純代碼乾貨系列
/*
* 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>
static int DEBUG = 0; //是否啓用調試,來查看日誌運行記錄,默認0,不啓用
#define BUFFER_SIZE 1024
#define LOCKFILE "/var/run/judged.pid"
#define LOCKMODE (S_IRUSR|S_IWUSR|S_IRGRP|S_IROTH)
#define STD_MB 1048576
#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 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;
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_username[BUFFER_SIZE];
static char http_password[BUFFER_SIZE];
static bool STOP = false;
static MYSQL *conn;
static MYSQL_RES *res; //mysql讀取結果集,在_get_http/mysql_jobs()中被更新
static MYSQL_ROW row;
//static FILE *fp_log;
static char query[BUFFER_SIZE];//在init_mysql_conf中更新,固定取2倍最大判題客戶端的待評判題目solution_id
void call_for_exit(int s) {
STOP = true;
printf("Stopping judged...\n");
}
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, "a+");
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);
}
int after_equal(char * c) {
int i = 0;
for (; c[i] != '\0' && c[i] != '='; i++)
;
return ++i;
}
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);
}
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, "0,1,2,3,4,5,6,7,8,9,10");
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);
}
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, max_running * 2);
sleep_tmp = sleep_time;
// fclose(fp);
}
}
//當有代評測提交,並且進程數允許的情況下,創建新的子進程調用該評測函數
//輸入:代評測提交的solution_id, 子進程在ID[]中的保存位置 i
void run_client(int runid, int clientid) {
char buf[BUFFER_SIZE], runidstr[BUFFER_SIZE];
//在Linux系統中,Resouce limit指在一個進程的執行過程中,它所能得到的資源的限制,
//比如進程的core file的最大值,虛擬內存的最大值等 ,這是運行時間,內存大小實現的關鍵
/*
結構體中 rlim_cur是要取得或設置的資源軟限制的值,rlim_max是硬限制
這兩個值的設置有一個小的約束:
1) 任何進程可以將軟限制改爲小於或等於硬限制
2)任何進程都可以將硬限制降低,但普通用戶降低了就無法提高,該值必須等於或大於軟限制
3) 只有超級用戶可以提高硬限制
setrlimit(int resource,const struct rlimit rlptr);返回:若成功爲0,出錯爲非0
RLIMIT_CPU:CPU時間的最大量值(秒),當超過此軟限制時向該進程發送SIGXCPU信號
RLIMIT_FSIZE:可以創建的文件的最大字節長度,當超過此軟限制時向進程發送SIGXFSZ
*/
struct rlimit LIM;
LIM.rlim_max = 800;
LIM.rlim_cur = 800;
setrlimit(RLIMIT_CPU, &LIM);//cpu運行時間限制
LIM.rlim_max = 80 * STD_MB;
LIM.rlim_cur = 80 * STD_MB;
setrlimit(RLIMIT_FSIZE, &LIM);//可文件大小限制,防止惡意程序的嗎?
LIM.rlim_max = STD_MB << 11;//左移11 STD_MB是2^20 MB 2^11MB 2GB機器起碼的2GB虛擬內存?
LIM.rlim_cur = STD_MB << 11;
setrlimit(RLIMIT_AS, &LIM);//最大運行的虛擬內存大小限制
LIM.rlim_cur = LIM.rlim_max = 200;
setrlimit(RLIMIT_NPROC, &LIM);//每個實際用戶ID所擁有的最大子進程數,這些都是爲了防止惡意程序的吧??
//buf[0]=clientid+'0'; buf[1]=0;
sprintf(runidstr, "%d", runid);//轉換成字符?還是字符串?
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
//返回值:如果執行成功則函數不會返回, 執行失敗則直接返回-1, 失敗原因存於errno 中.
