Linux C++ 实现时间轮 优化超时检测机制

参考资料:
http://www.ijilei.com/8357
https://www.zhihu.com/question/38427301
https://www.ibm.com/developerworks/cn/linux/l-cn-timers/
http://www.cnblogs.com/processakai/archive/2012/04/11/2442294.html

思路和代码的编写主要是参考的csdn上的一个java的代码
http://blog.csdn.net/mindfloating/article/details/8033340
我参考java代码的思路来编写的C++代码 ,说来其实也没啥技术难度,把代码分享下供后来的技术人使用

我使用c++ 实现的时间轮主要是用于检测超时,是tcp会话的超时与否
所以定义一个sessionKey作为唯一的主键key.

因为我使用了C++11中的unordered_map,所以需要重载operator == 操作符,并自己编写hash函数,也就是SessionHash中的函数

class Sessionkey{public:    Sessionkey(){srcIp=dstIp=srcPort=dstPort = 0;};    Sessionkey(const Sessionkey& skey);    Sessionkey(uint32_t src,uint32_t dst,uint16_t sp,uint16_t dp):srcIp(src),dstIp(dst),srcPort(sp),dstPort(dp){}    bool operator == (const Sessionkey &skey) const;public:    uint32_t srcIp;    uint32_t dstIp;    uint16_t srcPort;    uint16_t dstPort;};class SessionHash{public:    size_t operator()(const Sessionkey& sk) const;};

#include "sessionKey.h"#include "murmurHash.h"Sessionkey::Sessionkey(const Sessionkey& sk){    srcIp   = sk.srcIp;    dstIp = sk.dstIp;    srcPort = sk.srcPort;    dstPort = sk.dstPort;}bool Sessionkey::operator==(const Sessionkey& sk) const{    return  (srcIp == sk.srcIp) && (dstIp == sk.dstIp)        && (srcPort == sk.srcPort) && (dstPort == sk.dstPort);}/*通过Sessionkey的全部成员构造hash值,切勿随意在Sessionkey类中添加成员变量*/size_t SessionHash::operator()(const Sessionkey& sk) const {    ull64_t ul64 = murmurHash64A(&sk, sizeof(sk), 0xee6b27eb);    return ul64;}

哈希值生成算法采用的是

ull64_t murmurHash64A ( const void * key, int len, ull64_t seed ){    //const uint64_t m = BIG_CONSTANT(0xc6a4a7935bd1e995);    const ull64_t m = 0xc6a4a7935bd1e995;    const int r = 47;    ull64_t h = seed ^ (len * m);    const ull64_t * data = (const ull64_t *)key;    const ull64_t * end = data + (len/8);    while(data != end)    {        ull64_t k = *data++;        k *= m;         k ^= k >> r;         k *= m;         h ^= k;        h *= m;     }    const unsigned char * data2 = (const unsigned char*)data;    switch(len & 7)    {    case 7: h ^= ull64_t(data2[6]) << 48;    case 6: h ^= ull64_t(data2[5]) << 40;    case 5: h ^= ull64_t(data2[4]) << 32;    case 4: h ^= ull64_t(data2[3]) << 24;    case 3: h ^= ull64_t(data2[2]) << 16;    case 2: h ^= ull64_t(data2[1]) << 8;    case 1: h ^= ull64_t(data2[0]);        h *= m;    };    h ^= h >> r;    h *= m;    h ^= h >> r;    return h;}

