Make packing algorithm cancellable

src/CromulentBisgetti.ContainerPacking/Algorithms/EB_AFIT.cs

@@ -2,6 +2,7 @@
 using System;
 using System.Collections.Generic;
 using System.Linq;
+using System.Threading;
 
 namespace CromulentBisgetti.ContainerPacking.Algorithms
 {
@@ -20,9 +21,9 @@ public class EB_AFIT : IPackingAlgorithm
  /// <param name="container">The container to pack items into.</param>
  /// <param name="items">The items to pack.</param>
  /// <returns>The bin packing result.</returns>
- public AlgorithmPackingResult Run(Container container, List<Item> items)
+ public AlgorithmPackingResult Run(Container container, List<Item> items, CancellationToken cancellationToken)
  {
- Initialize(container, items);
+ Initialize(container, items, cancellationToken);
  ExecuteIterations(container);
  Report(container);
 
@@ -41,8 +42,6 @@ public AlgorithmPackingResult Run(Container container, List<Item> items)
  }
 
  result.PackedItems = itemsPackedInOrder;
-
-
 
  if (result.UnpackedItems.Count == 0)
  {
@@ -52,13 +51,14 @@ public AlgorithmPackingResult Run(Container container, List<Item> items)
  return result;
  }
 
- #endregion Public Methods
+ #endregion Public Methods
 
- #region Private Variables
+ #region Private Variables
 
- private List<Item> itemsToPack;
+ private List<Item> itemsToPack;
  private List<Item> itemsPackedInOrder;
  private List<Layer> layers;
+ private CancellationToken algorithmCancellationToken;
  private ContainerPackingResult result;
 
  private ScrapPad scrapfirst;
@@ -70,7 +70,6 @@ public AlgorithmPackingResult Run(Container container, List<Item> items)
  private bool layerDone;
  private bool packing;
  private bool packingBest = false;
- private bool quit = false;
 
  private int bboxi;
  private int bestIteration;
@@ -288,7 +287,7 @@ private void ExecuteIterations(Container container)
  int layersIndex;
  decimal bestVolume = 0.0M;
 
- for (int containerOrientationVariant = 1; (containerOrientationVariant <= 6) && !quit; containerOrientationVariant++)
+ for (int containerOrientationVariant = 1; (containerOrientationVariant <= 6) && !algorithmCancellationToken.IsCancellationRequested; containerOrientationVariant++)
  {
  switch (containerOrientationVariant)
  {
@@ -321,7 +320,7 @@ private void ExecuteIterations(Container container)
  ListCanditLayers();
  layers = layers.OrderBy(l => l.LayerEval).ToList();
 
- for (layersIndex = 1; (layersIndex <= layerListLen) && !quit; layersIndex++)
+ for (layersIndex = 1; (layersIndex <= layerListLen) && !algorithmCancellationToken.IsCancellationRequested; layersIndex++)
  {
  packedVolume = 0.0M;
  packedy = 0;
@@ -347,7 +346,7 @@ private void ExecuteIterations(Container container)
  packedy = packedy + layerThickness;
  remainpy = py - packedy;
 
- if (layerinlayer != 0 && !quit)
+ if (layerinlayer != 0 && !algorithmCancellationToken.IsCancellationRequested)
  {
  prepackedy = packedy;
  preremainpy = remainpy;
@@ -365,9 +364,9 @@ private void ExecuteIterations(Container container)
  }
 
  FindLayer(remainpy);
- } while (packing && !quit);
+ } while (packing && !algorithmCancellationToken.IsCancellationRequested);
 
- if ((packedVolume > bestVolume) && !quit)
+ if ((packedVolume > bestVolume) && !algorithmCancellationToken.IsCancellationRequested)
  {
  bestVolume = packedVolume;
  bestVariant = containerOrientationVariant;
@@ -525,10 +524,12 @@ private void FindSmallestZ()
  /// <summary>
  /// Initializes everything.
  /// </summary>
- private void Initialize(Container container, List<Item> items)
+ private void Initialize(Container container, List<Item> items, CancellationToken cancellationToken)
  {
  itemsToPack = new List<Item>();
  itemsPackedInOrder = new List<Item>();
+ algorithmCancellationToken = cancellationToken;
+
  result = new ContainerPackingResult();
 
  // The original code uses 1-based indexing everywhere. This fake entry is added to the beginning
@@ -565,13 +566,12 @@ private void Initialize(Container container, List<Item> items)
  scrapfirst.Post = null;
  packingBest = false;
  hundredPercentPacked = false;
- quit = false;
  }
 