//execl()其中後綴"l"代表list也就是參數列表的意思,第一參數path字符指針所指向要執行的文件路徑,
//接下來的參數代表執行該文件時傳遞的參數列表:argv[0],argv[1]... 最後一個參數須用空指針NULL作結束。
// 執行/bin目錄下的ls, 第一參數爲程序名ls, 第二個參數爲"-al", 第三個參數爲"/etc/passwd"
//execl("/bin/ls", "ls", "-al", "/etc/passwd", (char *) 0);
//這裏第一個參數爲程序名稱judge_client,第二個參數爲代評測題目id, 第三個爲本進程pid保存位置,第四個參數爲oj目錄
//默認/home/judge,第五個參數爲“debug”
execl("/usr/bin/judge_client", "/usr/bin/judge_client", runidstr, buf,
oj_home, "debug", (char *) NULL);
//exit(0);
}
//執行sql語句成功返回1,否則返回0
//並且關閉是否conn,它在init裏初始化開始的
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;
}
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 0;
}
} else {
return executesql("set names utf8");
}
}
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);
}
}
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;
return ret;
}
//功能:取得待評測題目信息到jobs數組
//輸入:int * jobs :保存solution_id/runid
//輸出:如果查詢成功則返回:要評測題目數量
//如果查詢待判題目不成功則返回0
int _get_jobs_mysql(int * jobs) {
//mysql.h
//如果查詢數據包括二進制或者更快速度 用這個
//如果執行成功,返回0;不成功非0
if (mysql_real_query(conn, query, strlen(query))) {
if (DEBUG)
write_log("%s", mysql_error(conn));
sleep(20);
return 0;
}
//mysql.h
//返回具有多個結果的MYSQL_RES結果集合。如果出現錯誤,返回NULL
//具體參見百度
res = mysql_store_result(conn);
int i = 0;
int ret = 0;
//遍歷結果集mysql_fetch_row()
while ((row = mysql_fetch_row(res)) != NULL) {
jobs[i++] = atoi(row[0]);
}
ret = i; //要評測jobs末端 如 0 1 2 有數據,則i=3代表數據
while (i <= max_running * 2)
jobs[i++] = 0; //設定的最大工作數目爲max_running*2,將0-8置位0共9個 max_running*2+1數組開這麼大
return ret;
return ret;
}
int get_jobs(int * jobs) {
if (http_judge) { //web和core默認連接方式:數據庫,web插入solution,core輪訓/更新solution-result,web輪訓solution-result
return _get_jobs_http(jobs);
} else
return _get_jobs_mysql(jobs);//讀取要判題的任務數量
}
//更新初始化solution表格
//更新成功返回1;否則0
// 疑問:OJ_CI爲2,and result < 2這句怎麼都是不成立,這個Sql語句怎麼都不會執行成功纔對啊
//用limit 1加了一層保障。避免where 條件出現異常時,錯誤更新影響太多。
//不知道php初始寫多少,但是調用給的參數爲2啊,不懂!!!!
bool _check_out_mysql(int solution_id, int result) {
char sql[BUFFER_SIZE]; //sql語句保存
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);
//執行sql語句,成功返回0;否則非0
if (mysql_real_query(conn, sql, strlen(sql))) {
syslog(LOG_ERR | LOG_DAEMON, "%s", mysql_error(conn));
return false;
} else {
//影響行數,更新數大於0,執行成功,返回1,否則0
if (mysql_affected_rows(conn) > 0ul)
return true;
else
return false;
}
}
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;
}
//初始更新solution表
//依據參數不同執行不同的更新函數
bool check_out(int solution_id, int result) {
if (http_judge) {
return _check_out_http(solution_id, result);
} else
