chore: avoid unnecessary json marshal

[crenshaw-dev]

We have a utility function stripTypeInformation that json marshals and then unmarshals an unstructured in order to remove type information before diffing.

The only caller of stripTypeInformation immediately JSON-marshals the new unstructured, i.e. we JSON-marshal the unstructured object twice. Instead of having a separate utility function, we can take advantage of the remarshal function's marshaled copy of the unstructured to unmarshal and perform type-stripping.

I ran a 120s memory profile on an Intuit app controller. remarshal was responsible for 2% of the memory use. A 120s CPU profile showed remarshal as responsible for 3% of the CPU use. So I think the function is worth optimizing.

Testing with a medium-size manifest (about 100 lines) showed the following difference in benchmark:

before: Benchmark_remarshal-16              7328            155438 ns/op           90839 B/op       1338 allocs/op
after:  Benchmark_remarshal-16             10000            119162 ns/op           77498 B/op       1090 allocs/op

So 15% less memory and 23% less CPU time. The difference should be more dramatic with larger manifests.

I didn't commit the benchmark code, but here it is for reference:

func Benchmark_remarshal(b *testing.B) {
	manifest := []byte(`
apiVersion: v1
kind: Service
metadata:
  annotations:
    argocd.argoproj.io/sync-options: ServerSideApply=true
    kubectl.kubernetes.io/last-applied-configuration: >
      {"apiVersion":"v1","kind":"Service","metadata":{"annotations":{"argocd.argoproj.io/sync-options":"ServerSideApply=true"},"name":"multiple-protocol-port-svc","namespace":"default"},"spec":{"ports":[{"name":"rtmpk","port":1986,"protocol":"UDP","targetPort":1986},{"name":"rtmp","port":1935,"protocol":"TCP","targetPort":1935},{"name":"rtmpq","port":1935,"protocol":"UDP","targetPort":1935}]}}
  creationTimestamp: '2022-06-24T19:37:02Z'
  labels:
    app.kubernetes.io/instance: big-crd
  managedFields:
    - apiVersion: v1
      fieldsType: FieldsV1
      fieldsV1:
        'f:metadata':
          'f:annotations':
            'f:argocd.argoproj.io/sync-options': {}
          'f:labels':
            'f:app.kubernetes.io/instance': {}
        'f:spec':
          'f:ports':
            'k:{"port":1935,"protocol":"TCP"}':
              .: {}
              'f:name': {}
              'f:port': {}
              'f:targetPort': {}
            'k:{"port":1986,"protocol":"UDP"}':
              .: {}
              'f:name': {}
              'f:port': {}
              'f:protocol': {}
              'f:targetPort': {}
            'k:{"port":443,"protocol":"TCP"}':
              .: {}
              'f:name': {}
              'f:port': {}
              'f:targetPort': {}
          'f:type': {}
      manager: argocd-controller
      operation: Apply
      time: '2022-06-30T16:28:09Z'
    - apiVersion: v1
      fieldsType: FieldsV1
      fieldsV1:
        'f:metadata':
          'f:annotations':
            .: {}
            'f:kubectl.kubernetes.io/last-applied-configuration': {}
        'f:spec':
          'f:internalTrafficPolicy': {}
          'f:ports':
            .: {}
            'k:{"port":1935,"protocol":"TCP"}':
              .: {}
              'f:name': {}
              'f:port': {}
              'f:protocol': {}
              'f:targetPort': {}
            'k:{"port":1986,"protocol":"UDP"}':
              .: {}
              'f:name': {}
              'f:port': {}
              'f:protocol': {}
              'f:targetPort': {}
          'f:sessionAffinity': {}
      manager: kubectl-client-side-apply
      operation: Update
      time: '2022-06-25T04:18:10Z'
    - apiVersion: v1
      fieldsType: FieldsV1
      fieldsV1:
        'f:status':
          'f:loadBalancer':
            'f:ingress': {}
      manager: kube-vpnkit-forwarder
      operation: Update
      subresource: status
      time: '2022-06-29T12:36:34Z'
  name: multiple-protocol-port-svc
  namespace: default
  resourceVersion: '2138591'
  uid: af42e800-bd33-4412-bc77-d204d298613d
spec:
  clusterIP: 10.111.193.74
  clusterIPs:
    - 10.111.193.74
  externalTrafficPolicy: Cluster
  ipFamilies:
    - IPv4
  ipFamilyPolicy: SingleStack
  ports:
    - name: rtmpk
      nodePort: 31648
      port: 1986
      protocol: UDP
      targetPort: 1986
    - name: rtmp
      nodePort: 30018
      port: 1935
      protocol: TCP
      targetPort: 1935
    - name: https
      nodePort: 31975
      port: 443
      protocol: TCP
      targetPort: 443
  sessionAffinity: None
  type: NodePort
status:
  loadBalancer: {}
`)
	un := unstructured.Unstructured{}
	err := yaml.Unmarshal(manifest, &un)
	require.NoError(b, err)
	opts := applyOptions(diffOptionsForTest())

	b.ResetTimer()

	for i := 0; i < b.N; i++ {
		remarshal(&un, opts)
	}
}

[leoluz]

Please check my comment.

