feat: expose ConstraintMetaModel at build time (#1343)

Fixes #1323.

quarkus-integration/quarkus/deployment/pom.xml

@@ -101,6 +101,16 @@
           </execution>
         </executions>
       </plugin>
+      <plugin>
+        <groupId>org.revapi</groupId>
+        <artifactId>revapi-maven-plugin</artifactId>
+        <configuration>
+          <!-- Introduction of API package to check -->
+          <oldArtifacts>
+            <artifact>${project.groupId}:timefold-solver-quarkus-deployment:1.18.0</artifact>
+          </oldArtifacts>
+        </configuration>
+      </plugin>
       <plugin>
         <artifactId>maven-surefire-plugin</artifactId>
         <configuration>

quarkus-integration/quarkus/deployment/src/build/revapi-differences.json

@@ -0,0 +1,9 @@
+[
+  {
+    "extension": "revapi.differences",
+    "configuration": {
+      "differences": [
+      ]
+    }
+  }
+]

quarkus-integration/quarkus/deployment/src/build/revapi-filter.json

@@ -0,0 +1,12 @@
+[
+  {
+    "extension": "revapi.filter",
+    "configuration": {
+      "elements": {
+        "include": [
+          "class ai\\.timefold\\.solver\\.quarkus\\.deployment\\.api.*"
+        ]
+      }
+    }
+  }
+]

quarkus-integration/quarkus/deployment/src/main/java/ai/timefold/solver/quarkus/deployment/SolverConfigBuildItem.java

@@ -15,7 +15,8 @@ public final class SolverConfigBuildItem extends SimpleBuildItem {
      * Constructor for multiple solver configurations.
      */
     public SolverConfigBuildItem(Map<String, SolverConfig> solverConfig, GeneratedGizmoClasses generatedGizmoClasses) {
-        this.solverConfigurations = solverConfig;
+        // Defensive copy to avoid changing the map in dependent build items.
+        this.solverConfigurations = Map.copyOf(solverConfig);
         this.generatedGizmoClasses = generatedGizmoClasses;
     }
 

quarkus-integration/quarkus/deployment/src/main/java/ai/timefold/solver/quarkus/deployment/TimefoldProcessor.java

@@ -30,6 +30,7 @@
 import ai.timefold.solver.core.api.domain.solution.ProblemFactCollectionProperty;
 import ai.timefold.solver.core.api.score.calculator.EasyScoreCalculator;
 import ai.timefold.solver.core.api.score.calculator.IncrementalScoreCalculator;
+import ai.timefold.solver.core.api.score.stream.ConstraintMetaModel;
 import ai.timefold.solver.core.api.score.stream.ConstraintProvider;
 import ai.timefold.solver.core.api.solver.SolverFactory;
 import ai.timefold.solver.core.api.solver.SolverManager;
@@ -40,10 +41,12 @@
 import ai.timefold.solver.core.impl.domain.solution.descriptor.SolutionDescriptor;
 import ai.timefold.solver.core.impl.heuristic.selector.common.nearby.NearbyDistanceMeter;
 import ai.timefold.solver.quarkus.TimefoldRecorder;
+import ai.timefold.solver.quarkus.bean.BeanUtil;
 import ai.timefold.solver.quarkus.bean.DefaultTimefoldBeanProvider;
 import ai.timefold.solver.quarkus.bean.TimefoldSolverBannerBean;
 import ai.timefold.solver.quarkus.bean.UnavailableTimefoldBeanProvider;
 import ai.timefold.solver.quarkus.config.TimefoldRuntimeConfig;
+import ai.timefold.solver.quarkus.deployment.api.ConstraintMetaModelBuildItem;
 import ai.timefold.solver.quarkus.deployment.config.SolverBuildTimeConfig;
 import ai.timefold.solver.quarkus.deployment.config.TimefoldBuildTimeConfig;
 import ai.timefold.solver.quarkus.devui.DevUISolverConfig;
@@ -573,6 +576,29 @@ private SolverConfig loadSolverConfig(IndexView indexView,
         return solverConfig;
     }
 
+    @BuildStep
+    void buildConstraintMetaModel(SolverConfigBuildItem solverConfigBuildItem,
+            BuildProducer<ConstraintMetaModelBuildItem> constraintMetaModelBuildItemBuildProducer) {
+        if (solverConfigBuildItem.getSolverConfigMap().isEmpty()) {
+            return;
+        }
+
+        Map<String, ConstraintMetaModel> constraintMetaModelsBySolverNames = new HashMap<>();
+        solverConfigBuildItem.getSolverConfigMap().forEach((solverName, solverConfig) -> {
+            // Gizmo-generated member accessors are not yet available at build time.
+            DomainAccessType originalDomainAccessType = solverConfig.getDomainAccessType();
+            solverConfig.setDomainAccessType(DomainAccessType.REFLECTION);
+
+            var solverFactory = SolverFactory.create(solverConfig);
+            ConstraintMetaModel constraintMetaModel = BeanUtil.buildConstraintMetaModel(solverFactory);
+            // Avoid changing the original solver config.
+            solverConfig.setDomainAccessType(originalDomainAccessType);
+            constraintMetaModelsBySolverNames.put(solverName, constraintMetaModel);
+        });
+
+        constraintMetaModelBuildItemBuildProducer.produce(new ConstraintMetaModelBuildItem(constraintMetaModelsBySolverNames));
+    }
+
     @BuildStep
     @Record(RUNTIME_INIT)
     void recordAndRegisterRuntimeBeans(TimefoldRecorder recorder, RecorderContext recorderContext,

quarkus-integration/quarkus/deployment/src/main/java/ai/timefold/solver/quarkus/deployment/api/ConstraintMetaModelBuildItem.java

