From f61fd5d1be054c27eb682c6856b278babeba7438 Mon Sep 17 00:00:00 2001
From: orgin <boyce.duan@gmail.com>
Date: Thu, 30 Jun 2022 09:50:32 +0800
Subject: [PATCH] =?UTF-8?q?=E6=96=B0=E5=A2=9E=E5=BE=AA=E7=8E=AF=E9=98=9F?=
 =?UTF-8?q?=E5=88=97?=
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---
 util/queue/squeue.go         | 159 +++++++++++++++++++++++++++++++++++
 util/queue/syncqueue_test.go |  52 ++++++++++++
 2 files changed, 211 insertions(+)
 create mode 100644 util/queue/squeue.go
 create mode 100644 util/queue/syncqueue_test.go

diff --git a/util/queue/squeue.go b/util/queue/squeue.go
new file mode 100644
index 0000000..c99ebf1
--- /dev/null
+++ b/util/queue/squeue.go
@@ -0,0 +1,159 @@
+package queue
+
+import (
+	"sync"
+)
+
+/*
+ 这是一个循环队列
+*/
+type SQueue[ElementType any] struct {
+	elements []ElementType
+	head int
+	tail int
+	locker sync.RWMutex
+}
+
+//游标,通过该游标获取数据
+type SCursor[ElementType any] struct {
+	pos int
+	squeue *SQueue[ElementType]
+}
+
+func NewSQueue[ElementType any](maxElementNum int) *SQueue[ElementType]{
+	queue := &SQueue[ElementType]{}
+	queue.elements = make([]ElementType,maxElementNum+1)
+
+	return queue
+}
+
+//游标移动到队首
+func (s *SCursor[ElementType]) First(){
+	s.squeue.locker.RLock()
+	defer s.squeue.locker.RUnlock()
+	s.pos = s.squeue.head
+}
+
+//从当前位置移动游标,注意如果在多协程读或者pop时，可能会导致游标失效
+func (s *SCursor[ElementType]) Next() (elem ElementType,ret bool){
+	s.squeue.locker.RLock()
+	defer s.squeue.locker.RUnlock()
+
+	if s.pos == s.squeue.tail {
+		return
+	}
+
+	s.pos++
+	s.pos =  (s.pos)%(len(s.squeue.elements))
+	return s.squeue.elements[s.pos],true
+}
+
+//获取队列元数个数
+func (s *SQueue[ElementType]) Len() int {
+	s.locker.RLock()
+	defer s.locker.RUnlock()
+
+	if s.head <= s.tail {
+		return s.head - s.tail
+	}
+
+	//(len(s.elements)-1-s.head)+(s.tail+1)
+	return len(s.elements)-s.head+s.tail
+}
+
+//获取游标，默认是队首
+func (s *SQueue[ElementType]) GetCursor() (cur SCursor[ElementType]){
+	s.locker.RLock()
+	defer s.locker.RUnlock()
+
+	cur.squeue = s
+	cur.pos = s.head
+	return
+}
+
+//获取指定位置的游标
+func (s *SQueue[ElementType]) GetPosCursor(pos int) (cur SCursor[ElementType],ret bool){
+	s.locker.RLock()
+	defer s.locker.RUnlock()
+
+	if s.head < s.tail {
+		if pos<=s.head || pos>s.tail{
+			return
+		}
+
+		ret = true
+		cur.squeue = s
+		cur.pos = pos
+		return
+	}
+
+	if pos >s.tail && pos <=s.head {
+		return
+	}
+
+	cur.squeue = s
+	cur.pos = pos
+	return
+}
+
+//从队首移除掉指定数量元素
+func (s *SQueue[ElementType]) RemoveElement(elementNum int) (removeNum int) {
+	s.locker.Lock()
+	defer s.locker.Unlock()
+
+	for ;s.head == s.tail && removeNum >= elementNum;{
+		removeNum++
+		s.head++
+		s.head = s.head%len(s.elements)
+	}
+
+	return
+}
+
+//从队首Pop元素
+func (s *SQueue[ElementType]) Pop() (elem ElementType,ret bool){
+	s.locker.Lock()
+	defer s.locker.Unlock()
+
+	if s.head == s.tail {
+		return
+	}
+
+	s.head++
+	s.head = s.head%len(s.elements)
+	return s.elements[s.head],true
+}
+
+//从队尾Push数据
+func (s *SQueue[ElementType]) Push(elem ElementType) bool {
+	s.locker.Lock()
+	defer s.locker.Unlock()
+
+	nextPos := (s.tail+1) % len(s.elements)
+	if nextPos == s.head {
+		//is full
+		return false
+	}
+
+	s.tail = nextPos
+	s.elements[s.tail] = elem
+	return true
+}
+
+//判断队列是否为空
+func (s *SQueue[ElementType]) IsEmpty() bool{
+	s.locker.RLock()
+	defer s.locker.RUnlock()
+
+	return s.head == s.tail
+}
+
+//判断队列是否已满 
+func (s *SQueue[ElementType]) IsFull() bool{
+	s.locker.RLock()
+	defer s.locker.RUnlock()
+
+	nextPos := (s.tail+1) % len(s.elements)
+	return nextPos == s.head
+}
+
diff --git a/util/queue/syncqueue_test.go b/util/queue/syncqueue_test.go
new file mode 100644
index 0000000..3e5efa9
--- /dev/null
+++ b/util/queue/syncqueue_test.go
@@ -0,0 +1,52 @@
+package queue
+
+import (
+	"testing"
+)
+
+func Test_Example(t *testing.T) {
+	//1.创建阶列
+	queue := NewSQueue[int](5)
+
+	//2.判断是否为空
+	t.Log("is empty :", queue.IsEmpty())
+	t.Log("is full :", queue.IsFull())
+
+	//3.游标使用
+	cursor := queue.GetCursor()
+	cursor.First()
+	for {
+		elem, ret := cursor.Next()
+		if ret == false {
+			break
+		}
+		t.Log("elem:", elem)
+	}
+
+	//4.push数据
+	for i := 0; i < 6; i++ {
+		t.Log("push:", queue.Push(i))
+	}
+
+	t.Log("is empty :", queue.IsEmpty())
+	t.Log("is full :", queue.IsFull())
+
+	//5.游标遍历
+	cursor.First()
+	for {
+		elem, ret := cursor.Next()
+		if ret == false {
+			break
+		}
+		t.Log("elem:", elem)
+	}
+
+	//pop数据所有
+	for i := 0; i < 6; i++ {
+		elem, ret := queue.Pop()
+		t.Log("pop:", elem, "-", ret, " len:", queue.Len())
+	}
+
+	t.Log("is empty :", queue.IsEmpty())
+	t.Log("is full :", queue.IsFull())
+}