Solution Quality Evaluator

src/main/java/edu/kit/provideq/toolbox/Bound.java

@@ -0,0 +1,10 @@
+package edu.kit.provideq.toolbox;
+
+/**
+ * Represents a bound value with its type.
+ *
+ * @param value the estimated value
+ * @param boundType the type of the bound
+ */
+public record Bound(String value, BoundType boundType) {
+}

src/main/java/edu/kit/provideq/toolbox/BoundType.java

@@ -0,0 +1,15 @@
+package edu.kit.provideq.toolbox;
+
+/**
+ * Represents the bound type of bounds.
+ */
+public enum BoundType {
+  /**
+   * An upper bound.
+   */
+  UPPER,
+  /**
+   * A lower bound.
+   */
+  LOWER
+}

src/main/java/edu/kit/provideq/toolbox/BoundWithInfo.java

@@ -0,0 +1,10 @@
+package edu.kit.provideq.toolbox;
+
+/**
+ * Represents a bound estimation for the solution of a problem.
+ *
+ * @param bound the value
+ * @param executionTime the time it took to estimate the value
+ */
+public record BoundWithInfo(Bound bound, long executionTime) {
+}

src/main/java/edu/kit/provideq/toolbox/api/BoundDto.java

@@ -0,0 +1,13 @@
+package edu.kit.provideq.toolbox.api;
+
+import edu.kit.provideq.toolbox.BoundType;
+import edu.kit.provideq.toolbox.BoundWithInfo;
+
+public record BoundDto(String bound, BoundType boundType, long executionTime) {
+  public BoundDto(BoundWithInfo boundWithInfo) {
+    this(
+        boundWithInfo.bound().value(),
+        boundWithInfo.bound().boundType(),
+        boundWithInfo.executionTime());
+  }
+}

src/main/java/edu/kit/provideq/toolbox/api/EstimationRouter.java

@@ -0,0 +1,130 @@
+package edu.kit.provideq.toolbox.api;
+
+import static org.springdoc.core.fn.builders.apiresponse.Builder.responseBuilder;
+import static org.springdoc.core.fn.builders.content.Builder.contentBuilder;
+import static org.springdoc.core.fn.builders.parameter.Builder.parameterBuilder;
+import static org.springdoc.core.fn.builders.schema.Builder.schemaBuilder;
+import static org.springdoc.webflux.core.fn.SpringdocRouteBuilder.route;
+import static org.springframework.http.MediaType.APPLICATION_JSON;
+import static org.springframework.http.MediaType.APPLICATION_JSON_VALUE;
+import static org.springframework.web.reactive.function.server.RequestPredicates.accept;
+import static org.springframework.web.reactive.function.server.ServerResponse.ok;
+
+import edu.kit.provideq.toolbox.meta.Problem;
+import edu.kit.provideq.toolbox.meta.ProblemManager;
+import edu.kit.provideq.toolbox.meta.ProblemManagerProvider;
+import edu.kit.provideq.toolbox.meta.ProblemType;
+import io.swagger.v3.oas.annotations.enums.ParameterIn;
+import java.util.Objects;
+import java.util.UUID;
+import org.springdoc.core.fn.builders.operation.Builder;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.core.ParameterizedTypeReference;
+import org.springframework.http.HttpStatus;
+import org.springframework.web.reactive.config.EnableWebFlux;
+import org.springframework.web.reactive.function.server.RouterFunction;
+import org.springframework.web.reactive.function.server.ServerRequest;
+import org.springframework.web.reactive.function.server.ServerResponse;
+import org.springframework.web.server.ResponseStatusException;
+import reactor.core.publisher.Mono;
+
+/**
+ * This router handles requests regarding {@link Problem} instance solution bound estimations.
+ * The /bound endpoint is only available for problem types that have an estimator.
+ */
+@Configuration
+@EnableWebFlux
+public class EstimationRouter {
+  public static final String PROBLEM_ID_PARAM_NAME = "problemId";
+  private ProblemManagerProvider managerProvider;
+
+  @Bean
+  RouterFunction<ServerResponse> getEstimationRoutes() {
+    return managerProvider.getProblemManagers().stream()
+            .filter(manager -> manager.getType().getEstimator().isPresent())
+            .map(this::defineGetRoute)
+            .reduce(RouterFunction::and)
+            .orElse(null);
+  }
+
+  /**
+   * Estimate Operation: GET /problems/TYPE/{problemId}/bound.
+   */
+  private RouterFunction<ServerResponse> defineGetRoute(ProblemManager<?, ?> manager) {
+    return route().GET(
+            getEstimationRouteForProblemType(manager.getType()),
+            accept(APPLICATION_JSON),
+            req -> handleGet(manager, req),
+            ops -> handleGetDocumentation(manager, ops)
+    ).build();
+  }
+
+  private <InputT, ResultT> Mono<ServerResponse> handleGet(
+          ProblemManager<InputT, ResultT> manager,
+          ServerRequest req
+  ) {
+    var problemId = req.pathVariable(PROBLEM_ID_PARAM_NAME);
+    var problem = findProblemOrThrow(manager, problemId);
+
+    Mono<BoundDto> bound;
+    try {
+      problem.estimateBound();
+      bound = Mono.just(new BoundDto(problem.getBound().orElseThrow()));
+    } catch (IllegalStateException | NoSuchElementException e) {
+      throw new ResponseStatusException(HttpStatus.BAD_REQUEST, e.getMessage());
+    }
+
+    return ok().body(bound, new ParameterizedTypeReference<>() {
+    });
+  }
+
+  private void handleGetDocumentation(
+          ProblemManager<?, ?> manager,
+          Builder ops
+  ) {
+    ProblemType<?, ?> problemType = manager.getType();
+    ops
+        .operationId(getEstimationRouteForProblemType(problemType))
+        .tag(problemType.getId())
+        .description("Estimates the solution bound for the problem with the given ID.")
+        .parameter(parameterBuilder().in(ParameterIn.PATH).name(PROBLEM_ID_PARAM_NAME))
+        .response(responseBuilder()
+              .responseCode(String.valueOf(HttpStatus.OK.value()))
+              .content(getOkResponseContent())
+        );
+  }
+
+  private static org.springdoc.core.fn.builders.content.Builder getOkResponseContent() {
+    return contentBuilder()
+            .mediaType(APPLICATION_JSON_VALUE)
+            .schema(schemaBuilder().implementation(BoundDto.class));
+  }
+
+  private <InputT, ResultT> Problem<InputT, ResultT> findProblemOrThrow(
+          ProblemManager<InputT, ResultT> manager,
+          String id
+  ) {
+    UUID uuid;
+    try {
+      uuid = UUID.fromString(id);
+    } catch (IllegalArgumentException e) {
+      throw new ResponseStatusException(HttpStatus.BAD_REQUEST, "Invalid problem ID");
+    }
+
+    return manager.findInstanceById(uuid)
+            .orElseThrow(() -> new ResponseStatusException(HttpStatus.NOT_FOUND,
+                    "Could not find a problem for this type with this problem ID!"));
+  }
+
+  private String getEstimationRouteForProblemType(ProblemType<?, ?> type) {
+    return "/problems/%s/{%s}/bound".formatted(type.getId(), PROBLEM_ID_PARAM_NAME);
+  }
+
+  @Autowired
+  void setManagerProvider(ProblemManagerProvider managerProvider) {
+    this.managerProvider = managerProvider;
+  }
+
+}