- /// <summary>
- /// Lists all possible layer heights by giving a weight value to each of them.
- /// </summary>
- private void ListCanditLayers()
+ /// <summary>
+ /// Lists all possible layer heights by giving a weight value to each of them.
+ /// </summary>
+ private void ListCanditLayers()
  {
  bool same;
  decimal exdim = 0;
@@ -752,7 +752,7 @@ private void PackLayer()
  scrapfirst.CumX = px;
  scrapfirst.CumZ = 0;
 
- for (; !quit;)
+ for (; !algorithmCancellationToken.IsCancellationRequested;)
  {
  FindSmallestZ();
 
@@ -1037,8 +1037,6 @@ private void PackLayer()
  /// </summary>
  private void Report(Container container)
  {
- quit = false;
-
  switch (bestVariant)
  {
  case 1:
@@ -1112,11 +1110,11 @@ private void Report(Container container)
  remainpz = pz;
  }
 
- if (!quit)
+ if (!algorithmCancellationToken.IsCancellationRequested)
  {
  FindLayer(remainpy);
  }
- } while (packing && !quit);
+ } while (packing && !algorithmCancellationToken.IsCancellationRequested);
  }
 
  /// <summary>

src/CromulentBisgetti.ContainerPacking/Algorithms/IPackingAlgorithm.cs

@@ -1,5 +1,6 @@
 using CromulentBisgetti.ContainerPacking.Entities;
 using System.Collections.Generic;
+using System.Threading;
 
 namespace CromulentBisgetti.ContainerPacking.Algorithms
 {
@@ -13,7 +14,8 @@ public interface IPackingAlgorithm
  /// </summary>
  /// <param name="container">The container.</param>
  /// <param name="items">The items to pack.</param>
+ /// <param name="cancellationToken">Algorith will check this token to detect if the current packing attempt should be cancelled.</param>
  /// <returns>The algorithm packing result.</returns>
- AlgorithmPackingResult Run(Container container, List<Item> items);
+ AlgorithmPackingResult Run(Container container, List<Item> items, CancellationToken cancellationToken);
  }
 }

src/CromulentBisgetti.ContainerPacking/PackingService.cs

@@ -4,6 +4,7 @@
 using System.Collections.Generic;
 using System.Diagnostics;
 using System.Linq;
+using System.Threading;
 using System.Threading.Tasks;
 
 namespace CromulentBisgetti.ContainerPacking
@@ -20,7 +21,14 @@ public static class PackingService
  /// <param name="itemsToPack">The items to pack.</param>
  /// <param name="algorithmTypeIDs">The list of algorithm type IDs to use for packing.</param>
  /// <returns>A container packing result with lists of the packed and unpacked items.</returns>
- public static List<ContainerPackingResult> Pack(List<Container> containers, List<Item> itemsToPack, List<int> algorithmTypeIDs)
+ public static List<ContainerPackingResult> Pack(List<Container> containers, List<Item> itemsToPack, List<int> algorithmTypeIDs)
+ {
+ var source = new CancellationTokenSource();
+
+ return Pack(containers, itemsToPack, algorithmTypeIDs, source.Token);
+ }
+
+ public static List<ContainerPackingResult> Pack(List<Container> containers, List<Item> itemsToPack, List<int> algorithmTypeIDs, CancellationToken cancellationToken)
  {
  Object sync = new Object { };
  List<ContainerPackingResult> result = new List<ContainerPackingResult>();
@@ -45,7 +53,7 @@ public static List<ContainerPackingResult> Pack(List<Container> containers, List
 
  Stopwatch stopwatch = new Stopwatch();
  stopwatch.Start();
- AlgorithmPackingResult algorithmResult = algorithm.Run(container, items);
+ AlgorithmPackingResult algorithmResult = algorithm.Run(container, items, cancellationToken);
  stopwatch.Stop();
 
  algorithmResult.PackTimeInMilliseconds = stopwatch.ElapsedMilliseconds;

