feat: introduce task cancelling

src/main/java/de/dhbwstuttgart/core/ConsoleInterface.java

@@ -51,8 +51,8 @@ public class ConsoleInterface {
     if (serverPort.isPresent()) {
       if (unifyServer.isPresent()) throw new RuntimeException("Cannot use unifyServer when in server mode!");
 
-      JavaTXServer server = new JavaTXServer();
-      server.listen(serverPort.get());
+      JavaTXServer server = new JavaTXServer(serverPort.get());
+      server.listen();
     }
     else {
       JavaTXCompiler compiler = new JavaTXCompiler(input, classpath, outputPath != null ? new File(outputPath) : null, unifyServer);

src/main/java/de/dhbwstuttgart/core/JavaTXCompiler.java

@@ -65,6 +65,9 @@ import org.apache.commons.io.output.NullOutputStream;
 
 public class JavaTXCompiler {
 
+	// do not use this in any code, that can be executed serverside!
+	public static PlaceholderRegistry defaultClientPlaceholderRegistry = new PlaceholderRegistry();
+
 	// public static JavaTXCompiler INSTANCE;
 	final CompilationEnvironment environment;
 	Boolean resultmodel = true;
@@ -101,6 +104,9 @@ public class JavaTXCompiler {
 	}
 
 	public JavaTXCompiler(List<File> sources, List<File> contextPath, File outputPath, Optional<String> unifyServer) throws IOException, ClassNotFoundException {
+		// ensure new default placeholder registry for tests
+		defaultClientPlaceholderRegistry = new PlaceholderRegistry();
+
 		this.unifyServer = unifyServer;
 		var path = new ArrayList<>(contextPath);
 		if (contextPath.isEmpty()) {
@@ -311,7 +317,7 @@ public class JavaTXCompiler {
 		Set<Set<UnifyPair>> results = new HashSet<>();
 		UnifyResultModel urm = null;
 		// urm.addUnifyResultListener(resultListener);
-		UnifyContext context = new UnifyContext(logFile, log, true, urm, usedTasks, PlaceholderRegistry.defaultRegistry);
+		UnifyContext context = new UnifyContext(logFile, log, true, urm, usedTasks, defaultClientPlaceholderRegistry);
 		try {
 			logFile = logFile == null ? new FileWriter(new File("log_" + sourceFiles.keySet().iterator().next().getName())) : logFile;
 			IFiniteClosure finiteClosure = UnifyTypeFactory.generateFC(allClasses, logFile, getClassLoader(), this, context.placeholderRegistry());

src/main/java/de/dhbwstuttgart/core/JavaTXServer.java

@@ -4,13 +4,27 @@ import de.dhbwstuttgart.server.SocketServer;
 
 public class JavaTXServer {
 
-  public void listen(int port) {
+  public static boolean isRunning = false;
+
+  final SocketServer socketServer;
+
+  public JavaTXServer(int port) {
+    this.socketServer = new SocketServer(port);
+    isRunning = true;
+  }
+
+  public void listen() {
+    socketServer.start();
+  }
+
+  public void forceStop() {
     try {
-      SocketServer socketServer = new SocketServer(port);
-      socketServer.start();
-    } catch (Exception e) {
-      e.printStackTrace();
+      socketServer.stop();
     }
+    catch (InterruptedException exception) {
+      System.err.println("Interrupted socketServer: " + exception);
+    }
+    isRunning = false;
   }
 
 

src/main/java/de/dhbwstuttgart/parser/SyntaxTreeGenerator/FCGenerator.java

@@ -111,7 +111,7 @@ public class FCGenerator {
         //Generics mit gleichem Namen müssen den selben TPH bekommen
         for(GenericTypeVar gtv : forType.getGenerics()){
             if(!gtvs.containsKey(gtv.getName())){
-                TypePlaceholder replacePlaceholder = TypePlaceholder.fresh(new NullToken(), placeholderRegistry);
+                TypePlaceholder replacePlaceholder = TypePlaceholder.fresh(new NullToken());
                 gtvs.put(gtv.getName(), replacePlaceholder);
                 newGTVs.put(gtv.getName(), replacePlaceholder);
             }

