From 45f64e672f87417ab3b611d134548c45dcd59d1b Mon Sep 17 00:00:00 2001
From: Siarhei Fedartsou <siarhei.fedartsou@gmail.com>
Date: Tue, 21 May 2024 20:41:25 +0200
Subject: [PATCH] Draft: re-use forward heap in map matching

---
 .../routing_algorithms/routing_base_mld.hpp   | 32 ++++++++++---------
 .../routing_algorithms/map_matching.cpp       |  4 +++
 2 files changed, 21 insertions(+), 15 deletions(-)

diff --git a/include/engine/routing_algorithms/routing_base_mld.hpp b/include/engine/routing_algorithms/routing_base_mld.hpp
index d4e3e9f21..e1ede1ef0 100644
--- a/include/engine/routing_algorithms/routing_base_mld.hpp
+++ b/include/engine/routing_algorithms/routing_base_mld.hpp
@@ -701,25 +701,27 @@ double getNetworkDistance(SearchEngineData<Algorithm> &engine_working_data,
                           const PhantomNode &target_phantom,
                           EdgeWeight weight_upper_bound = INVALID_EDGE_WEIGHT)
 {
-    forward_heap.Clear();
     reverse_heap.Clear();
 
-    if (source_phantom.IsValidForwardSource())
+    if (forward_heap.Empty())
     {
-        forward_heap.Insert(source_phantom.forward_segment_id.id,
-                            EdgeWeight{0} - source_phantom.GetForwardWeightPlusOffset(),
-                            {source_phantom.forward_segment_id.id,
-                             false,
-                             EdgeDistance{0} - source_phantom.GetForwardDistance()});
-    }
+        if (source_phantom.IsValidForwardSource())
+        {
+            forward_heap.Insert(source_phantom.forward_segment_id.id,
+                                EdgeWeight{0} - source_phantom.GetForwardWeightPlusOffset(),
+                                {source_phantom.forward_segment_id.id,
+                                 false,
+                                 EdgeDistance{0} - source_phantom.GetForwardDistance()});
+        }
 
-    if (source_phantom.IsValidReverseSource())
-    {
-        forward_heap.Insert(source_phantom.reverse_segment_id.id,
-                            EdgeWeight{0} - source_phantom.GetReverseWeightPlusOffset(),
-                            {source_phantom.reverse_segment_id.id,
-                             false,
-                             EdgeDistance{0} - source_phantom.GetReverseDistance()});
+        if (source_phantom.IsValidReverseSource())
+        {
+            forward_heap.Insert(source_phantom.reverse_segment_id.id,
+                                EdgeWeight{0} - source_phantom.GetReverseWeightPlusOffset(),
+                                {source_phantom.reverse_segment_id.id,
+                                 false,
+                                 EdgeDistance{0} - source_phantom.GetReverseDistance()});
+        }
     }
 
     if (target_phantom.IsValidForwardTarget())
diff --git a/src/engine/routing_algorithms/map_matching.cpp b/src/engine/routing_algorithms/map_matching.cpp
index 9f8a1d2a5..12c6ac4d3 100644
--- a/src/engine/routing_algorithms/map_matching.cpp
+++ b/src/engine/routing_algorithms/map_matching.cpp
@@ -225,6 +225,8 @@ SubMatchingList mapMatching(SearchEngineData<Algorithm> &engine_working_data,
                     continue;
                 }
 
+                forward_heap.Clear();
+
                 for (const auto s_prime : util::irange<std::size_t>(0UL, current_viterbi.size()))
                 {
                     const double emission_pr = emission_log_probabilities[t][s_prime];
@@ -264,6 +266,8 @@ SubMatchingList mapMatching(SearchEngineData<Algorithm> &engine_working_data,
                         model.breakage[t] = false;
                     }
                 }
+
+                forward_heap.Clear();
             }
 
             if (model.breakage[t])