进程池和线程池 - 用线程池实现的简单Web服务器

#ifndef HTTPCONNECTION_H
#define HTTPCONNECTION_H

#include <unistd.h>
#include <signal.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 <assert.h>
#include <sys/stat.h>
#include <string.h>
#include <pthread.h>
#include <stdio.h>
#include <sys/mman.h>
#include <stdarg.h>
#include "locker.h"

class http_conn
{
public:
    /*文件名的最大长度*/
    static const int FILENAME_LEN = 200;
    /*读缓冲区的大小*/
    static const int READ_BUFFER_SIZE = 2048;
    /*写缓冲区的大小*/
    static const int WRITE_BUFFER_SIZE = 1024;
    /*HTTP请求方法，但我们仅支持GET*/
    enum METHOD{
        GET = 0, POST, HEAD, PUT, DELETE, 
        TRACE, OPTIONS, CONNECT, PATCH};
    /*解析客户请求时，主状态机所处的状态*/
    enum CHECK_STATE{CHECK_STATE_REQUESTLINE = 0,
                     CHECK_STATE_HEADER,
                     CHECK_STATE_CONTENT};
    /*服务器处理HTTP请求的可能结果*/
    enum HTTP_CODE{NO_REQUEST, GET_REQUEST, BAD_REQUEST,
            NO_RESOURCE, FORBIDDEN_REQUEST, FILE_REQUEST,
            INTERNAL_ERROR, CLOSED_CONNECTION};
    /*行的读取状态*/
    enum LINE_STATUS{LINE_OK = 0, LINE_BAD, LINE_OPEN};

public:
    http_conn(){};
    ~http_conn(){};
    
public:
    /*初始化新接受的连接*/
    void  init(int sockfd, const sockaddr_in &addr);
    /*关闭连接*/
    void close_conn(bool real_close = true);
    /*处理客户请求*/
    void  process();
    /*非阻塞读操作*/
    bool read();
    /*非阻塞写操作*/
    bool write();

private:
    /*初始化连接*/
    void  init();
    /*解析HTTP请求*/
    HTTP_CODE process_read();
    /*填充HTTP应答*/
    bool process_write(HTTP_CODE ret);

    /*下面这一组函数被process_read调用以分析HTTP请求*/
    HTTP_CODE parse_request_line(char* text);
    HTTP_CODE parse_headers(char* text);
    HTTP_CODE parse_content(char* text);
    HTTP_CODE do_request();

    char* get_line(){return m_read_buf + m_start_line;}
    LINE_STATUS parse_line();

    /*下面这一组函数被process_write调用以填充HTTP应答*/
    void unmap();
    bool add_response(const char* format, ...);
    bool add_content(const char* connect);
    bool add_status_line(int status, const char* title);
    bool add_headers(int content_length);
    bool add_content_length(int content_length);
    bool add_linger();
    bool add_blank_line();
    
public:
    /*所有socket上的事件都被注册到一个epoll内核时间表，
    所以将epoll文件描述符设置为静态的*/
    static int m_epollfd;
    /*统计用户数量*/
    static int m_user_count;

private:
    /*该HTTP连接的socket和对方的socket地址*/
    int m_sockfd;
    sockaddr_in m_address;

    /*读缓冲区*/
    char m_read_buf[READ_BUFFER_SIZE];
    /*标识读缓冲中已经读入的客户数据的最后一个字节的下一个位置*/
    int m_read_idx;
    /*当前正在分析的字符在读缓冲中的位置*/
    int m_checked_idx;
    /*当前正在解析的行的起始位置*/
    int m_start_line;
    
    /*写缓冲区*/
    char m_write_buf[WRITE_BUFFER_SIZE];
    /*写缓冲区中待发送的字节数*/
    int m_write_idx;

    /*主状态机当前所处的状态*/
    CHECK_STATE m_check_state;
    /*请求方法*/
    METHOD m_method;

    /*客户请求的目标文件的完整路径，
    其内容等于doc_root + m_url, doc_root是网站根目录*/
    char m_real_file[FILENAME_LEN];
    /*客户请求的目标文件的文件名*/
    char* m_url;
    /*HTTP 协议版本号，我们仅支持HTTP/1.1*/
    char* m_version;
    /*主机名*/
    char* m_host;
    /*HTTP请求的消息体长度*/
    int m_connect_length;
    /*HTTP请求是否要求保持连接*/
    bool m_linger;

