inline int lowerbits(int x) {
    return x & (-x);
}

binary(12) = 00001100   (就展示最低的一个字节)
lowerbits(12) = 00000100  (取最后一个1之后的部分)

int count(int n) {
    int res = 0;
    while (n > 0) {
        res += b[n];
        n -= lowerbits(n);
    }
    return res;
}

// delta 是第 i 位数字的变化值
void add(int i, int delta) {
    while (i < N) {
        i += delta;
        i += lowerbits(i);
    }
}

void init() {
    for (int i = 1; i < N; i++) {
        add(i, a[i]);
    }
}

void init() {
    for (int i = 1; i < N; i++) {
        pre[i] = pre[i - 1] + a[i];
        b[i] = pre[i] - pre[i - lowerbits(i)];
    }
}

#include <iostream>
using namespace std;

class A {
public:
    A() = default;
    A(int a, int b, int c) : pub(a), pro(b), priv(c) {}
    int pub;
protected:
    int pro;
private:
    int priv;
};

class B : public A { // 公有继承
public:
    B(int a, int b, int c) {
        pub = a;
        pro = b;
        // pri = c;
        // test.cc:20:9: error: ‘pri’ was not declared in this scope
        //       pri = c;
        //       ^~~
    }
};


int main() {
    B b(1, 2, 3);
    cout << "b.pub:" << b.pub << endl;
    // cout << "b.pro:" << b.pro << endl;
    // test.cc:31:27: error: ‘int A::pro’ is protected within this context
    //  cout << "b.pro:" << b.pro << endl;
    //                        ^~~
    // cout << "b.priv:" << b.priv << endl;
    // test.cc:32:28: error: ‘int A::priv’ is private within this context
    //  cout << "b.priv:" << b.priv << endl;
    //                         ^~~~
    return 0;
}

#include <iostream>
using namespace std;

class A {
public:
    A() = default;
    A(int a, int b, int c) : pub(a), pro(b), priv(c) {}
    int pub;
protected:
    int pro;
private:
    int priv;
};

class B : protected A { // 保护继承 
public:
    B(int a, int b, int c) {
        pub = a;
        pro = b;
    }
};

int main() {
    B b(1, 2, 3);
    cout << "b.pub:" << b.pub << endl;
    return 0;
}

#include <iostream>
using namespace std;

class A {
public:
    void func(int a) {
        cout << "A::func(int a)" << endl;
    }
};

class B : public A {
public:
    void func(int a, int b) {
        cout << "B::func(int a, int b)" << endl;
    }
};

int main() {
    B b;
    b.func(10);
    return 0;
}

/*
*hello_world.cu
*/
#include<stdio.h>
__global__ void hello_world(void) {
  printf("GPU: Hello world! \n");
}

int main(int argc, char **argv) {
  printf("CPU: Hello world!\n");
  hello_world<<<1,10>>>();
  cudaDeviceReset(); //if no this line, it can not output hello world from gpu
  return 0;
}

__global__ // 是告诉编译器这个是个可以在设备上执行的核函数

hello_world<<<1, 10>>>(); // 其中变量的含义是<<<线程块的个数,每个线程块中线程的个数>>> 一个核函数被执行的次数就是两个参数的乘积

cudaDeviceReset();

kernel_name<<<grid, block, share_mem, stream>>>(argument list);

kernel_name<<<4, 8>>>(argument list);

cudaError_t cudaDeviceSynchronize(void);

__global__ void sumArraysOnGPU(float *A, float *B, float *C) {
  int i = threadIdx.x;
  C[i] = A[i] + B[i];
}

#include <cuda_runtime.h>
#include <stdio.h>
// 错误检验的宏
#define CHECK(call)\
{\
  const cudaError_t error=call;\
  if(error!=cudaSuccess)\
  {\
      printf("ERROR: %s:%d,",__FILE__,__LINE__);\
      printf("code:%d,reason:%s\n",error,cudaGetErrorString(error));\
      exit(1);\
  }\
}

