void PipeControlChannel::backgroundProcessor()
{
BALL_LOG_SET_CATEGORY(LOG_CATEGORY);
while (d_isRunningFlag) {
if (0 != readNamedPipe()) {
BALL_LOG_WARN << "Error processing M-trap: "
"unable to read from named pipe '"
<< d_pipeName << "'"
<< BALL_LOG_END;
return; // RETURN
}
}
BALL_LOG_TRACE << "The background thread has stopped" << BALL_LOG_END;
}
int main(void){
/* Create the ANONYMOUS PIPE. This is used sending a message from the CHILD
* to the PARENT. The contents of this message are then passed as an
* ARGUMENT when executing the writer program. */
pipe(fd_anon);
// Install SIGNAL HANDLERS:
sigset_t sig;
sigemptyset(&sig);
newhandler.sa_mask = sig;
newhandler.sa_flags = 0;
newhandler.sa_handler = next;
if(sigaction(SIGALRM, &newhandler, &oldhandler) == -1){
printf("\nERROR INSTALLING SIGALRM!\n");
exit(-1);
}
newhandler.sa_handler = checkAnonPipe;
if(sigaction(SIGUSR1, &newhandler, &oldhandler) == -1){
printf("\nERROR INSTALLING SIGUSR1!\n");
exit(-1);
}
int ppid = getpid();
int cpid = fork();
if(cpid == 0){
// IF CHILD, initiate the NCURSES ENVIRONMENT.
/* NOTE: It's worth mentioning that this process will later be
* FORKED again to create a second process that will handle
* the INPUT WINDOW while this one handles the OUTPUT WINDOW.
* From hereon, I'll refer to this process as CHILD0 and the
* CHILD of this process as CHILD1. */
initscr();
cbreak();
noecho();
keypad(stdscr, TRUE);
nodelay(stdscr,TRUE);
start_color();
init_pair(1, COLOR_WHITE, COLOR_BLUE);
refresh();
// Create the OUTPUT WINDOW:
int wid = 10;
int len = 30;
int y_min = 1;
int y_max = (wid-2);
int x_min = 1;
int x_max = (len-2);
int y_curr = y_min;
int x_curr = x_min;
WINDOW *win = newwin(wid, len, 5, 1);
box(win, 0, 0);
wbkgd(win, COLOR_PAIR(1));
wrefresh(win);
wmove(win, y_curr, x_curr);
refresh();
cpid = fork();
if(cpid == 0){
// IF CHILD1, handle the OUTPUT WINDOW...
char *msg;
output_start:
msg = readNamedPipe();
getyx(win, y_curr, x_curr);
if(y_curr > y_max)
y_curr = y_min;
wmove(win, y_curr, x_curr);
wprintw(win, msg);
wrefresh(win);
wmove(win, (y_curr+1), x_min);
refresh();
goto output_start;
} else{
// IF CHILD0, handle the INPUT WINDOW...
/* NOTE: Remember how I created the OUTPUT WINDOW before the
* FORK? Because that WINDOW now exists in both the
* context of CHILD0 and CHILD1, I'm going to delete
* it in CHILD0 before proceeding to the creation of
* the INPUT WINDOW.
* The reason I created the OUTPUT WINDOW first was
* because if it was initialized inside of CHILD1, it
* caused a protential issue where if CHILD0 finished
* creating the INPUT WINDOW before CHILD1 finished
* its WINDOW, it would affect the way the latter was
* being drawn. */
delwin(win);
// Create INPUT WINDOW:
wid = 3;
len = 30;
y_max = (wid-2);
x_max = (len-2);
win = newwin(wid, len, 22, 1);
box(win, 0, 0);
wbkgd(win, COLOR_PAIR(1));
wrefresh(win);
std::string msg;
input_start:
wmove(win, y_min, x_min);
refresh();
getyx(win, y_curr, x_curr);
int ch;
while(ch = getch()){
if(ch == '\n')
break;
if(ch != ERR){
if(ch == KEY_BACKSPACE){
if(strlen(msg.c_str()) != 0){
msg.pop_back();
getyx(win, y_curr, x_curr);
wmove(win,
y_curr, (x_curr-1));
wprintw(win, " ");
wmove(win,
y_curr, (x_curr-1));
}
} else if(ch == KEY_UP ||
ch == KEY_DOWN ||
ch == KEY_LEFT ||
ch == KEY_RIGHT){
; /* Ignore input of arforementioned
* key codes in IF STMT. */
} else{
if(strlen(msg.c_str()) < x_max){
std::string chr;
chr.push_back((char)ch);
msg.push_back((char)ch);
wprintw(win, chr.c_str());
}
}
wrefresh(win);
getyx(win, y_curr, x_curr);
wmove(win, y_curr, x_curr);
refresh();
}
}
writeAnonPipe(msg);
/* Signal the PARENT that there's a message in the ANONYMOUS
* PIPE (see line above). This simply changes the msg_avail
* BOOLEAN to TRUE in the context of the PARENT. */
kill(ppid, SIGUSR1);
msg.clear();
wmove(win, y_min, x_min);
refresh();
for(int i = x_min; i <= x_max; i++)
wprintw(win, " ");
wrefresh(win);
goto input_start;
}
} else{
// IF PARENT, begin the round-robin SCHEDULER routine...
char *msg;
scheduler_start:
if(msg_avail){
msg = readAnonPipe();
execute(msg);
}
alarm(3);
pause();
goto scheduler_start;
}
return 0;
}