写在前面：该文章只针对学习开发后端HUSTOJ的Judged、Judge_client部分（目前不研究sim部分)代码的同学。 默认你已了解HUSTOJ是个什么东西和他的所分的各个部分的功能。并且你已经在你的电脑上搭建好了本地的HUSTOJ
首先我想说题主目前是普通本科大二在读生，如果某些方面写的不详细或不太正确的地方还请见谅，欢迎在下面留言交流。
好，接下来进入正文。
先谈下学习源码之前的准备工作
1.如果你想了解HUSTOJ后端源码具体都是写什么意思，你要熟练掌握c语言，（自己用c语言写过几千几万行代码应该差不多了）,毕竟源码都是c语言写的，你如果很基础的c语言语法都不了解，那就没得看了。然后你如果是初次接触项目，你会发现里面很多调用的系统已有函数是你从未接触过的，你可以边百度边看（不需要深究，只用大致知道这里这个函数用来干啥就可以）。
2.因为这个项目是在Linux系统上进行的，你需要了解如何在Linux上编写c语言。而且你要大致了解一下Linux相关知识，比如vim编辑器，比如makefile，比如Linux终端的一些常用命令，因为要用到的东西很多，所以不需要学很深，只需要都了解一些常规操作就可以。
3.你要了解一些进程相关的知识，因为Judged就是一个守护进程，所以你要明白这个守护进程是用来干啥的。
4.掌握了以上三个，你可能就拥有了读这些代码的能力，但是你要理解每部分是什么意思，你还需要会在Linux终端下调试你想调试的部分代码，也就是你要会DEBUG。
5.最后如果你不仅想要明白后端这些代码的原理，还想要明白前端和后端是如何实现交互的，你可能就需要掌握数据库的相关知识和工作原理，web的一些相关知识等等。当然目前题主也只是做到前四点，开始看这些源码。
接下来我们来说源码部分。
后端源码分为core里面分为judged、judge_client、sim三部分，分别实现了判题的守护进程，判题的核心代码，判断相似性三个功能。
下面我就给出judged部分的有关分析，方便更多人节省时间学习。
上面这张图就是Judged工作的框架，看代码的时候可以跟着这个整体的框架看，可以看出，它的主要功能就是为了不停的轮询数据库，当用户在网页上提交代码后web端会存入数据库时就会发现题目，然后进行一些相应判断后会调用Judge_client开始判题。
好的，了解了它的工作原理，我们开始看代码，下面的代码我明白了的部分注释很详细了，我就不多做解释了。
（推荐一篇巨佬的博客，开源评测系统hustoj-代码解读1这篇博客里出现过的注释下面我就不注释了，可以两篇结合起来看，相信可以帮你省掉很多时间）。
/*
* Copyright 2008 sempr <[email protected]>
*
* Refacted and modified by zhblue<[email protected]>
* Bug report email [email protected]
*
* This file is part of HUSTOJ.
*
* HUSTOJ is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* HUSTOJ is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with HUSTOJ. if not, see <http://www.gnu.org/licenses/>.
