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【HUSTOJ 判题机源码解读系列03】judge.cc 源码详细注释
本文是 HUSTOJ 中一个比较重要的模块——judge.cc 源代码文件全文注释版本，部分直观的代码不会注释。
做个复习：
- judge.cc 是用来调度判题的
- judge_client.cc 是真正执行判题逻辑的
/** Copyright 2008 sempr <iamsempr@gmail.com>** Refacted and modified by zhblue<newsclan@gmail.com>* Bug report email newsclan@gmail.com** 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 <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>
#ifdef OJ_USE_MYSQL
#include <mysql/mysql.h>
#endif#define BUFFER_SIZE 1024
#define LOCKFILE "/var/run/judged.pid"
#define LOCKMODE (S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH)
#define STD_MB 1048576LL// 魔术值，定义 OJ 中的各种值
#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 + 32] = LOCKFILE;
static char host_name[BUFFER_SIZE];
static char user_name[BUFFER_SIZE];
static char password[BUFFER_SIZE];
static char db_name[BUFFER_SIZE];
static char oj_home[BUFFER_SIZE];
static char oj_lang_set[BUFFER_SIZE];
static int port_number;
static int max_running; // 并行判题最大数量
static int sleep_time;
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_apipath[BUFFER_SIZE];
static char http_loginpath[BUFFER_SIZE];
static char http_username[BUFFER_SIZE];
static char http_password[BUFFER_SIZE];
static int prefetch = 80; // 预获取的题目数量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 int use_docker = 0; // 使用 docker 作为沙箱判题
static char docker_path[BUFFER_SIZE];
static int internal_client = 1;
static int oj_dedicated = 0;static bool STOP = false;
static int DEBUG = 0;
static int ONCE = 0;
#ifdef _mysql_h
static MYSQL *conn;
static MYSQL_RES *res;
static MYSQL_ROW row;
// static FILE *fp_log;
static char query[BUFFER_SIZE * 4];
#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);memset(buf, 0, BUFFER_SIZE);
}// main 函数接受 SIGQUIT | SIGINT | SIGTERM 信号的处理函数
// signal(SIGQUIT, call_for_exit);
// signal(SIGINT, call_for_exit);
// signal(SIGTERM, call_for_exit);
// 具体操作是屏蔽这些信号终止能够终止进程
// 需要使用 pkill -9 judged 命令强行终止进程
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");}
}// 打印日志的工具函数
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);
}// 返回字符 = 后面第一个字符的下标
// 例如 after_equal("key=value")
// 012345678
// key=value
// ↑
// 返回 4（指向 'v' 字符）
int after_equal(char *c)
{int i = 0;for (; c[i] != '\0' && c[i] != '='; i++);return ++i;
}// 去除字符串 c 前后的空白字符
// 输入：" hello "
// 返回："hello"
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);
}// 从 buf 中读取 key=value 格式的值，并去除前后空格存入 value
// 例如：
// 调用：read_buf("username = eling", "username", value);
// 执行结果：函数返回 1, value = eling
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;
}// read_int 从 buf 中读取 key=value 格式的整数值，并存入 value 变量
// 例如：
// 调用：read_buf("size = 12", "size", value);
// 执行结果：函数返回 1， value = 12
void read_int(char *buf, const char *key, int *value)
{char buf2[BUFFER_SIZE];if (read_buf(buf, key, buf2))sscanf(buf2, "%d", value);
}// 读取 /home/judge/src/etc/judge.conf 配置文件
// 然后将这些配置赋值给上面定义的那些全局变量
void init_judge_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, "0,1,3,6");strcpy(oj_udpserver, "127.0.0.1");strcpy(docker_path, "/usr/bin/docker");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_DEDICATED", &oj_dedicated);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_APIPATH", http_apipath);read_buf(buf, "OJ_HTTP_LOGINPATH", http_loginpath);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);read_int(buf, "OJ_USE_DOCKER", &use_docker);read_int(buf, "OJ_INTERNAL_CLIENT", &internal_client);read_buf(buf, "OJ_DOCKER_PATH", docker_path);}
#ifdef _mysql_hif (oj_tot == 1){sprintf(query,"SELECT solution_id FROM solution WHERE language in (%s) and result<2 ORDER BY result, solution_id limit %d",oj_lang_set, prefetch * max_running);}else{sprintf(query,"SELECT solution_id FROM solution WHERE language in (%s) and result<2 and MOD(solution_id,%d)=%d ORDER BY result, solution_id ASC limit %d",oj_lang_set, oj_tot, oj_mod, prefetch * max_running);}
#endifsleep_tmp = sleep_time;fclose(fp);}
}// 启动 judge_client 进程判题
