Thread cache generator.

This allows us to poll the event loop & update the progress
on a time interval rather than on an items-completed
interval (the later of which can't easily take host machine
performance into account).

Fixes https://gitlab.com/kicad/code/kicad/-/issues/16506

pcbnew/drc/drc_cache_generator.cpp

@@ -1,7 +1,7 @@
 /*
  * This program source code file is part of KiCad, a free EDA CAD application.
  *
- * Copyright (C) 2022 KiCad Developers.
+ * Copyright (C) 2022-2024 KiCad Developers.
  *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public License
@@ -39,6 +39,8 @@ bool DRC_CACHE_GENERATOR::Run()
     int&           largestPhysicalClearance = m_board->m_DRCMaxPhysicalClearance;
     DRC_CONSTRAINT worstConstraint;
     LSET           boardCopperLayers = LSET::AllCuMask( m_board->GetCopperLayerCount() );
+    thread_pool&   tp = GetKiCadThreadPool();
+
 
     largestClearance = std::max( largestClearance, m_board->GetMaxClearanceValue() );
 
@@ -81,11 +83,8 @@ bool DRC_CACHE_GENERATOR::Run()
         }
     }
 
-    // This is the number of tests between 2 calls to the progress bar.
+    size_t              count = 0;
-    // Note that zones are -not- done here, so it's reasonably fast.
+    std::atomic<size_t> done( 1 );
-    size_t progressDelta = 500;
-    size_t count = 0;
-    size_t ii = 0;
 
     auto countItems =
             [&]( BOARD_ITEM* item ) -> bool
@@ -97,7 +96,7 @@ bool DRC_CACHE_GENERATOR::Run()
     auto addToCopperTree =
             [&]( BOARD_ITEM* item ) -> bool
             {
-                if( !reportProgress( ii++, count, progressDelta ) )
+                if( m_drcEngine->IsCancelled() )
                     return false;
 
                 LSET copperLayers = item->GetLayerSet() & boardCopperLayers;
@@ -117,6 +116,7 @@ bool DRC_CACHE_GENERATOR::Run()
                         m_board->m_CopperItemRTreeCache->Insert( item, layer, largestClearance );
                 }
 
+                done.fetch_add( 1 );
                 return true;
             };
 
@@ -133,13 +133,23 @@ bool DRC_CACHE_GENERATOR::Run()
 
     forEachGeometryItem( itemTypes, LSET::AllCuMask(), countItems );
 
+    std::future<void> retn = tp.submit(
+            [&]()
+            {
+                std::unique_lock<std::mutex> cacheLock( m_board->m_CachesMutex );
+
+                if( !m_board->m_CopperItemRTreeCache )
+                    m_board->m_CopperItemRTreeCache = std::make_shared<DRC_RTREE>();
+
+                forEachGeometryItem( itemTypes, LSET::AllCuMask(), addToCopperTree );
+            } );
+
+    std::future_status status = retn.wait_for( std::chrono::milliseconds( 250 ) );
+
+    while( status != std::future_status::ready )
     {
-        std::unique_lock<std::mutex> cacheLock( m_board->m_CachesMutex );
+        m_drcEngine->ReportProgress( static_cast<double>( done ) / count );
-
+        status = retn.wait_for( std::chrono::milliseconds( 250 ) );
-        if( !m_board->m_CopperItemRTreeCache )
-            m_board->m_CopperItemRTreeCache = std::make_shared<DRC_RTREE>();
-
-        forEachGeometryItem( itemTypes, LSET::AllCuMask(), addToCopperTree );
     }
 
     if( !reportPhase( _( "Tessellating copper zones..." ) ) )
@@ -151,9 +161,7 @@ bool DRC_CACHE_GENERATOR::Run()
     for( FOOTPRINT* footprint : m_board->Footprints() )
         footprint->BuildCourtyardCaches();
 
-    thread_pool&                     tp = GetKiCadThreadPool();
     std::vector<std::future<size_t>> returns;
-    std::atomic<size_t>              done( 1 );
 
     returns.reserve( allZones.size() );
 
@@ -188,9 +196,11 @@ bool DRC_CACHE_GENERATOR::Run()
     for( ZONE* zone : allZones )
         returns.emplace_back( tp.submit( cache_zones, zone ) );
 
+    done.store( 1 );
+
     for( const std::future<size_t>& ret : returns )
     {
-        std::future_status status = ret.wait_for( std::chrono::milliseconds( 250 ) );
+        status = ret.wait_for( std::chrono::milliseconds( 250 ) );
 
         while( status != std::future_status::ready )
         {