connectivity_algo.cpp

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/*
 * This program source code file is part of KICAD, a free EDA CAD application.
 *
 * Copyright (C) 2016-2018 CERN
 * Copyright The KiCad Developers, see AUTHORS.txt for contributors.
 *
 * @author Tomasz Wlostowski <[email protected]>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */
 
 
#include <algorithm>
#include <chrono>
#include <limits>
#include <mutex>
#include <ranges>
 
#include <connectivity/connectivity_algo.h>
#include <core/union_find.h>
#include <progress_reporter.h>
#include <geometry/geometry_utils.h>
#include <board.h>
#include <board_commit.h>
#include <thread_pool.h>
#include <footprint.h>
#include <pad.h>
#include <pcb_shape.h>
#include <pcb_track.h>
 
#include <wx/log.h>
 
#ifdef PROFILE
#include <core/profile.h>
#endif
 
 
bool CN_CONNECTIVITY_ALGO::Remove( BOARD_ITEM* aItem )
{
    bool anythingDeleted = false;
    markItemNetAsDirty( aItem );
 
    switch( aItem->Type() )
    {
    case PCB_FOOTPRINT_T:
        for( PAD* pad : static_cast<FOOTPRINT*>( aItem )->Pads() )
        {
            if( m_itemMap.find( pad ) != m_itemMap.end() ) // prevent double deletion
            {
                m_itemMap[pad].MarkItemsAsInvalid();
                m_itemMap.erase( pad );
                anythingDeleted = true;
            }
        }
 
        m_itemList.SetDirty( true );
        break;
 
    case PCB_PAD_T:
    case PCB_TRACE_T:
    case PCB_ARC_T:
    case PCB_VIA_T:
    case PCB_ZONE_T:
    case PCB_SHAPE_T:
        if( m_itemMap.find( aItem ) != m_itemMap.end() ) // prevent double deletion
        {
            m_itemMap[aItem].MarkItemsAsInvalid();
            m_itemMap.erase ( aItem );
            m_itemList.SetDirty( true );
            anythingDeleted = true;
        }
        break;
 
    default:
        return false;
    }
 
 
    // Once we delete an item, it may connect between lists, so mark both as potentially invalid
    if( anythingDeleted )
        m_itemList.SetHasInvalid( true );
 
    return true;
}
 
 
void CN_CONNECTIVITY_ALGO::markItemNetAsDirty( const BOARD_ITEM* aItem )
{
    if( aItem->IsConnected() )
    {
        const BOARD_CONNECTED_ITEM* citem = static_cast<const BOARD_CONNECTED_ITEM*>( aItem );
        MarkNetAsDirty( citem->GetNetCode() );
    }
    else
    {
        if( aItem->Type() == PCB_FOOTPRINT_T )
        {
            const FOOTPRINT* footprint = static_cast<const FOOTPRINT*>( aItem );
 
            for( PAD* pad : footprint->Pads() )
                MarkNetAsDirty( pad->GetNetCode() );
        }
    }
}
 
 
bool CN_CONNECTIVITY_ALGO::Add( BOARD_ITEM* aItem )
{
    auto alreadyAdded =
            [this]( BOARD_ITEM* item )
            {
                auto it = m_itemMap.find( item );
 
                if( it == m_itemMap.end() )
                    return false;
 
                // Don't be fooled by an empty ITEM_MAP_ENTRY auto-created by operator[].
                return !it->second.GetItems().empty();
            };
 
    switch( aItem->Type() )
    {
    case PCB_NETINFO_T:
        MarkNetAsDirty( static_cast<NETINFO_ITEM*>( aItem )->GetNetCode() );
        break;
 
    case PCB_FOOTPRINT_T:
    {
        if( static_cast<FOOTPRINT*>( aItem )->GetAttributes() & FP_JUST_ADDED )
            return false;
 
        for( PAD* pad : static_cast<FOOTPRINT*>( aItem )->Pads() )
        {
            if( !pad->IsOnCopperLayer() )
                continue;
 
            if( alreadyAdded( pad ) )
                return false;
 
            add( m_itemList, pad );
        }
 
        break;
    }
 
    case PCB_PAD_T:
    {
        if( !aItem->IsOnCopperLayer() )
            return false;
 
        if( FOOTPRINT* fp = aItem->GetParentFootprint() )
        {
            if( fp->GetAttributes() & FP_JUST_ADDED )
                return false;
        }
 
        if( alreadyAdded( aItem ) )
            return false;
 
        add( m_itemList, static_cast<PAD*>( aItem ) );
        break;
    }
 
    case PCB_TRACE_T:
        if( alreadyAdded( aItem ) )
            return false;
 
