Repository navigation
Expand file tree
/
Copy pathlock.go
More file actions
99 lines (84 loc) · 2.53 KB
/
Copy pathlock.go
File metadata and controls
99 lines (84 loc) · 2.53 KB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
// Copyright (c) 2015-2021 MinIO, Inc.
//
// This file is part of MinIO Object Storage stack
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program. If not, see <http://www.gnu.org/licenses/>.
// Package lock - implements filesystem locking wrappers around an
// open file descriptor.
package lock
import (
"errors"
"os"
"sync"
)
// ErrAlreadyLocked is returned if the underlying fd is already locked.
var ErrAlreadyLocked = errors.New("file already locked")
// RLockedFile represents a read locked file, implements a special
// closer which only closes the associated *os.File when the ref count.
// has reached zero, i.e when all the readers have given up their locks.
type RLockedFile struct {
*LockedFile
mutex sync.Mutex
refs int // Holds read lock refs.
}
// IsClosed - Check if the rlocked file is already closed.
func (r *RLockedFile) IsClosed() bool {
r.mutex.Lock()
defer r.mutex.Unlock()
return r.refs == 0
}
// IncLockRef - is used by called to indicate lock refs.
func (r *RLockedFile) IncLockRef() {
r.mutex.Lock()
r.refs++
r.mutex.Unlock()
}
// Close - this closer implements a special closer
// closes the underlying fd only when the refs
// reach zero.
func (r *RLockedFile) Close() (err error) {
r.mutex.Lock()
defer r.mutex.Unlock()
if r.refs == 0 {
return os.ErrInvalid
}
r.refs--
if r.refs == 0 {
err = r.File.Close()
}
return err
}
// Provides a new initialized read locked struct from *os.File
func newRLockedFile(lkFile *LockedFile) (*RLockedFile, error) {
if lkFile == nil {
return nil, os.ErrInvalid
}
return &RLockedFile{
LockedFile: lkFile,
refs: 1,
}, nil
}
// RLockedOpenFile - returns a wrapped read locked file, if the file
// doesn't exist at path returns an error.
func RLockedOpenFile(path string) (*RLockedFile, error) {
lkFile, err := LockedOpenFile(path, os.O_RDONLY, 0o666)
if err != nil {
return nil, err
}
return newRLockedFile(lkFile)
}
// LockedFile represents a locked file
type LockedFile struct {
*os.File
}