*/
#include <time.h>
#include <stdio.h>
#include <string.h>
#include <ctype.h>
#include <stdlib.h>
#include <unistd.h>
#include <syslog.h>
#include <errno.h>
#include <fcntl.h>
#include <stdarg.h>
#include <mysql/mysql.h>
#include <sys/wait.h>
#include <sys/stat.h>
#include <signal.h>
#include <sys/resource.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#define BUFFER_SIZE 1024
#define LOCKFILE "/var/run/judged.pid"
#define LOCKMODE (S_IRUSR|S_IWUSR|S_IRGRP|S_IROTH)
#define STD_MB 1048576LL
#define OJ_WT0 0
#define OJ_WT1 1
#define OJ_CI 2
#define OJ_RI 3
#define OJ_AC 4
#define OJ_PE 5
#define OJ_WA 6
#define OJ_TL 7
#define OJ_ML 8
#define OJ_OL 9
#define OJ_RE 10
#define OJ_CE 11
#define OJ_CO 12
static char lock_file[BUFFER_SIZE]=LOCKFILE;
static char host_name[BUFFER_SIZE]; //主机地址
static char user_name[BUFFER_SIZE]; //用户名
static char password[BUFFER_SIZE]; //密码
static char db_name[BUFFER_SIZE]; //数据库名称
static char oj_home[BUFFER_SIZE]; //判题目录 默认/home/judge
static char oj_lang_set[BUFFER_SIZE];
static int port_number;//端口
static int max_running;//最大进程数
static int sleep_time;//轮询时间间隔
static int sleep_tmp;
static int oj_tot;
static int oj_mod;
static int http_judge = 0;
static char http_baseurl[BUFFER_SIZE];
static char http_username[BUFFER_SIZE];
static char http_password[BUFFER_SIZE];
static int oj_udp = 0;
static char oj_udpserver[BUFFER_SIZE];
static int oj_udpport=1536;
static int oj_udp_fd;
static int oj_redis = 0;
static char oj_redisserver[BUFFER_SIZE];
static int oj_redisport;
static char oj_redisauth[BUFFER_SIZE];
static char oj_redisqname[BUFFER_SIZE];
static int turbo_mode = 0;
static bool STOP = false;
static int DEBUG = 0; //是否启用调试 默认否
static int ONCE = 0;
#ifdef _mysql_h
static MYSQL *conn;
static MYSQL_RES *res; //mysql读取结果集，在_get_http/mysql_jobs()中被更新
static MYSQL_ROW row;
//static FILE *fp_log;
static char query[BUFFER_SIZE];
#endif
void wait_udp_msg(int fd)
{
char buf[BUFFER_SIZE]; //......1024..
socklen_t len;
int count;
struct sockaddr_in clent_addr; //clent_addr............
memset(buf, 0, BUFFER_SIZE);
len = sizeof(clent_addr);
count = recvfrom(fd, buf, BUFFER_SIZE, 0, (struct sockaddr*)&clent_addr, &len); //recvfrom...............
if(count == -1)
{
printf("recieve data fail!\n");
return;
}
printf("udp client:%s\n",buf); //..client......
memset(buf, 0, BUFFER_SIZE);
// sprintf(buf, "I have recieved %d bytes data!\n", count); //..client
// printf("server:%s\n",buf); //..........
// sendto(fd, buf, BUFF_LEN, 0, (struct sockaddr*)&clent_addr, len); //.....client......clent_addr.....
}
void call_for_exit(int s) {
if(DEBUG){
STOP = true;
printf("Stopping judged...\n");
}else{
printf("HUSTOJ Refusing to stop...\n Please use kill -9 !\n");
}
} //STOP为true时，输出停止判断。 其实就判断你现在是否已经打开了调试模式
void write_log(const char *fmt, ...) {
va_list ap;
char buffer[4096];
// time_t t = time(NULL);
// int l;
sprintf(buffer, "%s/log/client.log", oj_home);