[leoluz]

This doesn't seem to provide the same results if compared with the original code. Previously we were stripping the types from obj and using that to marshal into data. In the new code, data will just hold the Marshal(obj) result which could lead to a different behaviour. To validate this, it would be better to write unit tests that validate the type stripping logic. Checking on Pod resources values will probably be an easy way to validate this:

    resources:
      requests:
        memory: "64Mi"
        cpu: "250m"
      limits:
        memory: "128Mi"
        cpu: "500m"

[crenshaw-dev]

data is only used only for another Unmarshal (or, more specifically, unmarshaling via json.NewDecoder, but the behavior should be the same).

So before we had:

unstructured -> marshal -> unmarshal to unstructured -> marshal -> unmarshal to schema type

Now it will be:

unstructured -> marshal -> unmarshal to schema type

i.e. we're skipping unmarshal to unstructured (which is just map[string]interface{}) and the second marshal.

My belief is that those to steps don't remove any type information that unstructured -> marshal doesn't already remove.

But I'll write some tests to give us a bit more confidence that we're not losing anything important.

[agaudreault]

LGTM and covered by TestRemarshalResources.

[leoluz]

@agaudreault, @crenshaw-dev The TestRemarshalResources seems to validate the type. However, it isn't clear to me what the outcome of data holding a different value could bring.

[crenshaw-dev]

@leoluz PTAL

The only way data is used is in unmarshaling to reflect.New(reflect.TypeOf(item).Elem()).Interface() (i.e. the schema type).

The "happy path" is already covered by TestRemarshalResources, i.e. we unmarshal into the schema type without an error. So the only uncovered behavior change is when there's some problem unmarshaling data into unmarshalledObj.

I've added tests to ensure the happy path still works when the input type isn't the json library's preferred type (i.e. float instead of float64).

I've also added a test to ensure that the unhappy path behaves the same (i.e. the input value can't be unmarshaled into the schema type).

I think this covers the relevant cases.

[crenshaw-dev]

Refactored the test to make SonarCloud happy.

[sonarcloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud

[rumstead]

LGTM here are the tests I ran before and after.

func TestRemarshal2(t *testing.T) {
	type args struct {
		obj []byte
		o   options
	}
	tests := []struct {
		name string
		args args
		want map[string]interface{}
	}{
		{name: "PodFloatCpu", args: args{
			obj: []byte(`
apiVersion: v1
kind: Pod
metadata:
  name: my-pod
spec:
  containers:
  - image: nginx:1.7.9
    name: nginx
    resources:
      requests:
        cpu: 0.2
        memory: 25600Mi
`),
			o: options{log: textlogger.NewLogger(textlogger.NewConfig())},
		}, want: map[string]interface{}{
			"cpu":    "200m",
			"memory": "25Gi",
		}},
		{name: "PodMilliCoreCpu", args: args{
			obj: []byte(`
apiVersion: v1
kind: Pod
metadata:
  name: my-pod
spec:
  containers:
  - image: nginx:1.7.9
    name: nginx
    resources:
      requests:
        cpu: 5000m
        memory: 25600Mi
`),
			o: options{log: textlogger.NewLogger(textlogger.NewConfig())},
		}, want: map[string]interface{}{
			"cpu":    "5",
			"memory": "25Gi",
		}},
		{name: "PodMemoryBytes", args: args{
			obj: []byte(`
apiVersion: v1
kind: Pod
metadata:
  name: my-pod
spec:
  containers:
  - image: nginx:1.7.9
    name: nginx
    resources:
      requests:
        cpu: 5000m
        memory: 25600
`),
			o: options{log: textlogger.NewLogger(textlogger.NewConfig())},
		}, want: map[string]interface{}{
			"cpu":    "5",
			"memory": "25600",
		}},
		{name: "PodMemoryMi", args: args{
			obj: []byte(`
apiVersion: v1
kind: Pod
metadata:
  name: my-pod
spec:
  containers:
  - image: nginx:1.7.9
    name: nginx
    resources:
      requests:
        cpu: 5000m
        memory: 25600Mi
`),
			o: options{log: textlogger.NewLogger(textlogger.NewConfig())},
		}, want: map[string]interface{}{
			"cpu":    "5",
			"memory": "25Gi",
		}},
		{name: "PodMemoryGi", args: args{
			obj: []byte(`
apiVersion: v1
kind: Pod
metadata:
  name: my-pod
spec:
  containers:
  - image: nginx:1.7.9
    name: nginx
    resources:
      requests:
        cpu: 5000m
        memory: 25Gi
`),
			o: options{log: textlogger.NewLogger(textlogger.NewConfig())},
		}, want: map[string]interface{}{
			"cpu":    "5",
			"memory": "25Gi",
		}},
	}
	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			mBefore := unstructured.Unstructured{}
			err := yaml.Unmarshal(tt.args.obj, &mBefore)
			if err != nil {
				assert.Fail(t, err.Error())
			}
			mAfter := remarshal(&mBefore, tt.args.o)
			requestsAfter := mAfter.Object["spec"].(map[string]interface{})["containers"].([]interface{})[0].(map[string]interface{})["resources"].(map[string]interface{})["requests"].(map[string]interface{})
			assert.Equalf(t, tt.want, requestsAfter, "remarshal(%v, %v)", tt.want, requestsAfter)
		})
	}
}

[leoluz]

LGTM.
Tks for the added tests. 🤞🏻