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Copy pathKEventLoop.cpp
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166 lines (150 loc) · 4.31 KB
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#include "KEventLoop.h"
#include "../poller/KChannel.h"
#include "../poller/KEventManager.h"
#include "KAsyncWaker.h"
#include <signal.h>
#include <sys/eventfd.h>
using namespace kback;
// 通过 __thread 来保证一个线程只能创建一个 EventLoop
// __thread 变量是每个线程有的一份独立的实体
// 类似于static 只在编译期初始化
__thread EventLoop *t_loopInThisThread = 0;
const int kPollTimeMs = 1000;
EventLoop::EventLoop()
: looping_(false), threadId_(std::this_thread::get_id()),
eventmanager_(new EventManager(this)), quit_(false),
callingPendingFunctors_(false), asyncwaker(new AsyncWaker(this)) {
#ifdef USE_STD_COUT
std::cout << "LOG_TRACE: "
<< "EventLoop created " << this << " in thread " << threadId_
<< std::endl;
#endif
if (t_loopInThisThread) {
#ifdef USE_STD_COUT
std::cout << "LOG_FATAL: "
<< "Another EventLoop " << t_loopInThisThread
<< " exists in this thread " << threadId_ << std::endl;
#endif
} else {
t_loopInThisThread = this;
}
}
EventLoop::~EventLoop() {
assert(!looping_);
t_loopInThisThread = nullptr;
}
void EventLoop::loop() {
assert(!looping_);
assertInLoopThread();
looping_ = true;
quit_ = false;
while (!quit_) {
activeChannels_.clear();
// 这里poll在轮询中，为阻塞的，想要回调活动事件，必须想办法唤醒
// muduo这里采用了一个很巧妙的办法，专门用一个文件描述符来进行唤醒
pollReturnTime_ = eventmanager_->poll(kPollTimeMs, &activeChannels_);
for (auto it = activeChannels_.begin(); it != activeChannels_.end(); ++it) {
(*it)->handleEvent(pollReturnTime_);
}
doPendingFunctors();
}
#ifdef USE_STD_COUT
std::cout << "LOG_TRACE: "
<< "EventLoop " << this << " stop looping" << std::endl;
#endif
looping_ = false;
}
void EventLoop::quit() {
quit_ = true;
if (!isInLoopThread()) {
asyncwaker->wakeup();
}
}
// channel 中注册了事件，需要更新，但是
// 为了保证线程安全，channel自己是不会更新的，
// 将更新的工作转交给loop, 然后在loop线程中 同步poll 中的channel
void EventLoop::updateChannel(Channel *channel) {
assert(channel->ownerLoop() == this);
assertInLoopThread();
// EventLoop 实际上不负责更新channel
eventmanager_->updateChannel(channel);
}
void EventLoop::removeChannel(Channel *channel) {
assert(channel->ownerLoop() == this);
assertInLoopThread();
eventmanager_->removeChannel(channel);
}
void EventLoop::abortNotInLoopThread() {
#ifdef USE_STD_COUT
std::cerr << "LOG_FATAL: "
<< "EventLoop::abortNotInLoopThread - EventLoop " << this
<< " was created in threadId_ = " << threadId_
<< ", current thread id = " << std::this_thread::get_id()
<< std::endl;
#endif
std::abort();
}
// 执行装载的的回调函数，下面的处理方法很巧妙
void EventLoop::doPendingFunctors() {
#ifdef USE_LOCKFREEQUEUE
callingPendingFunctors_ = true;
// 遍历执行回调函数
for (;;) {
Functor functor;
bool flag = pendingFunctors_.Try_Dequeue(functor);
if (flag) {
if (functor != nullptr) {
functor();
}
} else {
break;
}
}
#else
{
std::vector<Functor> functors;
callingPendingFunctors_ = true;
#ifdef USE_SPINLOCK
spinlock.lock();
functors.swap(pendingFunctors_);
spinlock.unlock();
#else
std::lock_guard<std::mutex> lock(mutex_);
functors.swap(pendingFunctors_);
#endif
// 遍历执行回调函数
for (auto &functor : functors) {
functor();
}
}
#endif
callingPendingFunctors_ = false;
}
// !这个函数是在loop启动之前调用的，用于设置channel
void EventLoop::runInLoop(const Functor &cb) {
if (isInLoopThread()) {
cb();
} else {
queueInLoop(cb);
}
}
// queueInLoop 是public的，不一定要被runInLoop调用，也可以被直接调用
void EventLoop::queueInLoop(const Functor &cb) {
{
#ifdef USE_LOCKFREEQUEUE
pendingFunctors_.Enqueue(cb);
#else
#ifdef USE_SPINLOCK
spinlock.lock();
pendingFunctors_.push_back(cb);
spinlock.unlock();
#else
std::lock_guard<std::mutex> lock(mutex_);
pendingFunctors_.push_back(cb);
#endif
#endif
}
if (!isInLoopThread() || callingPendingFunctors_) {
asyncwaker->wakeup();
}
}