BIND9 递归查询超时机制

最新推荐文章于 2023-11-13 19:37:16 发布

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本文深入探讨了如何在特定场景下设置重试间隔的算法实现，包括首次尝试后的指数退避策略以及如何根据往返时间调整重试间隔，确保系统稳定性和效率。

static inline void
fctx_setretryinterval(fetchctx_t *fctx, unsigned int rtt) {
	unsigned int seconds;
	unsigned int us;

	/*
	 * We retry every .8 seconds the first two times through the address
	 * list, and then we do exponential back-off.
	 */
	if (fctx->restarts < 3)
		us = 800000;
	else
		us = (800000 << (fctx->restarts - 2));

	/*
	 * Double the round-trip time.
	 */
	rtt *= 2;

	/*
	 * Always wait for at least the doubled round-trip time.
	 */
	if (us < rtt)
		us = rtt;

	/*
	 * But don't ever wait for more than 10 seconds.
	 */
	if (us > 10000000)
		us = 10000000;

	seconds = us / 1000000;
	us -= seconds * 1000000;
	isc_interval_set(&fctx->interval, seconds, us * 1000);
}