        add( m_itemList, static_cast<PCB_TRACK*>( aItem ) );
        break;
 
    case PCB_ARC_T:
        if( alreadyAdded( aItem ) )
            return false;
 
        add( m_itemList, static_cast<PCB_ARC*>( aItem ) );
        break;
 
    case PCB_VIA_T:
        if( alreadyAdded( aItem ) )
            return false;
 
        add( m_itemList, static_cast<PCB_VIA*>( aItem ) );
        break;
 
    case PCB_SHAPE_T:
        if( !aItem->IsOnCopperLayer() )
            return false;
 
        if( alreadyAdded( aItem ) )
            return false;
 
        if( !IsCopperLayer( aItem->GetLayer() ) )
            return false;
 
        add( m_itemList, static_cast<PCB_SHAPE*>( aItem ) );
        break;
 
    case PCB_ZONE_T:
    {
        if( !aItem->IsOnCopperLayer() )
            return false;
 
        ZONE* zone = static_cast<ZONE*>( aItem );
 
        if( alreadyAdded( aItem ) )
            return false;
 
        m_itemMap[zone] = ITEM_MAP_ENTRY();
 
        // Don't check for connections on layers that only exist in the zone but
        // were disabled in the board
        BOARD* board = zone->GetBoard();
        LSET layerset = board->GetEnabledLayers() & zone->GetLayerSet();
 
        layerset.RunOnLayers(
                [&]( PCB_LAYER_ID layer )
                {
                    for( CN_ITEM* zitem : m_itemList.Add( zone, layer ) )
                        m_itemMap[zone].Link( zitem );
                } );
 
        break;
    }
 
    default:
        return false;
    }
 
    markItemNetAsDirty( aItem );
 
    return true;
}
 
 
void CN_CONNECTIVITY_ALGO::RemoveInvalidRefs()
{
    for( CN_ITEM* item : m_itemList )
        item->RemoveInvalidRefs();
}
 
 
void CN_CONNECTIVITY_ALGO::searchConnections()
{
    std::lock_guard lock( m_mutex );
#ifdef PROFILE
    PROF_TIMER garbage_collection( "garbage-collection" );
#endif
    std::vector<CN_ITEM*> garbage;
    garbage.reserve( 1024 );
 
    m_parentConnectivityData->RemoveInvalidRefs();
 
    if( m_isLocal )
        m_globalConnectivityData->RemoveInvalidRefs();
 
    m_itemList.RemoveInvalidItems( garbage );
 
    for( CN_ITEM* item : garbage )
        delete item;
 
#ifdef PROFILE
    garbage_collection.Show();
    PROF_TIMER search_basic( "search-basic" );
#endif
 
    thread_pool& tp = GetKiCadThreadPool();
    std::vector<CN_ITEM*> dirtyItems;
    std::copy_if( m_itemList.begin(), m_itemList.end(), std::back_inserter( dirtyItems ),
                  [] ( CN_ITEM* aItem )
                  {
                      return aItem->Dirty();
                  } );
 
    if( m_progressReporter )
    {
        m_progressReporter->SetMaxProgress( dirtyItems.size() );
 
        if( !m_progressReporter->KeepRefreshing() )
            return;
    }
 
    if( m_itemList.IsDirty() )
    {
        // Collect deferred net code changes to avoid data races in parallel search.
        // Vias connected to zones have their net codes updated after all parallel work
        // completes, but only if the via has no higher-priority connections (tracks, pads).
        std::vector<std::pair<CN_ITEM*, int>> deferredNetCodes;
        std::mutex deferredNetCodesMutex;
 
        // One task per item made the queue and its futures cost more than the searches they
        // carried, so hand the pool blocks of items instead.
        auto returns = tp.submit_loop( size_t( 0 ), dirtyItems.size(),
                [&dirtyItems, this, &deferredNetCodes, &deferredNetCodesMutex]( const size_t ii )
                {
                    if( m_progressReporter && m_progressReporter->IsCancelled() )
                        return;
 
                    CN_VISITOR visitor( dirtyItems[ii], &deferredNetCodes, &deferredNetCodesMutex );
                    m_itemList.FindNearby( dirtyItems[ii], visitor );
 
                    if( m_progressReporter )
                        m_progressReporter->AdvanceProgress();
                } );
 
        // Here we balance returns with a 250ms timeout to allow UI updating
        while( !returns.wait_for( std::chrono::milliseconds( 250 ) ) )
        {
            if( m_progressReporter )
                m_progressReporter->KeepRefreshing();
        }
 