__global__ void sumArraysGPU(float* a, float* b, float* res) {
  int i = threadIdx.x;
  res[i] = a[i] + b[i];
}

void initialData(float* vec, int n) {
    for (int i = 0; i < n; i++) {
        vec[i] = (float)i;
    }
}

int main(int argc,char **argv) {
  int dev = 0;
  cudaSetDevice(dev);

  int nElem = 32;
  printf("Vector size:%d\n", nElem);
  int nByte = sizeof(float)*nElem;
  float *a_h = (float*)malloc(nByte); // 输入数据 a
  float *b_h = (float*)malloc(nByte); // 输入数据 b
  float *res_from_gpu_h = (float*)malloc(nByte); // 用于接受从 gpu 返回的结果
  memset(res_from_gpu_h, 0, nByte);

  float *a_d, *b_d, *res_d; // 核函数的输入核输出地址（在 gpu 上申请的内存）
  CHECK(cudaMalloc((float**)&a_d, nByte)); // 在 gpu 上申请内存
  CHECK(cudaMalloc((float**)&b_d, nByte));
  CHECK(cudaMalloc((float**)&res_d, nByte));

  initialData(a_h, nElem);
  initialData(b_h, nElem);

  CHECK(cudaMemcpy(a_d, a_h, nByte, cudaMemcpyHostToDevice)); // 将输入数据拷贝到 gpu
  CHECK(cudaMemcpy(b_d, b_h, nByte, cudaMemcpyHostToDevice));

  dim3 block(nElem);
  dim3 grid(nElem / block.x);
  sumArraysGPU<<<grid, block>>>(a_d, b_d, res_d); // 调用核函数
  printf("Execution configuration<<<%d, %d>>>\n", block.x, grid.x);

  CHECK(cudaMemcpy(res_from_gpu_h, res_d, nByte, cudaMemcpyDeviceToHost)); // 将核函数结果从 gpu 返回给 主机

  cudaFree(a_d);
  cudaFree(b_d);
  cudaFree(res_d);

  free(a_h);
  free(b_h);
  free(res_from_gpu_h);

  return 0;
}

#ifndef THREADPOOL_H
#define THREADPOOL_H

#include <list>
#include <cstdio>
#include <exception>
#include <pthread.h>
#include "locker.h"

// 线程池类，定义为模板类是为了代码复用，模板参数T是任务类
template< typename T >
class threadpool
{
public:
    // thread_number是线程池中线程的数量， max_requests是请求队列中最多允许的 等待处理的请求的数量
    threadpool( int thread_number = 8, int max_requests = 10000 );
    ~threadpool();
    // 向请求队列添加任务
    bool append( T* request );

private:
    // 工作线程运行的函数， 它不断从工作队列中取出任务执行之
    static void* worker( void* arg );
    void run();

private:
    int m_thread_number; // 线程池中线程数
    int m_max_requests;  // 请求队列中允许的最大请求数量
    pthread_t* m_threads; // 描述线程池的数组，其大小为m_thread_number
    std::list< T* > m_workqueue; // 请求队列
    locker m_queuelocker; // 保护请求队列的互斥锁
    sem m_queuestat; // 是否有任务要处理
    bool m_stop; // 是否结束线程
};

template< typename T >
threadpool< T >::threadpool( int thread_number, int max_requests ) : 
        m_thread_number( thread_number ), m_max_requests( max_requests ), m_stop( false ), m_threads( NULL )
{
    if( ( thread_number <= 0 ) || ( max_requests <= 0 ) )
    {
        throw std::exception();
    }

    m_threads = new pthread_t[ m_thread_number ];
    if( ! m_threads )
    {
        throw std::exception();
    }
    // 创建thread_number个线程，并将它们设置为脱离线程
    for ( int i = 0; i < thread_number; ++i )
    {
        printf( "create the %dth thread\n", i );
        if( pthread_create( m_threads + i, NULL, worker, this ) != 0 )
        {
            delete [] m_threads;
            throw std::exception();
        }
        if( pthread_detach( m_threads[i] ) )
        {
            delete [] m_threads;
            throw std::exception();
        }
    }
}

template< typename T >
threadpool< T >::~threadpool()
{
    delete [] m_threads;
    m_stop = true;
}

