working commit

app/locker/locker.go

@@ -0,0 +1,66 @@
+package locker
+
+import (
+	"sync"
+)
+
+type Elem struct {
+	Pipe  chan bool
+	Usage int
+}
+
+func NewElem() *Elem {
+	return &Elem{
+		Pipe: make(chan bool, 1),
+	}
+}
+
+type Locker struct {
+	mtx  sync.Mutex
+	lMap map[string]*Elem
+}
+
+func NewLocker() *Locker {
+	lock := &Locker{
+		lMap: make(map[string]*Elem),
+	}
+	return lock
+}
+
+func (lock *Locker) WaitAndLock(name string) {
+	lock.mtx.Lock()
+	p, exist := lock.lMap[name]
+	if !exist {
+		p = NewElem()
+		lock.lMap[name] = p
+		p.Pipe <- true
+	}
+	p.Usage += 1
+	lock.mtx.Unlock()
+	select {
+	case <-p.Pipe:
+		// NOP
+	}
+}
+
+func (lock *Locker) Done(name string) {
+	lock.mtx.Lock()
+	p, exist := lock.lMap[name]
+	if exist {
+		p.Pipe <- true
+		if p.Usage > 0 {
+			p.Usage -= 1
+		}
+	}
+	garbageKeys := make([]string, 0)
+	for key, _ := range lock.lMap {
+		elem := lock.lMap[key]
+		if elem.Usage == 0 && key != name {
+			garbageKeys = append(garbageKeys, key)
+		}
+	}
+	for _, key := range garbageKeys {
+		delete(lock.lMap, key)
+	}
+	lock.mtx.Unlock()
+}