【转载】C++定时器实现-白红宇

【转载】C++定时器实现

阅读量：4350 次

发布时间：2019-06-07

本文共 8637 字，大约阅读时间需要 28 分钟。

写这篇文章前搜了下网上类似的文章，有很多，所以笔者的这篇文章就不对定时器的常见实现方法加以说明，也不进行性能比较，直接上代码。

基于multimap实现的比较简单，这里略过。

前导

对于大多数的服务器程序，其定时器一般支持单线程就够了，一般使用方法见下面代码。如果需要多线程怎么办，笔者一般用一个简单的办法：多线程的业务线程中不包含定时器管理器，单独启一个线程用来管理所有定时器，当时间触发时，向业务线程投递定时器消息即可。

#include 
     
      #include 
      
       #include 
       
        #include "Timer.h"void TimerHandler(){    std::cout << "TimerHandler" << std::endl;}int main(){    TimerManager tm;    Timer t(tm);    t.Start(&TimerHandler, 1000);    while (true)    {        tm.DetectTimers();        std::this_thread::sleep_for(std::chrono::milliseconds(100));    }    std::cin.get();    return 0;}

1 最小堆实现

#include 
     
      #include 
      
        class TimerManager; class Timer{public:    enum TimerType { ONCE, CIRCLE };     Timer(TimerManager& manager);    ~Timer();     template
       
            void Start(Fun fun, unsigned interval, TimerType timeType = CIRCLE);    void Stop(); private:    void OnTimer(unsigned long long now); private:    friend class TimerManager;    TimerManager& manager_;    TimerType timerType_;    boost::function
        
          timerFun_;    unsigned interval_;    unsigned long long expires_;     size_t heapIndex_;}; class TimerManager{public:    static unsigned long long GetCurrentMillisecs();    void DetectTimers();private:    friend class Timer;    void AddTimer(Timer* timer);    void RemoveTimer(Timer* timer);     void UpHeap(size_t index);    void DownHeap(size_t index);    void SwapHeap(size_t, size_t index2); private:    struct HeapEntry    {        unsigned long long time;        Timer* timer;    };    std::vector
         
           heap_;}; template
          
           inline void Timer::Start(Fun fun, unsigned interval, TimerType timeType){ Stop(); interval_ = interval; timerFun_ = fun; timerType_ = timeType; timer->expires_ = timer->interval_ + TimerManager::GetCurrentMillisecs(); manager_.AddTimer(this);} // cpp file //#define _CRT_SECURE_NO_WARNINGS#include "config.h"#include "timer.h"#ifdef _MSC_VER# include 
           
            #else# include 
            
             #endif //// Timer Timer::Timer(TimerManager& manager) : manager_(manager) , heapIndex_(-1){} Timer::~Timer(){ Stop();} void Timer::Stop(){ if (heapIndex_ != -1) { manager_.RemoveTimer(this); heapIndex_ = -1; }} void Timer::OnTimer(unsigned long long now){ if (timerType_ == Timer::CIRCLE) { expires_ = interval_ + now; manager_.AddTimer(this); } else { heapIndex_ = -1; } timerFun_();} //// TimerManager void TimerManager::AddTimer(Timer* timer){ timer->heapIndex_ = heap_.size(); HeapEntry entry = { timer->expires_, timer }; heap_.push_back(entry); UpHeap(heap_.size() - 1);} void TimerManager::RemoveTimer(Timer* timer){ size_t index = timer->heapIndex_; if (!heap_.empty() && index < heap_.size()) { if (index == heap_.size() - 1) { heap_.pop_back(); } else { SwapHeap(index, heap_.size() - 1); heap_.pop_back(); size_t parent = (index - 1) / 2; if (index > 0 && heap_[index].time < heap_[parent].time) UpHeap(index); else DownHeap(index); } }} void TimerManager::DetectTimers(){ unsigned long long now = GetCurrentMillisecs(); while (!heap_.empty() && heap_[0].time <= now) { Timer* timer = heap_[0].timer; RemoveTimer(timer); timer->OnTimer(now); }} void TimerManager::UpHeap(size_t index){ size_t parent = (index - 1) / 2; while (index > 0 && heap_[index].time < heap_[parent].time) { SwapHeap(index, parent); index = parent; parent = (index - 1) / 2; }} void TimerManager::DownHeap(size_t index){ size_t child = index * 2 + 1; while (child < heap_.size()) { size_t minChild = (child + 1 == heap_.size() || heap_[child].time < heap_[child + 1].time) ? child : child + 1; if (heap_[index].time < heap_[minChild].time) break; SwapHeap(index, minChild); index = minChild; child = index * 2 + 1; }} void TimerManager::SwapHeap(size_t index1, size_t index2){ HeapEntry tmp = heap_[index1]; heap_[index1] = heap_[index2]; heap_[index2] = tmp; heap_[index1].timer->heapIndex_ = index1; heap_[index2].timer->heapIndex_ = index2;} unsigned long long TimerManager::GetCurrentMillisecs(){#ifdef _MSC_VER _timeb timebuffer; _ftime(&timebuffer); unsigned long long ret = timebuffer.time; ret = ret * 1000 + timebuffer.millitm; return ret;#else timeval tv; ::gettimeofday(&tv, 0); unsigned long long ret = tv.tv_sec; return ret * 1000 + tv.tv_usec / 1000;#endif}

