Add additional init checks to ExponentialBucketer.

PiperOrigin-RevId: 441529868

pkg/metric/metric.go

@@ -551,6 +551,9 @@ func NewExponentialBucketer(numFiniteBuckets int, width uint64, scale, growth fl
 	if numFiniteBuckets < exponentialMinBuckets || numFiniteBuckets > exponentialMaxBuckets {
 		panic(fmt.Sprintf("number of finite buckets must be in [%d, %d]", exponentialMinBuckets, exponentialMaxBuckets))
 	}
+	if scale < 0 || growth < 0 {
+		panic(fmt.Sprintf("scale and growth for exponential buckets must be >0, got scale=%f and growth=%f", scale, growth))
+	}
 	b := &ExponentialBucketer{
 		numFiniteBuckets: numFiniteBuckets,
 		width:            float64(width),
@@ -562,6 +565,9 @@ func NewExponentialBucketer(numFiniteBuckets int, width uint64, scale, growth fl
 	b.lowerBounds[0] = 0
 	for i := 1; i <= numFiniteBuckets; i++ {
 		b.lowerBounds[i] = int64(b.width*float64(i) + b.scale*math.Pow(b.growth, float64(i-1)))
+		if b.lowerBounds[i] < 0 {
+			panic(fmt.Sprintf("encountered bucket width overflow at bucket %d", i))
+		}
 	}
 	b.maxSample = b.lowerBounds[numFiniteBuckets] - 1
 	return b

pkg/metric/metric_test.go

@@ -830,6 +830,9 @@ func TestBucketerPanics(t *testing.T) {
 		"NewDurationBucketer @ 2": func() {
 			NewDurationBucketer(2, time.Second, time.Minute)
 		},
+		"NewDurationBucketer @ 80": func() {
+			NewDurationBucketer(80, time.Microsecond, 50*time.Microsecond)
+		},
 	} {
 		t.Run(name, func(t *testing.T) {
 			var recovered interface{}