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Use correct upper bound condition for MLD routing

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Michael Krasnyk 2017-03-14 16:04:15 +01:00
parent 152f77b665
commit a75fd560d7
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GPG Key ID: 49C12AD0F43D2108
1 changed files with 33 additions and 57 deletions
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90
include/engine/routing_algorithms/routing_base_mld.hpp
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@ -26,9 +26,7 @@ void routingStep(const datafacade::ContiguousInternalMemoryDataFacade<algorithm:
const std::pair<LevelID, CellID> &parent_cell, const std::pair<LevelID, CellID> &parent_cell,
const std::function<LevelID(const NodeID)> &get_query_level, const std::function<LevelID(const NodeID)> &get_query_level,
NodeID &middle_node, NodeID &middle_node,
EdgeWeight &path_upper_bound, EdgeWeight &path_upper_bound)
EdgeWeight &forward_upper_bound,
EdgeWeight &reverse_upper_bound)
{ {
const auto &partition = facade.GetMultiLevelPartition(); const auto &partition = facade.GetMultiLevelPartition();
const auto &cells = facade.GetCellStorage(); const auto &cells = facade.GetCellStorage();
@ -36,25 +34,21 @@ void routingStep(const datafacade::ContiguousInternalMemoryDataFacade<algorithm:
const auto node = forward_heap.DeleteMin(); const auto node = forward_heap.DeleteMin();
const auto weight = forward_heap.GetKey(node); const auto weight = forward_heap.GetKey(node);
auto update_upper_bounds = [&](NodeID to, EdgeWeight forward_weight, EdgeWeight edge_weight) { // Upper bound for the path source -> target with
// Upper bound for the path source -> target with // weight(source -> node) = weight weight(to -> target) ≤ reverse_weight
// weight(source -> node) = forward_weight, weight(node -> to) = edge_weight and // is weight + reverse_weight
// weight(to -> target) ≤ reverse_weight is forward_weight + edge_weight + reverse_weight // More tighter upper bound requires additional condition reverse_heap.WasRemoved(to)
// More tighter upper bound requires additional condition reverse_heap.WasRemoved(to) // with weight(to -> target) = reverse_weight and all weights ≥ 0
// with weight(to -> target) = reverse_weight and all weights ≥ 0 if (reverse_heap.WasInserted(node))
if (reverse_heap.WasInserted(to)) {
auto reverse_weight = reverse_heap.GetKey(node);
auto path_weight = weight + reverse_weight;
if (path_weight >= 0 && path_weight < path_upper_bound)
{ {
auto reverse_weight = reverse_heap.GetKey(to); middle_node = node;
auto path_weight = forward_weight + edge_weight + reverse_weight; path_upper_bound = path_weight;
if (path_weight >= 0 && path_weight < path_upper_bound)
{
middle_node = to;
path_upper_bound = path_weight;
forward_upper_bound = forward_weight + edge_weight;
reverse_upper_bound = reverse_weight + edge_weight;
}
} }
}; }
const auto &node_data = forward_heap.GetData(node); const auto &node_data = forward_heap.GetData(node);
const auto level = get_query_level(node); const auto level = get_query_level(node);
@ -63,9 +57,6 @@ void routingStep(const datafacade::ContiguousInternalMemoryDataFacade<algorithm:
(node_data.parent == node || // is the first point of the path (node_data.parent == node || // is the first point of the path
node_data.edge_id != SPECIAL_EDGEID); // or an overlay entreé point node_data.edge_id != SPECIAL_EDGEID); // or an overlay entreé point
// Edge case: single node path
update_upper_bounds(node, weight, 0);
if (check_overlay_edges) if (check_overlay_edges)
{ {
if (DIRECTION == FORWARD_DIRECTION) if (DIRECTION == FORWARD_DIRECTION)
@ -83,13 +74,11 @@ void routingStep(const datafacade::ContiguousInternalMemoryDataFacade<algorithm:
if (!forward_heap.WasInserted(to)) if (!forward_heap.WasInserted(to))
{ {
forward_heap.Insert(to, to_weight, {node}); forward_heap.Insert(to, to_weight, {node});
update_upper_bounds(to, weight, shortcut_weight);
} }