src/main/java/de/dhbwstuttgart/syntaxtree/factory/NameGenerator.java

@@ -0,0 +1,98 @@
+package de.dhbwstuttgart.syntaxtree.factory;
+
+import de.dhbwstuttgart.core.JavaTXCompiler;
+import de.dhbwstuttgart.core.JavaTXServer;
+
+public class NameGenerator {
+
+    private static String strNextName = "A";
+    
+    /**
+     * Setzt den zu Beginn der Typinferenz auf "A" zurueck.
+     * Dies ist bei JUnit-Test noetig                       
+     * <code>TypePlaceholder</code>. <br>Author: Martin Pluemicke
+     * @return void
+     */
+    public static void reset() {
+    	strNextName = "A";
+    }
+    
+    /**
+     * Berechnet einen neuen, eindeutigen Namen f�r eine neue                          
+     * <code>TypePlaceholder</code>. <br>Author: J�rg B�uerle
+     * @return Der Name
+     */
+    public static String makeNewName()
+    {
+        // otth: Funktion berechnet einen neuen Namen anhand eines alten gespeicherten
+        String strReturn = strNextName;
+    
+        // n�chster Name berechnen und in strNextName speichern        
+        inc( strNextName.length() - 1 );
+
+        if (JavaTXServer.isRunning) {
+            throw new RuntimeException("Using the NameGenerator on a server is not allowed");
+        }
+        JavaTXCompiler.defaultClientPlaceholderRegistry.addPlaceholder(strReturn);
+        return strReturn;        
+    }
+
+    /**
+     * Hilfsfunktion zur Berechnung eines neuen Namens
+     * <br>Author: J�rg B�uerle
+     * @param i
+     */
+    private static void inc(int i)
+    {
+        // otth: Hilfsfunktion zur Berechnung eines neuen Namens
+        // otth: Erh�hung des Buchstabens an der Stelle i im String strNextName
+        // otth: Nach �berlauf: rekursiver Aufruf
+    
+        // falls i = -1 --> neuer Buchstabe vorne anf�gen
+        if ( i == -1 )
+        {
+            strNextName = "A" + strNextName;
+            return;
+        }
+    
+        char cBuchstabe = (char)(strNextName.charAt( i ));
+        cBuchstabe++;
+        if ( cBuchstabe - 65 > 25 )
+        {
+            // aktuelle Stelle: auf A zuruecksetzen
+            manipulate( i, 'A' );
+            
+            // vorherige Stelle erh�hen
+            inc( i - 1 );
+        }
+        else
+        {
+            // aktueller Buchstabe �ndern
+            manipulate( i, cBuchstabe );
+        }
+        
+    }
+
+    /**
+     * Hilfsfunktion zur Berechnung eines neuen Namens.
+     * <br>Author: J�rg B�uerle
+     * @param nStelle
+     * @param nWert
+     */
+    private static void manipulate( int nStelle, char nWert )
+    {
+        // otth: Hilfsfunktion zur Berechnung eines neuen Namens
+        // otth: Ersetzt im String 'strNextName' an der Position 'nStelle' den Buchstaben durch 'nWert'
+        
+        String strTemp = "";
+        for( int i = 0; i < strNextName.length(); i++)
+        {
+            if ( i == nStelle )
+                strTemp = strTemp + nWert;
+            else
+                strTemp = strTemp + strNextName.charAt( i );
+        }
+        strNextName = strTemp;
+    }
+    
+}

src/main/java/de/dhbwstuttgart/syntaxtree/type/TypePlaceholder.java

@@ -7,6 +7,7 @@ import de.dhbwstuttgart.typeinference.unify.UnifyContext;
 
 import de.dhbwstuttgart.parser.NullToken;
 import de.dhbwstuttgart.syntaxtree.ASTVisitor;
+import de.dhbwstuttgart.syntaxtree.factory.NameGenerator;
 import de.dhbwstuttgart.typeinference.result.ResultSetVisitor;
 import org.antlr.v4.runtime.Token;
 
@@ -65,20 +66,16 @@ public class TypePlaceholder extends RefTypeOrTPHOrWildcardOrGeneric implements
      * @return
      */
     public static TypePlaceholder fresh(Token position){
-      return fresh(position, 0, true);
+		return new TypePlaceholder(NameGenerator.makeNewName(), position, 0, true);
     }
 
-    public static TypePlaceholder fresh(Token position, PlaceholderRegistry placeholderRegistry){
-      return fresh(position, 0, true, placeholderRegistry);
-    }
+  public static TypePlaceholder fresh(Token position, PlaceholderRegistry placeholderRegistry){
+    String newName = placeholderRegistry.generateFreshPlaceholderName();
+    return new TypePlaceholder(newName, position, 0, true);
+  }
 
     public static TypePlaceholder fresh(Token position, int variance, boolean wildcardable){
-      return fresh(position, variance, wildcardable, PlaceholderRegistry.defaultRegistry);
-    }
-
-    public static TypePlaceholder fresh(Token position, int variance, boolean wildcardable, PlaceholderRegistry placeholderRegistry){
-      String newName = placeholderRegistry.generateFreshPlaceholderName();
-		  return new TypePlaceholder(newName, position, variance, wildcardable);
+		return new TypePlaceholder(NameGenerator.makeNewName(), position, variance, wildcardable);
     }
 
     public static RefTypeOrTPHOrWildcardOrGeneric of(String name) {

src/main/java/de/dhbwstuttgart/typeinference/assumptions/FunNClass.java

@@ -7,6 +7,7 @@ import de.dhbwstuttgart.syntaxtree.GenericDeclarationList;
 import de.dhbwstuttgart.syntaxtree.GenericTypeVar;
 import de.dhbwstuttgart.syntaxtree.Method;
 import de.dhbwstuttgart.syntaxtree.factory.ASTFactory;
+import de.dhbwstuttgart.syntaxtree.factory.NameGenerator;
 import de.dhbwstuttgart.syntaxtree.type.GenericRefType;
 
