Function dijkstra_

common/dijkstra.c:123–264

Do Dijkstra: start in this case is the dst node. */

/* Do Dijkstra: start in this case is the dst node. */
const struct dijkstra *
dijkstra_(const tal_t *ctx,
	  const struct gossmap *map,
	  const struct gossmap_node *start,
	  struct amount_msat amount,
	  double riskfactor,
	  bool (*channel_ok)(const struct gossmap *map,
			     const struct gossmap_chan *c,
			     int dir,
			     struct amount_msat amount,
			     void *arg),
	  u64 (*path_score)(u32 distance,
			    struct amount_msat cost,
			    struct amount_msat risk,
			    int dir,
			    const struct gossmap_chan *c),
	  void *arg)
{
	struct dijkstra *dij;
	const struct gossmap_node **heap;
	size_t heapsize;
	struct gheap_ctx gheap_ctx;

	/* There doesn't seem to be much difference with fanout 2-4. */
	gheap_ctx.fanout = 2;
	/* There seems to be a slight decrease if we alter this value. */
	gheap_ctx.page_chunks = 1;
	gheap_ctx.item_size = sizeof(*heap);
	gheap_ctx.less_comparer = less_comparer;
	gheap_ctx.less_comparer_ctx = NULL;
	gheap_ctx.item_mover = item_mover;

	dij = tal_arr(ctx, struct dijkstra, gossmap_max_node_idx(map));

	/* Pay no attention to the man behind the curtain! */
	global_map = map;
	global_dijkstra = dij;

	/* Wikipedia's article on Dijkstra is excellent:
	 *    https://en.wikipedia.org/wiki/Dijkstra's_algorithm
	 * (License https://creativecommons.org/licenses/by-sa/3.0/)
	 *
	 * So I quote here:
	 *
	 * 1. Mark all nodes unvisited. Create a set of all the unvisited
	 * nodes called the unvisited set.
	 *
	 * 2. Assign to every node a tentative distance value: set it to zero
	 * for our initial node and to infinity for all other nodes. Set the
	 * initial node as current.[14]
	 */
	heap = mkheap(NULL, dij, map, start, amount);
	heapsize = tal_count(heap);

	/*
	 * 3. For the current node, consider all of its unvisited neighbouds
	 * and calculate their tentative distances through the current
	 * node. Compare the newly calculated tentative distance to the