        // Apply deferred zone net changes, but only for vias that have no non-zone
        // connections.  Tracks and pads take priority over zones for net assignment;
        // cluster-based propagation will handle those vias.
        //
        // A single via can touch zones of several different nets (e.g. a through via
        // crossing a GND plane and a power plane).  The order in which those candidate
        // nets are collected depends on the parallel search and is not stable across
        // connectivity rebuilds, so we must not simply pick the first one: doing so makes
        // the via's net flip arbitrarily on every rebuild (i.e. on every undo/redo).
        // Instead, if the via's existing net matches any zone it touches, we keep it.
        // This preserves a deliberately-assigned net and only falls back to a
        // deterministic choice (lowest net code) when the current net no longer touches
        // any zone.
        std::sort( deferredNetCodes.begin(), deferredNetCodes.end(),
                   []( const auto& a, const auto& b ) { return a.first < b.first; } );
 
        for( auto it = deferredNetCodes.begin(); it != deferredNetCodes.end(); )
        {
            CN_ITEM* cnItem = it->first;
 
            // Entries for the same via are contiguous after the sort above.
            auto groupEnd = it;
 
            while( groupEnd != deferredNetCodes.end() && groupEnd->first == cnItem )
                ++groupEnd;
 
            if( std::ranges::any_of( cnItem->ConnectedItems(),
                                     []( const CN_ITEM* c )
                                     {
                                         return c->Parent()->Type() != PCB_ZONE_T;
                                     } ) )
            {
                // Connected to a track or pad, so cluster propagation owns the net.
                it = groupEnd;
                continue;
            }
 
            int  existingNet = cnItem->Parent()->GetNetCode();
            bool keepExisting = false;
            int  bestNet = std::numeric_limits<int>::max();
 
            for( auto entry = it; entry != groupEnd; ++entry )
            {
                if( entry->second == existingNet )
                {
                    keepExisting = true;
                    break;
                }
 
                bestNet = std::min( bestNet, entry->second );
            }
 
            if( !keepExisting )
                cnItem->Parent()->SetNetCode( bestNet );
 
            it = groupEnd;
        }
 
        if( m_progressReporter )
            m_progressReporter->KeepRefreshing();
    }
 
#ifdef PROFILE
        search_basic.Show();
#endif
 
    m_itemList.ClearDirtyFlags();
}
 
 
const CN_CONNECTIVITY_ALGO::CLUSTERS CN_CONNECTIVITY_ALGO::SearchClusters( CLUSTER_SEARCH_MODE aMode )
{
    return SearchClusters( aMode, ( aMode == CSM_PROPAGATE ), -1 );
}
 
 
const CN_CONNECTIVITY_ALGO::CLUSTERS
CN_CONNECTIVITY_ALGO::SearchClusters( CLUSTER_SEARCH_MODE aMode, bool aExcludeZones, int aSingleNet )
{
    bool withinAnyNet = ( aMode != CSM_PROPAGATE );
 
    CLUSTERS clusters;
 
    if( m_itemList.IsDirty() )
        searchConnections();
 
    // Numbering stays local rather than stamped on the items because several DRC threads can
    // be inside this function at once, each with a different view of who takes part
    std::vector<CN_ITEM*> members;
    std::vector<int>      memberOf( m_itemList.Size(), -1 );
 
    members.reserve( m_itemList.Size() );
 
    // aSingleNet restricts which items may seed a cluster, not which may be reached, since
    // propagation mode crosses nets once started.  Hold the net test back for the emit
    std::vector<bool> selected;
    selected.reserve( m_itemList.Size() );
 
    for( CN_ITEM* item : m_itemList )
    {
        bool participates = item->Valid()
                            && !( withinAnyNet && item->Net() <= 0 )
                            && !( withinAnyNet && aSingleNet >= 0 && item->Net() != aSingleNet )
                            && !( aExcludeZones && item->Parent()->Type() == PCB_ZONE_T );
 
        if( participates )
        {
            memberOf[item->ListIndex()] = static_cast<int>( members.size() );
            members.push_back( item );
            selected.push_back( aSingleNet < 0 || item->Net() == aSingleNet );
        }
    }
 
    if( m_progressReporter && m_progressReporter->IsCancelled() )
        return CLUSTERS();
 
    // Every member of a cluster carries the cluster's net, so gating a neighbour on the near
    // end's net selects the same edges as gating it on the component root's
    KI_UNION_FIND forest( members.size() );
 
    // Stays serial although Unite() is lock-free, because DRC enters here from inside a
    // thread pool task and feeding work back to a pool we already occupy deadlocks it
    for( size_t ii = 0; ii < members.size(); ++ii )
    {
        CN_ITEM* item = members[ii];
 
        for( CN_ITEM* neighbour : item->ConnectedItems() )
        {
            int listIndex = neighbour->ListIndex();
 