return _check_out_mysql(solution_id, result);
}
int work() {
// char buf[1024];
static int retcnt = 0;//統計 已經 完成評測次數
int i = 0;
static pid_t ID[100]; //short類型的宏定義,進程表中的索引項,進程號;保存正在執行的子進程pid
static int workcnt = 0;//統計 現用 judge_client進程數量
int runid = 0; //solution_id,測試運行編號
int jobs[max_running * 2 + 1];//max_running 從judge.conf獲取,一般爲4,這裏設置爲工作目錄:9
pid_t tmp_pid = 0;
//for(i=0;i<max_running;i++){
// ID[i]=0;
//}
//sleep_time=sleep_tmp;
/* get the database info */
if (!get_jobs(jobs)) //如果讀取失敗或者要評測題目數量爲0,jobs[]被置爲:1001,1002,0,...0;默認9位
retcnt = 0;
/* exec the submit *///遍歷評測每個solution_id的題目,只負責把所以題目全部投入到新的評判進程裏
//不管是否評測完成
for (int j = 0; jobs[j] > 0; j++) {
runid = jobs[j]; //讀取solution_id,待評測提交題目id
//老式併發處理中,默認oj_tot 爲 1 oj_mod 爲0,在init_sql_conf中設置 所以無用
if (runid % oj_tot != oj_mod)
continue;
if (DEBUG) //調試用默認0 無用
write_log("Judging solution %d", runid);
//workcnt 爲static 變量,相當於死鎖,統計現用run_client進程 數目
//本if 等待可用 子進程,並且用 i 騰出保存 新子進程的位置
if (workcnt >= max_running) { // if no more client can running
//如果達到了可用最大進程數目,那麼等待一個子進程結束
//waitpid,參考linux 下 c 語言編程下的 進程管理
//waitpid()會暫時停止目前進程的執行,直到有信號來到或子進程結束
//pid_t waitpid(pid_t pid,int * status,int options);
//pid=-1 代表任意子進程;status 取回子進程識別碼,這裏不需要所以NULL;
//參數options提供了一些額外的選項來控制waitpid,比如不等待繼續執行,這裏0代表不使用,進程掛起
//如果 有子進程已經結束,那麼執行到這裏的時候會直接跳過,子進程也會由殭屍進程釋放
//返回結束的子進程pid
tmp_pid = waitpid(-1, NULL, 0); // wait 4 one child exit
workcnt--;//子進程結束了個,那麼現用judge_client數量減一
retcnt++;//評測完成數加1
//清除保存在 ID[]裏的已經結束的子進程信息
for (i = 0; i < max_running; i++) // get the client id
if (ID[i] == tmp_pid)
break; // got the client id
ID[i] = 0;
} else { // have free client
for (i = 0; i < max_running; i++) // find the client id
if (ID[i] == 0)
break; // got the client id
}
//其實這裏worknct<max_running 一定成立,除非waitpid()出錯
//check_out:更新初始化表,但是怎麼都不該執行成功纔對的啊,爲什麼還能成功呢
//如果可以開始新的子進程進行評測
if (workcnt < max_running && check_out(runid, OJ_CI)) {
workcnt++;//正運行子進程數目加1----這裏是不是太早了,子進程創建一定能成功?????
//應該在子進程裏更新這個數值吧
ID[i] = fork(); //創建子進程 ,將子進程pid返回給父進程,將0返回給子進程 // start to fork
//這句寫的覺得難理解,父進程會將其更新爲新進程pid
//子進程呢,創建之初會更新爲0,那到底是多少???????
//按照程序,子進程會完整複製父進程的代碼,數據,堆棧
//那麼如果是父進程在執行那麼ID[i] 不爲0而是子進程pid
//如果是子進程的在執行,那麼數據段又是ID[i]爲0????
//那static 的作用呢
if (ID[i] == 0) {//如果成立,那麼代表是在執行子進程代碼,執行run_judge_client
if (DEBUG)
write_log("<<=sid=%d===clientid=%d==>>\n", runid, i);
run_client(runid, i); //在子進程裏更新ID[0]=pid // if the process is the son, run it
exit(0);//子進程執行完畢退出0,父進程不會執行這段if ,在run_client裏進程會跳轉到execl(judge_client)
//執行成功不返回,不成功返回非0,保存在erro裏,那麼這裏又是怎麼執行到的,子進程如何退出的??????