FILE *fp = fopen(buffer, "ae+");
if (fp == NULL) {
fprintf(stderr, "openfile error!\n");
system("pwd");
}
va_start(ap, fmt);
vsprintf(buffer, fmt, ap);
fprintf(fp, "%s\n", buffer);
if (DEBUG)
printf("%s\n", buffer);
va_end(ap);
fclose(fp);
} //将可变参数列表转化成格式化字符串写入buffer[4096]中。
//如果DEBUG=1，（即启用调试开查看日志运行目录） 则输出文件内容
int after_equal(char * c) {
int i = 0;
for (; c[i] != '\0' && c[i] != '='; i++)
;
return ++i;
} //返回参数长度
void trim(char * c) {
char buf[BUFFER_SIZE];
char * start, *end;
strcpy(buf, c);
start = buf;
while (isspace(*start))
start++;
end = start;
while (!isspace(*end))
end++;
*end = '\0';
strcpy(c, start);
} //截取参数数组中第一个非空字符到该字符后的第一个空字符
bool read_buf(char * buf, const char * key, char * value) {
if (strncmp(buf, key, strlen(key)) == 0) {
strcpy(value, buf + after_equal(buf));
trim(value);
if (DEBUG)
printf("%s\n", value);
return 1;
}
return 0;
}
void read_int(char * buf, const char * key, int * value) {
char buf2[BUFFER_SIZE];
if (read_buf(buf, key, buf2))
sscanf(buf2, "%d", value);
}
// read the configue file
void init_mysql_conf() {
FILE *fp = NULL;
char buf[BUFFER_SIZE];
host_name[0] = 0;
user_name[0] = 0;
password[0] = 0;
db_name[0] = 0;
port_number = 3306;
max_running = 3;
sleep_time = 1;
oj_tot = 1;
oj_mod = 0;
strcpy(oj_lang_set, "0,1,2,3");
strcpy(oj_udpserver, "127.0.0.1");
fp = fopen("./etc/judge.conf", "r");
if (fp != NULL) {
while (fgets(buf, BUFFER_SIZE - 1, fp)) {
read_buf(buf, "OJ_HOST_NAME", host_name);
read_buf(buf, "OJ_USER_NAME", user_name);
read_buf(buf, "OJ_PASSWORD", password);
read_buf(buf, "OJ_DB_NAME", db_name);
read_int(buf, "OJ_PORT_NUMBER", &port_number);
read_int(buf, "OJ_RUNNING", &max_running);
read_int(buf, "OJ_SLEEP_TIME", &sleep_time);
read_int(buf, "OJ_TOTAL", &oj_tot);
read_int(buf, "OJ_MOD", &oj_mod);
read_int(buf, "OJ_HTTP_JUDGE", &http_judge);
read_buf(buf, "OJ_HTTP_BASEURL", http_baseurl);
read_buf(buf, "OJ_HTTP_USERNAME", http_username);
read_buf(buf, "OJ_HTTP_PASSWORD", http_password);
read_buf(buf, "OJ_LANG_SET", oj_lang_set);
read_int(buf, "OJ_UDP_ENABLE", &oj_udp);
read_buf(buf, "OJ_UDP_SERVER", oj_udpserver);
read_int(buf, "OJ_UDP_PORT", &oj_udpport);
read_int(buf, "OJ_REDISENABLE", &oj_redis);
read_buf(buf, "OJ_REDISSERVER", oj_redisserver);
read_int(buf, "OJ_REDISPORT", &oj_redisport);
read_buf(buf, "OJ_REDISAUTH", oj_redisauth);
read_buf(buf, "OJ_REDISQNAME", oj_redisqname);
read_int(buf, "OJ_TURBO_MODE", &turbo_mode);
}
#ifdef _mysql_h
sprintf(query,
"SELECT solution_id FROM solution WHERE language in (%s) and result<2 and MOD(solution_id,%d)=%d ORDER BY result ASC,solution_id ASC limit %d",
oj_lang_set, oj_tot, oj_mod, 2 *max_running );
#endif
sleep_tmp = sleep_time;
// fclose(fp);
}
}
//上面五个函数看起来有点难懂，百度了一下，应该是为了读取配置文件./etc/judge.conf，
//然后为了避免一些项与项之间的影响，所以要判断几个条件
//然后我进入这个配置文件看来一下，是一系列变量的赋值，应该就是配置需要用到的一些东西
//这个函数用来评测。当有待评测提交，并且进程数允许的情况下，创建新的子进程调用该评测函数。大致看了一下代码，应该是
//用来判断它所能得到的一些资源是否超出限制（cpu，文件大小，虚拟内存，最大子进程数等）。