template< typename T >
bool threadpool< T >::append( T* request )
{
    m_queuelocker.lock(); // 操作工作队列要加锁，因为他被所有线程共享
    if ( m_workqueue.size() > m_max_requests )
    {
        m_queuelocker.unlock();
        return false;
    }
    m_workqueue.push_back( request );
    m_queuelocker.unlock();
    m_queuestat.post();
    return true;
}

template< typename T >
void* threadpool< T >::worker( void* arg )
{
    threadpool* pool = ( threadpool* )arg;
    pool->run();
    return pool;
}

template< typename T >
void threadpool< T >::run()
{
    while ( ! m_stop )
    {
        m_queuestat.wait();
        m_queuelocker.lock();
        if ( m_workqueue.empty() )
        {
            m_queuelocker.unlock();
            continue;
        }
        T* request = m_workqueue.front();
        m_workqueue.pop_front();
        m_queuelocker.unlock();
        if ( ! request )
        {
            continue;
        }
        request->process(); // 模板类需要实现这个接口
    }
}

#endif

#include <stdlib.h>
#include <stdio.h>
#include <assert.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/epoll.h>
#include <fcntl.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <string.h>

static const char* request = "GET http://localhost/index.html HTTP/1.1\r\nConnection: keep-alive\r\n\r\nxxxxxxxxxxxx";

int setnonblocking( int fd )
{
    int old_option = fcntl( fd, F_GETFL );
    int new_option = old_option | O_NONBLOCK;
    fcntl( fd, F_SETFL, new_option );
    return old_option;
}

void addfd( int epoll_fd, int fd )
{
    epoll_event event;
    event.data.fd = fd;
    event.events = EPOLLOUT | EPOLLET | EPOLLERR;
    epoll_ctl( epoll_fd, EPOLL_CTL_ADD, fd, &event );
    setnonblocking( fd );
}

// 向服务器写len个字节数据
bool write_nbytes( int sockfd, const char* buffer, int len )
{
    int bytes_write = 0;
    printf( "write out %d bytes to socket %d\n", len, sockfd );
    while( 1 ) 
    {   
        bytes_write = send( sockfd, buffer, len, 0 );
        if ( bytes_write == -1 )
        {   
            return false;
        }   
        else if ( bytes_write == 0 ) 
        {   
            return false;
        }   

        len -= bytes_write;
        buffer = buffer + bytes_write;
        if ( len <= 0 ) 
        {   
            return true;
        }   
    }   
}

// 从服务器读取数据
bool read_once( int sockfd, char* buffer, int len )
{
    int bytes_read = 0;
    memset( buffer, '\0', len );
    bytes_read = recv( sockfd, buffer, len, 0 );
    if ( bytes_read == -1 )
    {
        return false;
    }
    else if ( bytes_read == 0 )
    {
        return false;
    }
    printf( "read in %d bytes from socket %d with content: %s\n", bytes_read, sockfd, buffer );

    return true;
}

// 向服务器发起num个tcp连接，可以通过num更改压力
void start_conn( int epoll_fd, int num, const char* ip, int port )
{
    int ret = 0;
    struct sockaddr_in address;
    bzero( &address, sizeof( address ) );
    address.sin_family = AF_INET;
    inet_pton( AF_INET, ip, &address.sin_addr );
    address.sin_port = htons( port );

    for ( int i = 0; i < num; ++i )
    {
        sleep( 1 );
        int sockfd = socket( PF_INET, SOCK_STREAM, 0 );
        printf( "create 1 sock\n" );
        if( sockfd < 0 )
        {
            continue;
        }

        if (  connect( sockfd, ( struct sockaddr* )&address, sizeof( address ) ) == 0  )
        {
            printf( "build connection %d\n", i );
            addfd( epoll_fd, sockfd );
        }
    }
}

void close_conn( int epoll_fd, int sockfd )
{
    epoll_ctl( epoll_fd, EPOLL_CTL_DEL, sockfd, 0 );
    close( sockfd );
}