#ifndef __TIME_WHEEL_H__#define __TIME_WHEEL_H__#include <stdio.h>#include <stdlib.h>#include <sys/time.h>#include <string>#include <vector>#include <unordered_map>#include <mutex>#include <sessionKey.h>#include <glog/logging.h>#include "lfds611.h"using namespace std;/****************************全局函数定义区**********************************/#define TIMEOUT_SESSKEY_CNT  1000 //default#define SESSKEY_BUFFER_CNT  2000void *tickStepThreadGlobal(void* param);typedef std::unordered_map<Sessionkey,int,SessionHash> tDurationMap;/*定义槽类Slot*/class Slot{public:    Slot();    Slot(int nId);    ~Slot();    void addElement(Sessionkey& key,int num);    void removeElement(Sessionkey& key);public:    /*unordered_map的int是预留字段*/    tDurationMap slotDurationMap;//sessionKey和int    int id;};typedef std::unordered_map<Sessionkey,Slot*,SessionHash> tRelationMap;/*时间轮类*/class CTimeWheel{public:    CTimeWheel();    ~CTimeWheel();    /*tickDuration:一个tick持续时间    ticksPerWheel 一轮的tick数(会话超时时间)       timeUnit:时间单位,如毫秒*/    //构造函数中开启tick step线程    CTimeWheel(int tickDuration,int ticksPerWheel,int timeUnit);public:    /*添加元素,返回新加入元素的timeout时间*/    long addElement(Sessionkey& key,int num);    bool removeElement(Sessionkey& key);    /*开启线程步进tick数*/    void tickStepRun();private:    void waitForNextTick();    int getPreviousTickIndex();    bool checkAdd(Sessionkey& key);    void notifyExpired(int idx);//此处有疑问    /*返回值以秒为单位*/    long getCurrentTime();public:    /*读写加锁*/    mutex mtx;    /*时间轮,元素是Slot类型*/    std::vector<Slot*> wheel;    /*维护sessionKey和slot槽对应关系的哈希表*/    tRelationMap keyToSlotMap;    /*存储超时会话的SessionKey*/    struct lfds611_queue_state *timeoutSessionQueue;    Sessionkey  *sessKeyPool;private:    uint32_t tickDuration;    uint32_t ticksPerWheel;    uint32_t currentTickIndex;    pthread_t tickThread;    long startTime;    long tick;};#endif /* __STW_TIMER_H__ */