            // An adjacency that outlived its item would otherwise index the map out of range
            if( listIndex < 0 || listIndex >= (int) memberOf.size() )
                continue;
 
            int index = memberOf[listIndex];
 
            if( index < 0 )
                continue;
 
            if( withinAnyNet && neighbour->Net() != item->Net() )
                continue;
 
            forest.Unite( ii, static_cast<size_t>( index ) );
        }
    }
 
    if( m_progressReporter && m_progressReporter->IsCancelled() )
        return CLUSTERS();
 
    // Index order makes cluster contents a function of the item list alone, so the origin pad
    // elected on a cluster spanning several nets no longer follows the heap layout
    std::vector<int>  clusterOf( members.size(), -1 );
    std::vector<bool> clusterSelected;
 
    for( size_t ii = 0; ii < members.size(); ++ii )
    {
        size_t root = forest.FindCompress( ii );
 
        if( clusterOf[root] < 0 )
        {
            clusterOf[root] = static_cast<int>( clusters.size() );
            clusters.push_back( std::make_shared<CN_CLUSTER>() );
            clusterSelected.push_back( false );
        }
 
        clusters[clusterOf[root]]->Add( members[ii] );
 
        if( selected[ii] )
            clusterSelected[clusterOf[root]] = true;
    }
 
    // A component reached only from items outside aSingleNet was never a result
    if( aSingleNet >= 0 )
    {
        CLUSTERS keep;
 
        for( size_t ii = 0; ii < clusters.size(); ++ii )
        {
            if( clusterSelected[ii] )
                keep.push_back( std::move( clusters[ii] ) );
        }
 
        clusters = std::move( keep );
    }
 
    std::sort( clusters.begin(), clusters.end(),
               []( const std::shared_ptr<CN_CLUSTER>& a, const std::shared_ptr<CN_CLUSTER>& b )
               {
                   return a->OriginNet() < b->OriginNet();
               } );
 
    return clusters;
}
 
 
void CN_CONNECTIVITY_ALGO::Build( BOARD* aBoard, PROGRESS_REPORTER* aReporter )
{
    // Nothing queries the index until searchConnections(), so index the board in one packed
    // load rather than run the R*-tree insertion heuristic once per item
    CN_LIST::BULK_ADD_SCOPE bulkAdd( m_itemList );
 
    // Generate CN_ZONE_LAYERs for each island on each layer of each zone
    //
    std::vector<CN_ZONE_LAYER*> zitems;
 
    for( ZONE* zone : aBoard->Zones() )
    {
        if( zone->IsOnCopperLayer() )
        {
            m_itemMap[zone] = ITEM_MAP_ENTRY();
            markItemNetAsDirty( zone );
 
            // Don't check for connections on layers that only exist in the zone but
            // were disabled in the board
            BOARD* board = zone->GetBoard();
            LSET layerset = board->GetEnabledLayers() & zone->GetLayerSet() & LSET::AllCuMask();
 
            layerset.RunOnLayers(
                    [&]( PCB_LAYER_ID layer )
                    {
                        for( int j = 0; j < zone->GetFilledPolysList( layer )->OutlineCount(); j++ )
                            zitems.push_back( new CN_ZONE_LAYER( zone, layer, j ) );
                    } );
        }
    }
 
    // Setup progress metrics
    //
    int    progressDelta = 50;
    double size = 0.0;
 
    size += zitems.size();        // Once for building RTrees
    size += zitems.size();        // Once for adding to connectivity
    size += aBoard->Tracks().size();
    size += aBoard->Drawings().size();
 
    for( FOOTPRINT* footprint : aBoard->Footprints() )
        size += footprint->Pads().size();
 
    size *= 1.5;                  // Our caller gets the other third of the progress bar
 
    progressDelta = std::max( progressDelta, (int) size / 4 );
 
    auto report =
            [&]( int progress )
            {
                if( aReporter && ( progress % progressDelta ) == 0 )
                {
                    aReporter->SetCurrentProgress( progress / size );
                    aReporter->KeepRefreshing( false );
                }
            };
 
    // Generate RTrees for CN_ZONE_LAYER items (in parallel)
    //
    thread_pool& tp = GetKiCadThreadPool();
    // Extra blocks let the pool balance islands with different fill sizes
    auto returns = tp.submit_loop( size_t( 0 ), zitems.size(),
            [aReporter, &zitems]( const size_t ii )
            {
                try
                {
                    if( aReporter && aReporter->IsCancelled() )
                        return;
 
                    zitems[ii]->BuildRTree();
 
                    if( aReporter )
                        aReporter->AdvanceProgress();
                }
                catch( ... )
                {
                    // Preserve per-island failure isolation within a shared task
                }
            }, 4 * tp.get_thread_count() );
 
    try
    {
        while( !returns.wait_for( std::chrono::milliseconds( 250 ) ) )
        {
            if( aReporter )
                aReporter->KeepRefreshing();
        }
    }
    catch( ... )
    {
        // Workers must release zitems before this frame unwinds
        returns.wait();
        throw;
    }
 