int main( int argc, char* argv[] )
{
    assert( argc == 4 );
    int epoll_fd = epoll_create( 100 );
    start_conn( epoll_fd, atoi( argv[ 3 ] ), argv[1], atoi( argv[2] ) );
    epoll_event events[ 10000 ];
    char buffer[ 2048 ];
    while ( 1 )
    {
        int fds = epoll_wait( epoll_fd, events, 10000, 2000 );
        for ( int i = 0; i < fds; i++ )
        {   
            int sockfd = events[i].data.fd;
            if ( events[i].events & EPOLLIN )
            {   
                if ( ! read_once( sockfd, buffer, 2048 ) )
                {
                    close_conn( epoll_fd, sockfd );
                }
                struct epoll_event event;
                event.events = EPOLLOUT | EPOLLET | EPOLLERR; // 读完之后设置成可写
                event.data.fd = sockfd;
                epoll_ctl( epoll_fd, EPOLL_CTL_MOD, sockfd, &event );
            }
            else if( events[i].events & EPOLLOUT ) 
            {
                if ( ! write_nbytes( sockfd, request, strlen( request ) ) )
                {
                    close_conn( epoll_fd, sockfd );
                }
                struct epoll_event event;
                event.events = EPOLLIN | EPOLLET | EPOLLERR; // 写完之后设置成可读
                event.data.fd = sockfd;
                epoll_ctl( epoll_fd, EPOLL_CTL_MOD, sockfd, &event );
            }
            else if( events[i].events & EPOLLERR )
            {
                close_conn( epoll_fd, sockfd );
            }
        }
    }
}

#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <assert.h>
#include <stdio.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <fcntl.h>
#include <stdlib.h>
#include <sys/epoll.h>
#include <signal.h>
#include <sys/wait.h>
#include <sys/stat.h>

#include "processpool.h"

// 用于处理客户cgi请求的类，他可以作为processpool类的模板参数
class cgi_conn {
 public:
  cgi_conn(){};
  ~cgi_conn(){};
  // 初始化客户连接，清空读缓冲区
  void init(int epollfd, int sockfd, const sockaddr_in& client_addr) {
    m_epollfd = epollfd;
    m_sockfd = sockfd;
    m_address = client_addr;
    memset(m_buf, '\0', BUFFER_SIZE);
    m_read_idx = 0;
  }

  void process() {
    int idx = 0;
    int ret = -1;
    // 循环读取和分析客户数据
    while (true) {
      idx = m_read_idx;
      ret = recv(m_sockfd, m_buf + idx, BUFFER_SIZE - 1 - idx, 0);
      // 如果读操作发生错误，则关闭客户连接，如果是暂时无数据可读，则退出循环
      if (ret < 0) {
        if (errno != EAGAIN) {
          removefd(m_epollfd, m_sockfd);
        }
        break;
      } else if (ret == 0) {
        // 如果对方关闭连接，服务器也关闭连接
        removefd(m_epollfd, m_sockfd);
        break;
      } else {
        m_read_idx += ret;
        printf("user content is: %s\n", m_buf);
        for (; idx < m_read_idx; ++idx) {
          if ((idx >= 1) && (m_buf[idx - 1] == '\r') && (m_buf[idx] == '\n')) {
            break;
          }
        }
        // 如果没有遇到字符\r\n 则需要读取更多客户数据
        if (idx == m_read_idx) {
          continue;
        }
        m_buf[idx - 1] = '\0';

        char* filename = m_buf;
        // 判断客户要运行的cgi程序是否存在
        if (access(filename, F_OK) == -1) {
          removefd(m_epollfd, m_sockfd);
          break;
        }
        // 创建子进程来执行cgi程序
        ret = fork();
        if (ret == -1) {
          removefd(m_epollfd, m_sockfd);
          break;
        } else if (ret > 0) { // 父进程
          // 父进程只需要关闭连接
          removefd(m_epollfd, m_sockfd);
          break;
        } else {
          // 子进程需要将标准输出定向到 m_sockfd,并执行cgi程序
          close(STDOUT_FILENO);
          dup(m_sockfd); // 把m_sockfd重定向到标准输出
          execl(m_buf, m_buf, 0);
          exit(0);
        }
      } // 读数据end
    } // while end

