Init V4 community edition (#2265)

* Init V4 community edition

* Init V4 community edition

pkg/queue/registry.go

@@ -0,0 +1,60 @@
+package queue
+
+import "sync"
+
+type (
+	// TaskRegistry is used in slave node to track in-memory stateful tasks.
+	TaskRegistry interface {
+		// NextID returns the next available Task ID.
+		NextID() int
+		// Get returns the Task by ID.
+		Get(id int) (Task, bool)
+		// Set sets the Task by ID.
+		Set(id int, t Task)
+		// Delete deletes the Task by ID.
+		Delete(id int)
+	}
+
+	taskRegistry struct {
+		tasks   map[int]Task
+		current int
+		mu      sync.Mutex
+	}
+)
+
+// NewTaskRegistry creates a new TaskRegistry.
+func NewTaskRegistry() TaskRegistry {
+	return &taskRegistry{
+		tasks: make(map[int]Task),
+	}
+}
+
+func (r *taskRegistry) NextID() int {
+	r.mu.Lock()
+	defer r.mu.Unlock()
+
+	r.current++
+	return r.current
+}
+
+func (r *taskRegistry) Get(id int) (Task, bool) {
+	r.mu.Lock()
+	defer r.mu.Unlock()
+
+	t, ok := r.tasks[id]
+	return t, ok
+}
+
+func (r *taskRegistry) Set(id int, t Task) {
+	r.mu.Lock()
+	defer r.mu.Unlock()
+
+	r.tasks[id] = t
+}
+
+func (r *taskRegistry) Delete(id int) {
+	r.mu.Lock()
+	defer r.mu.Unlock()
+
+	delete(r.tasks, id)
+}