    /*客户请求的目标我文件被mmap到内存中的起始位置*/
    char* m_file_address;
    /*目标文件的状态，通过它我们可以判断文件是否存在、是否为目录、
    是否为可读，并获取文件大小等信息*/
    struct stat m_file_stat;
    /*我们将用writev来执行写操作，所以定义下面两个成员
    其中m_iv_count表示写内存块的数量*/
    struct iovec m_iv[2];
    int m_iv_count;
};

#endif

#include "http_conn.h"
#include <errno.h>
#include <stdlib.h>
#include <sys/uio.h>

const char* ok_200_title = "OK";
const char* error_400_title = "Bad Request";
const char* error_400_form = "Your request has bad syntax or is inherently impossible to satisfy.\n";
const char* error_403_title = "Forbidden";
const char* error_403_form = "You do not have permission to get file from this server.\n";
const char* error_404_title = "Not found";
const char* error_404_form = "THe requested file was not found on this server.\n";
const char* error_500_title = "Internal Error";
const char* error_500_form = "There was an unusual problem serving the requested file.\n";

/*网站的根目录*/
const char* doc_root = "./";

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 epollfd, int fd, bool one_shot)
{
    epoll_event event;
    event.data.fd = fd;
    event.events = EPOLLIN | EPOLLET | EPOLLRDHUP;
    if(one_shot){
        event.events |= EPOLLONESHOT;
    }
    epoll_ctl(epollfd, EPOLL_CTL_ADD, fd, &event);
    setnonblocking(fd);
}

void removefd(int epollfd, int fd)
{
    epoll_ctl(epollfd, EPOLL_CTL_DEL, fd, 0);
    close(fd);
}

void modfd(int epollfd, int fd, int ev)
{
    epoll_event event;
    event.data.fd = fd;
    event.events = ev | EPOLLET | EPOLLONESHOT | EPOLLRDHUP;
    epoll_ctl(epollfd, EPOLL_CTL_MOD, fd, &event);
}

int http_conn::m_user_count = 0;
int http_conn::m_epollfd = -1;

void http_conn::close_conn(bool real_close)
{
    if(real_close && (m_sockfd != -1)){
        removefd(m_epollfd, m_sockfd);
        m_sockfd = -1;
        m_user_count--;
    }
}

void http_conn::init(int sockfd, const sockaddr_in& addr)
{
    m_sockfd = sockfd;
    m_address = addr;
    /*如下两行是为了避免TIME_WAIT状态，仅用于调试，
    实际使用应该去掉*/
    int reuse = 1;
    setsockopt(m_sockfd, SOL_SOCKET, SO_REUSEADDR, &reuse, sizeof(reuse));

    addfd(m_epollfd, sockfd, true);
    m_user_count++;

    init();
}

void http_conn::init()
{
    m_check_state = CHECK_STATE_REQUESTLINE;
    m_linger = false;

    m_method = GET;
    m_url = 0;
    m_version = 0;
    m_connect_length = 0;
    m_host = 0;
    m_start_line = 0;
    m_checked_idx = 0;
    m_read_idx = 0;
    m_write_idx  = 0;

    memset(m_read_buf, '\0', READ_BUFFER_SIZE);
    memset(m_write_buf, '\0', WRITE_BUFFER_SIZE);
    memset(m_real_file, '\0', FILENAME_LEN);
}

/*从状态机*/
http_conn::LINE_STATUS http_conn::parse_line()
{
    char temp;
    for(;m_checked_idx < m_read_idx; ++m_checked_idx){
        temp = m_read_buf[m_checked_idx];
        if(temp == '\r'){
            if(m_checked_idx + 1 == m_read_idx){
                return LINE_OPEN;
            }
            else if(m_read_buf[m_checked_idx+1] == '\n'){
                m_read_buf[m_checked_idx++] = '\0';
                m_read_buf[m_checked_idx++] = '\0';
                return LINE_OK;
            }
        }
        else if(temp == '\n'){
            if(m_checked_idx > 1 && m_read_buf[m_checked_idx-1] == '\r'){
                m_read_buf[m_checked_idx-1] = '\0';
                m_read_buf[m_checked_idx++] = '\0';
                return LINE_OK;
            }
            return LINE_BAD;
        }
    }
    return LINE_OPEN;
}

/*循环读取客户数据，指导无数据可读或对方关闭连接*/
bool http_conn::read()
{
    if(m_read_idx >= READ_BUFFER_SIZE){
        return false;
    }

    int bytes_read = 0;
    while(true){
        bytes_read = recv(m_sockfd, m_read_buf + m_read_idx, 
                READ_BUFFER_SIZE - m_read_idx, 0);
        if(bytes_read == -1){
            if( errno == EAGAIN || errno == EWOULDBLOCK){
                break;
            }
            return false;
        }
        else if(bytes_read == 0){
            return false;
        }
        m_read_idx += bytes_read;
    }
    return true;
}