@@ -0,0 +1,24 @@
+package ai.timefold.solver.quarkus.deployment.api;
+
+import java.util.Map;
+
+import ai.timefold.solver.core.api.score.stream.ConstraintMetaModel;
+
+import io.quarkus.builder.item.SimpleBuildItem;
+
+/**
+ * Represents a {@link ai.timefold.solver.core.api.score.stream.ConstraintMetaModel} at the build time for the purpose
+ * of Quarkus augmentation.
+ */
+public final class ConstraintMetaModelBuildItem extends SimpleBuildItem {
+
+    private final Map<String, ConstraintMetaModel> constraintMetaModelsBySolverNames;
+
+    public ConstraintMetaModelBuildItem(Map<String, ConstraintMetaModel> constraintMetaModelsBySolverNames) {
+        this.constraintMetaModelsBySolverNames = Map.copyOf(constraintMetaModelsBySolverNames);
+    }
+
+    public Map<String, ConstraintMetaModel> constraintMetaModelsBySolverNames() {
+        return constraintMetaModelsBySolverNames;
+    }
+}

quarkus-integration/quarkus/deployment/src/main/java/ai/timefold/solver/quarkus/deployment/api/package-info.java

@@ -0,0 +1,7 @@
+/**
+ * Public {@link io.quarkus.builder.item.BuildItem}s consumable by other Quarkus extensions.
+ * <p>
+ * All classes in this package are part of the public API of this extension.
+ * Moreover, the extension is responsible for creating instances of these classes during the build phase.
+ */
+package ai.timefold.solver.quarkus.deployment.api;

quarkus-integration/quarkus/runtime/src/main/java/ai/timefold/solver/quarkus/bean/BeanUtil.java

@@ -0,0 +1,32 @@
+package ai.timefold.solver.quarkus.bean;
+
+import java.util.Objects;
+
+import ai.timefold.solver.core.api.score.stream.ConstraintMetaModel;
+import ai.timefold.solver.core.api.solver.SolverFactory;
+import ai.timefold.solver.core.impl.score.stream.common.AbstractConstraintStreamScoreDirectorFactory;
+import ai.timefold.solver.core.impl.solver.DefaultSolverFactory;
+
+public class BeanUtil {
+
+    public static ConstraintMetaModel buildConstraintMetaModel(SolverFactory<?> solverFactory) {
+        if (Objects.requireNonNull(solverFactory) instanceof DefaultSolverFactory<?> defaultSolverFactory) {
+            var scoreDirectorFactory = defaultSolverFactory.getScoreDirectorFactory();
+            if (scoreDirectorFactory instanceof AbstractConstraintStreamScoreDirectorFactory<?, ?> castScoreDirectorFactory) {
+                return castScoreDirectorFactory.getConstraintMetaModel();
+            } else {
+                throw new IllegalStateException(
+                        "Cannot provide %s because the score director does not use the Constraint Streams API."
+                                .formatted(ConstraintMetaModel.class.getSimpleName()));
+            }
+        } else {
+            throw new IllegalStateException(
+                    "%s is not supported by the solver factory (%s)."
+                            .formatted(ConstraintMetaModel.class.getSimpleName(), solverFactory.getClass().getName()));
+        }
+    }
+
+    private BeanUtil() {
+        throw new IllegalStateException("Utility class");
+    }
+}

quarkus-integration/quarkus/runtime/src/main/java/ai/timefold/solver/quarkus/bean/DefaultTimefoldBeanProvider.java

@@ -24,8 +24,6 @@
 import ai.timefold.solver.core.api.solver.SolverManager;
 import ai.timefold.solver.core.config.solver.SolverConfig;
 import ai.timefold.solver.core.config.solver.SolverManagerConfig;
-import ai.timefold.solver.core.impl.score.stream.common.AbstractConstraintStreamScoreDirectorFactory;
-import ai.timefold.solver.core.impl.solver.DefaultSolverFactory;
 
 import io.quarkus.arc.DefaultBean;
 import io.quarkus.arc.Lock;
@@ -63,14 +61,8 @@ <Solution_> SolverFactory<Solution_> solverFactory(SolverConfig solverConfig) {
     @Produces
     ConstraintMetaModel constraintProviderMetaModel(SolverFactory<?> solverFactory) {
         if (constraintMetaModel == null) {
-            var scoreDirectorFactory = ((DefaultSolverFactory<?>) solverFactory).getScoreDirectorFactory();
-            if (scoreDirectorFactory instanceof AbstractConstraintStreamScoreDirectorFactory<?, ?> castScoreDirectorFactory) {
-                constraintMetaModel = castScoreDirectorFactory.getConstraintMetaModel();
-            } else {
-                throw new IllegalStateException(
-                        "Cannot provide %s because the score director does not use the Constraint Streams API."
-                                .formatted(ConstraintMetaModel.class.getSimpleName()));
-            }
+            // The metamodel is not compatible with Quarkus code recording, thus we need to rebuild it at runtime.
+            constraintMetaModel = BeanUtil.buildConstraintMetaModel(solverFactory);
         }
         return constraintMetaModel;
     }