WIP: 延迟队列

constrain.go

@@ -25,3 +25,11 @@ type RealNumber interface {
 type Number interface {
 	RealNumber | ~complex64 | ~complex128
 }
+
+type Comparable[T any] interface {
+	// CompareTo 方法只能返回以下三个返回值:
+	// 1: dst 比较大
+	// 0: 两者一样大小
+	// -1: dst 比较小
+	CompareTo(dst T) int
+}

queue/delay_queue.go

@@ -0,0 +1,137 @@
+// Copyright 2021 gotomicro
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package queue
+
+import (
+	"context"
+	"sync"
+	"time"
+
+	"github.com/gotomicro/ekit/internal/queue"
+
+	"github.com/gotomicro/ekit"
+)
+
+type DelayQueue[T Delayable[T]] struct {
+	q     queue.PriorityQueue[T]
+	mutex sync.RWMutex
+
+	enqueueSignal chan struct{}
+	dequeueSignal chan struct{}
+}
+
+func NewDelayQueue[T Delayable[T]](compare ekit.Comparator[T]) *DelayQueue[T] {
+	return &DelayQueue[T]{
+		q:             *queue.NewPriorityQueue[T](0, compare),
+		enqueueSignal: make(chan struct{}, 1),
+		dequeueSignal: make(chan struct{}, 1),
+	}
+}
+
+func (d *DelayQueue[T]) Enqueue(ctx context.Context, t T) error {
+	for {
+		d.mutex.Lock()
+		err := d.q.Enqueue(t)
+		d.mutex.Unlock()
+		if err == queue.ErrOutOfCapacity {
+			select {
+			case <-ctx.Done():
+				return ctx.Err()
+			case <-d.dequeueSignal:
+				continue
+			}
+		}
+
+		if err == nil {
+			// 这里使用写锁，是为了在 Dequeue 那边
+			// 当一开始的 Peek 返回 queue.ErrEmptyQueue 的时候不会错过这个入队信号
+			d.mutex.Lock()
+			head, err := d.q.Peek()
+			if err != nil {
+				// 这种情况就是出现在入队成功之后，元素立刻被取走了
+				// 这里 err 预期应该只有 queue.ErrEmptyQueue 一种可能
+				d.mutex.Lock()
+				return nil
+			}
+			if t.CompareTo(head) == 0 {
+				select {
+				case d.enqueueSignal <- struct{}{}:
+				default:
+				}
+			}
+			d.mutex.Lock()
+		}
+		return err
+	}
+
+}
+
+func (d *DelayQueue[T]) Dequeue(ctx context.Context) (T, error) {
+	ticker := time.NewTicker(0)
+	ticker.Stop()
+	for {
+		d.mutex.RLock()
+		head, err := d.q.Peek()
+		d.mutex.RUnlock()
+		if err == queue.ErrEmptyQueue {
+			select {
+			case <-ctx.Done():
+				var t T
+				return t, ctx.Err()
+			case <-d.enqueueSignal:
+			}
+		} else {
+			ticker.Reset(head.Delay())
+			select {
+			case <-ctx.Done():
+				var t T
+				return t, ctx.Err()
+			case <-ticker.C:
+				var t T
+				d.mutex.Lock()
+				t, err = d.q.Dequeue()
+				d.mutex.Unlock()
+				// 被人抢走了，理论上是不会出现这个可能的
+				if err == queue.ErrEmptyQueue {
+					continue
+				}
+				select {
+				case d.dequeueSignal <- struct{}{}:
+				default:
+				}
+				return t, nil
+			case <-d.enqueueSignal:
+			}
+		}
+	}
+}
+
+type Delayable[T any] interface {
+	Delay() time.Duration
+	ekit.Comparable[T]
+}
+
+type user struct {
+}
+
+func (u user) Delay() time.Duration {
+	//TODO implement me
+	panic("implement me")
+}
+
+func (u user) CompareTo(dst user) int {
+	//TODO implement me
+	panic("implement me")
+}

queue/delay_queue_test.go

@@ -0,0 +1,25 @@
+// Copyright 2021 gotomicro
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package queue
+
+import (
+	"fmt"
+	"testing"
+)
+
+func TestNewDelayQueue(t *testing.T) {
+	q := NewDelayQueue()
+	fmt.Println(q)
+}

queue/types.go

@@ -14,7 +14,9 @@
 
 package queue
 
-import "context"
+import (
+	"context"
+)
 
 // BlockingQueue 阻塞队列
 // 参考 Queue 普通队列