/*解析HTTP请求行，获得请求方法，目标URL，以及HTTP版本号*/
http_conn::HTTP_CODE http_conn::parse_request_line(char* text)
{
    m_url = strpbrk(text, " \t");
    if(!m_url){
        return BAD_REQUEST;
    }
    *m_url++ ='\0';

    char* method = text;
    if(strcasecmp(method, "GET") == 0){
        m_method = GET;
    }
    else{
        return BAD_REQUEST;
    }

    m_url += strspn(m_url, " \t");
    m_version = strpbrk(m_url, " \t");
    if(!m_version){
        return BAD_REQUEST;
    }
    *m_version++ = '\0';
    m_version += strspn(m_version, " \t");
    if(strcasecmp(m_version, "HTTP/1.1") != 0){
        return BAD_REQUEST;
    }

    if(strncasecmp(m_url, "http://", 7) == 0){
        m_url += 7;
        m_url = strchr(m_url, '/');
    }

    if(!m_url || m_url[0] != '/'){
        return BAD_REQUEST;
    }
    m_check_state = CHECK_STATE_HEADER;
    return NO_REQUEST;
}

/*解析HTTP请求的一个头部信息*/
http_conn::HTTP_CODE http_conn::parse_headers(char* text)
{
    /*遇到空行，表示头部字段解析完毕*/
    if(text[0] == '\0'){
        /*如果HTTP请求有消息体，则还需要读取m_content_leng字节的消息提，
        状态机转移到CHECK_STATE_CONTENT*/
        if(m_connect_length != 0){
            m_check_state = CHECK_STATE_CONTENT;
            return NO_REQUEST;
        }
        /*否则说明我们已经得到了一个完整的HTTP请求*/
        return GET_REQUEST;
    }
    /*处理Connection 头部信息*/
    else if(strncasecmp(text, "Connection:", 11) == 0){
        text += 11;
        text += strspn(text, " \t");
        if(strcasecmp(text, "keep-alive") == 0){
            m_linger = true;
        }
    }
    /*处理Connect-Length头部信息*/
    else if(strncasecmp(text, "Content-Length:",15) == 0){
        text += 15;
        text += strspn(text, " \t");
        m_connect_length = atol(text);
    }
    /*处理Host头部字段*/
    else if(strncasecmp(text, "Host:", 5) == 0){
        text += 5;
        text += strspn(text, " \t");
        m_host = text;
    }
    else{
        printf("oop! unknown header %s\n", text);
    }
    return NO_REQUEST;
}

/*我们没有真正解析HTTP请求的消息体，只是判断它是否被完整的读入了*/
http_conn::HTTP_CODE http_conn::parse_content(char* text)
{
    if(m_read_idx >= (m_connect_length + m_checked_idx)){
        text[m_connect_length] = '\0';
        return GET_REQUEST;
    }
    return NO_REQUEST;
}

/*主状态机*/
http_conn::HTTP_CODE http_conn::process_read()
{
    LINE_STATUS line_status = LINE_OK;
    HTTP_CODE ret = NO_REQUEST;
    char *text = 0;
    while((m_check_state == CHECK_STATE_CONTENT && line_status == LINE_OK)
        || (line_status = parse_line()) == LINE_OK){
        
        text = get_line();
        m_start_line = m_checked_idx;
        printf("got 1 http line: %s\n", text);

        switch (m_check_state)
        {
            case CHECK_STATE_REQUESTLINE:{
                ret = parse_request_line(text);
                if(ret ==  BAD_REQUEST){
                    return BAD_REQUEST;
                }
                break;
            }
            case CHECK_STATE_HEADER:{
                ret = parse_headers(text);
                if(ret == BAD_REQUEST){
                    return BAD_REQUEST;
                }
                else if (ret == GET_REQUEST)
                {
                    return do_request();
                }
                break;
            }
            case CHECK_STATE_CONTENT:{
                ret = parse_content(text);
                if(ret == GET_REQUEST){
                    return do_request();
                }
                line_status = LINE_OPEN;
                break;
            }
            default:{
                return INTERNAL_ERROR;
            }
        }
    }
    return NO_REQUEST;
}