    // Add CN_ZONE_LAYERS, tracks, and pads to connectivity
    //
    int ii = zitems.size();
 
    for( CN_ZONE_LAYER* zitem : zitems )
    {
        m_itemList.Add( zitem );
        m_itemMap[ zitem->Parent() ].Link( zitem );
        report( ++ii );
    }
 
    for( PCB_TRACK* tv : aBoard->Tracks() )
    {
        Add( tv );
        report( ++ii );
    }
 
    for( FOOTPRINT* footprint : aBoard->Footprints() )
    {
        for( PAD* pad : footprint->Pads() )
        {
            Add( pad );
            report( ++ii );
        }
    }
 
    for( BOARD_ITEM* drawing : aBoard->Drawings() )
    {
        if( PCB_SHAPE* shape = dynamic_cast<PCB_SHAPE*>( drawing ) )
        {
            if( shape->IsOnCopperLayer() )
                Add( shape );
        }
 
        report( ++ii );
    }
 
    if( aReporter )
    {
        aReporter->SetCurrentProgress( (double) ii / (double) size );
        aReporter->KeepRefreshing( false );
    }
}
 
 
void CN_CONNECTIVITY_ALGO::LocalBuild( const std::shared_ptr<CONNECTIVITY_DATA>& aGlobalConnectivity,
                                       const std::vector<BOARD_ITEM*>& aLocalItems )
{
    m_isLocal = true;
    m_globalConnectivityData = aGlobalConnectivity;
 
    for( BOARD_ITEM* item : aLocalItems )
    {
        switch( item->Type() )
        {
        case PCB_TRACE_T:
        case PCB_ARC_T:
        case PCB_VIA_T:
        case PCB_PAD_T:
        case PCB_FOOTPRINT_T:
        case PCB_SHAPE_T:
            Add( item );
            break;
 
        default:
            break;
        }
    }
}
 
 
void CN_CONNECTIVITY_ALGO::propagateConnections( BOARD_COMMIT* aCommit )
{
    for( const std::shared_ptr<CN_CLUSTER>& cluster : m_connClusters )
    {
        if( cluster->IsConflicting() )
        {
            // Conflicting pads in cluster: we don't know the user's intent so best to do
            // nothing.
            wxLogTrace( wxT( "CN" ), wxT( "Conflicting pads in cluster %p; skipping propagation" ),
                        cluster.get() );
        }
        else if( cluster->HasValidNet() )
        {
            // Propagate from the origin (will be a pad if there are any, or another item if
            // there are no pads).
            int n_changed = 0;
 
            for( CN_ITEM* item : *cluster )
            {
                if( item->Valid() && item->CanChangeNet()
                        && item->Parent()->GetNetCode() != cluster->OriginNet() )
                {
                    MarkNetAsDirty( item->Parent()->GetNetCode() );
                    MarkNetAsDirty( cluster->OriginNet() );
 
                    if( aCommit )
                        aCommit->Modify( item->Parent() );
 
                    item->Parent()->SetNetCode( cluster->OriginNet() );
                    n_changed++;
                }
            }
 
            if( n_changed )
            {
                wxLogTrace( wxT( "CN" ), wxT( "Cluster %p: net: %d %s" ),
                            cluster.get(),
                            cluster->OriginNet(),
                            (const char*) cluster->OriginNetName().c_str() );
            }
            else
            {
                wxLogTrace( wxT( "CN" ), wxT( "Cluster %p: no changeable items to propagate to" ),
                            cluster.get() );
            }
        }
        else
        {
            wxLogTrace( wxT( "CN" ), wxT( "Cluster %p: connected to unused net" ),
                        cluster.get() );
        }
    }
}
 
 
void CN_CONNECTIVITY_ALGO::PropagateNets( BOARD_COMMIT* aCommit )
{
    updateJumperPads();
    m_connClusters = SearchClusters( CSM_PROPAGATE );
    propagateConnections( aCommit );
}
 
 
void CN_CONNECTIVITY_ALGO::FillIsolatedIslandsMap( std::map<ZONE*, std::map<PCB_LAYER_ID, ISOLATED_ISLANDS>>& aMap,
                                                   bool aConnectivityAlreadyRebuilt )
{
    int progressDelta = 50;
    int ii = 0;
 
