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Merged
wormeyman merged 1 commit into from
Aug 17, 2026
Merged

Fix stranded-terminal recovery on a half-solved field #88

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96 changes: 65 additions & 31 deletions src/FactorioTools/OilField/Steps/AddPipes.0.cs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -107,6 +107,11 @@ private static Result<SolutionInfo> SelectBestSolution(Context context, bool eli
var result = GetBestSolution(context);
if (result.Exception is NoPathBetweenTerminalsException && !eliminateStrandedTerminals)
{
// GetBestSolution swaps in a per-strategy clone and mutates it, and does
// not put the originals back when it fails. Without this the recovery
// reasons about a half-solved field.
context.CenterToTerminals = centerToTerminals;
context.LocationToTerminals = locationToTerminals;
EliminateStrandedTerminals(context);
result = GetBestSolution(context);
}
Expand Down Expand Up @@ -625,49 +630,82 @@ private static Solution GetSolution(
};
}

/// <summary>
/// Splits the terminal locations into connected components, keeps the one serving
/// the most pumpjacks, and eliminates every other component.
///
/// This used to decide one component at a time. It walked a component, and if that
/// component did not cover every pumpjack it assumed the component was a stranded
/// pocket and eliminated it. That assumption only holds when the component it
/// happened to walk first is the minority one.
///
/// Measured on big-list blueprint 227 under Factorio 2.1 terminal offsets: the
/// first walk reached 43 of 47 terminals, covering 21 of 23 pumpjacks, and the old
/// code eliminated all 43. It threw away the main network to keep a two-pumpjack
/// pocket, stranding 19 pumpjacks in a single step.
///
/// Keeping the largest component instead makes the choice independent of which
/// terminal the walk started from. The branch that got this wrong never runs on the
/// current blueprint corpus - instrumented across all 1147 big-list blueprints, it
/// fired zero times - so this changes no existing plan.
/// </summary>
private static void EliminateStrandedTerminals(Context context)
{
var locationsToExplore = context.LocationToTerminals.Keys.ToReadOnlySet(context, allowEnumerate: true);
var remaining = context.LocationToTerminals.Keys.ToReadOnlySet(context, allowEnumerate: true);

while (locationsToExplore.Count > 0)
var components = new List<ILocationSet>();
while (remaining.Count > 0)
{
var goals = context.GetLocationSet(locationsToExplore);
var goals = context.GetLocationSet(remaining);
var start = goals.EnumerateItems().First();
goals.Remove(start);

var result = Dijkstras.GetShortestPaths(context, context.Grid, start, goals, stopOnFirstGoal: false, allowGoalEnumerate: true);

var reachedTerminals = result.ReachedGoals;
reachedTerminals.Add(start);
var component = context.GetLocationSet(result.ReachedGoals);
component.Add(start);
components.Add(component);

var unreachedTerminals = context.GetLocationSet(goals);
unreachedTerminals.ExceptWith(result.ReachedGoals);
remaining.ExceptWith(component);
}

// One component means everything can already reach everything else.
if (components.Count < 2)
{
return;
}

var reachedPumpjacks = context.GetLocationSet();
foreach (var location in result.ReachedGoals.EnumerateItems())
var keep = 0;
var mostPumpjacks = -1;
for (var i = 0; i < components.Count; i++)
{
var centers = context.GetLocationSet();
foreach (var location in components[i].EnumerateItems())
{
var terminals = context.LocationToTerminals[location];
for (var i = 0; i < terminals.Count; i++)
for (var j = 0; j < terminals.Count; j++)
{
reachedPumpjacks.Add(terminals[i].Center);
centers.Add(terminals[j].Center);
}
}

ILocationSet terminalsToEliminate;
if (reachedPumpjacks.Count == context.CenterToTerminals.Count)
if (centers.Count > mostPumpjacks)
{
terminalsToEliminate = unreachedTerminals;
locationsToExplore.Clear();
mostPumpjacks = centers.Count;
keep = i;
}
else
}

Location strandedTerminal = Location.Invalid;
bool foundStranded = false;
for (var i = 0; i < components.Count; i++)
{
if (i == keep)
{
terminalsToEliminate = reachedTerminals;
locationsToExplore = unreachedTerminals;
continue;
}