  } // process end

 private:
  static const int BUFFER_SIZE = 1024;
  static int m_epollfd;
  int m_sockfd;
  sockaddr_in m_address;
  char m_buf[BUFFER_SIZE];
  int m_read_idx; // 读的光标位置
};

int cgi_conn::m_epollfd = -1;

int main(int argc, char* argv[]) {
  if (argc <= 2) {
    printf("usage: %s ip_address port_number\n", basename(argv[0]));
    return 1;
  }
  const char* ip = argv[1];
  int port = atoi(argv[2]);

  int listenfd = socket(PF_INET, SOCK_STREAM, 0);
  assert(listenfd >= 0);

  int ret = 0;
  struct sockaddr_in address;
  bzero(&address, sizeof(address));
  address.sin_family = AF_INET;
  inet_pton(AF_INET, ip, &address.sin_addr);
  address.sin_port = htons(port);

  ret = bind(listenfd, (struct sockaddr*)&address, sizeof(address));
  assert(ret != -1);

  ret = listen(listenfd, 5);
  assert(ret != -1);

  processpool<cgi_conn>* pool = processpool<cgi_conn>::create(listenfd); // 创建唯一进程池实例
  if (pool) {
    pool->run();
    delete pool;
  }
  close(listenfd); // 正如前文提到的，main函数创建了文件描述符listenfd，那么就由它亲自关闭之

  return 0;
}

#ifndef PROCESSPOOL_H
#define PROCESSPOOL_H

#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <assert.h>
#include <stdio.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <fcntl.h>
#include <stdlib.h>
#include <sys/epoll.h>
#include <signal.h>
#include <sys/wait.h>
#include <sys/stat.h>

class process {
public:
    process() : m_pid(-1) {}

public:
    pid_t m_pid;
    int m_pipefd[2]; // 父进程和子进程通信用管道
};

template <typename T> // 模板参数是处理逻辑任务的类
class processpool {
private:
    // 定义为私有，只能通过create静态函数来创建processpool实例
    processpool(int listenfd, int process_number = 8);

public:
    // 单例模式，是程序正确处理信号的必要条件
    static processpool<T> *create(int listenfd, int process_number = 8) {
        if (!m_instance) {
            m_instance = new processpool<T>(listenfd, process_number);
        }
        return m_instance;
    }
    ~processpool() {
        delete[] m_sub_process;
    }
    void run();

private:
    void setup_sig_pipe();
    void run_parent();
    void run_child();

private:
    static const int MAX_PROCESS_NUMBER = 16; // 最大子进程数量
    static const int USER_PER_PROCESS = 65536; // 每个子进程处理最大客户数量
    static const int MAX_EVENT_NUMBER = 10000; // epoll最多能处理的事件数
    int m_process_number; // 进程总数
    int m_idx; // 子进程在池中序号
    int m_epollfd; // 每个进程有个epoll内核事件表
    int m_listenfd; // 监听socket
    int m_stop; // 子进程通过m_stop判断是否停止运行
    process *m_sub_process; // 保存所有子进程描述信息
    static processpool<T> *m_instance; // 进程池静态实例
};
template <typename T>
processpool<T> *processpool<T>::m_instance = NULL;

static int sig_pipefd[2]; // 信号管道 统一事件源

static int setnonblocking(int fd) {
    int old_option = fcntl(fd, F_GETFL);
    int new_option = old_option | O_NONBLOCK;
    fcntl(fd, F_SETFL, new_option);
    return old_option;
}

static void addfd(int epollfd, int fd) {
    epoll_event event;
    event.data.fd = fd;
    event.events = EPOLLIN | EPOLLET;
    epoll_ctl(epollfd, EPOLL_CTL_ADD, fd, &event);
    setnonblocking(fd);
}

static void removefd(int epollfd, int fd) { // 从epollfd表示的内核事件表中删除fd的 所有事件
    epoll_ctl(epollfd, EPOLL_CTL_DEL, fd, 0);
    close(fd);
}

static void sig_handler(int sig) {
    int save_errno = errno;
    int msg = sig;
    send(sig_pipefd[1], (char *)&msg, 1, 0);
    errno = save_errno;
}

static void addsig(int sig, void(handler)(int), bool restart = true) {
    struct sigaction sa;
    memset(&sa, '\0', sizeof(sa));
    sa.sa_handler = handler;
    if (restart)
    {
        sa.sa_flags |= SA_RESTART;
    }
    sigfillset(&sa.sa_mask);
    assert(sigaction(sig, &sa, NULL) != -1);
}