src/main/java/edu/kit/provideq/toolbox/api/ProblemDto.java

@@ -1,12 +1,14 @@
 package edu.kit.provideq.toolbox.api;
 
+import edu.kit.provideq.toolbox.BoundWithInfo;
 import edu.kit.provideq.toolbox.Solution;
 import edu.kit.provideq.toolbox.meta.Problem;
 import edu.kit.provideq.toolbox.meta.ProblemSolver;
 import edu.kit.provideq.toolbox.meta.ProblemState;
 import edu.kit.provideq.toolbox.meta.setting.SolverSetting;
 import java.util.Collections;
 import java.util.List;
+import java.util.Optional;
 
 /**
  * Data transfer object for {@link Problem problems}, used in REST API request bodies and responses.
@@ -16,6 +18,7 @@ public class ProblemDto<InputT, ResultT> {
   private String typeId;
   private InputT input;
   private Solution<ResultT> solution;
+  private Optional<BoundWithInfo> bound;
   private ProblemState state;
   private String solverId;
   private List<SolverSetting> solverSettings;
@@ -38,6 +41,7 @@ public static <InputT, ResultT> ProblemDto<InputT, ResultT> fromProblem(
     dto.typeId = problem.getType().getId();
     dto.input = problem.getInput().orElse(null);
     dto.solution = problem.getSolution();
+    dto.bound = problem.getBound();
     dto.state = problem.getState();
     dto.solverId = problem.getSolver()
         .map(ProblemSolver::getId)
@@ -67,6 +71,10 @@ public Solution<ResultT> getSolution() {
     return solution;
   }
 
+  public Optional<BoundWithInfo> getBound() {
+    return bound;
+  }
+
   public ProblemState getState() {
     return state;
   }
@@ -100,6 +108,7 @@ public String toString() {
         + ", solverId=" + solverId
         + ", input=" + input
         + ", solution=" + solution
+        + ", value=" + bound
         + ", solverSettings=" + solverSettings
         + ", subProblems=" + subProblems
         + '}';

src/main/java/edu/kit/provideq/toolbox/demonstrators/DemonstratorConfiguration.java

@@ -16,7 +16,8 @@ public class DemonstratorConfiguration {
   public static final ProblemType<String, String> DEMONSTRATOR = new ProblemType<>(
       "demonstrator",
       String.class,
-      String.class
+      String.class,
+      null
   );
 
   @Bean

src/main/java/edu/kit/provideq/toolbox/featuremodel/anomaly/dead/DeadFeatureConfiguration.java

@@ -26,7 +26,8 @@ public class DeadFeatureConfiguration {
   public static final ProblemType<String, String> FEATURE_MODEL_ANOMALY_DEAD = new ProblemType<>(
       "feature-model-anomaly-dead",
       String.class,
-      String.class
+      String.class,
+      null
   );
 