void run_client(int runid, int clientid)
{// 使用 setrlimit 系统调用// 能够限制进程使用的 CPU、内存、硬盘等计算机的资源// 有很多条件编译语句，针对不同的平台，做不同的限制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 = 1024 * STD_MB;LIM.rlim_cur = 1024 * 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 __i386LIM.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;
#endifsetrlimit(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);// char * const envp[]={(char * const )"PYTHONIOENCODING=utf-8",// (char * const )"LANG=zh_CN.UTF-8",// (char * const )"LANGUAGE=zh_CN.UTF-8",// (char * const )"LC_ALL=zh_CN.UTF-8",NULL};// if (!DEBUG)if (use_docker){char docker_v[BUFFER_SIZE * 3];sprintf(docker_v, "%s:/home/judge", oj_home);if (internal_client)execl(docker_path, docker_path, "container", "run", "--pids-limit", "100", "--rm", "--cap-add", "SYS_PTRACE", "--net=host","-v", docker_v, "hustoj", "/usr/bin/judge_client", runidstr, buf, (char *)NULL);elseexecl(docker_path, docker_path, "container", "run", "--pids-limit", "100", "--rm", "--cap-add", "SYS_PTRACE", "--net=host","-v", docker_v, "hustoj", "/home/judge/src/core/judge_client/judge_client", runidstr, buf, (char *)NULL);}else{// 使用 execl 系统调用运行 /usr/bin/judge_client 系统调用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);if (use_docker){printf("DOCKER IS DOWN!\n");}// 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(2);conn = NULL;return 1;}elsereturn 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 * 2];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%s\"";int ret = 0;FILE *fjobs = read_cmd_output(cmd, http_baseurl, http_apipath);ret = read_int_http(fjobs);pclose(fjobs);return ret > 0;
}
void login()
{if (!check_login()){char cmd[BUFFER_SIZE * 5];sprintf(cmd,"wget --post-data=\"user_id=%s&password=%s\" --load-cookies=cookie --save-cookies=cookie --keep-session-cookies -q -O - \"%s%s\"",http_username, http_password, http_baseurl, http_loginpath);system(cmd);}
}
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%s\"";FILE *fjobs = read_cmd_output(cmd, oj_lang_set, max_running, http_baseurl, http_apipath);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 * prefetch)jobs[i++] = 0;return ret;
}
#ifdef _mysql_h
/*** 从数据库中获取等待判题的 solution 的 solution_id* 通过 jobs 将 solution_id 数组传出* 返回值是获取到的 solution_id 的数量*/
int _get_jobs_mysql(int *jobs)
{// jobs 是传入参数// 总体的逻辑就是从 solution 表中查询 未判题的 solution_id，然后将 solution_id 通过传入参数传出// 具体的 sql 在下面// SELECT solution_id FROM solution WHERE language in (%s) and result<2 and MOD(solution_id,%d)=%d ORDER BY result, solution_id ASC limit %dif (mysql_real_query(conn, query, strlen(query))){if (DEBUG)write_log("%s", mysql_error(conn));sleep(2);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 memoryres = NULL;}elsei = 0;ret = i;while (i <= max_running * prefetch)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 * prefetch)jobs[i++] = 0;if (DEBUG)printf("redis return %d jobs", ret);return ret;
}int get_jobs(int *jobs)
{// http_judge 是配置// 判题机支持 mysql 获取判题任务和 http 获取任务// 默认是 mysqlif (http_judge){return _get_jobs_http(jobs);}else{if (oj_redis){return _get_jobs_redis(jobs);}else{
#ifdef _mysql_hreturn _get_jobs_mysql(jobs);
#elsereturn 0;
#endif}}
}#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;elsereturn false;}
}
#endifbool _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%s\"";int ret = 0;FILE *fjobs = read_cmd_output(cmd, solution_id, result, http_baseurl, http_apipath);fscanf(fjobs, "%d", &ret);pclose(fjobs);return ret;
}/*** 更新评测结果*/
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_hreturn _check_out_mysql(solution_id, result);
#elsereturn 0;
#endif}
}
static int workcnt = 0;/*** 从数据库获取任务，并且使用 fork() 创建子进程执行任务* @return int */
int work()
