fix: update lego.

vendor/github.com/sacloud/libsacloud/utils/mutexkv/mutexkv.go

@@ -0,0 +1,43 @@
+package mutexkv
+
+import (
+	"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.
+type MutexKV struct {
+	lock  sync.Mutex
+	store map[string]*sync.Mutex
+}
+
+// Lock the mutex for the given key. Caller is responsible for calling Unlock
+// for the same key
+func (m *MutexKV) Lock(key string) {
+	m.get(key).Lock()
+}
+
+// Unlock the mutex for the given key. Caller must have called Lock for the same key first
+func (m *MutexKV) Unlock(key string) {
+	m.get(key).Unlock()
+}
+
+// Returns a mutex for the given key, no guarantee of its lock status
+func (m *MutexKV) get(key string) *sync.Mutex {
+	m.lock.Lock()
+	defer m.lock.Unlock()
+	mutex, ok := m.store[key]
+	if !ok {
+		mutex = &sync.Mutex{}
+		m.store[key] = mutex
+	}
+	return mutex
+}
+
+// NewMutexKV Returns a properly initalized MutexKV
+func NewMutexKV() *MutexKV {
+	return &MutexKV{
+		store: make(map[string]*sync.Mutex),
+	}
+}