mirror of
https://github.com/ceph/ceph-csi.git
synced 2024-11-14 02:10:21 +00:00
46 lines
1.3 KiB
Go
46 lines
1.3 KiB
Go
|
/*
|
||
|
|
Copyright 2017 The Kubernetes Authors.
|
||
|
|
|
||
|
|
Licensed under the Apache License, Version 2.0 (the "License");
|
||
|
|
you may not use this file except in compliance with the License.
|
||
|
|
You may obtain a copy of the License at
|
||
|
|
|
||
|
|
http://www.apache.org/licenses/LICENSE-2.0
|
||
|
|
|
||
|
|
Unless required by applicable law or agreed to in writing, software
|
||
|
|
distributed under the License is distributed on an "AS IS" BASIS,
|
||
|
|
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
||
|
|
See the License for the specific language governing permissions and
|
||
|
|
limitations under the License.
|
||
|
|
*/
|
||
|
|
|
||
|
|
package io
|
||
|
|
|
||
|
|
import (
|
||
|
|
"bytes"
|
||
|
|
"fmt"
|
||
|
|
"io/ioutil"
|
||
|
|
)
|
||
|
|
|
||
|
|
// ConsistentRead repeatedly reads a file until it gets the same content twice.
|
||
|
|
// This is useful when reading files in /proc that are larger than page size
|
||
|
|
// and kernel may modify them between individual read() syscalls.
|
||
|
|
func ConsistentRead(filename string, attempts int) ([]byte, error) {
|
||
|
|
oldContent, err := ioutil.ReadFile(filename)
|
||
|
|
if err != nil {
|
||
|
|
return nil, err
|
||
|
|
}
|
||
|
|
for i := 0; i < attempts; i++ {
|
||
|
|
newContent, err := ioutil.ReadFile(filename)
|
||
|
|
if err != nil {
|
||
|
|
return nil, err
|
||
|
|
}
|
||
|
|
if bytes.Compare(oldContent, newContent) == 0 {
|
||
|
|
return newContent, nil
|
||
|
|
}
|
||
|
|
// Files are different, continue reading
|
||
|
|
oldContent = newContent
|
||
|
|
}
|
||
|
|
return nil, fmt.Errorf("could not get consistent content of %s after %d attempts", filename, attempts)
|
||
|
|
}
|