    progressDelta = std::max( progressDelta, (int) aMap.size() / 4 );
 
    if( !aConnectivityAlreadyRebuilt )
    {
        for( const auto& [ zone, islands ] : aMap )
        {
            Remove( zone );
            Add( zone );
            ii++;
 
            if( m_progressReporter && ( ii % progressDelta ) == 0 )
            {
                m_progressReporter->SetCurrentProgress( (double) ii / (double) aMap.size() );
                m_progressReporter->KeepRefreshing( false );
            }
 
            if( m_progressReporter && m_progressReporter->IsCancelled() )
                return;
        }
    }
 
    m_connClusters = SearchClusters( CSM_CONNECTIVITY_CHECK );
 
    // Bucket the zone items in one pass. A search per zone layer is O(zone layers x items).
    // Keep the cluster and item order, which sets the recorded outline order.
    struct ZONE_CLUSTER_ITEM
    {
        CN_ZONE_LAYER* m_item;
        bool           m_orphaned;
    };
 
    std::unordered_map<const BOARD_ITEM*, std::map<PCB_LAYER_ID, std::vector<ZONE_CLUSTER_ITEM>>>
            zoneItems;
 
    for( const auto& [ zone, zoneIslands ] : aMap )
        zoneItems[zone];
 
    for( const std::shared_ptr<CN_CLUSTER>& cluster : m_connClusters )
    {
        const bool orphaned = cluster->IsOrphaned();
 
        for( CN_ITEM* item : *cluster )
        {
            auto it = zoneItems.find( item->Parent() );
 
            if( it != zoneItems.end() )
            {
                it->second[item->GetBoardLayer()].push_back(
                        { static_cast<CN_ZONE_LAYER*>( item ), orphaned } );
            }
        }
    }
 
    for( auto& [ zone, zoneIslands ] : aMap )
    {
        const auto& layerItems = zoneItems[zone];
 
        for( auto& [ layer, layerIslands ] : zoneIslands )
        {
            if( zone->GetFilledPolysList( layer )->IsEmpty() )
                continue;
 
            auto layerIt = layerItems.find( layer );
            bool notInConnectivity = layerIt == layerItems.end();
 
            if( !notInConnectivity )
            {
                for( const ZONE_CLUSTER_ITEM& entry : layerIt->second )
                {
                    if( entry.m_orphaned )
                        layerIslands.m_IsolatedOutlines.push_back( entry.m_item->SubpolyIndex() );
                    else if( entry.m_item->HasSingleConnection() )
                        layerIslands.m_SingleConnectionOutlines.push_back( entry.m_item->SubpolyIndex() );
                }
            }
 
            // Non-copper zones (silk, mask, etc.) are never added to the connectivity graph,
            // so notInConnectivity is always true for them.  Without the IsCopperLayer guard
            // outline 0 of every non-copper multi-island fill gets dropped on every refill
            // (issue 24089).
            if( notInConnectivity && IsCopperLayer( layer ) )
                layerIslands.m_IsolatedOutlines.push_back( 0 );
        }
    }
}
 
 
const CN_CONNECTIVITY_ALGO::CLUSTERS& CN_CONNECTIVITY_ALGO::GetClusters()
{
    m_ratsnestClusters = SearchClusters( CSM_RATSNEST );
    return m_ratsnestClusters;
}
 
 
void CN_CONNECTIVITY_ALGO::MarkNetAsDirty( int aNet )
{
    if( aNet < 0 )
        return;
 
    if( (int) m_dirtyNets.size() <= aNet )
    {
        int lastNet = m_dirtyNets.size() - 1;
 
        if( lastNet < 0 )
            lastNet = 0;
 
        m_dirtyNets.resize( aNet + 1 );
 
        for( int i = lastNet; i < aNet + 1; i++ )
            m_dirtyNets[i] = true;
    }
 
    m_dirtyNets[aNet] = true;
}
 
 
void CN_VISITOR::checkZoneItemConnection( CN_ZONE_LAYER* aZoneLayer, CN_ITEM* aItem )
{
    PCB_LAYER_ID          layer = aZoneLayer->GetLayer();
    BOARD_CONNECTED_ITEM* item = aItem->Parent();
 
    if( !item->IsOnLayer( layer ) )
        return;
 
    auto connect =
            [&]()
            {
                // We don't propagate nets from zones, so via-zone net changes are deferred
                // and applied only if the via has no higher-priority connections (tracks, pads).
                if( aItem->Parent()->Type() == PCB_VIA_T && aItem->CanChangeNet() )
                {
                    std::lock_guard<std::mutex> lock( *m_deferredNetCodesMutex );
                    m_deferredNetCodes->emplace_back( aItem, aZoneLayer->Net() );
                }
 
                aZoneLayer->Connect( aItem );
                aItem->Connect( aZoneLayer );
            };
 