 

src/main/java/de/dhbwstuttgart/typeinference/result/PairNoResult.java

@@ -38,7 +38,7 @@ implements ISerializableData {
     public SerialMap toSerial(KeyStorage keyStorage) {
         SerialMap serialized = new SerialMap();
         serialized.put("left", this.getLeft().toSerial(keyStorage));
-        serialized.put("right", this.getLeft().toSerial(keyStorage));
+        serialized.put("right", this.getRight().toSerial(keyStorage));
         // create the wrapper and put this as the object
         var serializedWrapper = super.toSerial(keyStorage);
         serializedWrapper.put("object", serialized);

src/main/java/de/dhbwstuttgart/typeinference/result/PairTPHEqualTPH.java

@@ -21,7 +21,7 @@ public class PairTPHEqualTPH extends ResultPair<TypePlaceholder, TypePlaceholder
     public SerialMap toSerial(KeyStorage keyStorage) {
         SerialMap serialized = new SerialMap();
         serialized.put("left", this.getLeft().toSerial(keyStorage));
-        serialized.put("right", this.getLeft().toSerial(keyStorage));
+        serialized.put("right", this.getRight().toSerial(keyStorage));
         // create the wrapper and put this as the object
         var serializedWrapper = super.toSerial(keyStorage);
         serializedWrapper.put("object", serialized);

src/main/java/de/dhbwstuttgart/typeinference/result/PairTPHsmallerTPH.java

@@ -46,7 +46,7 @@ public class PairTPHsmallerTPH extends ResultPair<TypePlaceholder,TypePlaceholde
     public SerialMap toSerial(KeyStorage keyStorage) {
         SerialMap serialized = new SerialMap();
         serialized.put("left", this.getLeft().toSerial(keyStorage));
-        serialized.put("right", this.getLeft().toSerial(keyStorage));
+        serialized.put("right", this.getRight().toSerial(keyStorage));
         // create the wrapper and put this as the object
         var serializedWrapper = super.toSerial(keyStorage);
         serializedWrapper.put("object", serialized);

src/main/java/de/dhbwstuttgart/typeinference/result/ResultSet.java

@@ -7,6 +7,7 @@ import de.dhbwstuttgart.server.packet.dataContainers.serialized.SerialList;
 import de.dhbwstuttgart.server.packet.dataContainers.serialized.SerialMap;
 import de.dhbwstuttgart.typeinference.unify.UnifyContext;
 import java.util.ArrayList;
+import java.util.Comparator;
 import java.util.HashSet;
 import java.util.Set;
 
@@ -59,15 +60,19 @@ public class ResultSet implements ISerializableData {
 
   public String toString() {
     var results = new ArrayList<>(this.results);
-    results.sort(Ordering.usingToString());
+    results.sort(
+      Comparator
+        .comparingInt((ResultPair o) -> o.getLeft().toString().length())
+        .thenComparing(o -> o.getLeft().toString())
+        .thenComparingInt(o -> o.getRight().toString().length())
+        .thenComparing(o -> o.getRight().toString())
+    );
     return results.toString();
   }
 
   @Override
   public boolean equals(Object o) {
-    if (o instanceof ResultSet) {
-      ResultSet other = (ResultSet) o;
-
+    if (o instanceof ResultSet other) {
       // sort both result lists
       var thisElements = new ArrayList<>(this.results);
       thisElements.sort(Ordering.usingToString());

src/main/java/de/dhbwstuttgart/typeinference/typeAlgo/TYPEStmt.java

@@ -13,6 +13,7 @@ import de.dhbwstuttgart.parser.SyntaxTreeGenerator.AssignToLocal;
 import de.dhbwstuttgart.parser.scope.JavaClassName;
 import de.dhbwstuttgart.syntaxtree.*;
 import de.dhbwstuttgart.syntaxtree.factory.ASTFactory;
+import de.dhbwstuttgart.syntaxtree.factory.NameGenerator;
 import de.dhbwstuttgart.syntaxtree.statement.*;
 import de.dhbwstuttgart.syntaxtree.type.ExtendsWildcardType;
 import de.dhbwstuttgart.syntaxtree.type.GenericRefType;
@@ -743,7 +744,7 @@ public class TYPEStmt implements StatementVisitor {
             List<GenericRefType> funNParams = new ArrayList<>();
             for (int i = 0; i < numArgs + 1; i++) {
                 // funNParams.add(TypePlaceholder.fresh(new NullToken()));
-                funNParams.add(new GenericRefType(PlaceholderRegistry.defaultRegistry.generateFreshPlaceholderName(), new NullToken()));
+                funNParams.add(new GenericRefType(NameGenerator.makeNewName(), new NullToken()));
             }
             funNParams.get(funNParams.size() - 1);
             ret.add(new MethodAssumption(new FunNClass(funNParams), funNParams.get(funNParams.size() - 1), funNParams.subList(0, funNParams.size() - 1), new TypeScope() {

