Remove Flyway transformer by providing tighter integration

extensions/flyway/deployment/src/main/java/io/quarkus/flyway/FlywayProcessor.java

@@ -45,7 +45,6 @@
 import io.quarkus.deployment.annotations.BuildStep;
 import io.quarkus.deployment.annotations.ExecutionTime;
 import io.quarkus.deployment.annotations.Record;
-import io.quarkus.deployment.builditem.BytecodeTransformerBuildItem;
 import io.quarkus.deployment.builditem.CapabilityBuildItem;
 import io.quarkus.deployment.builditem.CombinedIndexBuildItem;
 import io.quarkus.deployment.builditem.FeatureBuildItem;
@@ -77,13 +76,6 @@ CapabilityBuildItem capability() {
         return new CapabilityBuildItem(Capability.FLYWAY);
     }
 
-    @BuildStep
-    void scannerTransformer(BuildProducer<BytecodeTransformerBuildItem> transformers) {
-        transformers
-                .produce(new BytecodeTransformerBuildItem(true, ScannerTransformer.FLYWAY_SCANNER_CLASS_NAME,
-                        new ScannerTransformer()));
-    }
-
     @BuildStep
     IndexDependencyBuildItem indexFlyway() {
         return new IndexDependencyBuildItem("org.flywaydb", "flyway-core");
@@ -106,21 +98,23 @@ void build(BuildProducer<FeatureBuildItem> featureProducer,
         List<String> applicationMigrations = discoverApplicationMigrations(getMigrationLocations(dataSourceNames));
         recorder.setApplicationMigrationFiles(applicationMigrations);
 
-        Set<Class<?>> javaMigrationClasses = new HashSet<>();
+        Set<Class<? extends JavaMigration>> javaMigrationClasses = new HashSet<>();
         addJavaMigrations(combinedIndexBuildItem.getIndex().getAllKnownImplementors(JAVA_MIGRATION), context,
                 reflectiveClassProducer, javaMigrationClasses);
         recorder.setApplicationMigrationClasses(javaMigrationClasses);
 
         resourceProducer.produce(new NativeImageResourceBuildItem(applicationMigrations.toArray(new String[0])));
     }
 
+    @SuppressWarnings("unchecked")
     private void addJavaMigrations(Collection<ClassInfo> candidates, RecorderContext context,
-            BuildProducer<ReflectiveClassBuildItem> reflectiveClassProducer, Set<Class<?>> javaMigrationClasses) {
+            BuildProducer<ReflectiveClassBuildItem> reflectiveClassProducer,
+            Set<Class<? extends JavaMigration>> javaMigrationClasses) {
         for (ClassInfo javaMigration : candidates) {
             if (Modifier.isAbstract(javaMigration.flags())) {
                 continue;
             }
-            javaMigrationClasses.add(context.classProxy(javaMigration.name().toString()));
+            javaMigrationClasses.add((Class<JavaMigration>) context.classProxy(javaMigration.name().toString()));
             reflectiveClassProducer.produce(new ReflectiveClassBuildItem(false, false, javaMigration.name().toString()));
         }
     }

extensions/flyway/runtime/src/main/java/io/quarkus/flyway/runtime/FlywayCreator.java

@@ -1,5 +1,7 @@
 package io.quarkus.flyway.runtime;
 
+import java.util.Arrays;
+
 import javax.sql.DataSource;
 
 import org.flywaydb.core.Flyway;
@@ -47,6 +49,18 @@ public Flyway createFlyway(DataSource dataSource) {
             configure.baselineDescription(flywayRuntimeConfig.baselineDescription.get());
         }
         configure.placeholders(flywayRuntimeConfig.placeholders);
+
+        /*
+         * Ensure that no classpath scanning takes place by setting the ClassProvider and the ResourceProvider
+         * (see Flyway#createResourceAndClassProviders)
+         */
+
+        // the static fields of this class have already been set at static-init
+        QuarkusPathLocationScanner quarkusPathLocationScanner = new QuarkusPathLocationScanner(
+                Arrays.asList(configure.getLocations()));
+        configure.javaMigrationClassProvider(new QuarkusFlywayClassProvider<>(quarkusPathLocationScanner.scanForClasses()));
+        configure.resourceProvider(new QuarkusFlywayResourceProvider(quarkusPathLocationScanner.scanForResources()));
+
         return configure.load();
     }
 }

extensions/flyway/runtime/src/main/java/io/quarkus/flyway/runtime/FlywayRecorder.java

@@ -8,6 +8,7 @@
 import javax.sql.DataSource;
 
 import org.flywaydb.core.Flyway;
+import org.flywaydb.core.api.migration.JavaMigration;
 import org.jboss.logging.Logger;
 
 import io.quarkus.agroal.runtime.DataSources;
@@ -26,7 +27,7 @@ public void setApplicationMigrationFiles(Collection<String> migrationFiles) {
         QuarkusPathLocationScanner.setApplicationMigrationFiles(migrationFiles);
     }
 
-    public void setApplicationMigrationClasses(Collection<Class<?>> migrationClasses) {
+    public void setApplicationMigrationClasses(Collection<Class<? extends JavaMigration>> migrationClasses) {
         log.debugv("Setting the following application migration classes: {0}", migrationClasses);
         QuarkusPathLocationScanner.setApplicationMigrationClasses(migrationClasses);
     }

extensions/flyway/runtime/src/main/java/io/quarkus/flyway/runtime/QuarkusFlywayClassProvider.java