    // Try quick checks first...
    if( item->Type() == PCB_PAD_T )
    {
        PAD* pad = static_cast<PAD*>( item );
 
        if( pad->ConditionallyFlashed( layer )
            && pad->GetZoneLayerOverride( layer ) == ZLO_FORCE_NO_ZONE_CONNECTION )
        {
            return;
        }
 
        // Don't connect zones to pads on backdrilled or post-machined layers
        if( pad->IsBackdrilledOrPostMachined( layer ) )
            return;
    }
    else if( item->Type() == PCB_VIA_T )
    {
        PCB_VIA* via = static_cast<PCB_VIA*>( item );
 
        if( via->ConditionallyFlashed( layer )
            && via->GetZoneLayerOverride( layer ) == ZLO_FORCE_NO_ZONE_CONNECTION )
        {
            return;
        }
 
        // Don't connect zones to vias on backdrilled or post-machined layers
        if( via->IsBackdrilledOrPostMachined( layer ) )
            return;
    }
 
    for( int i = 0; i < aItem->AnchorCount(); ++i )
    {
        if( aZoneLayer->ContainsPoint( aItem->GetAnchor( i ) ) )
        {
            connect();
            return;
        }
    }
 
    if( item->Type() == PCB_VIA_T || item->Type() == PCB_PAD_T )
    {
        // As long as the pad/via crosses the zone layer, check for the full effective shape
        // We check for the overlapping layers above
        if( aZoneLayer->Collide( item->GetEffectiveShape( layer, FLASHING::ALWAYS_FLASHED ).get() ) )
            connect();
 
        return;
    }
 
    if( aZoneLayer->Collide( item->GetEffectiveShape( layer ).get() ) )
        connect();
}
 
void CN_VISITOR::checkZoneZoneConnection( CN_ZONE_LAYER* aZoneLayerA, CN_ZONE_LAYER* aZoneLayerB )
{
    // CN_ZONE_LAYER now caches its own copy of the outline, so we just check if it's non-empty.
    if( !aZoneLayerA->HasValidOutline() || !aZoneLayerB->HasValidOutline() )
        return;
 
    const BOX2I& boxA = aZoneLayerA->BBox();
    const BOX2I& boxB = aZoneLayerB->BBox();
 
    PCB_LAYER_ID layer = aZoneLayerA->GetLayer();
 
    if( aZoneLayerB->GetLayer() != layer )
        return;
 
    if( !boxA.Intersects( boxB ) )
        return;
 
    const SHAPE_LINE_CHAIN& outlineA = aZoneLayerA->GetOutline();
 
    for( int i = 0; i < outlineA.PointCount(); i++ )
    {
        const VECTOR2I& pt = outlineA.CPoint( i );
 
        if( !boxB.Contains( pt ) )
            continue;
 
        if( aZoneLayerB->ContainsPoint( pt ) )
        {
            aZoneLayerA->Connect( aZoneLayerB );
            aZoneLayerB->Connect( aZoneLayerA );
            return;
        }
    }
 
    const SHAPE_LINE_CHAIN& outlineB = aZoneLayerB->GetOutline();
 
    for( int i = 0; i < outlineB.PointCount(); i++ )
    {
        const VECTOR2I& pt = outlineB.CPoint( i );
 
        if( !boxA.Contains( pt ) )
            continue;
 
        if( aZoneLayerA->ContainsPoint( pt ) )
        {
            aZoneLayerA->Connect( aZoneLayerB );
            aZoneLayerB->Connect( aZoneLayerA );
            return;
        }
    }
}
 
 
static FLASHING flashingFor( const BOARD_CONNECTED_ITEM* aItem, PCB_LAYER_ID aLayer )
{
    bool alwaysFlashed = false;
 
    if( aItem->Type() == PCB_PAD_T )
        alwaysFlashed = !static_cast<const PAD*>( aItem )->ConditionallyFlashed( aLayer );
    else if( aItem->Type() == PCB_VIA_T )
        alwaysFlashed = !static_cast<const PCB_VIA*>( aItem )->ConditionallyFlashed( aLayer );
 
    return alwaysFlashed ? FLASHING::ALWAYS_FLASHED : FLASHING::NEVER_FLASHED;
}
 
 
bool ItemsTouchOnLayer( const BOARD_CONNECTED_ITEM* aItemA, const BOARD_CONNECTED_ITEM* aItemB, PCB_LAYER_ID aLayer )
{
    std::shared_ptr<SHAPE> shapeA = aItemA->GetEffectiveShape( aLayer, flashingFor( aItemA, aLayer ) );
    std::shared_ptr<SHAPE> shapeB = aItemB->GetEffectiveShape( aLayer, flashingFor( aItemB, aLayer ) );
 