src/CromulentBisgetti.ContainerPackingTests/ContainerPackingCancelTests.cs

@@ -0,0 +1,54 @@
+using CromulentBisgetti.ContainerPacking;
+using CromulentBisgetti.ContainerPacking.Algorithms;
+using CromulentBisgetti.ContainerPacking.Entities;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+using System.Collections.Generic;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace CromulentBisgetti.ContainerPackingTests
+{
+ [TestClass]
+ public class ContainerPackingCancelTests
+ {
+ [TestMethod]
+ public async Task LongRunningTest_CanBeCancelled()
+ {
+ // One of the longer-running 700 tests, #479
+ var itemsToPack = new List<Item>
+ {
+ new Item(1, 64, 48, 64, 14),
+ new Item(2, 79, 25, 79, 23),
+ new Item(3, 89, 85, 89, 19),
+ new Item(4, 79, 66, 79, 17),
+ new Item(5, 79, 54, 79, 16),
+ new Item(6, 115, 95, 115, 11),
+ new Item(7, 76, 54, 76, 20),
+ new Item(8, 80, 44, 80, 10),
+ new Item(9, 66, 33, 66, 15),
+ new Item(10, 50, 32, 50, 15),
+ new Item(11, 116, 93, 116, 19),
+ new Item(12, 113, 64, 113, 11),
+ };
+ var containers = new List<Container>
+ {
+ new Container(1, 587, 233, 220),
+ };
+
+ var source = new CancellationTokenSource();
+
+ // start the packing task on another thread and give it a bit of time to start
+ var packingTask = Task.Run(() =>
+ PackingService.Pack(containers, itemsToPack, new List<int> { (int)AlgorithmType.EB_AFIT }, source.Token));
+ await Task.Delay(50);
+
+ // then cancel it. Packing should return quickly
+ source.Cancel();
+
+ var result = await packingTask;
+
+ var elapsedMilliSec = result[0].AlgorithmPackingResults[0].PackTimeInMilliseconds;
+ Assert.IsTrue(elapsedMilliSec < 100, $"Expected elapsed time to be less than 100 but found {elapsedMilliSec} msec");
+ }
+ }
+}

src/CromulentBisgetti.ContainerPackingTests/ContainerPackingTests.cs

@@ -6,6 +6,8 @@
 using CromulentBisgetti.ContainerPacking;
 using CromulentBisgetti.ContainerPacking.Entities;
 using CromulentBisgetti.ContainerPacking.Algorithms;
+using System.Globalization;
+using System.Diagnostics;
 
 namespace CromulentBisgetti.ContainerPackingTests
 {
@@ -19,6 +21,8 @@ public void EB_AFIT_Passes_700_Standard_Reference_Tests()
  string resourceName = "CromulentBisgetti.ContainerPackingTests.DataFiles.ORLibrary.txt";
  Assembly assembly = Assembly.GetExecutingAssembly();
 
+ var decimalPointCulture = CultureInfo.GetCultureInfo("en-us");
+
  using (Stream stream = assembly.GetManifestResourceStream(resourceName))
  {
  using (StreamReader reader = new StreamReader(stream))
@@ -53,21 +57,25 @@ public void EB_AFIT_Passes_700_Standard_Reference_Tests()
  containers.Add(new Container(0, Convert.ToDecimal(containerDims[0]), Convert.ToDecimal(containerDims[1]), Convert.ToDecimal(containerDims[2])));
 
  List<ContainerPackingResult> result = PackingService.Pack(containers, itemsToPack, new List<int> { (int)AlgorithmType.EB_AFIT });
-
+
+ Debug.WriteLine($"Test #{counter} took {result[0].AlgorithmPackingResults[0].PackTimeInMilliseconds}msec");
+
  // Assert that the number of items we tried to pack equals the number stated in the published reference.
  Assert.AreEqual(result[0].AlgorithmPackingResults[0].PackedItems.Count + result[0].AlgorithmPackingResults[0].UnpackedItems.Count, Convert.ToDecimal(testResults[1]));
 
  // Assert that the number of items successfully packed equals the number stated in the published reference.
  Assert.AreEqual(result[0].AlgorithmPackingResults[0].PackedItems.Count, Convert.ToDecimal(testResults[2]));
 
  // Assert that the packed container volume percentage is equal to the published reference result.
- // Make an exception for a couple of tests where this algorithm yields 87.20% and the published result 
- // was 87.21% (acceptable rounding error).
- Assert.IsTrue(result[0].AlgorithmPackingResults[0].PercentContainerVolumePacked == Convert.ToDecimal(testResults[3]) ||
- (result[0].AlgorithmPackingResults[0].PercentContainerVolumePacked == 87.20M && Convert.ToDecimal(testResults[3]) == 87.21M));
+ var actualPercentage = result[0].AlgorithmPackingResults[0].PercentContainerVolumePacked;
+ var expectedPrecentage = Convert.ToDecimal(testResults[3], decimalPointCulture);
+
+ Assert.IsTrue(
+ Math.Abs(actualPercentage - expectedPrecentage) < 0.02M,
+ $"Test #{counter} failed: expected%={expectedPrecentage}; actual%={actualPercentage};");
 
  // Assert that the packed item volume percentage is equal to the published reference result.
- Assert.AreEqual(result[0].AlgorithmPackingResults[0].PercentItemVolumePacked, Convert.ToDecimal(testResults[4]));
+ Assert.AreEqual(result[0].AlgorithmPackingResults[0].PercentItemVolumePacked, Convert.ToDecimal(testResults[4], decimalPointCulture));
 
  counter++;
  }