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Use CollisionCount for collision avoidance in StatefulSet controller #50490

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Merged
merged 1 commit into from
Aug 18, 2017
Merged

Use CollisionCount for collision avoidance in StatefulSet controller #50490

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58 changes: 26 additions & 32 deletions pkg/controller/history/controller_history.go
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Original file line number Diff line number Diff line change
Expand Up @@ -54,15 +54,17 @@ func ControllerRevisionName(prefix string, hash uint32) string {
return fmt.Sprintf("%s-%d", prefix, hash)
}

// NewControllerRevision returns the a ControllerRevision with a ControllerRef pointing parent and indicating that
// NewControllerRevision returns a ControllerRevision with a ControllerRef pointing to parent and indicating that
// parent is of parentKind. The ControllerRevision has labels matching selector, contains Data equal to data, and
// has a Revision equal to revision. If the returned error is nil, the returned ControllerRevision is valid. If the
// has a Revision equal to revision. The collisionCount is used when creating the name of the ControllerRevision
// so the name is likely unique. If the returned error is nil, the returned ControllerRevision is valid. If the
// returned error is not nil, the returned ControllerRevision is invalid for use.
func NewControllerRevision(parent metav1.Object,
parentKind schema.GroupVersionKind,
selector labels.Selector,
data runtime.RawExtension,
revision int64) (*apps.ControllerRevision, error) {
revision int64,
collisionCount *int32) (*apps.ControllerRevision, error) {
labelMap, err := labels.ConvertSelectorToLabelsMap(selector.String())
if err != nil {
return nil, err
Expand All @@ -86,15 +88,15 @@ func NewControllerRevision(parent metav1.Object,
Data: data,
Revision: revision,
}
hash := HashControllerRevision(cr, nil)
hash := HashControllerRevision(cr, collisionCount)
cr.Name = ControllerRevisionName(parent.GetName(), hash)
cr.Labels[ControllerRevisionHashLabel] = strconv.FormatInt(int64(hash), 10)
return cr, nil
}

// HashControllerRevision hashes the contents of revision's Data using FNV hashing. If probe is not nil, the byte value
// of probe is added written to the hash as well.
func HashControllerRevision(revision *apps.ControllerRevision, probe *uint32) uint32 {
func HashControllerRevision(revision *apps.ControllerRevision, probe *int32) uint32 {
hf := fnv.New32()
if len(revision.Data.Raw) > 0 {
hf.Write(revision.Data.Raw)
Expand Down Expand Up @@ -177,11 +179,13 @@ type Interface interface {
// returned error is not nil, the returned slice is not valid.
ListControllerRevisions(parent metav1.Object, selector labels.Selector) ([]*apps.ControllerRevision, error)
// CreateControllerRevision attempts to create the revision as owned by parent via a ControllerRef. If name
// collision occurs, a unique identifier is added to the hash of the revision and it is renamed using
// ControllerRevisionName. Implementations may cease to attempt to retry creation after some number of attempts
// and return an error. If the returned error is not nil, creation failed. If the returned error is nil, the
// returned ControllerRevision has been created.
CreateControllerRevision(parent metav1.Object, revision *apps.ControllerRevision) (*apps.ControllerRevision, error)
// collision occurs, collisionCount (incremented each time collision occurs except for the first time) is
// added to the hash of the revision and it is renamed using ControllerRevisionName. Implementations may
// cease to attempt to retry creation after some number of attempts and return an error. If the returned
// error is not nil, creation failed. If the returned error is nil, the returned ControllerRevision has been
// created.
// Callers must make sure that collisionCount is not nil. An error is returned if it is.
CreateControllerRevision(parent metav1.Object, revision *apps.ControllerRevision, collisionCount *int32) (*apps.ControllerRevision, error)
// DeleteControllerRevision attempts to delete revision. If the returned error is not nil, deletion has failed.
DeleteControllerRevision(revision *apps.ControllerRevision) error
// UpdateControllerRevision updates revision such that its Revision is equal to newRevision. Implementations
Expand Down Expand Up @@ -233,9 +237,10 @@ func (rh *realHistory) ListControllerRevisions(parent metav1.Object, selector la
return owned, err
}

func (rh *realHistory) CreateControllerRevision(parent metav1.Object, revision *apps.ControllerRevision) (*apps.ControllerRevision, error) {
// Initialize the probe to 0
probe := uint32(0)
func (rh *realHistory) CreateControllerRevision(parent metav1.Object, revision *apps.ControllerRevision, collisionCount *int32) (*apps.ControllerRevision, error) {
if collisionCount == nil {
return nil, fmt.Errorf("collisionCount should not be nil")
}

// Clone the input
any, err := scheme.Scheme.DeepCopy(revision)
Expand All @@ -246,18 +251,12 @@ func (rh *realHistory) CreateControllerRevision(parent metav1.Object, revision *

// Continue to attempt to create the revision updating the name with a new hash on each iteration
for {
var hash uint32
// The first attempt uses no probe to resolve collisions
if probe > 0 {
hash = HashControllerRevision(revision, &probe)
} else {
hash = HashControllerRevision(revision, nil)
}
hash := HashControllerRevision(revision, collisionCount)
// Update the revisions name and labels
clone.Name = ControllerRevisionName(parent.GetName(), hash)
created, err := rh.client.AppsV1beta1().ControllerRevisions(parent.GetNamespace()).Create(clone)
if errors.IsAlreadyExists(err) {
probe++
*collisionCount++
continue
}
return created, err
Expand Down Expand Up @@ -370,9 +369,10 @@ func (fh *fakeHistory) addRevision(revision *apps.ControllerRevision) (*apps.Con
return revision, fh.indexer.Update(revision)
}

func (fh *fakeHistory) CreateControllerRevision(parent metav1.Object, revision *apps.ControllerRevision) (*apps.ControllerRevision, error) {
// Initialize the probe to 0
probe := uint32(0)
func (fh *fakeHistory) CreateControllerRevision(parent metav1.Object, revision *apps.ControllerRevision, collisionCount *int32) (*apps.ControllerRevision, error) {
if collisionCount == nil {
return nil, fmt.Errorf("collisionCount should not be nil")
}

// Clone the input
any, err := scheme.Scheme.DeepCopy(revision)
Expand All @@ -384,18 +384,12 @@ func (fh *fakeHistory) CreateControllerRevision(parent metav1.Object, revision *

// Continue to attempt to create the revision updating the name with a new hash on each iteration
for {
var hash uint32
// The first attempt uses no probe to resolve collisions
if probe > 0 {
hash = HashControllerRevision(revision, &probe)
} else {
hash = HashControllerRevision(revision, nil)
}
hash := HashControllerRevision(revision, collisionCount)
// Update the revisions name and labels
clone.Name = ControllerRevisionName(parent.GetName(), hash)
created, err := fh.addRevision(clone)
if errors.IsAlreadyExists(err) {
probe++
*collisionCount++
continue
}
return created, err
Expand Down
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