f4f2985bdf
Changelog-EXPERIMENTAL: askrene: add dijkstra algorithm Signed-off-by: Lagrang3 <lagrang3@protonmail.com>
73 lines
2.5 KiB
C
73 lines
2.5 KiB
C
#ifndef LIGHTNING_PLUGINS_ASKRENE_ALGORITHM_H
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#define LIGHTNING_PLUGINS_ASKRENE_ALGORITHM_H
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/* Implementation of network algorithms: shortests path, minimum cost flow, etc.
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*/
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#include "config.h"
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#include <plugins/askrene/graph.h>
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/* Search any path from source to destination using Breadth First Search.
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*
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* input:
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* @ctx: tal allocator,
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* @graph: graph of the network,
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* @source: source node,
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* @destination: destination node,
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* @capacity: arcs capacity
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* @cap_threshold: an arc i is traversable if capacity[i]>=cap_threshold
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*
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* output:
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* @prev: prev[i] is the arc that leads to node i for an optimal solution, it
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* @return: true if the destination node was reached.
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*
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* precondition:
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* |capacity|=graph_max_num_arcs
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* |prev|=graph_max_num_nodes
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*
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* The destination is only used as a stopping condition, if destination is
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* passed with an invalid idx then the algorithm will produce a discovery tree
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* of all reacheable nodes from the source.
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* */
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bool BFS_path(const tal_t *ctx, const struct graph *graph,
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const struct node source, const struct node destination,
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const s64 *capacity, const s64 cap_threshold, struct arc *prev);
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/* Computes the distance from the source to every other node in the network
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* using Dijkstra's algorithm.
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*
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* input:
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* @ctx: tal context for internal allocation
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* @graph: topological information of the graph
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* @source: source node
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* @destination: destination node
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* @prune: if prune is true the algorithm stops when the optimal path is found
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* for the destination node
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* @capacity: arcs capacity
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* @cap_threshold: an arc i is traversable if capacity[i]>=cap_threshold
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* @cost: arc's cost
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* @potential: nodes' potential, ie. reduced cost for an arc
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* c_ij = cost_ij - potential[i] + potential[j]
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*
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* output:
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* @prev: for each node, this is the arc that was used to arrive to it, this can
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* be used to reconstruct the path from the destination to the source,
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* @distance: node's best distance
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* returns true if an optimal path is found for the destination, false otherwise
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*
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* precondition:
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* |capacity|=|cost|=graph_max_num_arcs
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* |prev|=|distance|=graph_max_num_nodes
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* cost[i]>=0
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* if prune is true the destination must be valid
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* */
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bool dijkstra_path(const tal_t *ctx, const struct graph *graph,
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const struct node source, const struct node destination,
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bool prune, const s64 *capacity, const s64 cap_threshold,
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const s64 *cost, const s64 *potential, struct arc *prev,
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s64 *distance);
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#endif /* LIGHTNING_PLUGINS_ASKRENE_ALGORITHM_H */
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