#include "timeWheel.h"void *tickStepThreadGlobal(void* param){    CTimeWheel* pThis = (CTimeWheel*)param;    pThis->tickStepRun();    return NULL;}Slot::Slot(){    id = 0;}Slot::Slot(int nId){    id = nId;}Slot::~Slot(){}void Slot::addElement(Sessionkey& key,int num){    if(0 == key.dstPort || 0 == key.srcPort)    {        VLOG(4)<<"addElement ERROR! 8888888888888888888888";    }    slotDurationMap.insert(make_pair(key,num));}void Slot::removeElement(Sessionkey& key){    slotDurationMap.erase(key);}/************************CTimeWheel类实现**********************************/CTimeWheel::CTimeWheel(){    tick = 0;    currentTickIndex = 0;}CTimeWheel::~CTimeWheel(){    /*释放申请的slot资源*/    for(uint32_t i=0;i<ticksPerWheel;i++)    {        Slot* delSlot = wheel.at(i);        free(delSlot);        delSlot = NULL;    }}CTimeWheel::CTimeWheel(int tickDuration,int ticksPerWheel,int timeUnit){    VLOG(3)<<"CTimeWheel Construct 2 Called!";    currentTickIndex = 0;    this->tickDuration = tickDuration*timeUnit;//单位:s    this->ticksPerWheel = ticksPerWheel + 1;    /*申请ticksPerWheel个slot槽*/    for(uint32_t i=0;i<this->ticksPerWheel;i++)    {        Slot* tmp = new Slot(i);        wheel.push_back(tmp);    }    sessKeyPool = new Sessionkey[SESSKEY_BUFFER_CNT];    /*申请无锁队列存储超时sessionkey*/    lfds611_queue_new(&timeoutSessionQueue,TIMEOUT_SESSKEY_CNT);    /*开启线程,传递this指针*/    if(pthread_create(&tickThread,NULL,tickStepThreadGlobal,this)!=0)    {        LOG(ERROR) <<"create tickStepThreadGlobal thread failed!";    }}void CTimeWheel::tickStepRun(){    //获取当前时间    startTime = getCurrentTime();    //设置tick为1    tick = 1;    //1.获取当前tick指针的slot    for(int i=0;;i++)    {        if(i == wheel.size())        {            i=0;        }        //加锁        mtx.try_lock();        currentTickIndex = i;        //解锁        mtx.unlock();        //2.对当前slot所有元素进行timeout处理(重要,暂时没完成)        notifyExpired(currentTickIndex);        //3.等待下一次tick到来        waitForNextTick();    }}void CTimeWheel::waitForNextTick(){    while(1)    {        long currentTime = getCurrentTime();        long sleepTime = tickDuration * tick - (currentTime - startTime);//单位        /*这块的值可能过大,加调试信息*/        //VLOG(3)<<"tick step Thread sleepTime is "<<sleepTime;        if(sleepTime <= 0)        {            break;        }        else        {            sleep(sleepTime);        }    }    //tick步进1    VLOG(3)<<"tick step add 1";    tick++;}long CTimeWheel::addElement(Sessionkey& key,int num){    //1.检测时间轮是否添加相同元素,有则删除后重新将元素插入到wheel中    if(false == checkAdd(key))    {        VLOG(3)<<"SessionKey is first Add";    }    //2.获取当前tick指针的前一个slot槽位    int previousTickindex = getPreviousTickIndex();    //3.添加元素到wheel->slot中    Slot* pSlot = wheel.at(previousTickindex);    if(NULL == pSlot)    {        return -1;    }    pSlot->addElement(key,num);    VLOG(3)<<"threadID "<<num<<" addElement to TimeWheel!";    //4.记录SessionKey和slot的对应关系    keyToSlotMap.insert(make_pair(key,pSlot));    VLOG(4)<<"keyToSlotMap size: "<<keyToSlotMap.size();    VLOG(3)<<"threadID "<<num<<" insert sessionKey to keyToSlotMap!";    //5.返回新加入元素的timeout时间    return (ticksPerWheel - 1) * tickDuration;}bool CTimeWheel::removeElement(Sessionkey& key){    Sessionkey reverseKey(key.dstIp,key.srcIp,key.dstPort,key.srcPort);    //删除keyToSlotMap关系表key对应元素    tRelationMap::iterator iteGot = keyToSlotMap.find(key);    if(iteGot == keyToSlotMap.end())    {        iteGot = keyToSlotMap.find(reverseKey);        if(iteGot == keyToSlotMap.end())        {            VLOG(3)<<"checkAdd function:sessionkey is not in keyToSlotMap";            return false;        }        else        {            Slot* pSlot = iteGot->second;            if(NULL == pSlot)            {                VLOG(3)<<"checkAdd() function,keyToSlotMap Element is NULL";                return false;            }            //4.删除wheel slot中的元素            pSlot->removeElement(reverseKey);            VLOG(3)<<"Erase key from wheel slot!";            //5.删除keyToSlotMap关系表中元素,便于后续添加和更新            keyToSlotMap.erase(reverseKey);            VLOG(3)<<"Erase key from keyToSlotMap!";            return true;        }    }    else    {        Slot* pSlot = iteGot->second;        if(NULL == pSlot)        {            VLOG(3)<<"checkAdd() function,keyToSlotMap Element is NULL";            return false;        }        //6.