Function FuzzXOR2Chunk

util/fuzzing/fuzz_test.go:191–286

FuzzXOR2Chunk fuzzes the XOR2 chunk round-trip. The seed and count parameters drive a deterministic RNG that generates start timestamps, timestamps, and values; nanMask forces StaleNaN on specific samples (bit i set → sample i is StaleNaN); stMode selects whether ST stays absent, constant, appears l

(f *testing.F)

// or changes with small or large deltas. This ensures the stale-NaN and ST
// encoding paths are exercised without relying on random chance.
func FuzzXOR2Chunk(f *testing.F) {
	for _, s := range GetCorpusForFuzzXOR2Chunk() {
		f.Add(s.Seed, s.N, s.NaNMask, s.STMode)
	}

	f.Fuzz(func(t *testing.T, seed int64, n uint8, nanMask uint64, stMode uint8) {
		count := int(n)%130 + 1
		r := rand.New(rand.NewSource(seed))

		type sample struct {
			st, t int64
			v     float64
		}
		samples := make([]sample, count)
		var ts int64
		activeST := int64(0)
		constantST := int64(0)
		lateSTIndex := 1
		if count > 1 {
			lateSTIndex = int(r.Int31n(int32(count-1))) + 1
		}
		for i := range count {
			ts += r.Int63n(10000) + 1
			v := math.Float64frombits(r.Uint64())
			if i < 64 && nanMask>>uint(i)&1 == 1 {
				v = math.Float64frombits(value.StaleNaN)
			}

			var st int64
			switch stMode % 5 {
			case 0:
				st = 0
			case 1:
				if i == 0 {
					constantST = ts - (r.Int63n(10000) + 1)
				}
				st = constantST
			case 2:
				if i >= lateSTIndex {
					if i == lateSTIndex {
						constantST = ts - (r.Int63n(10000) + 1)
					}
					st = constantST
				}
			case 3:
				if i == 0 {
					activeST = ts - (r.Int63n(10000) + 1)
				} else {
					activeST -= r.Int63n(8) - 3
				}
				st = activeST
			default:
				activeST = ts - r.Int63()
				st = activeST
			}

			samples[i] = sample{
				st: st,