@@ -0,0 +1,20 @@
+package io.quarkus.flyway.runtime;
+
+import java.util.Collection;
+import java.util.Collections;
+
+import org.flywaydb.core.api.ClassProvider;
+
+public class QuarkusFlywayClassProvider<I> implements ClassProvider<I> {
+
+    private final Collection<Class<? extends I>> classes;
+
+    public QuarkusFlywayClassProvider(Collection<Class<? extends I>> classes) {
+        this.classes = Collections.unmodifiableCollection(classes);
+    }
+
+    @Override
+    public Collection<Class<? extends I>> getClasses() {
+        return classes;
+    }
+}

extensions/flyway/runtime/src/main/java/io/quarkus/flyway/runtime/QuarkusFlywayResourceProvider.java

@@ -0,0 +1,56 @@
+package io.quarkus.flyway.runtime;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.List;
+
+import org.flywaydb.core.api.ResourceProvider;
+import org.flywaydb.core.internal.resource.LoadableResource;
+import org.flywaydb.core.internal.util.StringUtils;
+import org.jboss.logging.Logger;
+
+/**
+ * This class is very similar to {@link org.flywaydb.core.internal.scanner.Scanner}
+ * TODO: refactor upstream to move common methods to utility class
+ */
+public class QuarkusFlywayResourceProvider implements ResourceProvider {
+
+    private static final Logger log = Logger.getLogger(FlywayRecorder.class);
+
+    private final Collection<LoadableResource> resources;
+
+    public QuarkusFlywayResourceProvider(Collection<LoadableResource> resources) {
+        this.resources = resources;
+    }
+
+    @Override
+    public LoadableResource getResource(String name) {
+        for (LoadableResource resource : resources) {
+            String fileName = resource.getRelativePath();
+            if (fileName.equals(name)) {
+                return resource;
+            }
+        }
+        return null;
+    }
+
+    /**
+     * Returns all known resources starting with the specified prefix and ending with any of the specified suffixes.
+     *
+     * @param prefix The prefix of the resource names to match.
+     * @param suffixes The suffixes of the resource names to match.
+     * @return The resources that were found.
+     */
+    public Collection<LoadableResource> getResources(String prefix, String... suffixes) {
+        List<LoadableResource> result = new ArrayList<>();
+        for (LoadableResource resource : resources) {
+            String fileName = resource.getFilename();
+            if (StringUtils.startsAndEndsWith(fileName, prefix, suffixes)) {
+                result.add(resource);
+            } else {
+                log.debug("Filtering out resource: " + resource.getAbsolutePath() + " (filename: " + fileName + ")");
+            }
+        }
+        return result;
+    }
+}

extensions/flyway/runtime/src/main/java/io/quarkus/flyway/runtime/QuarkusPathLocationScanner.java

@@ -3,8 +3,10 @@
 import java.nio.charset.StandardCharsets;
 import java.util.ArrayList;
 import java.util.Collection;
+import java.util.Collections;
 
 import org.flywaydb.core.api.Location;
+import org.flywaydb.core.api.migration.JavaMigration;
 import org.flywaydb.core.internal.resource.LoadableResource;
 import org.flywaydb.core.internal.resource.classpath.ClassPathResource;
 import org.flywaydb.core.internal.scanner.classpath.ResourceAndClassScanner;
@@ -18,8 +20,8 @@
 public final class QuarkusPathLocationScanner implements ResourceAndClassScanner {
     private static final Logger LOGGER = Logger.getLogger(QuarkusPathLocationScanner.class);
     private static final String LOCATION_SEPARATOR = "/";
-    private static Collection<String> applicationMigrationFiles;
-    private static Collection<Class<?>> applicationMigrationClasses;
+    private static Collection<String> applicationMigrationFiles = Collections.emptyList(); // the set default to aid unit tests
+    private static Collection<Class<? extends JavaMigration>> applicationMigrationClasses = Collections.emptyList(); // the set default to aid unit tests
 
     private final Collection<LoadableResource> scannedResources;
 
@@ -72,15 +74,15 @@ private boolean canHandleMigrationFile(Collection<Location> locations, String mi
      * @return The non-abstract classes that were found.
      */
     @Override
-    public Collection<Class<?>> scanForClasses() {
+    public Collection<Class<? extends JavaMigration>> scanForClasses() {
         return applicationMigrationClasses;
     }
 
     public static void setApplicationMigrationFiles(Collection<String> applicationMigrationFiles) {
         QuarkusPathLocationScanner.applicationMigrationFiles = applicationMigrationFiles;
     }
 
-    public static void setApplicationMigrationClasses(Collection<Class<?>> applicationMigrationClasses) {
+    public static void setApplicationMigrationClasses(Collection<Class<? extends JavaMigration>> applicationMigrationClasses) {
         QuarkusPathLocationScanner.applicationMigrationClasses = applicationMigrationClasses;
     }
 }

extensions/flyway/runtime/src/main/java/io/quarkus/flyway/runtime/graal/ScannerSubstitutions.java

@@ -0,0 +1,24 @@
+package io.quarkus.flyway.runtime.graal;
+
+import java.nio.charset.Charset;
+import java.util.Collection;
+
+import org.flywaydb.core.api.Location;
+import org.flywaydb.core.internal.scanner.LocationScannerCache;
+import org.flywaydb.core.internal.scanner.ResourceNameCache;
+
+import com.oracle.svm.core.annotate.Substitute;
+import com.oracle.svm.core.annotate.TargetClass;
+
+/**
+ * Needed to get rid of some Android related classes
+ */
+@TargetClass(className = "org.flywaydb.core.internal.scanner.Scanner")
+public final class ScannerSubstitutions {
+
+    @Substitute
+    public ScannerSubstitutions(Class<?> implementedInterface, Collection<Location> locations, ClassLoader classLoader,
+            Charset encoding, ResourceNameCache resourceNameCache, LocationScannerCache locationScannerCache) {
+        throw new IllegalStateException("'org.flywaydb.core.internal.scanner.Scanner' is never used in Quarkus");
+    }
+}