Function TestRing_ShuffleShard_Stability

ring/ring_test.go:1998–2032

This test asserts on shard stability across multiple invocations and given the same input ring.

(t *testing.T)

// This test asserts on shard stability across multiple invocations and given the same input ring.
func TestRing_ShuffleShard_Stability(t *testing.T) {
	var (
		numTenants     = 100
		numInstances   = 50
		numZones       = 3
		numInvocations = 10
		shardSizes     = []int{3, 6, 9, 12, 15}
	)

	// Initialise the ring.
	ringDesc := &Desc{Ingesters: generateRingInstances(initTokenGenerator(t), numInstances, numZones, 128)}
	ring := newRingForTesting(Config{
		HeartbeatTimeout:     time.Hour,
		ZoneAwarenessEnabled: true,
	}, false)
	ring.setRingStateFromDesc(ringDesc, false, false, false)

	for i := 1; i <= numTenants; i++ {
		tenantID := fmt.Sprintf("%d", i)

		for _, size := range shardSizes {
			r := ring.ShuffleShard(tenantID, size)
			expected, err := r.GetAllHealthy(Read)
			require.NoError(t, err)

			// Assert that multiple invocations generate the same exact shard.
			for n := 0; n < numInvocations; n++ {
				r := ring.ShuffleShard(tenantID, size)
				actual, err := r.GetAllHealthy(Read)
				require.NoError(t, err)
				assert.ElementsMatch(t, expected.Instances, actual.Instances)
			}
		}
	}
}

func initTokenGenerator(t testing.TB) TokenGenerator {
	seed := time.Now().UnixNano()