feat(backoff): Add functional options for ExponentialBackOff Closes #136

exponential.go

@@ -71,6 +71,9 @@ type Clock interface {
 	Now() time.Time
 }
 
+// ExponentialBackOffOpts is a function type used to configure ExponentialBackOff options.
+type ExponentialBackOffOpts func(*ExponentialBackOff)
+
 // Default values for ExponentialBackOff.
 const (
 	DefaultInitialInterval     = 500 * time.Millisecond
@@ -81,7 +84,7 @@ const (
 )
 
 // NewExponentialBackOff creates an instance of ExponentialBackOff using default values.
-func NewExponentialBackOff() *ExponentialBackOff {
+func NewExponentialBackOff(opts ...ExponentialBackOffOpts) *ExponentialBackOff {
 	b := &ExponentialBackOff{
 		InitialInterval:     DefaultInitialInterval,
 		RandomizationFactor: DefaultRandomizationFactor,
@@ -91,10 +94,62 @@ func NewExponentialBackOff() *ExponentialBackOff {
 		Stop:                Stop,
 		Clock:               SystemClock,
 	}
+	for _, fn := range opts {
+		fn(b)
+	}
 	b.Reset()
 	return b
 }
 
+// WithInitialInterval sets the initial interval between retries.
+func WithInitialInterval(duration time.Duration) ExponentialBackOffOpts {
+	return func(ebo *ExponentialBackOff) {
+		ebo.InitialInterval = duration
+	}
+}
+
+// WithRandomizationFactor sets the randomization factor to add jitter to intervals.
+func WithRandomizationFactor(randomizationFactor float64) ExponentialBackOffOpts {
+	return func(ebo *ExponentialBackOff) {
+		ebo.RandomizationFactor = randomizationFactor
+	}
+}
+
+// WithMultiplier sets the multiplier for increasing the interval after each retry.
+func WithMultiplier(multiplier float64) ExponentialBackOffOpts {
+	return func(ebo *ExponentialBackOff) {
+		ebo.Multiplier = multiplier
+	}
+}
+
+// WithMaxInterval sets the maximum interval between retries.
+func WithMaxInterval(duration time.Duration) ExponentialBackOffOpts {
+	return func(ebo *ExponentialBackOff) {
+		ebo.MaxInterval = duration
+	}
+}
+
+// WithMaxElapsedTime sets the maximum total time for retries.
+func WithMaxElapsedTime(duration time.Duration) ExponentialBackOffOpts {
+	return func(ebo *ExponentialBackOff) {
+		ebo.MaxElapsedTime = duration
+	}
+}
+
+// WithRetryStopDuration sets the duration after which retries should stop.
+func WithRetryStopDuration(duration time.Duration) ExponentialBackOffOpts {
+	return func(ebo *ExponentialBackOff) {
+		ebo.Stop = duration
+	}
+}
+
+// WithClockProvider sets the clock used to measure time.
+func WithClockProvider(clock Clock) ExponentialBackOffOpts {
+	return func(ebo *ExponentialBackOff) {
+		ebo.Clock = clock
+	}
+}
+
 type systemClock struct{}
 
 func (t systemClock) Now() time.Time {

exponential_test.go

@@ -117,3 +117,45 @@ func assertEquals(t *testing.T, expected, value time.Duration) {
 		t.Errorf("got: %d, expected: %d", value, expected)
 	}
 }
+
+func TestNewExponentialBackOff(t *testing.T) {
+	// Create a new ExponentialBackOff with custom options
+	backOff := NewExponentialBackOff(
+		WithInitialInterval(1*time.Second),
+		WithMultiplier(2.0),
+		WithMaxInterval(10*time.Second),
+		WithMaxElapsedTime(30*time.Second),
+		WithRetryStopDuration(0),
+		WithClockProvider(SystemClock),
+	)
+
+	// Check that the backOff object is not nil
+	if backOff == nil {
+		t.Error("Expected a non-nil ExponentialBackOff object, got nil")
+	}
+
+	// Check that the custom options were applied correctly
+	if backOff.InitialInterval != 1*time.Second {
+		t.Errorf("Expected InitialInterval to be 1 second, got %v", backOff.InitialInterval)
+	}
+
+	if backOff.Multiplier != 2.0 {
+		t.Errorf("Expected Multiplier to be 2.0, got %v", backOff.Multiplier)
+	}
+
+	if backOff.MaxInterval != 10*time.Second {
+		t.Errorf("Expected MaxInterval to be 10 seconds, got %v", backOff.MaxInterval)
+	}
+
+	if backOff.MaxElapsedTime != 30*time.Second {
+		t.Errorf("Expected MaxElapsedTime to be 30 seconds, got %v", backOff.MaxElapsedTime)
+	}
+
+	if backOff.Stop != 0 {
+		t.Errorf("Expected Stop to be 0 (no stop), got %v", backOff.Stop)
+	}
+
+	if backOff.Clock != SystemClock {
+		t.Errorf("Expected Clock to be SystemClock, got %v", backOff.Clock)
+	}
+}