src/main/java/de/dhbwstuttgart/typeinference/unify/CancellableTask.java

@@ -0,0 +1,62 @@
+package de.dhbwstuttgart.typeinference.unify;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.concurrent.ConcurrentLinkedQueue;
+import java.util.concurrent.RecursiveTask;
+import java.util.concurrent.atomic.AtomicBoolean;
+
+/**
+ * An intermediate class for the recursive steps of the TypeUnifyTask:
+ * This allows to cancel parts of the recursion tree, instead of only  the whole execution as before. But in
+ * order for that to work, all cancellable child tasks must be added when they are created
+ *
+ * @param <T>
+ */
+public abstract class CancellableTask<T> extends RecursiveTask<T> {
+
+  private final AtomicBoolean executionCancelled = new AtomicBoolean(false);
+  private final List<CancellableTask<?>> childTasks = new ArrayList<>();
+  private CancellableTask<?> parentTask = null;
+
+  /**
+   * Set the execution for this task and all its (recursive) children to be cancelled
+   */
+  protected void cancelExecution() {
+    // is this branch already cancelled? Then do nothing
+    if (this.executionCancelled.get()) return;
+    executionCancelled.set(true);
+    this.cancelChildExecution();
+  }
+
+  public void cancelChildExecution() {
+    for (var childTask : childTasks) {
+      // no need to cancel a branch that is already finished
+      if (!childTask.isDone()) {
+        childTask.cancelExecution();
+      }
+    }
+  }
+
+  protected void cancelSiblingTasks() {
+    if (this.parentTask != null) {
+      boolean thisWasCancelledBefore = this.executionCancelled.get();
+      this.parentTask.cancelChildExecution();
+      this.executionCancelled.set(thisWasCancelledBefore);
+    }
+  }
+
+  public Boolean isExecutionCancelled() {
+    return executionCancelled.get();
+  }
+
+  public void addChildTask(CancellableTask<?> childTask) {
+    this.childTasks.add(childTask);
+    childTask.setParentTask(this);
+  }
+
+  private void setParentTask(CancellableTask<?> parentTask) {
+    this.parentTask = parentTask;
+  }
+
+}

src/main/java/de/dhbwstuttgart/typeinference/unify/PlaceholderRegistry.java

@@ -16,10 +16,6 @@ import java.util.concurrent.atomic.AtomicInteger;
  */
 public class PlaceholderRegistry implements ISerializableData {
 
-  // The default registry should only ever be used outside on the Client-Side and NEVER on the Server-Side!
-  // This includes at least the server-handled packets and the unification algorithm
-  public static PlaceholderRegistry defaultRegistry = new PlaceholderRegistry();
-
   private final Set<String> existingPlaceholders = ConcurrentHashMap.newKeySet();
   private final AtomicInteger placeholderCount = new AtomicInteger();
   public ArrayList<PlaceholderType> UnifyTypeFactory_PLACEHOLDERS = new ArrayList<>();
@@ -49,6 +45,14 @@ public class PlaceholderRegistry implements ISerializableData {
     return name;
   }
 
+  public PlaceholderRegistry deepClone() {
+    PlaceholderRegistry pr2 = new PlaceholderRegistry();
+    this.existingPlaceholders.forEach(pr2::addPlaceholder);
+    pr2.UnifyTypeFactory_PLACEHOLDERS.addAll(this.UnifyTypeFactory_PLACEHOLDERS);
+    pr2.placeholderCount.set(this.placeholderCount.get());
+    return pr2;
+  }
+
   /**
    * Generate a token that consists of uppercase letters and contains the given prefix and suffix from the value i
    *

src/main/java/de/dhbwstuttgart/typeinference/unify/TypeUnifyTask.java

@@ -59,7 +59,7 @@ import org.apache.commons.io.output.NullOutputStream;
  *
  * @author Florian Steurer
  */
-public class TypeUnifyTask extends RecursiveTask<CompletableFuture<Set<Set<UnifyPair>>>> {
+public class TypeUnifyTask extends CancellableTask<CompletableFuture<Set<Set<UnifyPair>>>> {
 
   @Serial
   private static final long serialVersionUID = 1L;
@@ -259,9 +259,6 @@ public class TypeUnifyTask extends RecursiveTask<CompletableFuture<Set<Set<Unify
           .collect(Collectors.toCollection(ArrayList::new));
         throw new TypeinferenceException("Unresolved constraints: " + res, new NullToken()); //return new HashSet<>();
       }
-      else {
-        System.out.println(res);
-      }
 
       if (this.myIsCancelled()) {
         return new HashSet<>();
@@ -855,6 +852,11 @@ public class TypeUnifyTask extends RecursiveTask<CompletableFuture<Set<Set<Unify
 
       if (parallel) {
         for (Set<Set<UnifyPair>> par_res : forkResults) {
+          if (variance == 0 && (!result.isEmpty() && (!isUndefinedPairSetSet(currentThreadResult)))) {
+            this.cancelChildExecution();
+            return CompletableFuture.completedFuture(result);
+          }
+
           if (!isUndefinedPairSetSet(par_res) && isUndefinedPairSetSet(result)) {
             //wenn korrektes Ergebnis gefunden alle Fehlerfaelle loeschen
             result = par_res;
@@ -887,6 +889,7 @@ public class TypeUnifyTask extends RecursiveTask<CompletableFuture<Set<Set<Unify
         // Iterator<Set<UnifyPair>> nextSetasListIt = new ArrayList<>(nextSetAsList).iterator();
         boolean shouldBreak = varianceCase.eraseInvalidSets(rekTiefe, aParDef, nextSetAsList);
         if (shouldBreak) {
+          this.cancelChildExecution();
           return CompletableFuture.completedFuture(result);
         }
 
