skipnonapplied.go

Documentation: k8s.io/apimachinery/pkg/util/managedfields/internal

     1  /*
     2  Copyright 2019 The Kubernetes Authors.
     3  
     4  Licensed under the Apache License, Version 2.0 (the "License");
     5  you may not use this file except in compliance with the License.
     6  You may obtain a copy of the License at
     7  
     8      http://www.apache.org/licenses/LICENSE-2.0
     9  
    10  Unless required by applicable law or agreed to in writing, software
    11  distributed under the License is distributed on an "AS IS" BASIS,
    12  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    13  See the License for the specific language governing permissions and
    14  limitations under the License.
    15  */
    16  
    17  package internal
    18  
    19  import (
    20  	"fmt"
    21  	"math/rand"
    22  
    23  	"k8s.io/apimachinery/pkg/api/meta"
    24  	"k8s.io/apimachinery/pkg/runtime"
    25  )
    26  
    27  type skipNonAppliedManager struct {
    28  	fieldManager           Manager
    29  	objectCreater          runtime.ObjectCreater
    30  	beforeApplyManagerName string
    31  	probability            float32
    32  }
    33  
    34  var _ Manager = &skipNonAppliedManager{}
    35  
    36  // NewSkipNonAppliedManager creates a new wrapped FieldManager that only starts tracking managers after the first apply.
    37  func NewSkipNonAppliedManager(fieldManager Manager, objectCreater runtime.ObjectCreater) Manager {
    38  	return NewProbabilisticSkipNonAppliedManager(fieldManager, objectCreater, 0.0)
    39  }
    40  
    41  // NewProbabilisticSkipNonAppliedManager creates a new wrapped FieldManager that starts tracking managers after the first apply,
    42  // or starts tracking on create with p probability.
    43  func NewProbabilisticSkipNonAppliedManager(fieldManager Manager, objectCreater runtime.ObjectCreater, p float32) Manager {
    44  	return &skipNonAppliedManager{
    45  		fieldManager:           fieldManager,
    46  		objectCreater:          objectCreater,
    47  		beforeApplyManagerName: "before-first-apply",
    48  		probability:            p,
    49  	}
    50  }
    51  
    52  // Update implements Manager.
    53  func (f *skipNonAppliedManager) Update(liveObj, newObj runtime.Object, managed Managed, manager string) (runtime.Object, Managed, error) {
    54  	accessor, err := meta.Accessor(liveObj)
    55  	if err != nil {
    56  		return newObj, managed, nil
    57  	}
    58  
    59  	// If managed fields is empty, we need to determine whether to skip tracking managed fields.
    60  	if len(managed.Fields()) == 0 {
    61  		// Check if the operation is a create, by checking whether lastObj's UID is empty.
    62  		// If the operation is create, P(tracking managed fields) = f.probability
    63  		// If the operation is update, skip tracking managed fields, since we already know managed fields is empty.
    64  		if len(accessor.GetUID()) == 0 {
    65  			if f.probability <= rand.Float32() {
    66  				return newObj, managed, nil
    67  			}
    68  		} else {
    69  			return newObj, managed, nil
    70  		}
    71  	}
    72  	return f.fieldManager.Update(liveObj, newObj, managed, manager)
    73  }
    74  
    75  // Apply implements Manager.
    76  func (f *skipNonAppliedManager) Apply(liveObj, appliedObj runtime.Object, managed Managed, fieldManager string, force bool) (runtime.Object, Managed, error) {
    77  	if len(managed.Fields()) == 0 {
    78  		gvk := appliedObj.GetObjectKind().GroupVersionKind()
    79  		emptyObj, err := f.objectCreater.New(gvk)
    80  		if err != nil {
    81  			return nil, nil, fmt.Errorf("failed to create empty object of type %v: %v", gvk, err)
    82  		}
    83  		liveObj, managed, err = f.fieldManager.Update(emptyObj, liveObj, managed, f.beforeApplyManagerName)
    84  		if err != nil {
    85  			return nil, nil, fmt.Errorf("failed to create manager for existing fields: %v", err)
    86  		}
    87  	}
    88  	return f.fieldManager.Apply(liveObj, appliedObj, managed, fieldManager, force)
    89  }
    90
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