Function __event_loop

examples/proxy.c:2018–2105

* Event loop shared between the parent, and the connections. Could be * split in two, as they don't handle the same types of events. For the per * connection loop, 'c' is valid. For the main loop, it's NULL. */

 * connection loop, 'c' is valid. For the main loop, it's NULL.
 */
static int __event_loop(struct io_uring *ring, struct conn *c)
{
	struct __kernel_timespec active_ts, idle_ts;
	int flags;

	idle_ts.tv_sec = 0;
	idle_ts.tv_nsec = 100000000LL;
	active_ts = idle_ts;
	if (wait_usec > 1000000) {
		active_ts.tv_sec = wait_usec / 1000000;
		wait_usec -= active_ts.tv_sec * 1000000;
	}
	active_ts.tv_nsec = wait_usec * 1000;

	gettimeofday(&last_housekeeping, NULL);

	flags = 0;
	while (1) {
		struct __kernel_timespec *ts = &idle_ts;
		struct io_uring_cqe *cqe;
		unsigned int head;
		int ret, i, to_wait;

		/*
		 * If wait_batch is set higher than 1, then we'll wait on
		 * that amount of CQEs to be posted each loop. If used with
		 * DEFER_TASKRUN, this can provide a substantial reduction
		 * in context switch rate as the task isn't woken until the
		 * requested number of events can be returned.
		 *
		 * Can be used with -t to set a wait_usec timeout as well.
		 * For example, if an application can deal with 250 usec
		 * of wait latencies, it can set -w8 -t250 which will cause
		 * io_uring to return when either 8 events have been received,
		 * or if 250 usec of waiting has passed.
		 *
		 * If we don't have any open connections, wait on just 1
		 * always.
		 */
		to_wait = 1;
		if (open_conns && !flags) {
			ts = &active_ts;
			to_wait = wait_batch;
		}

		vlog("Submit and wait for %d\n", to_wait);
		ret = io_uring_submit_and_wait_timeout(ring, &cqe, to_wait, ts, NULL);

		if (*ring->cq.koverflow)
			printf("overflow %u\n", *ring->cq.koverflow);
		if (*ring->sq.kflags &  IORING_SQ_CQ_OVERFLOW)
			printf("saw overflow\n");

		vlog("Submit and wait: %d\n", ret);

		i = flags = 0;
		io_uring_for_each_cqe(ring, head, cqe) {
			if (handle_cqe(ring, cqe))