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
|
// +build linux
package lock
import (
"github.com/containers/libpod/libpod/lock/shm"
)
// SHMLockManager manages shared memory locks.
type SHMLockManager struct {
locks *shm.SHMLocks
}
// NewSHMLockManager makes a new SHMLockManager with the given number of locks.
func NewSHMLockManager(path string, numLocks uint32) (Manager, error) {
locks, err := shm.CreateSHMLock(path, numLocks)
if err != nil {
return nil, err
}
manager := new(SHMLockManager)
manager.locks = locks
return manager, nil
}
// OpenSHMLockManager opens an existing SHMLockManager with the given number of
// locks.
func OpenSHMLockManager(path string, numLocks uint32) (Manager, error) {
locks, err := shm.OpenSHMLock(path, numLocks)
if err != nil {
return nil, err
}
manager := new(SHMLockManager)
manager.locks = locks
return manager, nil
}
// AllocateLock allocates a new lock from the manager.
func (m *SHMLockManager) AllocateLock() (Locker, error) {
semIndex, err := m.locks.AllocateSemaphore()
if err != nil {
return nil, err
}
lock := new(SHMLock)
lock.lockID = semIndex
lock.manager = m
return lock, nil
}
// RetrieveLock retrieves a lock from the manager given its ID.
func (m *SHMLockManager) RetrieveLock(id uint32) (Locker, error) {
lock := new(SHMLock)
lock.lockID = id
lock.manager = m
return lock, nil
}
// SHMLock is an individual shared memory lock.
type SHMLock struct {
lockID uint32
manager *SHMLockManager
}
// ID returns the ID of the lock.
func (l *SHMLock) ID() uint32 {
return l.lockID
}
// Lock acquires the lock.
func (l *SHMLock) Lock() {
if err := l.manager.locks.LockSemaphore(l.lockID); err != nil {
panic(err.Error())
}
}
// Unlock releases the lock.
func (l *SHMLock) Unlock() {
if err := l.manager.locks.UnlockSemaphore(l.lockID); err != nil {
panic(err.Error())
}
}
// Free releases the lock, allowing it to be reused.
func (l *SHMLock) Free() error {
return l.manager.locks.DeallocateSemaphore(l.lockID)
}
|