@@ -1387,15 +1390,13 @@ public class TypeUnifyTask extends RecursiveTask<CompletableFuture<Set<Set<Unify
     {
       List<Set<Constraint<UnifyPair>>> oderConstraintsVariance = oderConstraintsOutput.stream() //Alle Elemente rauswerfen, die Variance 0 haben oder keine TPH in LHS oder RHS sind
         .filter(x -> x.stream()
-          .anyMatch(y ->
-            y.stream().anyMatch(z ->
-              ( (z.getLhsType() instanceof PlaceholderType)
-                && (((PlaceholderType) (z.getLhsType())).getVariance() != 0))
-              ||
-              ( (z.getRhsType() instanceof PlaceholderType)
-                && (((PlaceholderType) (z.getRhsType())).getVariance() != 0))
-            )
-          )).toList();
+          .filter(y ->
+            y.stream().filter(z -> ((z.getLhsType() instanceof PlaceholderType)
+              && (((PlaceholderType) (z.getLhsType())).getVariance() != 0))
+              || ((z.getRhsType() instanceof PlaceholderType)
+              && (((PlaceholderType) (z.getRhsType())).getVariance() != 0))
+            ).findFirst().isPresent()
+          ).findFirst().isPresent()).collect(Collectors.toList());
       if (!oderConstraintsVariance.isEmpty()) {
         Set<Constraint<UnifyPair>> ret = oderConstraintsVariance.getFirst();
         oderConstraintsOutput.remove(ret);
@@ -1806,7 +1807,13 @@ public class TypeUnifyTask extends RecursiveTask<CompletableFuture<Set<Set<Unify
           //eingefuegt PL 2018-03-29 Anfang ? ext. theta hinzufuegen
           if (a.isWildcardable()) {
             Set<UnifyType> smaller_ext = smaller.stream().filter(x -> !(x instanceof ExtendsType) && !(x instanceof SuperType))
-              .map(ExtendsType::new)//.accept(new freshPlaceholder(), hm));}
+              .map(x -> {
+                //BinaryOperator<HashMap<PlaceholderType,PlaceholderType>> combiner = (aa,b) -> { aa.putAll(b); return aa;}; //Variablenumbenennung rausgenommen
+                //HashMap<PlaceholderType,PlaceholderType> hm = x.getInvolvedPlaceholderTypes().stream()                   //Variablen muessen wahrscheinlich erhalten bleiben
+                //		.reduce(new HashMap<PlaceholderType,PlaceholderType>(),
+                //				(aa, b)-> { aa.put(b,PlaceholderType.freshPlaceholder()); return aa; }, combiner);
+                return new ExtendsType(x);
+              })//.accept(new freshPlaceholder(), hm));}
               .collect(Collectors.toCollection(HashSet::new));
             smaller.addAll(smaller_ext);
           }
@@ -1926,7 +1933,13 @@ public class TypeUnifyTask extends RecursiveTask<CompletableFuture<Set<Set<Unify
     //writeLog("GREATER: " + greater + pair + "THETA: " + theta + "FBOUNDED: " + pair.getfBounded() + " ");
     if (a.isWildcardable()) {
       Set<UnifyType> greater_ext = greater.stream().filter(x -> !(x instanceof ExtendsType) && !(x instanceof SuperType))
-        .map(SuperType::new)//.accept(new freshPlaceholder(), hm));}
+        .map(x -> {
+          //BinaryOperator<HashMap<PlaceholderType,PlaceholderType>> combiner = (aa,b) -> { aa.putAll(b); return aa;}; //Variablenumbenennung rausgenommen
+          //HashMap<PlaceholderType,PlaceholderType> hm = x.getInvolvedPlaceholderTypes().stream()                   //Variablen muessen wahrscheinlich erhalten bleiben
+          //		.reduce(new HashMap<PlaceholderType,PlaceholderType>(),
+          //				(aa, b)-> { aa.put(b,PlaceholderType.freshPlaceholder()); return aa; }, combiner);
+          return new SuperType(x);
+        })//.accept(new freshPlaceholder(), hm));}
         .collect(Collectors.toCollection(HashSet::new));
       greater.addAll(greater_ext);
     }

src/main/java/de/dhbwstuttgart/typeinference/unify/cartesianproduct/Variance0Case.java