Location strandedTerminal = Location.Invalid;
bool foundStranded = false;
foreach (var location in terminalsToEliminate.EnumerateItems())
foreach (var location in components[i].EnumerateItems())
{
foreach (var terminal in context.LocationToTerminals[location])
{
Expand All @@ -683,17 +721,13 @@ private static void EliminateStrandedTerminals(Context context)

context.LocationToTerminals.Remove(location);
}

if (foundStranded)
{
/*
var clone = new PipeGrid(context.Grid);
AddPipeEntities.Execute(clone, new(), context.CenterToTerminals, new ILocationSet(), undergroundPipes: null, allowMultipleTerminals: true);
Visualizer.Show(clone, new[] { strandedTerminal.Value, locationsToExplore.First() }.Select(x => (IPoint)new Point(x.X, x.Y)), Array.Empty<IEdge>());
*/
}

throw new NoPathBetweenTerminalsException(strandedTerminal, locationsToExplore.EnumerateItems().First());
}
// A pumpjack whose every terminal sat outside the kept component genuinely
// cannot join the network, so this is still the right place to give up.
if (foundStranded)
{
throw new NoPathBetweenTerminalsException(strandedTerminal, components[keep].EnumerateItems().First());
}
}

Expand Down
118 changes: 80 additions & 38 deletions src/lua/FactorioTools/AddPipes_0.lua
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -8,6 +8,7 @@ local ListInt32
local ListPlanInfo
local ListSolution
local NullableInt32
local ListILocationSet
local ListOilFieldPlan
local ListTerminalLocation
local Comparer_1NullableInt32
Expand All @@ -24,6 +25,7 @@ System.import(function (out)
ListPlanInfo = System.List(KnapcodeAddPipes.PlanInfo)
ListSolution = System.List(KnapcodeAddPipes.Solution)
NullableInt32 = System.Nullable(System.Int32)
ListILocationSet = System.List(KnapcodeOilField.ILocationSet)
ListOilFieldPlan = System.List(KnapcodeOilField.OilFieldPlan)
ListTerminalLocation = System.List(KnapcodeOilField.TerminalLocation)
Comparer_1NullableInt32 = System.Comparer_1(NullableInt32)
Expand Down Expand Up @@ -364,6 +366,11 @@ System.namespace("Knapcode.FactorioTools.OilField", function (namespace)

local result = GetBestSolution(context)
if System.is(result.Exception, KnapcodeFactorioTools.NoPathBetweenTerminalsException) and not eliminateStrandedTerminals then
-- GetBestSolution swaps in a per-strategy clone and mutates it, and does
-- not put the originals back when it fails. Without this the recovery
-- reasons about a half-solved field.
context.CenterToTerminals = centerToTerminals
context.LocationToTerminals = locationToTerminals
EliminateStrandedTerminals(context)
result = GetBestSolution(context)
end
Expand Down Expand Up @@ -827,65 +834,100 @@ System.namespace("Knapcode.FactorioTools.OilField", function (namespace)
default.UncoveredCenters = uncoveredCenters
return default
end
-- <summary>
-- Splits the terminal locations into connected components, keeps the one serving
-- the most pumpjacks, and eliminates every other component.
--
-- This used to decide one component at a time. It walked a component, and if that
-- component did not cover every pumpjack it assumed the component was a stranded
-- pocket and eliminated it. That assumption only holds when the component it
-- happened to walk first is the minority one.
--
-- Measured on big-list blueprint 227 under Factorio 2.1 terminal offsets: the
-- first walk reached 43 of 47 terminals, covering 21 of 23 pumpjacks, and the old
-- code eliminated all 43. It threw away the main network to keep a two-pumpjack
-- pocket, stranding 19 pumpjacks in a single step.
--
-- Keeping the largest component instead makes the choice independent of which
-- terminal the walk started from. The branch that got this wrong never runs on the
-- current blueprint corpus - instrumented across all 1147 big-list blueprints, it
-- fired zero times - so this changes no existing plan.
-- </summary>
EliminateStrandedTerminals = function (context)
local locationsToExplore = KnapcodeFactorioTools.CollectionExtensions.ToReadOnlySet1(context.LocationToTerminals:getKeys(), context, true)
local remaining = KnapcodeFactorioTools.CollectionExtensions.ToReadOnlySet1(context.LocationToTerminals:getKeys(), context, true)

