wLock  mutex    // serializes writers
	writer muintptr // pending writer waiting for completing readers

	readerCount atomic.Int32 // number of pending readers
	readerWait  atomic.Int32 // number of departing readers

	readRank lockRank // semantic lock rank for read locking
}

// Lock ranking an rwmutex has two aspects:
//

 The following are generated from this model:

   * {{{./apidocs/index.html}Java sources}} with Reader and Writers for the Xpp3 XML parser, <<<ToAPiV3()>>> and <<<ToApiV4()>>> transformers, and <<<v4>>> package
     for Merger and v4 Reader and Writers for the Xpp3 XML parser,

   * A {{{./settings.html}Descriptor Reference}}

   * An {{{https://maven.apache.org/xsd/settings-1.2.0.xsd}XSD}}

	scenarios := map[string]struct {
		config   *config.KubeSchedulerConfiguration
		wantErrs field.ErrorList
	}{
		"good": {
			config: validConfig,
		},
		"bad-parallelism-invalid-value": {
			config: invalidParallelismValue,
			wantErrs: field.ErrorList{
				&field.Error{
					Type:  field.ErrorTypeInvalid,
					Field: "parallelism",
				},
			},
		},

func StaticPodControlPlane(client clientset.Interface, waiter apiclient.Waiter, pathMgr StaticPodPathManager, cfg *kubeadmapi.InitConfiguration, etcdUpgrade, renewCerts bool, oldEtcdClient, newEtcdClient etcdutil.ClusterInterrogator) error {
	recoverManifests := map[string]string{}
	var isExternalEtcd bool

	beforePodHashMap, err := waiter.WaitForStaticPodControlPlaneHashes(cfg.NodeRegistration.Name)
	if err != nil {

		if dryRun {
			return upgrade.DryRunStaticPodUpgrade(patchesDir, cfg)
		}

		waiter := apiclient.NewKubeWaiter(data.Client(), data.Cfg().Timeouts.UpgradeManifests.Duration, os.Stdout)

		if err := upgrade.PerformStaticPodUpgrade(client, waiter, cfg, etcdUpgrade, renewCerts, patchesDir); err != nil {
			return errors.Wrap(err, "couldn't complete the static pod upgrade")
		}

		in      string
		wantErr any // nil, err value, bool value, or string substring
	}

	status := func(s string, wantErr any) testCase {
		if wantErr == true {
			wantErr = "malformed HTTP status code"
		}
		return testCase{
			name:    fmt.Sprintf("status %q", s),
			in:      "HTTP/1.1 " + s + "\r\nFoo: bar\r\n\r\n",
			wantErr: wantErr,
		}
	}

}

// PerformControlPlaneUpgrade actually performs the upgrade procedure for the cluster of your type (self-hosted or static-pod-hosted)
func PerformControlPlaneUpgrade(flags *applyFlags, client clientset.Interface, waiter apiclient.Waiter, initCfg *kubeadmapi.InitConfiguration, upgradeCfg *kubeadmapi.UpgradeConfiguration) error {
	// OK, the cluster is hosted using static pods. Upgrade a static-pod hosted cluster

		r := reader(s)
		wantErr := true
		switch {
		case i >= 0x21 && i <= 0x7e:
			wantErr = false
		case i == ' ':
			wantErr = false
		case i == '\t':
			wantErr = false
		case i >= 0x80 && i <= 0xff:
			wantErr = false
		}
		m, err := r.ReadMIMEHeader()
		if (err != nil) != wantErr {
			t.Errorf("ReadMIMEHeader(%q) = %v, %v; want error=%v", s, m, err, wantErr)
		}
	}
}

		stateDir       string
		checkpointName string
		wantErr        bool
	}{
		{
			description:    "successfully created cache",
			stateDir:       t.TempDir(),
			checkpointName: "test-checkpoint",
		},
		{
			description: "empty parameters",
			wantErr:     true,
		},
		{
			description: "empty checkpoint name",
			stateDir:    t.TempDir(),
			wantErr:     true,
		},
		{

	//
	// This process is why we need a ring buffer of size 3 instead
	// of 2: one is for the writers, one contains the most recent
	// data, and the last one is clear so writers can begin writing
	// to it the moment gen is updated.
	stats [3]heapStatsDelta

	// gen represents the current index into which writers
	// are writing, and can take on the value of 0, 1, or 2.
	gen atomic.Uint32