    return shapeA->Collide( shapeB.get() );
}
 
 
bool CN_VISITOR::operator()( CN_ITEM* aCandidate )
{
    const BOARD_CONNECTED_ITEM* parentA = aCandidate->Parent();
    const BOARD_CONNECTED_ITEM* parentB = m_item->Parent();
 
    if( !aCandidate->Valid() || !m_item->Valid() )
        return true;
 
    if( parentA == parentB )
        return true;
 
    // Don't connect items in different nets that can't be changed
    if( !aCandidate->CanChangeNet() && !m_item->CanChangeNet() && aCandidate->Net() != m_item->Net() )
        return true;
 
    // If both m_item and aCandidate are marked dirty, they will both be searched
    // Since we are reciprocal in our connection, we arbitrarily pick one of the connections
    // to conduct the expensive search
    if( aCandidate->Dirty() && aCandidate < m_item )
        return true;
 
    // We should handle zone-zone connection separately
    if ( parentA->Type() == PCB_ZONE_T && parentB->Type() == PCB_ZONE_T )
    {
        checkZoneZoneConnection( static_cast<CN_ZONE_LAYER*>( m_item ),
                                 static_cast<CN_ZONE_LAYER*>( aCandidate ) );
        return true;
    }
 
    if( parentA->Type() == PCB_ZONE_T )
    {
        checkZoneItemConnection( static_cast<CN_ZONE_LAYER*>( aCandidate ), m_item );
        return true;
    }
 
    if( parentB->Type() == PCB_ZONE_T )
    {
        checkZoneItemConnection( static_cast<CN_ZONE_LAYER*>( m_item ), aCandidate );
        return true;
    }
 
    LSET commonLayers = parentA->GetLayerSet() & parentB->GetLayerSet();
 
    if( const BOARD* board = parentA->GetBoard() )
        commonLayers &= board->GetEnabledLayers();
 
    for( PCB_LAYER_ID layer : commonLayers )
    {
        if( ItemsTouchOnLayer( parentA, parentB, layer ) )
        {
            m_item->Connect( aCandidate );
            aCandidate->Connect( m_item );
            return true;
        }
    }
 
    return true;
};
 
 
void CN_CONNECTIVITY_ALGO::Clear()
{
    m_ratsnestClusters.clear();
    m_connClusters.clear();
    m_itemMap.clear();
    m_itemList.Clear();
 
}
 
void CN_CONNECTIVITY_ALGO::SetProgressReporter( PROGRESS_REPORTER* aReporter )
{
    m_progressReporter = aReporter;
}
 
 
void CN_CONNECTIVITY_ALGO::updateJumperPads()
{
    // Map of footprint -> map of pad number -> list of CN_ITEMs for pads with that number
    std::map<FOOTPRINT*, std::map<wxString, std::vector<CN_ITEM*>>> padsByFootprint;
 
    for( CN_ITEM* item : m_itemList )
    {
        if( !item->Valid() || item->Parent()->Type() != PCB_PAD_T )
            continue;
 
        auto pad = static_cast<const PAD*>( item->Parent() );
 
        FOOTPRINT* fp = pad->GetParentFootprint();
 
        padsByFootprint[fp][ pad->GetNumber() ].emplace_back( item );
    }
 
    for( auto& [footprint, padsMap] : padsByFootprint )
    {
        if( footprint->GetDuplicatePadNumbersAreJumpers() )
        {
            for( const std::vector<CN_ITEM*>& padsList : padsMap | std::views::values )
            {
                for( size_t i = 0; i < padsList.size(); ++i )
                {
                    for( size_t j = 1; j < padsList.size(); ++j )
                    {
                        padsList[i]->Connect( padsList[j] );
                        padsList[j]->Connect( padsList[i] );
                    }
                }
            }
        }
 
        for( const JUMPER_GROUP& group : footprint->JumperPadGroups().GetAll() )
        {
            std::vector<CN_ITEM*> toConnect;
 
            for( const wxString& padNumber : group.GetNames() )
                std::ranges::copy( padsMap[padNumber], std::back_inserter( toConnect ) );
 
            for( size_t i = 0; i < toConnect.size(); ++i )
            {
                for( size_t j = 1; j < toConnect.size(); ++j )
                {
                    toConnect[i]->Connect( toConnect[j] );
                    toConnect[j]->Connect( toConnect[i] );
                }
            }
        }
    }
}