// Apply attempts to apply the changes described by Delta onto latest,
// returning an error if the changes cannot be applied cleanly.
// IsConflicting will be true if the changes overlap, otherwise a
// generic error will be returned.
func (d *Delta) Apply(latest []byte) ([]byte, error) {
base, err := yaml.ToJSON(latest)
if err != nil {
return nil, err
}
changes, err := jsonpatch.CreateMergePatch(d.original, base)
if err != nil {
return nil, err
}
diff1 := make(map[string]interface{})
if err := json.Unmarshal(d.edit, &diff1); err != nil {
return nil, err
}
diff2 := make(map[string]interface{})
if err := json.Unmarshal(changes, &diff2); err != nil {
return nil, err
}
for _, fn := range d.preconditions {
hold1, _ := fn(diff1)
hold2, _ := fn(diff2)
if !hold1 || !hold2 {
return nil, ErrPreconditionFailed
}
}
glog.V(6).Infof("Testing for conflict between:\n%s\n%s", string(d.edit), string(changes))
hasConflicts, err := strategicpatch.HasConflicts(diff1, diff2)
if err != nil {
return nil, err
}
if hasConflicts {
return nil, ErrConflict
}
return jsonpatch.MergePatch(base, d.edit)
}
// patchResource divides PatchResource for easier unit testing
func patchResource(
ctx api.Context,
admit updateAdmissionFunc,
timeout time.Duration,
versionedObj runtime.Object,
patcher rest.Patcher,
name string,
patchType api.PatchType,
patchJS []byte,
namer ScopeNamer,
copier runtime.ObjectCopier,
resource unversioned.GroupVersionResource,
codec runtime.Codec,
) (runtime.Object, error) {
namespace := api.NamespaceValue(ctx)
var (
originalObjJS []byte
originalPatchedObjJS []byte
lastConflictErr error
)
// applyPatch is called every time GuaranteedUpdate asks for the updated object,
// and is given the currently persisted object as input.
applyPatch := func(_ api.Context, _, currentObject runtime.Object) (runtime.Object, error) {
// Make sure we actually have a persisted currentObject
if hasUID, err := hasUID(currentObject); err != nil {
return nil, err
} else if !hasUID {
return nil, errors.NewNotFound(resource.GroupResource(), name)
}
switch {
case len(originalObjJS) == 0 || len(originalPatchedObjJS) == 0:
// first time through,
// 1. apply the patch
// 2. save the originalJS and patchedJS to detect whether there were conflicting changes on retries
if js, err := runtime.Encode(codec, currentObject); err != nil {
return nil, err
} else {
originalObjJS = js
}
if js, err := getPatchedJS(patchType, originalObjJS, patchJS, versionedObj); err != nil {
return nil, err
} else {
originalPatchedObjJS = js
}
objToUpdate := patcher.New()
if err := runtime.DecodeInto(codec, originalPatchedObjJS, objToUpdate); err != nil {
return nil, err
}
if err := checkName(objToUpdate, name, namespace, namer); err != nil {
return nil, err
}
return objToUpdate, nil
default:
// on a conflict,
// 1. build a strategic merge patch from originalJS and the patchedJS. Different patch types can
// be specified, but a strategic merge patch should be expressive enough handle them. Build the
// patch with this type to handle those cases.
// 2. build a strategic merge patch from originalJS and the currentJS
// 3. ensure no conflicts between the two patches
// 4. apply the #1 patch to the currentJS object
currentObjectJS, err := runtime.Encode(codec, currentObject)
if err != nil {
return nil, err
}
currentPatch, err := strategicpatch.CreateStrategicMergePatch(originalObjJS, currentObjectJS, versionedObj)
if err != nil {
return nil, err
}
originalPatch, err := strategicpatch.CreateStrategicMergePatch(originalObjJS, originalPatchedObjJS, versionedObj)
if err != nil {
return nil, err
}
diff1 := make(map[string]interface{})
if err := json.Unmarshal(originalPatch, &diff1); err != nil {
return nil, err
}
diff2 := make(map[string]interface{})
if err := json.Unmarshal(currentPatch, &diff2); err != nil {
return nil, err
}
hasConflicts, err := strategicpatch.HasConflicts(diff1, diff2)
if err != nil {
return nil, err
}
if hasConflicts {
glog.V(4).Infof("patchResource failed for resource %s, because there is a meaningful conflict.\n diff1=%v\n, diff2=%v\n", name, diff1, diff2)
// Return the last conflict error we got if we have one
if lastConflictErr != nil {
return nil, lastConflictErr
}
// Otherwise manufacture one of our own
return nil, errors.NewConflict(resource.GroupResource(), name, nil)
}
newlyPatchedObjJS, err := getPatchedJS(api.StrategicMergePatchType, currentObjectJS, originalPatch, versionedObj)
if err != nil {
return nil, err
}
objToUpdate := patcher.New()
if err := runtime.DecodeInto(codec, newlyPatchedObjJS, objToUpdate); err != nil {
return nil, err
}
return objToUpdate, nil
}
}
// applyAdmission is called every time GuaranteedUpdate asks for the updated object,
// and is given the currently persisted object and the patched object as input.
applyAdmission := func(ctx api.Context, patchedObject runtime.Object, currentObject runtime.Object) (runtime.Object, error) {
return patchedObject, admit(patchedObject, currentObject)
}
updatedObjectInfo := rest.DefaultUpdatedObjectInfo(nil, copier, applyPatch, applyAdmission)
return finishRequest(timeout, func() (runtime.Object, error) {
updateObject, _, updateErr := patcher.Update(ctx, name, updatedObjectInfo)
for i := 0; i < MaxPatchConflicts && (errors.IsConflict(updateErr)); i++ {
lastConflictErr = updateErr
updateObject, _, updateErr = patcher.Update(ctx, name, updatedObjectInfo)
}
return updateObject, updateErr
})
}