void run_client(int runid, int clientid) {
char buf[BUFFER_SIZE], runidstr[BUFFER_SIZE];
struct rlimit LIM;
LIM.rlim_max = 800;
LIM.rlim_cur = 800;
setrlimit(RLIMIT_CPU, &LIM);
LIM.rlim_max = 800 * STD_MB;
LIM.rlim_cur = 800 * STD_MB;
setrlimit(RLIMIT_FSIZE, &LIM);
#ifdef __mips__
LIM.rlim_max = STD_MB << 12;
LIM.rlim_cur = STD_MB << 12;
#endif
#ifdef __arm__
LIM.rlim_max = STD_MB << 11;
LIM.rlim_cur = STD_MB << 11;
#endif
#ifdef __aarch64__
LIM.rlim_max = STD_MB << 15;
LIM.rlim_cur = STD_MB << 15;
#endif
#ifdef __i386
LIM.rlim_max = STD_MB << 11;
LIM.rlim_cur = STD_MB << 11;
#endif
#ifdef __x86_64__
LIM.rlim_max = STD_MB << 15;
LIM.rlim_cur = STD_MB << 15;
#endif
setrlimit(RLIMIT_AS, &LIM);
LIM.rlim_cur = LIM.rlim_max = 800* max_running;
setrlimit(RLIMIT_NPROC, &LIM);
//buf[0]=clientid+'0'; buf[1]=0;
sprintf(runidstr, "%d", runid);
sprintf(buf, "%d", clientid);
//write_log("sid=%s\tclient=%s\toj_home=%s\n",runidstr,buf,oj_home);
//sprintf(err,"%s/run%d/error.out",oj_home,clientid);
//freopen(err,"a+",stderr);
//if (!DEBUG)
execl("/usr/bin/judge_client", "/usr/bin/judge_client", runidstr, buf,
oj_home, (char *) NULL);
//else
// execl("/usr/bin/judge_client", "/usr/bin/judge_client", runidstr, buf,
// oj_home, "debug", (char *) NULL);
//exit(0);
}
#ifdef _mysql_h
int executesql(const char * sql) {
if (mysql_real_query(conn, sql, strlen(sql))) {
if (DEBUG)
write_log("%s", mysql_error(conn));
sleep(20);
conn = NULL;
return 1;
} else
return 0;
}
#endif
#ifdef _mysql_h
int init_mysql() {
if (conn == NULL) {
conn = mysql_init(NULL); // init the database connection
/* connect the database */
const char timeout = 30;
mysql_options(conn, MYSQL_OPT_CONNECT_TIMEOUT, &timeout);
if (!mysql_real_connect(conn, host_name, user_name, password, db_name,
port_number, 0, 0)) {
if (DEBUG)
write_log("%s", mysql_error(conn));
sleep(2);
return 1;
} else {
return executesql("set names utf8");
}
} else {
return executesql("commit");
}
}
#endif
FILE * read_cmd_output(const char * fmt, ...) {
char cmd[BUFFER_SIZE];
FILE * ret = NULL;
va_list ap;
va_start(ap, fmt);
vsprintf(cmd, fmt, ap);
va_end(ap);
//if(DEBUG) printf("%s\n",cmd);
ret = popen(cmd, "r");
return ret;
}
int read_int_http(FILE * f) {
char buf[BUFFER_SIZE];
fgets(buf, BUFFER_SIZE - 1, f);
return atoi(buf);
}
bool check_login() {
const char * cmd =
"wget --post-data=\"checklogin=1\" --load-cookies=cookie --save-cookies=cookie --keep-session-cookies -q -O - \"%s/admin/problem_judge.php\"";
int ret = 0;
FILE * fjobs = read_cmd_output(cmd, http_baseurl);
ret = read_int_http(fjobs);
pclose(fjobs);
return ret > 0;
}
void login() {
if (!check_login()) {
char cmd[BUFFER_SIZE];
sprintf(cmd,
"wget --post-data=\"user_id=%s&password=%s\" --load-cookies=cookie --save-cookies=cookie --keep-session-cookies -q -O - \"%s/login.php\"",
http_username, http_password, http_baseurl);
system(cmd);
}
}
//我看代码是在向jobs数组里赋值，应该是查询待评测题目信息到jobs数组里，
