Split ratsnest optimization into separate parallel threads.

Fixes https://gitlab.com/kicad/code/kicad/issues/12968

pcbnew/connectivity/connectivity_data.cpp

@@ -178,7 +178,14 @@ void CONNECTIVITY_DATA::updateRatsnest()
             [&]( const int a, const int b)
             {
                 for( int ii = a; ii < b; ++ii )
-                    dirty_nets[ii]->Update();
+                    dirty_nets[ ii ]->UpdateNet();
+            }).wait();
+
+    GetKiCadThreadPool().parallelize_loop( 0, dirty_nets.size(),
+            [&]( const int a, const int b)
+            {
+                for( int ii = a; ii < b; ++ii )
+                    dirty_nets[ii]->OptimizeNet();
             }).wait();
 
 #ifdef PROFILE

pcbnew/ratsnest/ratsnest_data.cpp

@@ -437,19 +437,24 @@ void RN_NET::optimizeRNEdges()
 }
 
 
-void RN_NET::Update()
+void RN_NET::UpdateNet()
 {
     compute();
+    m_dirty = false;
+}
 
+
+void RN_NET::OptimizeNet()
+{
 #ifdef PROFILE
     PROF_TIMER cnt( "optimize" );
 #endif
+
     optimizeRNEdges();
+
 #ifdef PROFILE
     cnt.Show();
 #endif
-
-    m_dirty = false;
 }
 
 

pcbnew/ratsnest/ratsnest_data.h

@@ -80,7 +80,8 @@ public:
     /**
      * Recompute ratsnest for a net.
      */
-    void Update();
+    void UpdateNet();
+    void OptimizeNet();
     void Clear();
 
     void AddCluster( std::shared_ptr<CN_CLUSTER> aCluster );