Working example for SO question 9575981 (http://stackoverflow.com/questions/9575981/how-to-put-a-time-limit-on-user-input/9576051)

9575981.cc

#include <iostream>
#include <vector>

#include <cstdio>
#include <unistd.h>
#include <pthread.h>
#include <termios.h>

using std::cout;
using std::getchar;

pthread_mutex_t qlock;
std::vector<char> queue;

inline void lock_queue() {
	pthread_mutex_lock(&qlock); // XXX handle rv
}

inline void unlock_queue() {
	pthread_mutex_unlock(&qlock); // XXX handle rv
}

#define DEFAULT_ACTION ' '
#define TERMINATE_ACTION 'q'

void perform_action(char action) {
	// magic processing...
	cout << action;
}

void* action_processor(void *) {
	char action;
	cout << "Starting timed processing loop...\n";
	do {
		usleep(1000000);
		lock_queue();
		if (queue.size() == 0) {
			action = DEFAULT_ACTION;
		} else {
			// either handle multiple key events somehow
			// or use the last key event:
			action = queue.back();
			queue.clear();
		}
		unlock_queue();
		perform_action(action);
	} while (action != TERMINATE_ACTION);

	cout << "\nExiting timed processing loop...\n";
	pthread_exit(NULL);
	return NULL;
}

void input_loop() {
	cout << "Starting input loop...\n";

	struct termios term;
	tcgetattr(0, &term);
	cfmakeraw(&term);
	tcsetattr(0, TCSAFLUSH, &term);

	char input;
	do {
		input = (char) getchar(); // XXX handle EOF
		lock_queue();
		queue.push_back(input);
		unlock_queue();
	} while (input != TERMINATE_ACTION);
	cout << "\nExiting input loop...\n";
}

int main(int argc, char *argv[]) {
	pthread_t thread;
	pthread_create(&thread, NULL, action_processor, NULL); // XXX handle rv
	input_loop();

	pthread_exit(NULL);
	return 0;
}