template <typename T>
processpool<T>::processpool(int listenfd, int process_number) // 进程池构造函数，参数listenfd是监听的socket，必须在创建进程池之前被创建
    : m_listenfd(listenfd), m_process_number(process_number), m_idx(-1), m_stop(false) {
    assert((process_number > 0) && (process_number <= MAX_PROCESS_NUMBER));

    m_sub_process = new process[process_number];
    assert(m_sub_process);

    for (int i = 0; i < process_number; ++i) {
        int ret = socketpair(PF_UNIX, SOCK_STREAM, 0, m_sub_process[i].m_pipefd);
        assert(ret == 0);

        m_sub_process[i].m_pid = fork();
        assert(m_sub_process[i].m_pid >= 0);
        if (m_sub_process[i].m_pid > 0) { // 父进程
            close(m_sub_process[i].m_pipefd[1]); // 只向子进程写
            continue;
        }
        else { // 子进程
            close(m_sub_process[i].m_pipefd[0]); // 只从父进程读
            m_idx = i;
            break;
        }
    }
}

template <typename T>
void processpool<T>::setup_sig_pipe() { // 统一事件源
    m_epollfd = epoll_create(5); // 创建epoll事件监听表和信号管道
    assert(m_epollfd != -1);

    int ret = socketpair(PF_UNIX, SOCK_STREAM, 0, sig_pipefd);
    assert(ret != -1);

    setnonblocking(sig_pipefd[1]);
    addfd(m_epollfd, sig_pipefd[0]);

    addsig(SIGCHLD, sig_handler); // 设置信号处理函数
    addsig(SIGTERM, sig_handler);
    addsig(SIGINT, sig_handler);
    addsig(SIGPIPE, SIG_IGN);
}

template <typename T>
void processpool<T>::run() { // 父进程中m_idx值为 -1， 子进程中m_idx值 >= 0，判断接下来运行的是父还是子进程的代码
    if (m_idx != -1)
    {
        run_child();
        return;
    }
    run_parent();
}

template <typename T>
void processpool<T>::run_child() {
    setup_sig_pipe();

    int pipefd = m_sub_process[m_idx].m_pipefd[1]; // 每个子进程都通过其在进程池中的序号值m_idx找到与父进程通信的管道
    addfd(m_epollfd, pipefd); // 子进程需要监听管道文件描述符pipefd 因为父进程将通过它通知子进程accept新连接

    epoll_event events[MAX_EVENT_NUMBER];
    T *users = new T[USER_PER_PROCESS];
    assert(users);
    int number = 0; // epoll事件数量
    int ret = -1;

    while (!m_stop) {
        number = epoll_wait(m_epollfd, events, MAX_EVENT_NUMBER, -1);
        if ((number < 0) && (errno != EINTR)) {
            printf("epoll failure\n");
            break;
        }

        for (int i = 0; i < number; i++) { // 处理每个事件
            int sockfd = events[i].data.fd;
            if ((sockfd == pipefd) && (events[i].events & EPOLLIN)) { // 父进程有数据给子进程
                int client = 0;
                ret = recv(sockfd, (char *)&client, sizeof(client), 0); // 从父子进程之间管道读取数据，结果保存client中读取成功有新客户
                if (((ret < 0) && (errno != EAGAIN)) || ret == 0) {
                    continue;
                } else {
                    struct sockaddr_in client_address;
                    socklen_t client_addrlength = sizeof(client_address);
                    int connfd = accept(m_listenfd, (struct sockaddr *)&client_address, &client_addrlength);
                    if (connfd < 0) {
                        printf("errno is: %d\n", errno);
                        continue;
                    }
                    addfd(m_epollfd, connfd); // 模板类T必须实现init方法，初始化一个客户连接。我们用connfd来索引处理的逻辑对象 提高效率
                    users[connfd].init(m_epollfd, connfd, client_address); // 实现在cgi_server.cpp中
                }
            } else if ((sockfd == sig_pipefd[0]) && (events[i].events & EPOLLIN)) { // 有信号，处理信号
                int sig;
                char signals[1024];
                ret = recv(sig_pipefd[0], signals, sizeof(signals), 0);
                if (ret <= 0) {
                    continue;
                } else {
                    for (int i = 0; i < ret; ++i) {
                        switch (signals[i]) {
                            case SIGCHLD: { // 回收子进程资源
                                pid_t pid;
                                int stat;
                                while ((pid = waitpid(-1, &stat, WNOHANG)) > 0) {
                                    continue;
                                }
                                break;
                            }
                            case SIGTERM:
                            case SIGINT: {
                                m_stop = true;
                                break;
                            }
                            default: {
                                break;
                            }
                        }
                    }
                }
            } else if (events[i].events & EPOLLIN) { // 其他数据可读 必然是客户请求到来 调用逻辑处理对象的process方法处理
                users[sockfd].process(); // 还没实现
            } else {
                continue;
            }
        }
    }