/*当得到一个完整、正确的HTTP请求时，我们就分析目标文件的属性
如果目标存在、对所有用户可读，且不是目录，
则使用mmap将其映射到内存地址m_file_address处，
并告诉调用者获取文件成功*/
http_conn::HTTP_CODE http_conn::do_request()
{
    strcpy(m_real_file, doc_root);
    int len = strlen(doc_root);
    strncpy(m_real_file + len, m_url, FILENAME_LEN - len - 1);
    if(stat(m_real_file, &m_file_stat) < 0){
        return NO_RESOURCE;
    }
    if(!(m_file_stat.st_mode & S_IROTH)){
        return FORBIDDEN_REQUEST;
    }
    if (S_ISDIR(m_file_stat.st_mode)){
        return BAD_REQUEST;
    }

    int fd = open(m_real_file, O_RDONLY);
    m_file_address = (char*)mmap(0, m_file_stat.st_size, PROT_READ, 
        MAP_PRIVATE, fd, 0);
    close(fd);
    return FILE_REQUEST;
}

/*对内存映射区执行munmap操作*/
void http_conn::unmap()
{
    if(m_file_address){
        munmap(m_file_address, m_file_stat.st_size);
        m_file_address = 0;
    }
}

/*写HTTP响应*/
bool http_conn::write()
{
    int temp = 0;
    int bytes_have_send = 0;
    int bytes_to_send = m_write_idx;
    if(bytes_to_send == 0){
        modfd(m_epollfd, m_sockfd, EPOLLIN);
        init();
        return true;
    }
    while(1){
        temp = writev(m_sockfd, m_iv, m_iv_count);
        if(temp <= -1){
            /*如果TCP写缓冲没有空间，则等待下一轮EPOLLOUT事件。
            虽然在此期间，服务器无法立即接收到同一客户的下一个请求，
            但这可以保证连接的完整性*/
            if(errno == EAGAIN){
                modfd(m_epollfd, m_sockfd, EPOLLOUT);
                return true;
            }
            unmap();
            return false;
        }

        bytes_to_send -= temp;
        bytes_have_send += temp;
        if(bytes_to_send <= bytes_have_send){
            /*发送HTTP响应成功，根据HTTP请求中的Connection字段决定是否立即关闭连接*/
            unmap();
            if(m_linger){
                init();
                modfd(m_epollfd, m_sockfd, EPOLLIN);
                return true;
            }
            else{
                modfd(m_epollfd, m_sockfd, EPOLLIN);
                return false;
            }
        }
    }
}

/*往写缓冲中写入待发送的数据*/
bool http_conn::add_response(const char* format, ...)
{
    if(m_write_idx >= WRITE_BUFFER_SIZE){
        return false;
    }
    va_list arg_list;
    va_start(arg_list, format);
    int len = vsnprintf(m_write_buf + m_write_idx, 
        WRITE_BUFFER_SIZE - 1 - m_write_idx, format, arg_list);
    if(len >= (WRITE_BUFFER_SIZE - 1 - m_write_idx)){
        return false;
    }
    m_write_idx += len;
    va_end(arg_list);
    return true;
}

bool http_conn::add_status_line(int status, const char* title)
{
    return add_response("%s %d %s\r\n", "HTTP/1.1", status, title);
}

bool http_conn::add_headers(int content_len)
{
    add_content_length(content_len);
    add_linger();
    add_blank_line();
}

bool http_conn::add_content_length(int content_len)
{
    return add_response("Content-Length: %d\r\n", content_len);
}

bool http_conn::add_linger()
{
    return add_response( "Connection: %s\r\n", (m_linger == true)?"keep-alive":"close");
}

bool http_conn::add_blank_line()
{
    return add_response("%s", "\r\n");
}

bool http_conn::add_content(const char* content)
{
    return add_response("%s", content);
}

/*根据服务器处理HTTP请求的结果，决定返回给客户端的内容*/
bool http_conn::process_write(HTTP_CODE ret)
{
    switch (ret)
    {
        case INTERNAL_ERROR:{
            add_status_line(500, error_500_title);
            add_headers(strlen(error_500_form));
            if(!add_content(error_500_form)){
                return false;
            }
            break;
        }
        case BAD_REQUEST:{
            add_status_line(400, error_400_title);
            add_headers(strlen(error_400_form));
            if(!add_content(error_400_form)){
                return false;
            }
            break;
        }
        case NO_REQUEST:{
            add_status_line(404, error_404_title);
            add_headers(strlen(error_404_form));
            if(!add_content(error_404_form)){
                return false;
            }
            break;
        }
        case NO_RESOURCE:{
            add_status_line(404, error_404_title);
            add_headers(strlen(error_404_form));
            if(!add_content(error_404_form)){
                return false;
            }
            break;
        }    
        case FORBIDDEN_REQUEST:{
            add_status_line(403, error_403_title);
            add_headers(strlen(error_403_form));
            if(!add_content(error_403_form)){
                return false;
            }
            break;
        }    
        case FILE_REQUEST:{
            add_status_line(200, ok_200_title);
            if(m_file_stat.st_size != 0){
                add_headers(m_file_stat.st_size);
                m_iv[0].iov_base = m_write_buf;
                m_iv[0].iov_len = m_write_idx;
                m_iv[1].iov_base = m_file_address;
                m_iv[1].iov_len = m_file_stat.st_size;
                m_iv_count = 2;
                return true;
            }
            else{
                const char* ok_string = "<html><body></body></html>";
                add_headers(strlen(ok_string));
                if(!add_content(ok_string)){
                    return false;
                }
            }
        }
        default:{
            return false;
        }
    }

