initial import

core/syncx/managedresource.go

@@ -0,0 +1,44 @@
+package syncx
+
+import "sync"
+
+type ManagedResource struct {
+	resource interface{}
+	lock     sync.RWMutex
+	generate func() interface{}
+	equals   func(a, b interface{}) bool
+}
+
+func NewManagedResource(generate func() interface{}, equals func(a, b interface{}) bool) *ManagedResource {
+	return &ManagedResource{
+		generate: generate,
+		equals:   equals,
+	}
+}
+
+func (mr *ManagedResource) MarkBroken(resource interface{}) {
+	mr.lock.Lock()
+	defer mr.lock.Unlock()
+
+	if mr.equals(mr.resource, resource) {
+		mr.resource = nil
+	}
+}
+
+func (mr *ManagedResource) Take() interface{} {
+	mr.lock.RLock()
+	resource := mr.resource
+	mr.lock.RUnlock()
+
+	if resource != nil {
+		return resource
+	}
+
+	mr.lock.Lock()
+	defer mr.lock.Unlock()
+	// maybe another Take() call already generated the resource.
+	if mr.resource == nil {
+		mr.resource = mr.generate()
+	}
+	return mr.resource
+}