Function channelfilter_cb

plugins/renepay/mods.c:1199–1244

 */

static struct command_result *channelfilter_cb(struct payment *payment)
{
	assert(payment);
	assert(pay_plugin->gossmap);
	const double HTLC_MAX_FRACTION = 0.01; // 1%
	const u64 HTLC_MAX_STOP_MSAT = 1000000000; // 1M sats

	u64 disabled_count = 0;


	u64 htlc_max_threshold = HTLC_MAX_FRACTION * payment->payment_info
		.amount.millisatoshis; /* Raw: a fraction of this amount. */
	/* Don't exclude channels with htlc_max above HTLC_MAX_STOP_MSAT even if
	 * that represents a fraction of the payment smaller than
	 * HTLC_MAX_FRACTION. */
	htlc_max_threshold = MIN(htlc_max_threshold, HTLC_MAX_STOP_MSAT);

	gossmap_apply_localmods(pay_plugin->gossmap, payment->local_gossmods);
	for (const struct gossmap_node *node =
		 gossmap_first_node(pay_plugin->gossmap);
	     node; node = gossmap_next_node(pay_plugin->gossmap, node)) {
		for (size_t i = 0; i < node->num_chans; i++) {
			int dir;
			const struct gossmap_chan *chan = gossmap_nth_chan(
			    pay_plugin->gossmap, node, i, &dir);
			const u64 htlc_max =
			    fp16_to_u64(chan->half[dir].htlc_max);
			if (htlc_max < htlc_max_threshold) {
				struct short_channel_id_dir scidd = {
				    .scid = gossmap_chan_scid(
					pay_plugin->gossmap, chan),
				    .dir = dir};
				disabledmap_add_channel(payment->disabledmap,
							scidd);
				disabled_count++;
			}
		}
	}
	gossmap_remove_localmods(pay_plugin->gossmap, payment->local_gossmods);
	// FIXME: prune the network over other parameters, eg. capacity,
	// fees, ...
	plugin_log(pay_plugin->plugin, LOG_DBG,
		   "channelfilter: disabling %" PRIu64 " channels.",
		   disabled_count);
	return payment_continue(payment);
}

REGISTER_PAYMENT_MODIFIER(channelfilter, channelfilter_cb);