    m_iv[0].iov_base = m_write_buf;
    m_iv[0].iov_len = m_write_idx;
    m_iv_count = 1;
    return true;
}

/*由线程池的工作线程调用， 这是处理HTTP请求的入口函数*/
void http_conn::process()
{
    HTTP_CODE read_ret = process_read();
    if(read_ret == NO_REQUEST){
        modfd(m_epollfd, m_sockfd, EPOLLIN);
        return;
    }

    bool write_ret = process_write(read_ret);
    if(!write_ret){
        close_conn();
    }
    modfd(m_epollfd, m_sockfd, EPOLLOUT);
}

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

#include "locker.h"
#include "threadpool.h"
#include "http_conn.h"

#define MAX_FD 65535
#define MAX_EVENT_NUMBER 10000

extern int addfd(int epollfd, int fd, bool one_shot);
extern int removefd(int epollfd, int fd);

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);
}

void show_error(int connfd, const char* info)
{
    printf("%s", info);
    send(connfd, info, strlen(info), 0);
    close(connfd);
}

int main(int argc, char const *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]);

    /*忽略SIGPIPE*/
    addsig(SIGPIPE, SIG_IGN);

    /*创建线程池*/
    threadpool<http_conn>* pool = NULL;
    try{
        pool = new threadpool<http_conn>();
    }
    catch(...){
        return 1;
    }

    /*预先为每个可能的客户连接分配一个http_conn对象*/
    http_conn* users = new http_conn[MAX_FD];
    assert(users);
    int user_count = 0;

    int listenfd = socket(PF_INET, SOCK_STREAM, 0);
    assert(listenfd >= 0);
    struct linger tmp = {1, 0};
    setsockopt(listenfd, SOL_SOCKET, SO_LINGER, &tmp, sizeof(tmp));

    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 >= 0);

    ret = listen(listenfd, 5);
    assert(ret >= 0);

    epoll_event events[MAX_EVENT_NUMBER];
    int epollfd = epoll_create(5);
    assert(epollfd != -1);
    addfd(epollfd, listenfd, false);
    http_conn::m_epollfd = epollfd;

    while(true){
        int number = epoll_wait(epollfd, events, MAX_EVENT_NUMBER, -1);
        if (number < 0 && errno != EINTR){
            printf("epoll failure");
            break;
        }

        for(int i = 0; i < number; ++i){
            int sockfd = events[i].data.fd;
            if(sockfd == listenfd){
                struct sockaddr_in client_address;
                socklen_t client_addrlength = sizeof(client_address);
                int connfd = accept(listenfd, (struct sockaddr*)&client_address,
                    &client_addrlength);
                if(connfd <= 0){
                    printf("errno is: %d\n", errno);
                    continue;
                }
                if(http_conn::m_user_count >= MAX_FD){
                    show_error(connfd, "Internal server busy");
                    continue;
                }
                /*初始化客户连接*/
                users[connfd].init(connfd, client_address);
            }
            else if(events[i].events & (EPOLLRDHUP | EPOLLHUP | EPOLLERR)){
                /*如果有异常，直接关闭客户端*/
                users[sockfd].close_conn();
            }
            else if(events[i].events & EPOLLIN){
                /*根据读的结果，决定是将任务添加到线程池，还是关闭链接*/
                if(users[sockfd].read()){
                    pool->append(users + sockfd);
                }
                else{
                    users[sockfd].close_conn();
                }
            }
            else if(events[i].events & EPOLLOUT){
                /*根据写的结果，决定是否关闭连接*/
                if(!users[sockfd].write()){
                    users[sockfd].close_conn();
                }
            }
            else{}
        }
    }

    close(epollfd);
    close(listenfd);
    delete[] users;
    delete pool;
    return 0;
}