	LocalID                string

watcher_test.go

@@ -11,6 +11,7 @@ import (
 	"github.com/casbin/casbin/v3"
 	"github.com/casbin/casbin/v3/persist"
 	rediswatcher "github.com/casbin/redis-watcher/v2"
+	"github.com/redis/go-redis/v9"
 )
 
 func initWatcherWithOptions(t *testing.T, wo rediswatcher.WatcherOptions, cluster ...bool) (*casbin.Enforcer, *rediswatcher.Watcher) {
@@ -314,3 +315,71 @@ func TestUpdateForUpdatePolicies(t *testing.T) {
 	w2.Close()
 	time.Sleep(time.Millisecond * 500)
 }
+
+func TestNewWatcherWithClusterUsingExistingClient(t *testing.T) {
+	// Create a regular Redis client that implements UniversalClient interface
+	// In production, this would be a cluster client
+	redisClient := redis.NewClient(&redis.Options{
+		Addr: "127.0.0.1:6379",
+	})
+
+	// Use the existing client for both pub and sub
+	// This demonstrates that UniversalClient type works with any Redis client type
+	wo := rediswatcher.WatcherOptions{
+		SubClient: redisClient,
+		PubClient: redisClient,
+	}
+
+	// Initialize watcher with existing client
+	// Pass empty string for addrs since we're using existing clients
+	// When SubClient and PubClient are provided, the addrs parameter is ignored
+	w, err := rediswatcher.NewWatcherWithCluster("", wo)
+	if err != nil {
+		t.Fatalf("Failed to create watcher with existing client: %v", err)
+	}
+	watcher := w.(*rediswatcher.Watcher)
+
+	// Verify the watcher works
+	_ = watcher.SetUpdateCallback(func(s string) {
+		t.Log("Received update:", s)
+	})
+
+	_ = watcher.Update()
+	time.Sleep(time.Millisecond * 500)
+
+	watcher.Close()
+	time.Sleep(time.Millisecond * 500)
+}
+
+func TestNewWatcherWithExistingClient(t *testing.T) {
+	// Create a regular Redis client externally
+	redisClient := redis.NewClient(&redis.Options{
+		Addr: "127.0.0.1:6379",
+	})
+
+	// Use the existing client for both pub and sub
+	wo := rediswatcher.WatcherOptions{
+		SubClient: redisClient,
+		PubClient: redisClient,
+	}
+
+	// Initialize watcher with existing client
+	// Pass empty string for addr since we're using existing clients
+	// When SubClient and PubClient are provided, the addr parameter is ignored
+	w, err := rediswatcher.NewWatcher("", wo)
+	if err != nil {
+		t.Fatalf("Failed to create watcher with existing client: %v", err)
+	}
+	watcher := w.(*rediswatcher.Watcher)
+
+	// Verify the watcher works
+	_ = watcher.SetUpdateCallback(func(s string) {
+		t.Log("Received update:", s)
+	})
+
+	_ = watcher.Update()
+	time.Sleep(time.Millisecond * 500)
+
+	watcher.Close()
+	time.Sleep(time.Millisecond * 500)
+}