//保存solution_id/runid 函数返回值是要评测题目的数量，查询不成功则返回0
int _get_jobs_http(int * jobs) {
login();
int ret = 0;
int i = 0;
char buf[BUFFER_SIZE];
const char * cmd =
"wget --post-data=\"getpending=1&oj_lang_set=%s&max_running=%d\" --load-cookies=cookie --save-cookies=cookie --keep-session-cookies -q -O - \"%s/admin/problem_judge.php\"";
FILE * fjobs = read_cmd_output(cmd, oj_lang_set, max_running, http_baseurl);
while (fscanf(fjobs, "%s", buf) != EOF) {
//puts(buf);
int sid = atoi(buf);
if (sid > 0)
jobs[i++] = sid;
//i++;
}
pclose(fjobs);
ret = i;
while (i <= max_running * 2)
jobs[i++] = 0;
return ret;
}
#ifdef _mysql_h
int _get_jobs_mysql(int * jobs) {
if (mysql_real_query(conn, query, strlen(query))) {
if (DEBUG)
write_log("%s", mysql_error(conn));
sleep(20);
return 0;
}
res = mysql_store_result(conn);
int i = 0;
int ret = 0;
while (res!=NULL && (row = mysql_fetch_row(res)) != NULL) {
jobs[i++] = atoi(row[0]);
}
if(res!=NULL&&!executesql("commit")){
mysql_free_result(res); // free the memory
res=NULL;
}
else i=0;
ret = i;
while (i <= max_running * 2)
jobs[i++] = 0;
return ret;
}
#endif
int _get_jobs_redis(int * jobs){
int ret=0;
const char * cmd="redis-cli -h %s -p %d -a %s --raw rpop %s";
while(ret<=max_running){
FILE * fjobs = read_cmd_output(cmd,oj_redisserver,oj_redisport,oj_redisauth,oj_redisqname);
if(fscanf(fjobs,"%d",&jobs[ret])==1){
ret++;
pclose(fjobs);
}else{
pclose(fjobs);
break;
}
}
int i=ret;
while (i <= max_running * 2)
jobs[i++] = 0;
if(DEBUG) printf("redis return %d jobs",ret);
return ret;
}
//这个函数是用来判断两种连接方式 http还是mysql
int get_jobs(int * jobs) {
if (http_judge) {
return _get_jobs_http(jobs);
} else {
if(oj_redis){
return _get_jobs_redis(jobs);
}else{
#ifdef _mysql_h
return _get_jobs_mysql(jobs);
#else
return 0;
#endif
}
}
}
//下面三个函数是对数据库的一些更新、设置的操作
#ifdef _mysql_h
bool _check_out_mysql(int solution_id, int result) {
char sql[BUFFER_SIZE];
sprintf(sql,
"UPDATE solution SET result=%d,time=0,memory=0,judgetime=NOW() WHERE solution_id=%d and result<2 LIMIT 1",
result, solution_id);
if (mysql_real_query(conn, sql, strlen(sql))) {
syslog(LOG_ERR | LOG_DAEMON, "%s", mysql_error(conn));
return false;
} else {
if (conn!=NULL&&mysql_affected_rows(conn) > 0ul)
return true;
else
return false;
}
}
#endif
bool _check_out_http(int solution_id, int result) {
login();
const char * cmd =
"wget --post-data=\"checkout=1&sid=%d&result=%d\" --load-cookies=cookie --save-cookies=cookie --keep-session-cookies -q -O - \"%s/admin/problem_judge.php\"";
int ret = 0;
FILE * fjobs = read_cmd_output(cmd, solution_id, result, http_baseurl);
fscanf(fjobs, "%d", &ret);
pclose(fjobs);
return ret;
}
bool check_out(int solution_id, int result) {
if(oj_redis||oj_tot>1) return true;
if (http_judge) {
return _check_out_http(solution_id, result);
} else{
#ifdef _mysql_h
return _check_out_mysql(solution_id, result);
#else
return 0;
#endif
}
}
static int workcnt = 0;
