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https://github.com/duanhf2012/origin.git
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109 lines
2.5 KiB
Go
109 lines
2.5 KiB
Go
package messagequeueservice
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import (
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"github.com/duanhf2012/origin/v2/util/algorithms"
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"sync"
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)
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type MemoryQueue struct {
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subscriber *Subscriber
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topicQueue []TopicData
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head int32
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tail int32
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locker sync.RWMutex
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}
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func (mq *MemoryQueue) Init(cap int32) {
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mq.topicQueue = make([]TopicData, cap+1)
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}
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// 从队尾Push数据
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func (mq *MemoryQueue) Push(topicData *TopicData) bool {
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mq.locker.Lock()
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defer mq.locker.Unlock()
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nextPos := (mq.tail + 1) % int32(len(mq.topicQueue))
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//如果队列满了
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if nextPos == mq.head {
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//将对首的数据删除掉
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mq.head++
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mq.head = mq.head % int32(len(mq.topicQueue))
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}
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mq.tail = nextPos
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mq.topicQueue[mq.tail] = *topicData
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return true
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}
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func (mq *MemoryQueue) findData(startPos int32, startIndex uint64, limit int32) ([]TopicData, bool) {
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//空队列，无数据
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if mq.head == mq.tail {
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return nil, true
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}
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var findStartPos int32
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var findEndPos int32
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findStartPos = startPos //(mq.head + 1) % cap(mq.topicQueue)
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if findStartPos <= mq.tail {
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findEndPos = mq.tail + 1
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} else {
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findEndPos = int32(len(mq.topicQueue))
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}
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if findStartPos >= findEndPos {
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return nil, false
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}
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// 要取的Seq 比内存中最小的数据的Seq还小，那么需要返回错误
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if mq.topicQueue[findStartPos].Seq > startIndex {
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return nil, false
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}
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//二分查找位置
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pos := int32(algorithms.BiSearch(mq.topicQueue[findStartPos:findEndPos], startIndex, 1))
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if pos == -1 {
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return nil, false
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}
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pos += findStartPos
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//取得结束位置
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endPos := limit + pos
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if endPos > findEndPos {
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endPos = findEndPos
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}
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return mq.topicQueue[pos:endPos], true
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}
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// 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
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func (mq *MemoryQueue) FindData(startIndex uint64, limit int32, dataQueue []TopicData) ([]TopicData, bool) {
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mq.locker.RLock()
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defer mq.locker.RUnlock()
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//队列为空时，应该从数据库查找
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if mq.head == mq.tail {
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return nil, false
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} else if mq.head < mq.tail {
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// 队列没有折叠
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datas,ret := mq.findData(mq.head + 1, startIndex, limit)
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if ret {
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dataQueue = append(dataQueue, datas...)
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}
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return dataQueue, ret
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} else {
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// 折叠先找后面的部分
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datas,ret := mq.findData(mq.head+1, startIndex, limit)
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if ret {
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dataQueue = append(dataQueue, datas...)
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return dataQueue, ret
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}
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// 后面没找到，从前面开始找
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datas,ret = mq.findData(0, startIndex, limit)
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dataQueue = append(dataQueue, datas...)
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return dataQueue, ret
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}
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}
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