    delete[] users;
    users = NULL;
    close(pipefd);
    //close( m_listenfd ); // 应该由m_listenfd的创建者来关闭，所谓的对象由哪个函数创建，就该由那个函数销毁
    close(m_epollfd);
}

template <typename T>
void processpool<T>::run_parent() {
    setup_sig_pipe();

    addfd(m_epollfd, m_listenfd);

    epoll_event events[MAX_EVENT_NUMBER];
    int sub_process_counter = 0;
    int new_conn = 1;
    int number = 0;
    int ret = -1;

    while (!m_stop) {
        number = epoll_wait(m_epollfd, events, MAX_EVENT_NUMBER, -1);
        if ((number < 0) && (errno != EINTR)) {
            printf("epoll failure\n");
            break;
        }

        for (int i = 0; i < number; i++) {
            int sockfd = events[i].data.fd;
            if (sockfd == m_listenfd) {
                int i = sub_process_counter; // 有新连接到来，就采用round robin方式将其分给一个子进程
                do {
                    if (m_sub_process[i].m_pid != -1) { // 选出空闲进程的进程数组索引
                        break;
                    }
                    i = (i + 1) % m_process_number;
                } while (i != sub_process_counter);

                if (m_sub_process[i].m_pid == -1) {
                    m_stop = true;
                    break;
                }
                sub_process_counter = (i + 1) % m_process_number;
                //send( m_sub_process[sub_process_counter++].m_pipefd[0], ( char* )&new_conn, sizeof( new_conn ), 0 );
                send(m_sub_process[i].m_pipefd[0], (char *)&new_conn, sizeof(new_conn), 0);
                printf("send request to child %d\n", i);
                //sub_process_counter %= m_process_number;
            } else if ((sockfd == sig_pipefd[0]) && (events[i].events & EPOLLIN)) { // 处理父进程收到的信号
                int sig;
                char signals[1024];
                ret = recv(sig_pipefd[0], signals, sizeof(signals), 0);
                if (ret <= 0) {
                    continue;
                } else {
                    for (int i = 0; i < ret; ++i) {
                        switch (signals[i]) {
                            case SIGCHLD: {
                                pid_t pid;
                                int stat;
                                while ((pid = waitpid(-1, &stat, WNOHANG)) > 0) {
                                    for (int i = 0; i < m_process_number; ++i) {
                                        // 如果进程池中第i个子进程退出了，则主进程关闭对应通信管道，并设置m_pid为-1，标记子进程已经退出
                                        if (m_sub_process[i].m_pid == pid) {
                                            printf("child %d join\n", i);
                                            close(m_sub_process[i].m_pipefd[0]);
                                            m_sub_process[i].m_pid = -1;
                                        }
                                    }
                                }
                                m_stop = true;
                                for (int i = 0; i < m_process_number; ++i) {
                                    if (m_sub_process[i].m_pid != -1) {
                                        m_stop = false;
                                    }
                                }
                                break;
                            }
                            case SIGTERM:
                            case SIGINT: {
                                printf("kill all the clild now\n"); // 杀了所有子进程
                                for (int i = 0; i < m_process_number; ++i) {
                                    int pid = m_sub_process[i].m_pid;
                                    if (pid != -1) {
                                        kill(pid, SIGTERM);
                                    }
                                }
                                break;
                            }
                            default: {
                                break;
                            }
                        }
                    }
                }
            } else {
                continue;
            }
        }
    }

    //close( m_listenfd ); // 由创建者关闭  见后文
    close(m_epollfd);
}

#endif