//觉这个函数应该是这个守护进程的核心部分，看了一下守护进程的运行框架。结合这个部分的代码
//我感觉应该是不断的去进行遍历所有评测题目投入到新的评测进程里，然后中间有一个处理就是要保证
//当前进程不能超过最大进程数，如果超过就wait，直到有一个进程结束。
int work() {
// char buf[1024];
int retcnt = 0;
int i = 0;
static pid_t ID[100];
int runid = 0;
int jobs[max_running * 2 + 1];
pid_t tmp_pid = 0;
//for(i=0;i<max_running;i++){
// ID[i]=0;
//}
for(i=0;i<max_running *2 +1 ;i++)
jobs[i]=0;
//sleep_time=sleep_tmp;
/* get the database info */
if (!get_jobs(jobs)){
return 0;
}
/* exec the submit */
for (int j = 0; jobs[j] > 0; j++) {
runid = jobs[j];
if (runid % oj_tot != oj_mod)
continue;
if (workcnt >= max_running) { // if no more client can running
tmp_pid = waitpid(-1, NULL, WNOHANG); // wait 4 one child exit
if (DEBUG) printf("try get one tmp_pid=%d\n",tmp_pid);
for (i = 0; i < max_running; i++){ // get the client id
if (ID[i] == tmp_pid){
workcnt--;
retcnt++;
ID[i] = 0;
break; // got the client id
}
}
} else { // have free client
for (i = 0; i < max_running; i++) // find the client id
if (ID[i] == 0)
break; // got the client id
}
if(i<max_running){
if (workcnt < max_running && check_out(runid, OJ_CI)) {
workcnt++;
ID[i] = fork(); // start to fork
if (ID[i] == 0) {
if (DEBUG){
write_log("Judging solution %d", runid);
write_log("<<=sid=%d===clientid=%d==>>\n", runid, i);
}
run_client(runid, i); // if the process is the son, run it
workcnt--;
exit(0);
}
} else {
// ID[i] = 0;
if(DEBUG){
if(workcnt<max_running)
printf("check out failure ! runid:%d pid:%d \n",i,ID[i]);
else
printf("workcnt:%d max_running:%d ! \n",workcnt,max_running);
}
}
}
if(DEBUG)
printf("workcnt:%d max_running:%d ! \n",workcnt,max_running);
}
while ((tmp_pid = waitpid(-1, NULL,WNOHANG)) > 0) {
for (i = 0; i < max_running; i++){ // get the client id
if (ID[i] == tmp_pid){
workcnt--;
retcnt++;
ID[i] = 0;
break; // got the client id
}
}
printf("tmp_pid = %d\n", tmp_pid);
}
if (!http_judge) {
#ifdef _mysql_h
if(res!=NULL) {
mysql_free_result(res); // free the memory
res=NULL;
}
executesql("commit");
#endif
}
if (DEBUG && retcnt)
write_log("<<%ddone!>>", retcnt);
//free(ID);
//free(jobs);
return retcnt;
}
int lockfile(int fd) {
struct flock fl;
fl.l_type = F_WRLCK;
fl.l_start = 0;
fl.l_whence = SEEK_SET;
fl.l_len = 0;
return (fcntl(fd, F_SETLK, &fl));
}
int already_running() {
int fd;
char buf[16];
fd = open(lock_file, O_RDWR | O_CREAT, LOCKMODE);
if (fd < 0) {
syslog(LOG_ERR | LOG_DAEMON, "can't open %s: %s", LOCKFILE,
strerror(errno));
exit(1);
}
if (lockfile(fd) < 0) {
if (errno == EACCES || errno == EAGAIN) {
close(fd);
return 1;
}
syslog(LOG_ERR | LOG_DAEMON, "can't lock %s: %s", LOCKFILE,
strerror(errno));
exit(1);
}
ftruncate(fd, 0);
sprintf(buf, "%d", getpid());
write(fd, buf, strlen(buf) + 1);
return (0);
}
//下面这个函数就是用来创建一个守护进程
//看了一下代码，就是一般创建守护进程的流程。
/*
->fork子进程（此时子进程继承了父进程的会话期、进程组、终端、工作目录、文件权限）
->退出父进程
->调用setsid函数创建一个新的对话并担任该会话组的组长（摆脱原继承的会话、进程、终端的控制）
->改变当前目录（因为继承原目录会导致一直运行无法卸载原目录）
->重设文件权限 通常调用umask(0) 将文件掩码设为0