}
} else {//理論上,在上個if裏已經保證了這裏爲ID[i] = 0,這裏估計是爲了進一步保證
ID[i] = 0;
}
}
//把本次輪訓到的代評測題目全部投入評測後
//在非掛起等待子進程的結束,如果有子進程評測完成結束
//在上個的for裏,當可用進程沒有的時候,那麼就必須等其中一個進程結束,那麼才能繼續執行,哪怕在for裏已經有
// 子進程結束是殭屍進程了,只要workcnt<max_running,那麼就也不處理子殭屍進程的回收問題,而是優先投入新的子進程
//進行評測
//那麼子殭屍進程 誰來回收,何時回收,怎麼回收,總不能等可用的全成了殭屍進程,在for裏用到的時候在進行回收吧
//如果可用進程數開的特別大,而一直沒有用戶提交,那豈不是,運行一段時間後,系統肯定會一直有max_running個進程的
//資源被佔用,而且大大大99%部分都是死的子殭屍進程,for只是用幾個收幾個,而不管也沒法管其他的,因爲for只有當
//有評測任務的時候纔會執行到,大部分沒有用戶提交程序評測的輪詢時間段裏,不順手回收下,豈不可惜!!!
//所以就是while()要完成的任務,父進程執行到這裏的時候,掃一眼是否有待回收子殭屍進程,有就 順手回收一個;
// 因爲不知道有多少待回收的,什麼時候要回收;所以只且只能在這個輪詢時間段裏回收一個
//這個while,純粹是順手牽羊行爲,當然也有更新評測完成數量的重要任務~~~
/*
如果使用了WNOHANG參數調用waitpid,即使沒有子進程退出,它也會立即返回,不會像wait那樣永遠等下去
1、當正常返回的時候,waitpid返回收集到的子進程的進程ID;
2、如果設置了選項WNOHANG,而調用中waitpid發現沒有已退出的子進程可收集,則返回0;
3、如果調用中出錯,則返回-1,這時errno會被設置成相應的值以指示錯誤所在;
*/
while ((tmp_pid = waitpid(-1, NULL, WNOHANG)) > 0) {
workcnt--;
retcnt++;
for (i = 0; i < max_running; i++) // get the client id
if (ID[i] == tmp_pid)
break; // got the client id
ID[i] = 0;
printf("tmp_pid = %d\n", tmp_pid);
}
//釋放數據庫資源
//這裏commit的調用,不知道是爲了關閉conn,還是數據庫不支持自動commit
//還是徹底縮小日誌,不給機會rollback,待學習??????
if (!http_judge) {
mysql_free_result(res); // free the memory
executesql("commit");
}
if (DEBUG && retcnt)
write_log("<<%ddone!>>", retcnt);
//free(ID);
//free(jobs);
//返回已經評測的次數
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(LOCKFILE, 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);
}
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 */
return (0);
}
int main(int argc, char** argv) {
DEBUG = (argc > 2);
if (argc > 1)
strcpy(oj_home, argv[1]);
else
strcpy(oj_home, "/home/judge");
chdir(oj_home); // change the dir
if (!DEBUG)
daemon_init();//創建一個daemon守護進程
if (strcmp(oj_home, "/home/judge") == 0 && already_running()) {
syslog(LOG_ERR | LOG_DAEMON,
"This daemon program is already running!\n");
return 1;
}
// struct timespec final_sleep;
// final_sleep.tv_sec=0;
// final_sleep.tv_nsec=500000000;
init_mysql_conf(); // set the database info
signal(SIGQUIT, call_for_exit);
signal(SIGKILL, call_for_exit);
signal(SIGTERM, call_for_exit);
int j = 1;
while (1) { // start to run
//這個while的好處在於,只要一有任務就抓緊佔用系統優先把所以任務處理完成,哪怕會空循環幾次的可能存在
//但是沒有任務後,就會進入到“懶散”的 休息sleep(time)後再輪詢是不是有任務,釋放系統的資源,避免Damon一直
//死循環佔用系統
while (j && (http_judge || !init_mysql())) {
j = work();//如果讀取失敗或者沒有要評測的數據,那麼返回0,利用那麼有限的幾個進程來評測無限的任務量
}
sleep(sleep_time);
j = 1;
}
return 0;
}