{// char buf[1024];static int error = 0; // 出错计数器int retcnt = 0; // return 值int i = 0;static pid_t ID[100]; // 父进程存储自己 fork 出来的子进程 ID 数组int runid = 0;// jobs 是一个存储等待判题的 solution ID 的数组。// 其大小由 `max_running * prefetch + 1` 决定，其中：// `max_running` 是配置项，表示最大并行判题的数量// 通过预获取更多的等待判题 solution，可以最大程度减少数据库访问次数，提高判题效率// 但并非每次从数据库都能获取 `max_running * prefetch + 1` 个等待判题的 solution， // 因此，jobs 数组的结构可能如下： // `[1001, 1002, 1003, ..., 1009, 0, 0, 0, ..., 0]` // 其中，值大于 0 的元素表示 `solution_id`，其余的 0 仅为占位符。 // 这也是后续判题任务派发的 `for` 循环中，使用 `jobs[j] > 0` 作为循环条件的原因。 int jobs[max_running * prefetch + 1];pid_t tmp_pid = 0;// 初始化 jobs 数组for (i = 0; i < max_running * prefetch + 1; i++)jobs[i] = 0;// 开始从数据库中获取判题任务// 如果没有获取任务，work() 函数直接返回 0if (!get_jobs(jobs)) {return 0;}// 注意：循环条件是 jobs[j] > 9for (int j = 0; jobs[j] > 0; j++){// runid 就是 solution_idrunid = jobs[j];// 该 OJ 为了兼容其老版本做的处理，不必理会if (runid % oj_tot != oj_mod)continue;// workcnt 记录当前正在运行的判题任务数量// 如果当前运行的任务数达到或超过 max_running（最大并行判题数），// 尝试回收已结束的判题子进程（僵尸进程）。// 1. 使用 waitpid(-1, NULL, WNOHANG) 尝试回收一个已退出的子进程（并非一定能够回收到，只是尝试）// 2. 如果找到已退出的进程，在 ID 数组中抹去该进程的记录，并调整计数：// workcnt--（当前运行任务数减少）// retcnt++（已完成任务数增加）// 3. 如果 use_docker 启用，但未能正确回收进程// 则可能发生错误，error++ 计数；否则，error = 0（避免误判 Docker 服务卡死）if (workcnt >= max_running){ // 回收僵尸进程 // if no more client can runningtmp_pid = waitpid(-1, NULL, WNOHANG); // wait 4 one child exitif (DEBUG)printf("try get one tmp_pid=%d\n", tmp_pid);for (i = 0; i < max_running; i++){ // get the client idif (ID[i] == tmp_pid){workcnt--;retcnt++;ID[i] = 0;// 重点：这的 i 就是空闲的 client_idbreak; // got the client id}}if (use_docker && (i == max_running || ID[i] != 0))error++;elseerror = 0; // check if docker service is hanged up}else{ // have free clientfor (i = 0; i < max_running; i++) // find the client idif (ID[i] == 0){// 和上面一样// 重点：当前的 i 记录了 空闲的 client_id// 这个 client_id 就是 /home/judge/src/ // 目录下的 run0, run1, run2 用于运行代码的沙箱的数字break; // got the client id}}if (i < max_running){// chekout(runid, OJ_CI)// 任务已经派发if (workcnt < max_running && check_out(runid, OJ_CI)){workcnt++;ID[i] = fork(); // start to forkif (ID[i] == 0){// 子进程开始执行 run_client 函数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 itworkcnt--;exit(0);}}else{// ID[i] = 0;if (DEBUG){if (workcnt < max_running)printf("check out failure ! runid:%d pid:%d \n", i, ID[i]);elseprintf("workcnt:%d max_running:%d ! \n", workcnt, max_running);}usleep(5000);}}if (DEBUG)printf("workcnt:%d max_running:%d ! \n", workcnt, max_running);if (use_docker && (error >= max_running * prefetch)){ // reboot dockerif (DEBUG)printf("---------------------------------------------restarting--------------------------------------\n");// system("/usr/sbin/service docker restart");
#ifdef _mysql_hexecutesql("update solution set result=1 where result >1 and result <4 ");
#endifsleep(1);error = 0;}}int NOHANG = 0;if (oj_dedicated && (rand() % 100 > 20))NOHANG = WNOHANG; // CPU 占用大约80%左右，不要打满// 这里开始死循环，等待上面 fork() 出来的子进程退出，然后然后做好判题记录while ((tmp_pid = waitpid(-1, NULL, NOHANG)) > 0){ // if run dedicated judge using WNOHANGfor (i = 0; i < max_running; i++){ // get the client idif (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_hif (res != NULL){mysql_free_result(res); // free the memoryres = 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);
}// 启动一个守护进程的常规操作
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_hif (turbo_mode == 2){char sql[BUFFER_SIZE];sprintf(sql, " CALL `sync_result`();");if (mysql_real_query(conn, sql, strlen(sql)));}
#endif
}
/*** TRUBO_MODE = 2 放弃用户表和问题表的数据一致性，以在大型比赛中添加更多的判题机来提高判题速度。*/
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]);elsestrcpy(oj_home, "/home/judge");chdir(oj_home); // change the dirsprintf(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;init_judge_conf(); // set the database infoif (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 exitn = 0;while (j && (http_judge
#ifdef _mysql_h|| !init_mysql()
#endif)){// 查看 workj = work();n += j;// 如果启用加速模式 并且if (turbo_mode == 2 && (n > max_running * 10 || j < max_running)){turbo_mode2();n = 0;}if (ONCE && j == 0)break;}turbo_mode2();if (ONCE && j == 0){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;}
#ifdef _mysql_hmysql_close(conn);
#endifreturn 0;
}
到此处，有关 HUSTOJ 判题机的 judge.cc 文件，也可以说是判题的调度模块就完成解读了，在后续文章中就会开始解读真正用来判题的 judge_cient.cc 运行机制和源代码解析了。