refactor: simplify the NewMutex() method

README.md

@@ -33,10 +33,7 @@ if err != nil {
 	panic(err)
 }
 
-mu, err := objsync.NewMutex(p, bucket, key)
-if err != nil {
-	panic(err)
-}
+mu := objsync.NewMutex(p, bucket, key)
 
 fencingToken, err := mu.Lock(ctx, 5*time.Second)
 if err != nil {

examples/main.go

@@ -25,10 +25,7 @@ func main() {
 	}
 
 	// Create a mutex.
-	mu, err := objsync.NewMutex(p, bucket, key)
-	if err != nil {
-		panic(err)
-	}
+	mu := objsync.NewMutex(p, bucket, key)
 
 	// Lock the mutex.
 	fencingToken, err := mu.Lock(ctx, 5*time.Second)

mutex.go

@@ -30,20 +30,21 @@ type Mutex struct {
 	etag     string
 }
 
+// The JSON content of the mutex object.
 type mutexContent struct {
 	ID      string     `json:"id,omitempty"`
 	Expires *time.Time `json:"expires,omitempty"`
 	Fence   int64      `json:"fence,omitempty"`
 }
 
 // NewMutex creates a new distributed mutex.
-func NewMutex(p provider.Provider, bucket, key string) (*Mutex, error) {
+func NewMutex(p provider.Provider, bucket, key string) *Mutex {
 	return &Mutex{
 		provider: p,
 		bucket:   bucket,
 		key:      key,
 		id:       uuid.New().String(),
-	}, nil
+	}
 }
 
 // Lock acquires the mutex. It blocks until the mutex is available.

mutex_test.go

@@ -48,10 +48,7 @@ func TestMutex(t *testing.T) {
 	g, ctx := errgroup.WithContext(ctx)
 	for i := 0; i < 3; i++ {
 		g.Go(func() error {
-			mu, err := objsync.NewMutex(p, bucket, key)
-			if err != nil {
-				return err
-			}
+			mu := objsync.NewMutex(p, bucket, key)
 
 			for j := 0; j < 5; j++ {
 				fencingToken, err := mu.Lock(ctx, 5*time.Second)
@@ -61,7 +58,7 @@ func TestMutex(t *testing.T) {
 
 				// Verify the mutex is held by only one goroutine.
 				if n := atomic.AddInt32(&lockCounter, 1); n > 1 {
-					return fmt.Errorf("lock is held by %d goroutines (fencingToken: %d)", n, fencingToken)
+					return fmt.Errorf("lock is held by %d goroutines", n)
 				}
 
 				// Is the fencing token monotonically increasing?