storage.go

Documentation: k8s.io/kubernetes/pkg/kubelet/nodeshutdown

     1  /*
     2  Copyright 2022 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 nodeshutdown
    18  
    19  import (
    20  	"encoding/json"
    21  	"io"
    22  	"os"
    23  	"path/filepath"
    24  	"time"
    25  )
    26  
    27  type storage interface {
    28  	Store(data interface{}) (err error)
    29  	Load(data interface{}) (err error)
    30  }
    31  
    32  type localStorage struct {
    33  	Path string
    34  }
    35  
    36  func (l localStorage) Store(data interface{}) (err error) {
    37  	b, err := json.Marshal(data)
    38  	if err != nil {
    39  		return err
    40  	}
    41  	return atomicWrite(l.Path, b, 0644)
    42  }
    43  
    44  func (l localStorage) Load(data interface{}) (err error) {
    45  	b, err := os.ReadFile(l.Path)
    46  	if err != nil {
    47  		if os.IsNotExist(err) {
    48  			return nil
    49  		}
    50  		return err
    51  	}
    52  	return json.Unmarshal(b, data)
    53  }
    54  
    55  func timestamp(t time.Time) float64 {
    56  	if t.IsZero() {
    57  		return 0
    58  	}
    59  	return float64(t.Unix())
    60  }
    61  
    62  type state struct {
    63  	StartTime time.Time `json:"startTime"`
    64  	EndTime   time.Time `json:"endTime"`
    65  }
    66  
    67  // atomicWrite atomically writes data to a file specified by filename.
    68  func atomicWrite(filename string, data []byte, perm os.FileMode) error {
    69  	f, err := os.CreateTemp(filepath.Dir(filename), ".tmp-"+filepath.Base(filename))
    70  	if err != nil {
    71  		return err
    72  	}
    73  	err = os.Chmod(f.Name(), perm)
    74  	if err != nil {
    75  		f.Close()
    76  		return err
    77  	}
    78  	n, err := f.Write(data)
    79  	if err != nil {
    80  		f.Close()
    81  		return err
    82  	}
    83  	if n < len(data) {
    84  		f.Close()
    85  		return io.ErrShortWrite
    86  	}
    87  	if err := f.Sync(); err != nil {
    88  		f.Close()
    89  		return err
    90  	}
    91  	if err := f.Close(); err != nil {
    92  		return err
    93  	}
    94  	return os.Rename(f.Name(), filename)
    95  }
    96
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