Function augment_flow

plugins/renepay/mcf.c:908–936

Augment a `flow` amount along the path defined by `prev`.*/

/* Augment a `flow` amount along the path defined by `prev`.*/
static void augment_flow(
		const struct linear_network *linear_network,
		struct residual_network *residual_network,
	        const u32 source,
		const u32 target,
		const struct arc *prev,
		s64 flow)
{
	u32 cur = target;

	while(cur!=source)
	{
		assert(cur < tal_count(prev));
		const struct arc arc = prev[cur];
		const struct arc dual = arc_dual(arc);

		assert(arc.idx < tal_count(residual_network->cap));
		assert(dual.idx < tal_count(residual_network->cap));

		residual_network->cap[arc.idx] -= flow;
		residual_network->cap[dual.idx] += flow;

		assert(residual_network->cap[arc.idx] >=0 );

		// we are traversing in the opposite direction to the flow,
		// hence the next node is at the tail of the arc.
		cur = arc_tail(linear_network,arc);
	}
}


// TODO(eduardo): unit test this