【HUSTOJ判题机源码解读系列03】judge.cc源码详细注释

【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 > * * Refacted and modified by zhblue<newsclan@gmail > * Bug report email newsclan@gmail * * 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:// .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_h if (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); } #endif sleep_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 __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); // 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); else execl(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; } 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 * 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 %d if (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 memory res = NULL; } else i = 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 mysql 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 } } } #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%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_h return _check_out_mysql(solution_id, result); #else return 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 0 if (!get_jobs(jobs)) { return 0; } // 注意：循环条件是 jobs[j] > 9 for (int j = 0; jobs[j] > 0; j++) { // runid 就是 solution_id runid = 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 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; // 重点：这的 i 就是空闲的 client_id break; // got the client id } } if (use_docker && (i == max_running || ID[i] != 0)) error++; else error = 0; // check if docker service is hanged up } else { // have free client for (i = 0; i < max_running; i++) // find the client id if (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 fork if (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 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); } usleep(5000); } } if (DEBUG) printf("workcnt:%d max_running:%d ! \n", workcnt, max_running); if (use_docker && (error >= max_running * prefetch)) { // reboot docker if (DEBUG) printf("---------------------------------------------restarting--------------------------------------\n"); // system("/usr/sbin/service docker restart"); #ifdef _mysql_h executesql("update solution set result=1 where result >1 and result <4 "); #endif sleep(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 WNOHANG 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); } // 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_h if (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]); 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; init_judge_conf(); // set the database info 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 )) { // 查看 work j = 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_h mysql_close(conn); #endif return 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。