删除wheel slot中的元素        pSlot->removeElement(key);        VLOG(3)<<"Erase key from wheel slot!";        //7.删除keyToSlotMap关系表中元素,便于后续添加和更新        keyToSlotMap.erase(key);        VLOG(3)<<"Erase key from keyToSlotMap!" << key.ToString();    }    /////////////测试代码///////////////////////    struct in_addr addrSrc,addrDst;    uint32_t srcIp = htonl(key.srcIp);    uint32_t dstIp = htonl(key.dstIp);    memcpy(&addrSrc,&srcIp,4);    memcpy(&addrDst,&dstIp,4);    string strSrcIP = inet_ntoa(addrSrc);    string strDstIP = inet_ntoa(addrDst);    //VLOG(4)<<strSrcIP<<"->"<<strDstIP;    //VLOG(4)<<key.srcPort<<"->"<<key.dstPort;    return true;}/*对当前tick索引对应slot中的所有元素做超时处理*/void CTimeWheel::notifyExpired(int idx){    //1.返回idx索引对应的slot槽    if(idx<0 || idx >= ticksPerWheel)//0~ticksPerWheel-1    {        VLOG(4)<<"notifyExpired() function Failed!Reason:invalid Index!";        return;    }    Slot*pSlot = wheel.at(idx);    if(NULL == pSlot)    {        VLOG(4)<<"notifyExpired() function Failed!Reason:wheel slot is empty!";        return;    }    //2.返回slot槽中元素集合    //VLOG(4)<<"slot Element size is "<<pSlot->slotDurationMap.size();    int index = 0;    tDurationMap::iterator iteMap;    for(iteMap=pSlot->slotDurationMap.begin();iteMap!=pSlot->slotDurationMap.end();iteMap++)    {        Sessionkey* timeoutKey = sessKeyPool+index;        Sessionkey key = iteMap->first;        timeoutKey->srcIp = key.srcIp;        timeoutKey->dstIp = key.dstIp;        timeoutKey->srcPort= key.srcPort;        timeoutKey->dstPort= key.dstPort;        //将超时的sessionkey压入Queue        lfds611_queue_enqueue(timeoutSessionQueue,(void*)timeoutKey);        struct in_addr addrSrc,addrDst;        uint32_t srcIp = htonl(timeoutKey->srcIp);        uint32_t dstIp = htonl(timeoutKey->dstIp);        memcpy(&addrSrc,&srcIp,4);        memcpy(&addrDst,&dstIp,4);        string strSrcIP = inet_ntoa(addrSrc);        string strDstIP = inet_ntoa(addrDst);        VLOG(4)<<strSrcIP<<"->"<<strDstIP;        VLOG(4)<<"srcPort:"<<timeoutKey->srcPort<<"dstPort:"<<timeoutKey->dstPort;        VLOG(4)<<"sessionKey enqueue enqueue enqueue";        //删除记录        removeElement(key);        if(++index  == SESSKEY_BUFFER_CNT)        {            index = 0;        }       }}bool CTimeWheel::checkAdd(Sessionkey& key){    //检测集合中是否存在,如存在则删除slot槽中元素,删除keyToSlotMap对应表中元素    Sessionkey reverseKey(key.dstIp,key.srcIp,key.dstPort,key.srcPort);    //删除keyToSlotMap关系表key对应元素    tRelationMap::iterator iteGot = keyToSlotMap.find(key);    if(iteGot == keyToSlotMap.end())    {        iteGot = keyToSlotMap.find(reverseKey);        if(iteGot == keyToSlotMap.end())        {            VLOG(3)<<"checkAdd function:sessionkey is not in keyToSlotMap";            return false;        }        else        {            Slot* pSlot = iteGot->second;            if(NULL == pSlot)            {                VLOG(3)<<"checkAdd() function,keyToSlotMap Element is NULL";                return false;            }            //4.删除wheel slot中的元素            pSlot->removeElement(reverseKey);            VLOG(3)<<"Erase key from wheel slot!";            //5.删除keyToSlotMap关系表中元素,便于后续添加和更新            keyToSlotMap.erase(reverseKey);            VLOG(3)<<"Erase key from keyToSlotMap!";            return true;        }    }    else    {        Slot* pSlot = iteGot->second;        if(NULL == pSlot)        {            VLOG(3)<<"checkAdd() function,keyToSlotMap Element is NULL";            return false;        }        //6.删除wheel slot中的元素        pSlot->removeElement(key);        VLOG(3)<<"Erase key from wheel slot!";        //7.删除keyToSlotMap关系表中元素,便于后续添加和更新        keyToSlotMap.erase(key);        VLOG(3)<<"Erase key from keyToSlotMap!";        return true;    }    return true;}int CTimeWheel::getPreviousTickIndex(){       //加锁    mtx.try_lock();    int cti = currentTickIndex;    if(0 == cti)    {        return ticksPerWheel - 1;//4    }    return cti - 1;    //解锁    mtx.unlock();}long CTimeWheel::getCurrentTime(){    struct timeval tv;    gettimeofday(&tv,NULL);    return tv.tv_sec  + tv.tv_usec / 1000000;}