   @Bean

src/main/java/edu/kit/provideq/toolbox/featuremodel/anomaly/voidmodel/VoidModelConfiguration.java

@@ -26,7 +26,8 @@ public class VoidModelConfiguration {
   public static final ProblemType<String, String> FEATURE_MODEL_ANOMALY_VOID = new ProblemType<>(
       "feature-model-anomaly-void",
       String.class,
-      String.class
+      String.class,
+      null
   );
 
   @Bean

src/main/java/edu/kit/provideq/toolbox/knapsack/KnapsackConfiguration.java

@@ -27,7 +27,8 @@ public class KnapsackConfiguration {
   public static final ProblemType<String, String> KNAPSACK = new ProblemType<>(
       "knapsack",
         String.class,
-        String.class
+        String.class,
+        null
     );
 
   @Bean

src/main/java/edu/kit/provideq/toolbox/maxcut/MaxCutConfiguration.java

@@ -27,7 +27,8 @@ public class MaxCutConfiguration {
   public static final ProblemType<String, String> MAX_CUT = new ProblemType<>(
       "max-cut",
       String.class,
-      String.class
+      String.class,
+      null
   );
 
   @Bean

src/main/java/edu/kit/provideq/toolbox/meta/Problem.java

@@ -1,5 +1,6 @@
 package edu.kit.provideq.toolbox.meta;
 
+import edu.kit.provideq.toolbox.BoundWithInfo;
 import edu.kit.provideq.toolbox.Solution;
 import edu.kit.provideq.toolbox.meta.setting.SolverSetting;
 import java.util.Collections;
@@ -29,6 +30,7 @@ public class Problem<InputT, ResultT> {
 
   private InputT input;
   private Solution<ResultT> solution;
+  private BoundWithInfo bound;
   private ProblemState state;
   private ProblemSolver<InputT, ResultT> solver;
   private List<SolverSetting> solverSettings;
@@ -82,6 +84,29 @@ public Mono<Solution<ResultT>> solve() {
         });
   }
 
+  public Mono<BoundWithInfo> estimateBound() {
+    if (this.input == null) {
+      throw new IllegalStateException("Cannot estimate value without input!");
+    }
+
+    var optionalEstimator = this.type.getEstimator();
+    if (optionalEstimator.isEmpty()) {
+      throw new IllegalStateException("Cannot estimate value without an estimator!");
+    }
+    var estimator = optionalEstimator.get();
+
+    long start = System.currentTimeMillis();
+
+    var bound = estimator.apply(this.input);
+    long finish = System.currentTimeMillis();
+    var executionTime = finish - start;
+
+    var boundWithExecutionTime = new BoundWithInfo(bound, executionTime);
+
+    return Mono.just(boundWithExecutionTime)
+        .doOnNext(boundValue -> this.bound = boundValue);
+  }
+
   public UUID getId() {
     return id;
   }
@@ -208,4 +233,8 @@ public String toString() {
             + ", solver=" + solver
             + '}';
   }
+
+  public Optional<BoundWithInfo> getBound() {
+    return Optional.ofNullable(bound);
+  }
 }

src/main/java/edu/kit/provideq/toolbox/meta/ProblemType.java

@@ -1,28 +1,37 @@
 package edu.kit.provideq.toolbox.meta;
 
+import edu.kit.provideq.toolbox.Bound;
+import java.util.Optional;
+import java.util.function.Function;
+
 /**
  * The type of problem to solve.
  */
 public class ProblemType<InputT, ResultT> {
   private final String id;
   private final Class<InputT> inputClass;
   private final Class<ResultT> resultClass;
+  private final Function<InputT, Bound> estimator;
 
   /**
    * Defines a new problem type.
    *
-   * @param id a unique string identifier for this type of problem.
-   * @param inputClass the Java class object corresponding to the {@link InputT} type parameter.
+   * @param id          a unique string identifier for this type of problem.
+   * @param inputClass  the Java class object corresponding to the {@link InputT} type parameter.
    * @param resultClass the Java class object corresponding to the {@link ResultT} type parameter.
+   * @param estimator   the bound estimator for this problem type.
+   *                    null if estimation is not supported.
    */
   public ProblemType(
       String id,
       Class<InputT> inputClass,
-      Class<ResultT> resultClass
+      Class<ResultT> resultClass,
+      Function<InputT, Bound> estimator
   ) {
     this.id = id;
     this.inputClass = inputClass;
     this.resultClass = resultClass;
+    this.estimator = estimator;
   }
 
   /**
@@ -46,12 +55,20 @@ public Class<ResultT> getResultClass() {
     return resultClass;
   }
 
+  /**
+   * Returns the bound estimator for this problem type.
+   */
+  public Optional<Function<InputT, Bound>> getEstimator() {
+    return Optional.ofNullable(estimator);
+  }
+
   @Override
   public String toString() {
     return "ProblemType{"
         + "id='%s'".formatted(id)
         + ", inputClass=%s".formatted(inputClass)
         + ", resultClass=%s".formatted(resultClass)
+        + ", estimator?=%s".formatted(estimator != null)
         + '}';
   }
 }