@@ -99,6 +99,7 @@ public class Variance0Case extends VarianceCase {
 
     /* FORK ANFANG */
     TypeUnify2Task forkOrig = new TypeUnify2Task(newElemsOrig, newEqOrig, newOderConstraintsOrig, a, fc, context, rekTiefe, new HashSet<>(methodSignatureConstraint));
+    typeUnifyTask.addChildTask(forkOrig);
     // schedule compute() on another thread
     CompletableFuture<Set<Set<UnifyPair>>> forkOrigFuture = CompletableFuture.supplyAsync(forkOrig::compute, context.executor()).thenCompose(f -> f);
     resultValues = resultValues.thenCombine(forkOrigFuture,
@@ -136,6 +137,7 @@ public class Variance0Case extends VarianceCase {
       List<Set<Constraint<UnifyPair>>> newOderConstraints = new ArrayList<>(oderConstraints);
       newElems.add(nSaL);
       TypeUnify2Task fork = new TypeUnify2Task(newElems, newEq, newOderConstraints, nSaL, fc, context, rekTiefe, new HashSet<>(methodSignatureConstraint));
+      typeUnifyTask.addChildTask(fork);
       // schedule compute() on another thread
       CompletableFuture<Set<Set<UnifyPair>>> forkFuture = CompletableFuture.supplyAsync(fork::compute, context.executor()).thenCompose(f -> f);
       resultValues = resultValues.thenCombine(forkFuture,
@@ -200,6 +202,7 @@ public class Variance0Case extends VarianceCase {
       writeLog("Not Removed: " + nextSetAsList);
 
       for (Set<UnifyPair> aPar : aParDef) {
+
         nextSetAsList.removeAll(nextSetasListOderConstraints);
         nextSetasListOderConstraints = new ArrayList<>();
         writeLog("Removed: " + nextSetasListOderConstraints);

src/main/java/de/dhbwstuttgart/typeinference/unify/cartesianproduct/Variance1Case.java

@@ -72,6 +72,7 @@ public class Variance1Case extends VarianceCase {
 
     /* FORK ANFANG */
     TypeUnify2Task forkOrig = new TypeUnify2Task(newElemsOrig, newEqOrig, newOderConstraintsOrig, a, fc, context, rekTiefe, methodSignatureConstraint);
+    typeUnifyTask.addChildTask(forkOrig);
     // schedule compute() on another thread
     CompletableFuture<Set<Set<UnifyPair>>> forkOrigFuture = CompletableFuture.supplyAsync(forkOrig::compute, context.executor()).thenCompose(f -> f);
     resultValues = resultValues.thenCombine(forkOrigFuture,
@@ -108,6 +109,7 @@ public class Variance1Case extends VarianceCase {
       List<Set<Constraint<UnifyPair>>> newOderConstraints = new ArrayList<>(oderConstraints);
       newElems.add(nSaL);
       TypeUnify2Task fork = new TypeUnify2Task(newElems, newEq, newOderConstraints, nSaL, fc, context, rekTiefe, new HashSet<>(methodSignatureConstraint));
+      typeUnifyTask.addChildTask(fork);
       // schedule compute() on another thread
       CompletableFuture<Set<Set<UnifyPair>>> forkFuture = CompletableFuture.supplyAsync(fork::compute, context.executor()).thenCompose(f -> f);
       resultValues = resultValues.thenCombine(forkFuture,

src/main/java/de/dhbwstuttgart/typeinference/unify/cartesianproduct/Variance2Case.java

@@ -60,6 +60,7 @@ public class Variance2Case extends VarianceCase {
 
     /* FORK ANFANG */
     TypeUnify2Task forkOrig = new TypeUnify2Task(newElemsOrig, newEqOrig, newOderConstraintsOrig, a, fc, context, rekTiefe, new HashSet<>(methodSignatureConstraint));
+    typeUnifyTask.addChildTask(forkOrig);
     CompletableFuture<Set<Set<UnifyPair>>> forkOrigFuture = CompletableFuture.supplyAsync(forkOrig::compute, context.executor()).thenCompose(f -> f);
     resultValuesFuture = forkOrigFuture.thenApply((currentThreadResult) -> {
       forkOrig.writeLog("final Orig 2");
@@ -89,6 +90,7 @@ public class Variance2Case extends VarianceCase {
       List<Set<Constraint<UnifyPair>>> newOderConstraints = new ArrayList<>(oderConstraints);
       newElems.add(nSaL);
       TypeUnify2Task fork = new TypeUnify2Task(newElems, newEq, newOderConstraints, nSaL, fc, context, rekTiefe, new HashSet<>(methodSignatureConstraintForParallel));
+      typeUnifyTask.addChildTask(fork);
       CompletableFuture<Set<Set<UnifyPair>>> forkFuture = CompletableFuture.supplyAsync(fork::compute, context.executor()).thenCompose(f -> f);
       resultValuesFuture = resultValuesFuture.thenCombine(forkFuture, (resultValues, fork_res) -> {
         if (typeUnifyTask.myIsCancelled()) {

src/main/java/de/dhbwstuttgart/typeinference/unify/cartesianproduct/VarianceM1Case.java

