我有一个C程序有两个线程:主线程连续从网络读取数据并将其输出到屏幕上,而辅助线程侦听并处理来自标准输入的按键。如何中断阻塞IO的后台线程?
当前我的程序捕获了SIGINT,SIGTERM和SIGPIPE以便干净地终止程序。我的问题是,在主线程结束时(一旦主循环已从信号处理程序终止),它会尝试使用tcsetattr
来恢复终端设置,但是这会阻塞,直到另一个线程上当前的fgetc
调用返回。
如何中断后台线程以使fgetc
调用返回并且主线程可以恢复终端设置并干净地退出?
我试过使用pthread_kill(thread, SIGINT)
但这只是导致我现有的信号处理程序再次被调用。
相关代码:
// If the program should still be running.
static sig_atomic_t running = 1;
// Background thread that reads keypresses.
pthread_t thread;
static void *get_keypresses();
static void receive_signal(int signal) {
(void)signal;
running = 0;
}
int main(int argc, char *argv[]) {
// Set up signal handling.
if(signal(SIGINT, receive_signal) == SIG_ERR) {
fprintf(stderr, "Error setting signal handler for SIGINT.\n");
}
if(signal(SIGTERM, receive_signal) == SIG_ERR) {
fprintf(stderr, "Error setting signal handler for SIGTERM.\n");
}
if(signal(SIGPIPE, receive_signal) == SIG_ERR) {
fprintf(stderr, "Error setting signal handler for SIGPIPE.\n");
}
// Set up thread attributes.
pthread_attr_t thread_attrs;
if(pthread_attr_init(&thread_attrs) != 0) {
perror("Unable to create thread attributes");
exit(2);
}
if(pthread_attr_setdetachstate(&thread_attrs, PTHREAD_CREATE_DETACHED) != 0) {
perror("Unable to set thread attributes");
exit(2);
}
// Set up terminal for reading keypresses.
struct termios orig_term_attr;
struct termios new_term_attr;
tcgetattr(fileno(stdin), &orig_term_attr);
memcpy(&new_term_attr, &orig_term_attr, sizeof(struct termios));
new_term_attr.c_lflag &= ~(ECHO|ICANON);
tcsetattr(fileno(stdin), TCSANOW, &new_term_attr);
// Start background thread to read keypresses.
if((pthread_create(&thread, &thread_attrs, &get_keypresses, NULL)) != 0) {
perror("Unable to create thread");
exit(2);
}
// Main loop.
while(running) {
// Read data from network and output to screen.
}
// Restore original terminal attributes. ***IT BLOCKS HERE***
tcsetattr(fileno(stdin), TCSANOW, &orig_term_attr);
return 0;
}
// Get input from the keyboard.
static void *get_keypresses() {
int c;
while(running) {
// Get keypress. ***NEEDS TO BE INTERRUPTED HERE***
if((c = fgetc(stdin)) != - 1) {
// Handle keypress.
}
}
return NULL;
}
这里有一篇文章介绍了一种可以用来中断的方法。这可以通过诸如@HapKom建议的内容之类的标志或类似集合来使用。还建议使用Sleep();在线程工作者函数中完成动作之后,例如。就在你的'// Handle keypress'注释下。 – ryyker