2 时间轮实现

// header file //#pragma once#include 
     
      #include 
      
       #include 
       
         class TimerManager; class Timer{public:    enum TimerType {ONCE, CIRCLE};     Timer(TimerManager& manager);    ~Timer();     template
        
             void Start(Fun fun, unsigned interval, TimerType timeType = CIRCLE);    void Stop(); private:    void OnTimer(unsigned long long now); private:    friend class TimerManager;     TimerManager& manager_;    TimerType timerType_;    boost::function
         
           timerFun_;    unsigned interval_;    unsigned long long expires_;     int vecIndex_;    std::list
          
           ::iterator itr_;}; class TimerManager{public: TimerManager(); static unsigned long long GetCurrentMillisecs(); void DetectTimers(); private: friend class Timer; void AddTimer(Timer* timer); void RemoveTimer(Timer* timer); int Cascade(int offset, int index); private: typedef std::list
           
             TimeList; std::vector
            
              tvec_; unsigned long long checkTime_;}; template
             
              inline void Timer::Start(Fun fun, unsigned interval, TimerType timeType){ Stop(); interval_ = interval; timerFun_ = fun; timerType_ = timeType; expires_ = interval_ + TimerManager::GetCurrentMillisecs(); manager_.AddTimer(this);} // cpp file // #define _CRT_SECURE_NO_WARNINGS#include "config.h"#include "timer2.h"#ifdef _MSC_VER# include 
              
               #else# include 
               
                #endif #define TVN_BITS 6#define TVR_BITS 8#define TVN_SIZE (1 << TVN_BITS)#define TVR_SIZE (1 << TVR_BITS)#define TVN_MASK (TVN_SIZE - 1)#define TVR_MASK (TVR_SIZE - 1)#define OFFSET(N) (TVR_SIZE + (N) *TVN_SIZE)#define INDEX(V, N) ((V >> (TVR_BITS + (N) *TVN_BITS)) & TVN_MASK) //// Timer Timer::Timer(TimerManager& manager) : manager_(manager) , vecIndex_(-1){} Timer::~Timer(){ Stop();} void Timer::Stop(){ if (vecIndex_ != -1) { manager_.RemoveTimer(this); vecIndex_ = -1; }} void Timer::OnTimer(unsigned long long now){ if (timerType_ == Timer::CIRCLE) { expires_ = interval_ + now; manager_.AddTimer(this); } else { vecIndex_ = -1; } timerFun_();} //// TimerManager TimerManager::TimerManager(){ tvec_.resize(TVR_SIZE + 4 * TVN_SIZE); checkTime_ = GetCurrentMillisecs();} void TimerManager::AddTimer(Timer* timer){ unsigned long long expires = timer->expires_; unsigned long long idx = expires - checkTime_; if (idx < TVR_SIZE) { timer->vecIndex_ = expires & TVR_MASK; } else if (idx < 1 << (TVR_BITS + TVN_BITS)) { timer->vecIndex_ = OFFSET(0) + INDEX(expires, 0); } else if (idx < 1 << (TVR_BITS + 2 * TVN_BITS)) { timer->vecIndex_ = OFFSET(1) + INDEX(expires, 1); } else if (idx < 1 << (TVR_BITS + 3 * TVN_BITS)) { timer->vecIndex_ = OFFSET(2) + INDEX(expires, 2); } else if ((long long) idx < 0) { timer->vecIndex_ = checkTime_ & TVR_MASK; } else { if (idx > 0xffffffffUL) { idx = 0xffffffffUL; expires = idx + checkTime_; } timer->vecIndex_ = OFFSET(3) + INDEX(expires, 3); } TimeList& tlist = tvec_[timer->vecIndex_]; tlist.push_back(timer); timer->itr_ = tlist.end(); --timer->itr_;} void TimerManager::RemoveTimer(Timer* timer){ TimeList& tlist = tvec_[timer->vecIndex_]; tlist.erase(timer->itr_);} void TimerManager::DetectTimers(){ unsigned long long now = GetCurrentMillisecs(); while (checkTime_ <= now) { int index = checkTime_ & TVR_MASK; if (!index && !Cascade(OFFSET(0), INDEX(checkTime_, 0)) && !Cascade(OFFSET(1), INDEX(checkTime_, 1)) && !Cascade(OFFSET(2), INDEX(checkTime_, 2))) { Cascade(OFFSET(3), INDEX(checkTime_, 3)); } ++checkTime_; TimeList& tlist = tvec_[index]; TimeList temp; temp.splice(temp.end(), tlist); for (TimeList::iterator itr = temp.begin(); itr != temp.end(); ++itr) { (*itr)->OnTimer(now); } }} int TimerManager::Cascade(int offset, int index){ TimeList& tlist = tvec_[offset + index]; TimeList temp; temp.splice(temp.end(), tlist); for (TimeList::iterator itr = temp.begin(); itr != temp.end(); ++itr) { AddTimer(*itr); } return index;} unsigned long long TimerManager::GetCurrentMillisecs(){#ifdef _MSC_VER _timeb timebuffer; _ftime(&timebuffer); unsigned long long ret = timebuffer.time; ret = ret * 1000 + timebuffer.millitm; return ret;#else timeval tv; ::gettimeofday(&tv, 0); unsigned long long ret = tv.tv_sec; return ret * 1000 + tv.tv_usec / 1000;#endif}

结束语

在曾经的很多项目中，定时器的实现都是使用map，也许效率不是太高，却从来没有成为性能的瓶颈。但是程序员通常是追求完美的，既然有更好解决方案，且其实现又不那么复杂，那就完全可以去尝试。

转载于:https://www.cnblogs.com/xiangcaizhen/p/7206725.html

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