@@ -72,6 +72,7 @@ public class VarianceM1Case extends VarianceCase {
 
     /* FORK ANFANG */
     TypeUnify2Task forkOrig = new TypeUnify2Task(newElemsOrig, newEqOrig, newOderConstraintsOrig, a, fc, context, rekTiefe, methodSignatureConstraint);
+    typeUnifyTask.addChildTask(forkOrig);
     // schedule compute() on another thread
     CompletableFuture<Set<Set<UnifyPair>>> forkOrigFuture = CompletableFuture.supplyAsync(forkOrig::compute, context.executor()).thenCompose(f -> f);
     resultValues = resultValues.thenCombine(forkOrigFuture,
@@ -109,6 +110,7 @@ public class VarianceM1Case extends VarianceCase {
       List<Set<Constraint<UnifyPair>>> newOderConstraints = new ArrayList<>(oderConstraints);
       newElems.add(nSaL);
       TypeUnify2Task fork = new TypeUnify2Task(newElems, newEq, newOderConstraints, nSaL, fc, context, rekTiefe, new HashSet<>(methodSignatureConstraint));
+      typeUnifyTask.addChildTask(fork);
       // schedule compute() on another thread
       CompletableFuture<Set<Set<UnifyPair>>> forkFuture = CompletableFuture.supplyAsync(fork::compute, context.executor()).thenCompose(f -> f);
       resultValues = resultValues.thenCombine(forkFuture,

src/main/java/de/dhbwstuttgart/typeinference/unify/model/Unifier.java

@@ -50,8 +50,7 @@ public class Unifier implements Function<UnifyType, UnifyType>, Iterable<Entry<P
 		Unifier tempU = new Unifier(source, target);
 		// Every new substitution must be applied to previously added substitutions
 		// otherwise the unifier needs to be applied multiple times to unify two terms
-		for(PlaceholderType pt : substitutions.keySet())
-			substitutions.put(pt, substitutions.get(pt).apply(tempU));
+		substitutions.replaceAll((pt, ut) -> ut.apply(tempU));
 		substitutions.put(source, target);
 	}
 

src/test/java/finiteClosure/SuperInterfacesTest.java

@@ -1,5 +1,6 @@
 package finiteClosure;
 
+import de.dhbwstuttgart.core.JavaTXCompiler;
 import de.dhbwstuttgart.parser.SyntaxTreeGenerator.FCGenerator;
 import de.dhbwstuttgart.syntaxtree.ClassOrInterface;
 import de.dhbwstuttgart.syntaxtree.factory.ASTFactory;
@@ -15,14 +16,14 @@ public class SuperInterfacesTest {
     public void test() throws ClassNotFoundException {
         Collection<ClassOrInterface> classes = new ArrayList<>();
         classes.add(ASTFactory.createClass(TestClass.class));
-        System.out.println(FCGenerator.toFC(classes, ClassLoader.getSystemClassLoader(), new PlaceholderRegistry()));
+        System.out.println(FCGenerator.toFC(classes, ClassLoader.getSystemClassLoader(), JavaTXCompiler.defaultClientPlaceholderRegistry));
     }
 
     @Test
     public void testGeneric() throws ClassNotFoundException {
         Collection<ClassOrInterface> classes = new ArrayList<>();
         classes.add(ASTFactory.createClass(TestClassGeneric.class));
-        System.out.println(FCGenerator.toFC(classes, ClassLoader.getSystemClassLoader(), new PlaceholderRegistry()));
+        System.out.println(FCGenerator.toFC(classes, ClassLoader.getSystemClassLoader(), JavaTXCompiler.defaultClientPlaceholderRegistry));
     }
 }
 