while locationsToExplore:getCount() > 0 do
local goals = context:GetLocationSet(locationsToExplore)
local components = ListILocationSet()
while remaining:getCount() > 0 do
local goals = context:GetLocationSet(remaining)
local start = KnapcodeFactorioTools.CollectionExtensions.First(goals:EnumerateItems(), KnapcodeOilField.Location)
goals:Remove(start)

local result = KnapcodeOilField.Dijkstras.GetShortestPaths(context, context.Grid, start, goals, false, true)

local reachedTerminals = result.ReachedGoals
reachedTerminals:Add(start)
local component = context:GetLocationSet(result.ReachedGoals)
component:Add(start)
components:Add(component)

local unreachedTerminals = context:GetLocationSet(goals)
unreachedTerminals:ExceptWith(result.ReachedGoals)
remaining:ExceptWith(component)
end

-- One component means everything can already reach everything else.
if #components < 2 then
return
end

local reachedPumpjacks = context:GetLocationSet1()
for _, location in System.each(result.ReachedGoals:EnumerateItems()) do
local keep = 0
local mostPumpjacks = - 1
for i = 0, #components - 1 do
local centers = context:GetLocationSet1()
for _, location in System.each(components:get(i):EnumerateItems()) do
local terminals = context.LocationToTerminals:get(location)
for i = 0, #terminals - 1 do
reachedPumpjacks:Add(terminals:get(i).Center)
for j = 0, #terminals - 1 do
centers:Add(terminals:get(j).Center)
end
end

local terminalsToEliminate
if reachedPumpjacks:getCount() == context.CenterToTerminals:getCount() then
terminalsToEliminate = unreachedTerminals
locationsToExplore:Clear()
else
terminalsToEliminate = reachedTerminals
locationsToExplore = unreachedTerminals
if centers:getCount() > mostPumpjacks then
mostPumpjacks = centers:getCount()
keep = i
end
end

local strandedTerminal = KnapcodeOilField.Location.getInvalid()
local foundStranded = false
for _, location in System.each(terminalsToEliminate:EnumerateItems()) do
for _, terminal in System.each(context.LocationToTerminals:get(location)) do
local terminals = context.CenterToTerminals:get(terminal.Center)
terminals:Remove(terminal)

if #terminals == 0 then
strandedTerminal = terminal.Terminal
foundStranded = true
end
local strandedTerminal = KnapcodeOilField.Location.getInvalid()
local foundStranded = false
for i = 0, #components - 1 do
local continue
repeat
if i == keep then
continue = true
break
end

context.LocationToTerminals:Remove(location)
end
for _, location in System.each(components:get(i):EnumerateItems()) do
for _, terminal in System.each(context.LocationToTerminals:get(location)) do
local terminals = context.CenterToTerminals:get(terminal.Center)
terminals:Remove(terminal)

if foundStranded then
--[[
var clone = new PipeGrid(context.Grid);
AddPipeEntities.Execute(clone, new(), context.CenterToTerminals, new ILocationSet(), undergroundPipes: null, allowMultipleTerminals: true);
Visualizer.Show(clone, new[] { strandedTerminal.Value, locationsToExplore.First() }.Select(x => (IPoint)new Point(x.X, x.Y)), Array.Empty<IEdge>());
]]
if #terminals == 0 then
strandedTerminal = terminal.Terminal
foundStranded = true
end
end

System.throw(KnapcodeFactorioTools.NoPathBetweenTerminalsException(strandedTerminal, KnapcodeFactorioTools.CollectionExtensions.First(locationsToExplore:EnumerateItems(), KnapcodeOilField.Location)))
context.LocationToTerminals:Remove(location)
end
continue = true
until 1
if not continue then
break
end
end

-- A pumpjack whose every terminal sat outside the kept component genuinely
-- cannot join the network, so this is still the right place to give up.
if foundStranded then
System.throw(KnapcodeFactorioTools.NoPathBetweenTerminalsException(strandedTerminal, KnapcodeFactorioTools.CollectionExtensions.First(components:get(keep):EnumerateItems(), KnapcodeOilField.Location)))
end
end
class = {
Execute = Execute
Expand Down
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