else if (to_weight < forward_heap.GetKey(to)) else if (to_weight < forward_heap.GetKey(to))
{ {
forward_heap.GetData(to) = {node}; forward_heap.GetData(to) = {node};
forward_heap.DecreaseKey(to, to_weight); forward_heap.DecreaseKey(to, to_weight);
update_upper_bounds(to, weight, shortcut_weight);
} }
} }
++destination; ++destination;
@ -110,13 +99,11 @@ void routingStep(const datafacade::ContiguousInternalMemoryDataFacade<algorithm:
if (!forward_heap.WasInserted(to)) if (!forward_heap.WasInserted(to))
{ {
forward_heap.Insert(to, to_weight, {node}); forward_heap.Insert(to, to_weight, {node});
update_upper_bounds(to, weight, shortcut_weight);
} }
else if (to_weight < forward_heap.GetKey(to)) else if (to_weight < forward_heap.GetKey(to))
{ {
forward_heap.GetData(to) = {node}; forward_heap.GetData(to) = {node};
forward_heap.DecreaseKey(to, to_weight); forward_heap.DecreaseKey(to, to_weight);
update_upper_bounds(to, weight, shortcut_weight);
} }
} }
++source; ++source;
@ -146,13 +133,11 @@ void routingStep(const datafacade::ContiguousInternalMemoryDataFacade<algorithm:
if (!forward_heap.WasInserted(to)) if (!forward_heap.WasInserted(to))
{ {
forward_heap.Insert(to, to_weight, {node, edge}); forward_heap.Insert(to, to_weight, {node, edge});
update_upper_bounds(to, weight, edge_data.weight);
} }
else if (to_weight < forward_heap.GetKey(to)) else if (to_weight < forward_heap.GetKey(to))
{ {
forward_heap.GetData(to) = {node, edge}; forward_heap.GetData(to) = {node, edge};
forward_heap.DecreaseKey(to, to_weight); forward_heap.DecreaseKey(to, to_weight);
update_upper_bounds(to, weight, edge_data.weight);
} }
} }
} }
@ -165,44 +150,35 @@ auto search(const datafacade::ContiguousInternalMemoryDataFacade<algorithm::MLD>
const std::pair<LevelID, CellID> &parent_cell, const std::pair<LevelID, CellID> &parent_cell,
const std::function<LevelID(const NodeID)> &get_query_level) const std::function<LevelID(const NodeID)> &get_query_level)
{ {
const auto &partition = facade.GetMultiLevelPartition(); const auto &partition = facade.GetMultiLevelPartition();
BOOST_ASSERT(!forward_heap.Empty() && forward_heap.MinKey() < INVALID_EDGE_WEIGHT);
BOOST_ASSERT(!reverse_heap.Empty() && reverse_heap.MinKey() < INVALID_EDGE_WEIGHT);
// run two-Target Dijkstra routing step. // run two-Target Dijkstra routing step.
NodeID middle = SPECIAL_NODEID; NodeID middle = SPECIAL_NODEID;
EdgeWeight weight = INVALID_EDGE_WEIGHT; EdgeWeight weight = INVALID_EDGE_WEIGHT;
EdgeWeight forward_search_radius = INVALID_EDGE_WEIGHT; EdgeWeight forward_heap_min = forward_heap.MinKey();
EdgeWeight reverse_search_radius = INVALID_EDGE_WEIGHT; EdgeWeight reverse_heap_min = reverse_heap.MinKey();
bool progress; while (forward_heap.Size() + reverse_heap.Size() > 0 &&
do forward_heap_min + reverse_heap_min < weight)
{ {
progress = false; if (!forward_heap.Empty())
if (!forward_heap.Empty() && (forward_heap.MinKey() < forward_search_radius))
{ {
progress = true; routingStep<FORWARD_DIRECTION>(
routingStep<FORWARD_DIRECTION>(facade, facade, forward_heap, reverse_heap, parent_cell, get_query_level, middle, weight);
forward_heap, if (!forward_heap.Empty())
reverse_heap, forward_heap_min = forward_heap.MinKey();
parent_cell,
get_query_level,
middle,
weight,
forward_search_radius,
reverse_search_radius);
} }
if (!reverse_heap.Empty() && (reverse_heap.MinKey() < reverse_search_radius)) if (!reverse_heap.Empty())
{ {
progress = true; routingStep<REVERSE_DIRECTION>(
routingStep<REVERSE_DIRECTION>(facade, facade, reverse_heap, forward_heap, parent_cell, get_query_level, middle, weight);
reverse_heap, if (!reverse_heap.Empty())
forward_heap, reverse_heap_min = reverse_heap.MinKey();
parent_cell,
get_query_level,
middle,
weight,
reverse_search_radius,
forward_search_radius);
} }
} while (progress); };
// No path found for both target nodes? // No path found for both target nodes?
if (weight == INVALID_EDGE_WEIGHT || SPECIAL_NODEID == middle) if (weight == INVALID_EDGE_WEIGHT || SPECIAL_NODEID == middle)