#include "EpollPoller.h"
#include "Logger.h"
#include "Channel.h"

#include <errno.h>
#include <unistd.h>
#include <strings.h>

//注意：channel的成员index_初始化时就为-1
const int kNew = -1; //表示Channel还没有添加到epoll里
const int kAdded = 1; //表示Channel已经添加到epoll里
const int kDeleted = 2; //表示Channel已经从epoll里删除了

EpollPoller::EpollPoller(EventLoop* loop)
  :Poller(loop)
   ,epollFd_(::epoll_create1(EPOLL_CLOEXEC))
   ,events_(kInitEventListSize){ //vector<epoll_event>
     if(epollFd_ < 0){
       LOG_FATAL("epoll_create1 error:%d \n",errno);
     }
}

EpollPoller::~EpollPoller(){
  ::close(epollFd_);
}
    
Timestamp EpollPoller::poll(int timeoutMs, ChannelList* activeChannels){
  //实际上使用LOG_DEBUG输出日志更为合理，因为高并发场景下这里的日志会被频繁打印的
  LOG_INFO("func=%s => fd total count:%lu \n", __FUNCTION__, channels_.size());
  int numEvents = ::epoll_wait(epollFd_,&*events_.begin(),static_cast<int>(events_.size()),timeoutMs);
  int savedErrno = errno;
  Timestamp now(Timestamp::now());

  if(numEvents > 0){
    LOG_INFO("%d events happened \n",numEvents);
    fillActiveChannels(numEvents,activeChannels);
    if(numEvents == events_.size()){ //如果发现全部都有监听消息发生，那么就应该进行扩容了
      events_.resize(events_.size()*2);
    }
  }
  else if(numEvents == 0){
    LOG_DEBUG("%s timeout! \n", __FUNCTION__);
  }
  else{
    if(savedErrno != EINTR){
      errno = savedErrno;//muduo源码中需要访问全局变量errno，因此源码中这里又赋值回去了
      LOG_ERROR("EpollPoller::poll() error!");
    }
  }
  return now;
}

void EpollPoller::updateChannel(Channel* channel){
  const int index = channel->index();
  LOG_INFO("func=%s => fd=%d events=%d index=%d \n", __FUNCTION__, channel->fd(), channel->events(), index);
  //要么是从来没添加过现在要添加，要么是之前被删除了现在又想添加
  if(index == kNew || index == kDeleted){
    if(index == kNew){
      int fd = channel->fd();
      channels_[fd] = channel;
    }
    channel->set_index(kAdded);
    update(EPOLL_CTL_ADD,channel);
  }
  else{ //否则channel已经在poller上注册过了
    int fd = channel->fd();
    if(channel->isNoneEvent()){ //如果是对所有事件都不感兴趣了，那就删除
      update(EPOLL_CTL_DEL,channel);
      channel->set_index(kDeleted);
    }
    else{//否则就是进行修改
      update(EPOLL_CTL_MOD,channel);
    }
  }
}

//从Poller中删除channel
void EpollPoller::removeChannel(Channel* channel){
  int fd = channel->fd();
  channels_.erase(fd);
  LOG_INFO("func=%s => fd=%d \n", __FUNCTION__, fd);
  int index = channel->index();
  if(index == kAdded){
    update(EPOLL_CTL_DEL,channel);
  }
  channel->set_index(kNew);
}

//填写活跃的连接
void EpollPoller::fillActiveChannels(int numEvents,ChannelList* activeChannels) const{
  for(int i=0; i<numEvents; ++i){
    Channel* channel = static_cast<Channel*>(events_[i].data.ptr);
    channel->set_revents(events_[i].events);
    activeChannels->push_back(channel); //EventLoop就拿到了它的poller给它返回的所有发生事件的channel列表了
  }
}

//更新Channel通道
void EpollPoller::update(int operation, Channel* channel){
  struct epoll_event event;
  bzero(&event, sizeof event);
  
  int fd = channel->fd();

  event.events = channel->events();
  event.data.fd = fd;
  event.data.ptr = channel;

  if(::epoll_ctl(epollFd_,operation,fd,&event) < 0){
    if(operation == EPOLL_CTL_DEL){
      LOG_ERROR("epoll_ctl_del error: %d \n",errno);
    }
    else{
      LOG_FATAL("epoll_ctl_add/mod error: %d \n",errno);
    }
  }
}