C++定时器
定时器：管理大量延时任务的模块，异步任务
addTimer(1000, func);
addTimer(1000, func);
addTimer(1000, func);
addTimer(1000, func);
数据结构： 有序结构， 增删改后仍然有序
最近要被触发的定时任务
可用：set/map/multiset/multiset/
跳表skiplist
时间轮
触发机制： 不要占用线程或者系统性能（sleep）
任务如何组织？
C语言：
struct TimerNode {
time_t expire;//not unique
callback func;
void* ctx;//args
};
C++11:
struct TimerNode {
time_t expire;//not unique
uint64_t id;//用于set数据结构
using callback = std::function
callback func;
};
优化
=====》
struct TimerNodeBase {
time_t expire;//not unique
uint64_t id;//用于set数据结
};
struct TimerNode : public TimerNodeBase {
callback func;//函数对象，拷贝成本高，所以通过继承现剥离
TimerNode(int times, int i, callback f) : expire:(times), func(f) , id(i) {}
};
-===》 std::set
//借助C++14 等价key
bool operator<(const TimerNodeBase &, const TimerNodeBase &) {
if (l.expire < r.expire)
return true;
else if (l.expire > r.expire)
return false;
else
return l.id < r.id;
}
class Timer {
public:
static inline time_t GetTicks() {
//返回最近的系统启动时间到当前时间，单位ms，
return std::chrono::duration_cast
//这里用steady_clock而不是system_clock是因为前者在修改系统时间不受影响
}
TimerNodeBase AddTimer(int msec, callback func) {
time_t exp = GetTick() + msec;
auto pairs = timeouts.emplace(exp, GetId(), func);
return (TimerNodeBase)*pairs.first;
}
void DelTimer(TimerNodeBase node) {
auto iter = timesout.find(node);
if (iter != timesout.end())
timesout.erase(iter);
}
private:
static inline uint64_t GetId() {
return gid++;
}
static uint64_t gid;
set
};
timerfd linux 2.6 内核用fd来管理定时器
creat timerfd
方式：
1 read(fd);
2. epoll //检测time事件
int main() {
int epfd = epoll_create(1);//大于0即可
int timerfd = timerfd_create(CLOCK_MONOTONIC, 0);
//注册事件
struct epoll_event ev = {.events= EPOLLIN | EPOLLET};//EPOLLET:edge trigger,only once边缘触发
epoll_ctl(epfd, EPOLL_CTL_ADD, timerfd, &ev);
//用unique ptr实现单例
unique_ptr
int i = 0;
timer->AddTimer(1000, [&](const TimerNode& node) {
});
//事件检测流程
struct epoll_event evs[64] = {0};
while (1) {
int n = epoll_wait(epfd, evs, 64, -1);
/handle timer
}
}
完整代码如下：
#include
#include
#include
#include
#include
#include
using namespace std;
struct TimerNodeBase {
time_t expire;
int64_t id;
};
struct TimerNode : public TimerNodeBase {
using Callback = std::function;
Callback func;
};
bool operator < (const TimerNodeBase &lhd, const TimerNodeBase &rhd) {
if (lhd.expire < rhd.expire)
return true;
else if (lhd.expire > rhd.expire)
return false;
return lhd.id < rhd.id;
}
class Timer {
public:
static time_t GetTick() {
auto sc = chrono::time_point_cast(chrono::steady_clock::now());
auto temp = chrono::duration_cast(sc.time_since_epoch());
return temp.count();
}
static int64_t GenID() {
return ++gid;
}
TimerNodeBase AddTimer(time_t msec, TimerNode::Callback func) {
TimerNode tnode;
tnode.expire = GetTick() + msec;
tnode.func = func;
tnode.id = GenID();
timermap.insert(tnode);
return static_cast(tnode);
}
bool DelTimer(TimerNodeBase &node) {
auto iter = timermap.find(node);
if (iter != timermap.end()) {
timermap.erase(iter);
return true;
}
return false;
}
bool CheckTimer() {
auto iter = timermap.begin();
if (iter != timermap.end() && iter->expire <= GetTick()) {
iter->func(*iter);
timermap.erase(iter);
return true;
}
return false;
}
time_t TimeToSleep() {
auto iter = timermap.begin();
if (iter == timermap.end()) {
return -1;
}
time_t diss = iter->expire-GetTick();
return diss > 0 ? diss : 0;
}
private:
static int64_t gid;
set> timermap;
};
int64_t Timer::gid = 0;
int main() {
int epfd = epoll_create(1);
unique_ptr timer = make_unique();
int i =0;
timer->AddTimer(1000, [&](const TimerNode &node) {
cout << Timer::GetTick() << "node id:" << node.id << " revoked times:" << ++i << endl;
});
timer->AddTimer(1000, [&](const TimerNode &node) {
cout << Timer::GetTick() << "node id:" << node.id << " revoked times:" << ++i << endl;
});
timer->AddTimer(3000, [&](const TimerNode &node) {
cout << Timer::GetTick() << "node id:" << node.id << " revoked times:" << ++i << endl;
});
auto node = timer->AddTimer(2100, [&](const TimerNode &node) {
cout << Timer::GetTick() << "node id:" << node.id << " revoked times:" << ++i << endl;
});
timer->DelTimer(node);
cout << "now time:" << Timer::GetTick() << endl;
epoll_event ev[64] = {0};
while (true) {
/*
-1 永久阻塞
0 没有事件立刻返回，有事件就拷贝到 ev 数组当中
t > 0 阻塞等待 t ms，
timeout 最近触发的定时任务离当前的时间
*/
int n = epoll_wait(epfd, ev, 64, timer->TimeToSleep());
for (int i = 0; i < n; i++) {
/**/
}
/* 处理定时事件*/
while(timer->CheckTimer());
}
return 0;
}