#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <errno.h>
#include <sys/eventfd.h>
#include <sys/select.h>
#include <sys/time.h>
#include <sys/types.h>
#include <pthread.h>

int efd[1024];
int fd_count = 250;
int write_sleep = 250;

void write_thread ()
{
	int index;
	uint64_t count = 0;
	srand (time (NULL));

	while (1)
	{
		index = rand () % fd_count;
		if (efd[index] != 0)
		{
			write (efd[index], &count, sizeof (uint64_t));
		}
		++count;
		usleep (write_sleep);
	}
}


int main (int argc, char **argv)
{
	fd_set fds;
	struct timeval timeout = { 0, 0 };
	int max_fd = 0;
	int sleep_time = 90;
	int count = 0;
	pthread_t pid;
	int i = 0;
	if (argc > 1)
	{
		for (i = 0; i < argc; ++i)
		{
			if (strcmp (argv[i], "-f") == 0)
			{
				fd_count = atoi (argv[i + 1]);
				if (fd_count > 1024)
					fd_count = 1024;
				++i;
			}
			else if (strcmp (argv[i], "-s") == 0)
			{
				sleep_time = atoi (argv[i + 1]);
				++i;
			}
			else if (strcmp (argv[i], "-w") == 0)
			{
				write_sleep = atoi (argv[i + 1]);
				++i;
			}
		}
	}
	for (i = 0; i < fd_count; ++i)
	{
		efd[i] = eventfd (0, EFD_NONBLOCK);
		if (efd[i] == 0)
		{
			printf ("create %dth fd failed,errno:%d\n", i, errno);
			return 0;
		}
	}

	pthread_create (&pid, NULL, (void*)write_thread, NULL);

	while (1)
	{
		FD_ZERO (&fds);
		for (i = 0; i < fd_count; ++i)
		{
			if (efd[i] != 0)
				FD_SET (efd[i], &fds);
			if (efd[i] > max_fd)
				max_fd = efd[i];
		}

		int ret = 0;
		timeout.tv_sec = 0;
		timeout.tv_usec = sleep_time;
		ret = select (max_fd, &fds, NULL, NULL, NULL);
		//usleep(sleep_time);
		uint64_t nosense;
		count = 0;
		for (i = 0; i < fd_count; ++i)
		{
			if (FD_ISSET (efd[i], &fds))
			{
				read (efd[i], &nosense, sizeof (uint64_t));
				++count;
			}
			if (count >= ret)
			{
				break;
			}
		}
	}
	for (i = 0; i < fd_count; ++i)
		close (efd[i]);
	return 0;
}