forked from GoogleCloudPlatform/magic-modules
/
mutexkv.go
76 lines (65 loc) · 1.97 KB
/
mutexkv.go
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
package transport
import (
"log"
"sync"
)
// MutexKV is a simple key/value store for arbitrary mutexes. It can be used to
// serialize changes across arbitrary collaborators that share knowledge of the
// keys they must serialize on.
//
// The initial use case is to let aws_security_group_rule resources serialize
// their access to individual security groups based on SG ID.
type MutexKV struct {
lock sync.Mutex
store map[string]*sync.RWMutex
}
// Locks the mutex for the given key. Caller is responsible for calling Unlock
// for the same key
func (m *MutexKV) Lock(key string) {
log.Printf("[DEBUG] Locking %q", key)
m.get(key).Lock()
log.Printf("[DEBUG] Locked %q", key)
}
// Unlock the mutex for the given key. Caller must have called Lock for the same key first
func (m *MutexKV) Unlock(key string) {
log.Printf("[DEBUG] Unlocking %q", key)
m.get(key).Unlock()
log.Printf("[DEBUG] Unlocked %q", key)
}
// Acquires a read-lock on the mutex for the given key. Caller is responsible for calling RUnlock
// for the same key
func (m *MutexKV) RLock(key string) {
log.Printf("[DEBUG] RLocking %q", key)
m.get(key).RLock()
log.Printf("[DEBUG] RLocked %q", key)
}
// Releases a read-lock on the mutex for the given key. Caller must have called RLock for the same key first
func (m *MutexKV) RUnlock(key string) {
log.Printf("[DEBUG] RUnlocking %q", key)
m.get(key).RUnlock()
log.Printf("[DEBUG] RUnlocked %q", key)
}
// Returns a mutex for the given key, no guarantee of its lock status
func (m *MutexKV) get(key string) *sync.RWMutex {
m.lock.Lock()
defer m.lock.Unlock()
mutex, ok := m.store[key]
if !ok {
mutex = &sync.RWMutex{}
m.store[key] = mutex
}
return mutex
}
// Returns a properly initialized MutexKV
func NewMutexKV() *MutexKV {
return &MutexKV{
store: make(map[string]*sync.RWMutex),
}
}
// Global MutexKV
var MutexStore = NewMutexKV()
func LockedCall(lockKey string, f func() error) error {
MutexStore.Lock(lockKey)
defer MutexStore.Unlock(lockKey)
return f()
}