在 createProcess(pid_t pidArray[]) 函数中我创建了新进程,如果它是子进程我打印它。但是在 while 循环中我每次都检查 killFlag,我的程序没有效率。我该如何解决这个问题?感谢您的任何帮助。在我的程序中,您可以通过按 + 添加进程或按 - 删除它,或者按 q 退出。
这是我的代码:
#include <ncurses.h>
#include <unistd.h>
#include <sys/wait.h>
#include <signal.h>
#include <string.h>
#include <stdlib.h>
bool printAllowed = false;
bool killFlag = true;
bool flag = false;
int processesCount = 0;
int currentProcessNumber = 0;
static const char *colors[] = { "\x1B[0m", "\x1B[31m","\x1B[32m","\x1B[33m","\x1B[34m","\x1B[35m","\x1B[36m","\x1B[37m" };
struct sigaction printSignal, killSignal;
void allowPrint(int sign){
printAllowed = true;
}
void setKillFlag(int sign){
killFlag = true;
}
int createProcess(pid_t pidArray[]){
if(processesCount > 100) return 1;
pidArray[processesCount] = fork();
processesCount++;
switch(pidArray[processesCount - 1]){
case 0:{
killFlag = false;
char buff[255];
int colorNumber = (processesCount > 7)? 0 : processesCount;
sprintf(buff,"%sProcess %d || ", colors[colorNumber], processesCount);
while(!killFlag) {
usleep(10000);
if(printAllowed){
for(int i = 0; i < strlen(buff); i++){
if(killFlag) { return -1;};
printf("%c", buff[i]);
refresh();
usleep(50000);
}
printAllowed = false;
// signal to parent that process stop print
kill(getppid(), SIGUSR2);
}
}
return -1;
}
case -1: printf("%sError!", colors[1]); return 1;
default: return 1;
}
}
bool killProcess(pid_t pidArray[]){
if (processesCount <= 0) return 1;
processesCount--;
// stop last child process
kill(pidArray[processesCount], SIGUSR2);
waitpid(pidArray[processesCount], NULL, NULL);
// if the process that printing now stopped
if (currentProcessNumber >= processesCount){
currentProcessNumber = 0; // start from beginning
flag = true; // flag last process by number
killFlag = true; // flag of end printing current process
}
return 1;
}
int controlProcesses(pid_t pidArray[]){
halfdelay(1);
switch((char)getchar()){
case '=': return createProcess(pidArray);
case '-': return killProcess(pidArray);
case 'q': return 0;
default: return 1;
}
}
void killAllProcesses(pid_t pidArray[]){
if(pidArray[--processesCount] != 0)
for( ;processesCount >= 0; processesCount--){
kill(pidArray[processesCount],SIGUSR2);
waitpid(pidArray[processesCount],NULL,NULL);
}
}
int main(){
initscr();
clear();
noecho();
refresh();
printSignal.sa_handler = allowPrint;
sigaction(SIGUSR1,&printSignal,NULL);
killSignal.sa_handler = setKillFlag;
sigaction(SIGUSR2,&killSignal,NULL);
pid_t pidArray[100];
while(int i = controlProcesses(pidArray)) {
if(i == -1) return 0;
if(killFlag && processesCount > 0){ // if current process stop printing
killFlag = false;
if(currentProcessNumber >= processesCount - 1) currentProcessNumber = 0; // if the number of current process is last, start from beginning
else if(!flag) currentProcessNumber++; // else if last stopped process wasn't the last by number go to next process
flag = false;
kill(pidArray[currentProcessNumber], SIGUSR1); // signal to child process start the printing
}
refresh();
}
// stop all child processes
killAllProcesses(pidArray);
clear();
endwin();
return 0;
}
请您参考如下方法:
您的 killFlags
(和 printAllowed
)声明错误。应该声明
volatile sig_atomic_t killFlags, printAllowed;
volatile预选赛真的很重要。否则,编译器会通过假设只能显式更改 killFlags
来优化(它不知道信号处理程序可以随时更改它,因此它可以通过将该变量保存在寄存器中来优化,等等) ...)。
仔细阅读signal(7)手册页。
如果你的循环是轮询 event loop (可能基于 poll(2) ...)您可能会考虑使用特定于 Linux 的 signalfd(2)打电话。