Init V4 community edition (#2265)

* Init V4 community edition

* Init V4 community edition

pkg/queue/scheduler.go

@@ -0,0 +1,124 @@
+package queue
+
+import (
+	"errors"
+	"github.com/cloudreve/Cloudreve/v4/pkg/logging"
+	"sync"
+	"sync/atomic"
+	"time"
+)
+
+var (
+	// ErrQueueShutdown the queue is released and closed.
+	ErrQueueShutdown = errors.New("queue has been closed and released")
+	// ErrMaxCapacity Maximum size limit reached
+	ErrMaxCapacity = errors.New("golang-queue: maximum size limit reached")
+	// ErrNoTaskInQueue there is nothing in the queue
+	ErrNoTaskInQueue = errors.New("golang-queue: no Task in queue")
+)
+
+type (
+	Scheduler interface {
+		// Queue add a new Task into the queue
+		Queue(task Task) error
+		// Request get a new Task from the queue
+		Request() (Task, error)
+		// Shutdown stop all worker
+		Shutdown() error
+	}
+	fifoScheduler struct {
+		sync.Mutex
+		taskQueue taskHeap
+		capacity  int
+		count     int
+		exit      chan struct{}
+		logger    logging.Logger
+		stopOnce  sync.Once
+		stopFlag  int32
+	}
+	taskHeap []Task
+)
+
+// Queue send Task to the buffer channel
+func (s *fifoScheduler) Queue(task Task) error {
+	if atomic.LoadInt32(&s.stopFlag) == 1 {
+		return ErrQueueShutdown
+	}
+	if s.capacity > 0 && s.count >= s.capacity {
+		return ErrMaxCapacity
+	}
+
+	s.Lock()
+	s.taskQueue.Push(task)
+	s.count++
+	s.Unlock()
+
+	return nil
+}
+
+// Request a new Task from channel
+func (s *fifoScheduler) Request() (Task, error) {
+	if atomic.LoadInt32(&s.stopFlag) == 1 {
+		return nil, ErrQueueShutdown
+	}
+
+	if s.count == 0 {
+		return nil, ErrNoTaskInQueue
+	}
+	s.Lock()
+	if s.taskQueue[s.taskQueue.Len()-1].ResumeTime() > time.Now().Unix() {
+		s.Unlock()
+		return nil, ErrNoTaskInQueue
+	}
+
+	data := s.taskQueue.Pop()
+	s.count--
+	s.Unlock()
+
+	return data.(Task), nil
+}
+
+// Shutdown the worker
+func (s *fifoScheduler) Shutdown() error {
+	if !atomic.CompareAndSwapInt32(&s.stopFlag, 0, 1) {
+		return ErrQueueShutdown
+	}
+
+	return nil
+}
+
+// NewFifoScheduler for create new Scheduler instance
+func NewFifoScheduler(queueSize int, logger logging.Logger) Scheduler {
+	w := &fifoScheduler{
+		taskQueue: make([]Task, 2),
+		capacity:  queueSize,
+		logger:    logger,
+	}
+
+	return w
+}
+
+// Implement heap.Interface
+func (h taskHeap) Len() int {
+	return len(h)
+}
+
+func (h taskHeap) Less(i, j int) bool {
+	return h[i].ResumeTime() < h[j].ResumeTime()
+}
+
+func (h taskHeap) Swap(i, j int) {
+	h[i], h[j] = h[j], h[i]
+}
+
+func (h *taskHeap) Push(x any) {
+	*h = append(*h, x.(Task))
+}
+
+func (h *taskHeap) Pop() any {
+	old := *h
+	n := len(old)
+	x := old[n-1]
+	*h = old[0 : n-1]
+	return x
+}