chore: reuse user token source (#26144)

charger/easee/identity.go

@@ -6,6 +6,7 @@ import (
 	"time"
 
 	"github.com/evcc-io/evcc/util"
+	"github.com/evcc-io/evcc/util/cache"
 	"github.com/evcc-io/evcc/util/oauth"
 	"github.com/evcc-io/evcc/util/request"
 	"golang.org/x/oauth2"
@@ -38,8 +39,12 @@ type tokenSource struct {
 	user, password string
 }
 
-// TokenSource creates an Easee token source
+// tokenSourceCache stores per-user token sources
+var tokenSourceCache = cache.New[oauth2.TokenSource]()
+
+// TokenSource returns a shared oauth2.TokenSource for the given user.
 func TokenSource(log *util.Logger, user, password string) (oauth2.TokenSource, error) {
+	return tokenSourceCache.GetOrCreate(user, func() (oauth2.TokenSource, error) {
 		c := &tokenSource{
 			Helper:   request.NewHelper(log),
 			user:     user,
@@ -47,8 +52,12 @@ func TokenSource(log *util.Logger, user, password string) (oauth2.TokenSource, e
 		}
 
 		token, err := c.authenticate()
+		if err != nil {
+			return nil, err
+		}
 
-	return oauth.RefreshTokenSource(token.AsOAuth2Token(), c.refreshToken), err
+		return oauth.RefreshTokenSource(token.AsOAuth2Token(), c.refreshToken), nil
+	})
 }
 
 func (c *tokenSource) authenticate() (*Token, error) {

charger/zaptec.go

@@ -121,7 +121,7 @@ func NewZaptec(ctx context.Context, user, password, id string, priority bool, pa
 	})
 
 	// Get shared token source for this user (per-user uniqueness)
-	ts, err := zaptec.GetTokenSource(tsCtx, user, password)
+	ts, err := zaptec.TokenSource(tsCtx, user, password)
 	if err != nil {
 		return nil, err
 	}

charger/zaptec/auth.go

@@ -6,6 +6,7 @@ import (
 	"sync"
 
 	"github.com/coreos/go-oidc/v3/oidc"
+	"github.com/evcc-io/evcc/util/cache"
 	"golang.org/x/oauth2"
 )
 
@@ -23,10 +24,9 @@ func (p *passwordTokenSource) Token() (*oauth2.Token, error) {
 	return p.config.PasswordCredentialsToken(p.ctx, p.user, p.pass)
 }
 
-// tokenSourceCache stores per-user token sources
 var (
-	tokenSourceMu    sync.Mutex
-	tokenSourceCache = make(map[string]oauth2.TokenSource)
+	// TokenSourceCache stores per-user token sources
+	tokenSourceCache = cache.New[oauth2.TokenSource]()
 
 	oidcProvider     *oidc.Provider
 	oidcProviderOnce sync.Once
@@ -41,19 +41,9 @@ func getOIDCProvider(ctx context.Context) (*oidc.Provider, error) {
 	return oidcProvider, oidcProviderErr
 }
 
-// GetTokenSource returns a shared oauth2.TokenSource for the given user credentials.
-// Multiple chargers using the same user credentials will share the same TokenSource,
-// ensuring tokens are reused and authentication is deduplicated.
-func GetTokenSource(ctx context.Context, user, pass string) (oauth2.TokenSource, error) {
-	tokenSourceMu.Lock()
-	defer tokenSourceMu.Unlock()
-
-	// Use username as the cache key (assuming username is unique)
-	if ts, exists := tokenSourceCache[user]; exists {
-		return ts, nil
-	}
-
-	// Get the cached OIDC provider (initialized once)
+// TokenSource returns a shared oauth2.TokenSource for the given user.
+func TokenSource(ctx context.Context, user, pass string) (oauth2.TokenSource, error) {
+	return tokenSourceCache.GetOrCreate(user, func() (oauth2.TokenSource, error) {
 		provider, err := getOIDCProvider(ctx)
 		if err != nil {
 			return nil, fmt.Errorf("failed to initialize OIDC provider: %w", err)
@@ -80,9 +70,6 @@ func GetTokenSource(ctx context.Context, user, pass string) (oauth2.TokenSource,
 			return nil, err
 		}
 
-	// Wrap with ReuseTokenSource to cache tokens
-	ts := oauth2.ReuseTokenSource(token, pts)
-	tokenSourceCache[user] = ts
-
-	return ts, nil
+		return oauth2.ReuseTokenSource(token, pts), nil
+	})
 }

util/cache/cache.go

@@ -0,0 +1,37 @@
+package cache
+
+import (
+	"sync"
+)
+
+// Cache provides thread-safe caching keyed by username
+type Cache[T any] struct {
+	mu    sync.Mutex
+	cache map[string]T
+}
+
+// New creates a new Cache instance
+func New[T any]() *Cache[T] {
+	return &Cache[T]{
+		cache: make(map[string]T),
+	}
+}
+
+// GetOrCreate atomically gets or creates a cached object
+func (c *Cache[T]) GetOrCreate(key string, createFn func() (T, error)) (T, error) {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
+	if res, ok := c.cache[key]; ok {
+		return res, nil
+	}
+
+	res, err := createFn()
+	if err != nil {
+		var zero T
+		return zero, err
+	}
+
+	c.cache[key] = res
+	return res, nil
+}