->关闭文件描述符 这里调用关闭了stdin stout sterr
*/
int daemon_init(void)
{
pid_t pid;
if ((pid = fork()) < 0)
return (-1);
else if (pid != 0)
exit(0); /* parent exit */
/* child continues */
setsid(); /* become session leader */
chdir(oj_home); /* change working directory */
umask(0); /* clear file mode creation mask */
close(0); /* close stdin */
close(1); /* close stdout */
close(2); /* close stderr */
int fd = open( "/dev/null", O_RDWR );
dup2( fd, 0 );
dup2( fd, 1 );
dup2( fd, 2 );
if ( fd > 2 ){
close( fd );
}
return (0);
}
void turbo_mode2(){
#ifdef _mysql_h
if(turbo_mode==2){
char sql[BUFFER_SIZE];
sprintf(sql," CALL `sync_result`();");
if (mysql_real_query(conn, sql, strlen(sql)));
}
#endif
}
int main(int argc, char** argv) {
int oj_udp_ret=0;
DEBUG = (argc > 2);
ONCE = (argc > 3);
if (argc > 1)
strcpy(oj_home, argv[1]);
else
strcpy(oj_home, "/home/judge");
chdir(oj_home); // change the dir
sprintf(lock_file,"%s/etc/judge.pid",oj_home);
if (!DEBUG)
daemon_init();
if ( already_running()) {
syslog(LOG_ERR | LOG_DAEMON,
"This daemon program is already running!\n");
printf("%s already has one judged on it!\n",oj_home);
return 1;
}
if(!DEBUG)
system("/sbin/iptables -A OUTPUT -m owner --uid-owner judge -j DROP");
// struct timespec final_sleep;
// final_sleep.tv_sec=0;
// final_sleep.tv_nsec=500000000;
#ifdef _mysql_h
init_mysql_conf(); // set the database info
#endif
if(oj_udp){
oj_udp_fd = socket(AF_INET, SOCK_DGRAM, 0);
if(oj_udp_fd<0)
printf("udp fd open failed! \n");
struct sockaddr_in ser_addr;
memset(&ser_addr, 0, sizeof(ser_addr));
ser_addr.sin_family = AF_INET;
ser_addr.sin_addr.s_addr = inet_addr(oj_udpserver);
ser_addr.sin_port = htons(oj_udpport);
struct timeval timeOut;
timeOut.tv_sec = sleep_time; //..5s..
timeOut.tv_usec = 0;
if (setsockopt(oj_udp_fd, SOL_SOCKET, SO_RCVTIMEO, &timeOut, sizeof(timeOut)) < 0)
{
printf("time out setting failed\n");
}
oj_udp_ret=bind(oj_udp_fd, (struct sockaddr*)&ser_addr, sizeof(ser_addr));
if(oj_udp_ret<0)
printf("udp fd open failed! \n");
}
signal(SIGQUIT, call_for_exit);
signal(SIGINT, call_for_exit);
signal(SIGTERM, call_for_exit);
int j = 1;
int n = 0;
while (!STOP) { // start to run until call for exit
n=0;
while (j && (http_judge
#ifdef _mysql_h
|| !init_mysql()
#endif
)) {
j = work();
n+=j;
if(turbo_mode==2&&(n>max_running*10||j<max_running)){
turbo_mode2();
n=0;
}
if(ONCE) break;
}
turbo_mode2();
if(ONCE) break;
if(n==0){
printf("workcnt:%d\n",workcnt);
if(oj_udp&&oj_udp_ret==0){
if(STOP) return 1;
wait_udp_msg(oj_udp_fd);
if(DEBUG) printf("udp job ... \n");
}else{
sleep(sleep_time);
if(DEBUG) printf("sleeping ... %ds \n",sleep_time);
}
}
j = 1;
}
return 0;
}
这篇博客只为帮助那些和我一样刚开始研究这个项目但不知如何下手的人。我只能给你提供一些方法和可能会省掉一些不必要的时间的路径，接下来还是要靠你自己艰难的沿着你已经确定的路走下去。
最后我想说，这个探索的过程是一个很艰难的过程，尽管在很多大牛眼里这只是一个平白无奇并未涉及很多技术的项目，但对于我们来说，不断的去探索，学习相关知识，学到最后你会发现你掌握的不仅仅是这个“平白无奇”的项目，其实，这就是一个自我“救赎”的过程，谁让我们学习能力确实不如别人呢。
先写到这里把，我如果有更多的发现会在代码上更改的。
非常感谢zhblue贡献了这么美丽的代码