Function get_flow_singlepath

plugins/askrene/child/mcf.c:897–934

Given a single path build a flow set. */

/* Given a single path build a flow set. */
static struct flow **
get_flow_singlepath(const tal_t *ctx, const struct pay_parameters *params,
		    const struct graph *graph, const struct gossmap *gossmap,
		    const struct node source, const struct node destination,
		    const u64 pay_amount, const struct arc *prev)
{
	struct flow **flows, *f;
	flows = tal_arr(ctx, struct flow *, 1);
	f = flows[0] = tal(flows, struct flow);

	size_t length = 0;

	for (u32 cur_idx = destination.idx; cur_idx != source.idx;) {
		assert(cur_idx != INVALID_INDEX);
		length++;
		struct arc arc = prev[cur_idx];
		struct node next = arc_tail(graph, arc);
		cur_idx = next.idx;
	}
	f->path = tal_arr(f, const struct gossmap_chan *, length);
	f->dirs = tal_arr(f, int, length);

	for (u32 cur_idx = destination.idx; cur_idx != source.idx;) {
		int chandir;
		u32 chanidx;
		struct arc arc = prev[cur_idx];
		arc_to_parts(arc, &chanidx, &chandir, NULL, NULL);

		length--;
		f->path[length] = gossmap_chan_byidx(gossmap, chanidx);
		f->dirs[length] = chandir;

		struct node next = arc_tail(graph, arc);
		cur_idx = next.idx;
	}
	f->delivers = params->amount;
	return flows;
}

// TODO(eduardo): choose some default values for the minflow parameters
/* eduardo: I think it should be clear that this module deals with linear