新增自定义持久化的消息队列

sysservice/messagequeueservice/MemoryQueue.go

@@ -0,0 +1,97 @@
+package messagequeueservice
+
+import (
+	"github.com/duanhf2012/origin/util/algorithms"
+	"sync"
+)
+
+type MemoryQueue struct {
+	subscriber *Subscriber
+
+	topicQueue []TopicData
+	head       int32
+	tail       int32
+
+	locker sync.RWMutex
+}
+
+func (mq *MemoryQueue) Init(cap int32) {
+	mq.topicQueue = make([]TopicData, cap+1)
+}
+
+// 从队尾Push数据
+func (mq *MemoryQueue) Push(topicData *TopicData) bool {
+	mq.locker.Lock()
+	defer mq.locker.Unlock()
+
+	nextPos := (mq.tail + 1) % int32(len(mq.topicQueue))
+	//如果队列满了
+	if nextPos == mq.head {
+		//将对首的数据删除掉
+		mq.head++
+		mq.head = mq.head % int32(len(mq.topicQueue))
+	}
+
+	mq.tail = nextPos
+	mq.topicQueue[mq.tail] = *topicData
+	return true
+}
+
+func (mq *MemoryQueue) findData(startPos int32, startIndex uint64, limit int32) ([]TopicData, bool) {
+	//空队列，无数据
+	if mq.head == mq.tail {
+		return nil, true
+	}
+
+	var findStartPos int32
+	var findEndPos int32
+	findStartPos = startPos //(mq.head + 1) % cap(mq.topicQueue)
+	if findStartPos <= mq.tail {
+		findEndPos = mq.tail + 1
+	} else {
+		findEndPos = int32(cap(mq.topicQueue))
+	}
+
+	//二分查找位置
+	pos := int32(algorithms.BiSearch(mq.topicQueue[findStartPos:findEndPos], startIndex, 1))
+	if pos == -1 {
+		return nil, true
+	}
+
+	pos += findStartPos
+	//取得结束位置
+	endPos := limit + pos
+	if endPos > findEndPos {
+		endPos = findEndPos
+	}
+
+	return mq.topicQueue[pos:endPos], true
+}
+
+// FindData 返回参数[]TopicData 表示查找到的数据，nil表示无数据。bool表示是否不应该在内存中来查
+func (mq *MemoryQueue) FindData(startIndex uint64, limit int32) ([]TopicData, bool) {
+	mq.locker.RLock()
+	defer mq.locker.RUnlock()
+
+	//队列为空时，应该从数据库查找
+	if mq.head == mq.tail {
+		return nil, false
+	}
+
+	/*
+		//先判断startIndex是否比第一个元素要大
+		headTopic := (mq.head + 1) % int32(len(mq.topicQueue))
+		//此时需要从持久化数据中取
+		if  startIndex+1 > mq.topicQueue[headTopic].Seq {
+			return nil, false
+		}
+	*/
+
+	retData, ret := mq.findData(mq.head+1, startIndex, limit)
+	if mq.head <= mq.tail || ret == true {
+		return retData, true
+	}
+
+	//如果是正常head在后，尾在前，从数组0下标开始找到tail
+	return mq.findData(0, startIndex, limit)
+}