reorganization of _examples and add some new examples such as iris+groupcache+mysql+docker

Former-commit-id: ed635ee95de7160cde11eaabc0c1dcb0e460a620

_examples/mvc/vuejs-todo-mvc/src/todo/item.go

@@ -0,0 +1,8 @@
+package todo
+
+type Item struct {
+	SessionID string `json:"-"`
+	ID        int64  `json:"id,omitempty"`
+	Title     string `json:"title"`
+	Completed bool   `json:"completed"`
+}

_examples/mvc/vuejs-todo-mvc/src/todo/service.go

@@ -0,0 +1,46 @@
+package todo
+
+import (
+	"sync"
+)
+
+type Service interface {
+	Get(owner string) []Item
+	Save(owner string, newItems []Item) error
+}
+
+type MemoryService struct {
+	// key = session id, value the list of todo items that this session id has.
+	items map[string][]Item
+	// protected by locker for concurrent access.
+	mu sync.RWMutex
+}
+
+func NewMemoryService() *MemoryService {
+	return &MemoryService{
+		items: make(map[string][]Item, 0),
+	}
+}
+
+func (s *MemoryService) Get(sessionOwner string) []Item {
+	s.mu.RLock()
+	items := s.items[sessionOwner]
+	s.mu.RUnlock()
+
+	return items
+}
+
+func (s *MemoryService) Save(sessionOwner string, newItems []Item) error {
+	var prevID int64
+	for i := range newItems {
+		if newItems[i].ID == 0 {
+			newItems[i].ID = prevID
+			prevID++
+		}
+	}
+
+	s.mu.Lock()
+	s.items[sessionOwner] = newItems
+	s.mu.Unlock()
+	return nil
+}