src/test/java/server/ServerTest.java

@@ -0,0 +1,141 @@
+package server;
+
+import de.dhbwstuttgart.core.JavaTXCompiler;
+import de.dhbwstuttgart.core.JavaTXServer;
+import de.dhbwstuttgart.environment.CompilationEnvironment;
+import de.dhbwstuttgart.server.SocketClient;
+import de.dhbwstuttgart.syntaxtree.ClassOrInterface;
+import de.dhbwstuttgart.syntaxtree.factory.ASTFactory;
+import de.dhbwstuttgart.syntaxtree.factory.UnifyTypeFactory;
+import de.dhbwstuttgart.typeinference.constraints.ConstraintSet;
+import de.dhbwstuttgart.typeinference.constraints.Pair;
+import de.dhbwstuttgart.typeinference.result.ResultSet;
+import de.dhbwstuttgart.typeinference.unify.PlaceholderRegistry;
+import de.dhbwstuttgart.typeinference.unify.TypeUnify;
+import de.dhbwstuttgart.typeinference.unify.UnifyContext;
+import de.dhbwstuttgart.typeinference.unify.UnifyResultListenerImpl;
+import de.dhbwstuttgart.typeinference.unify.UnifyResultModel;
+import de.dhbwstuttgart.typeinference.unify.UnifyTaskModel;
+import de.dhbwstuttgart.typeinference.unify.model.FiniteClosure;
+import de.dhbwstuttgart.typeinference.unify.model.PlaceholderType;
+import de.dhbwstuttgart.typeinference.unify.model.UnifyPair;
+import de.dhbwstuttgart.typeinference.unify.model.UnifyType;
+import java.io.File;
+import java.io.IOException;
+import java.io.Writer;
+import java.nio.file.Path;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.stream.Collectors;
+import org.junit.Ignore;
+import org.junit.Test;
+import targetast.TestCodegen;
+import static org.junit.Assert.*;
+
+@Ignore("Server tests create huge overhead, so they are ignored until required")
+public class ServerTest {
+
+  @Test
+  public void checkServer_Scalar() throws IOException, ClassNotFoundException {
+    compareLocalAndServerResult("Scalar.jav");
+  }
+
+  @Test
+  public void checkServer_Matrix() throws IOException, ClassNotFoundException {
+    compareLocalAndServerResult("Matrix.jav");
+  }
+
+  protected void compareLocalAndServerResult(final String filename) throws IOException, ClassNotFoundException {
+    File file = Path.of(TestCodegen.path.toString(), filename).toFile();
+
+    // get information from compiler
+    JavaTXCompiler compiler = new JavaTXCompiler(List.of(file));
+
+    // NOW: simulate the call to method typeInference. Once via server and once locally
+    // if everything works, they should neither interfere with each other, nor differ in their result
+
+    // get the values from the compiler
+    PlaceholderRegistry placeholderRegistry = JavaTXCompiler.defaultClientPlaceholderRegistry; //new PlaceholderRegistry();
+    ConstraintSet<Pair> cons = compiler.getConstraints(file);
+    ConstraintSet<UnifyPair> unifyCons = UnifyTypeFactory.convert(compiler, cons, placeholderRegistry);
+    unifyCons = unifyCons.map(ServerTest::distributeInnerVars);
+
+    FiniteClosure finiteClosure = UnifyTypeFactory.generateFC(
+      ServerTest.getAllClasses(compiler, file).stream().toList(),
+      Writer.nullWriter(),
+      compiler.classLoader,
+      compiler,
+      placeholderRegistry
+    );
+    UnifyTaskModel usedTasks = new UnifyTaskModel();
+
+
+
+    // create the server
+    JavaTXServer server = new JavaTXServer(5000);
+    try (ExecutorService executor = Executors.newSingleThreadExecutor()) {
+      // run the server in a separate thread
+      executor.submit(server::listen);
+    }
+
+    // run the unification on the server
+    PlaceholderRegistry prCopy = JavaTXCompiler.defaultClientPlaceholderRegistry.deepClone();
+    UnifyResultModel urm = new UnifyResultModel(cons, finiteClosure);
+    UnifyContext context = new UnifyContext(Writer.nullWriter(), false, true, urm, usedTasks, prCopy);
+    SocketClient socketClient = new SocketClient("ws://localhost:5000");
+    List<ResultSet> serverResult = socketClient.execute(finiteClosure, cons, unifyCons, context);
+
+    // close the server
+    server.forceStop();
+
+    // run the unification on the client (do this second, because it changes the initial placeholder registry)
+    UnifyResultListenerImpl li = new UnifyResultListenerImpl();
+    urm.addUnifyResultListener(li);
+    TypeUnify.unifyParallel(unifyCons.getUndConstraints(), unifyCons.getOderConstraints(), finiteClosure, context);
+    List<ResultSet> clientResult = li.getResults();
+
+
+    // create the bytecode from both results
+    var sf = compiler.sourceFiles.get(file);
+    var serverBytecode = compiler.generateBytecode(sf, serverResult);
+    var localBytecode = compiler.generateBytecode(sf, clientResult);
+
+    // test if the generated code is the same
+    for (var serverEntry : serverBytecode.entrySet()) {
+      var serverBytes = serverEntry.getValue();
+      var localBytes = localBytecode.get(serverEntry.getKey());
+      assertArrayEquals(serverBytes, localBytes);
+    }
+  }
+
+
+  protected static UnifyPair distributeInnerVars(UnifyPair x) {
+    UnifyType lhs, rhs;
+    if (((lhs = x.getLhsType()) instanceof PlaceholderType) && ((rhs = x.getRhsType()) instanceof PlaceholderType) && (((PlaceholderType) lhs).isInnerType() || ((PlaceholderType) rhs).isInnerType())) {
+      ((PlaceholderType) lhs).setInnerType(true);
+      ((PlaceholderType) rhs).setInnerType(true);
+    }
+    return x;
+  }
+
+  protected static Set<ClassOrInterface> getAllClasses(JavaTXCompiler compiler, File file)
+    throws ClassNotFoundException, IOException
+  {
+    var sf = compiler.sourceFiles.get(file);
+    Set<ClassOrInterface> allClasses = new HashSet<>();
+    allClasses.addAll(compiler.getAvailableClasses(sf));
+    allClasses.addAll(sf.getClasses());
+    var newClasses = CompilationEnvironment.loadDefaultPackageClasses(sf.getPkgName(), file, compiler).stream().map(ASTFactory::createClass).collect(Collectors.toSet());
+    for (var clazz : newClasses) {
+      // Don't load classes that get recompiled
+      if (sf.getClasses().stream().anyMatch(nf -> nf.getClassName().equals(clazz.getClassName())))
+        continue;
+      if (allClasses.stream().noneMatch(old -> old.getClassName().equals(clazz.getClassName())))
+        allClasses.add(clazz);
+    }
+    return allClasses;
+  }
+}