fix(parser): add a fallback if AOT fails (#3314)

packages/java/engine-core/pom.xml

@@ -93,6 +93,11 @@
       <artifactId>mockito-core</artifactId>
       <scope>test</scope>
     </dependency>
+    <dependency>
+      <groupId>org.mockito</groupId>
+      <artifactId>mockito-inline</artifactId>
+      <scope>test</scope>
+    </dependency>
     <dependency>
       <groupId>org.hamcrest</groupId>
       <artifactId>hamcrest-all</artifactId>

packages/java/engine-core/src/main/java/com/vaadin/hilla/engine/AotBrowserCallableFinder.java

@@ -64,10 +64,9 @@ private static String determineApplicationClass(
                         }
                     }).filter(Objects::nonNull).findFirst().orElse(null);
             if (mainClass == null) {
-                LOGGER.warn(
+                LOGGER.debug(
                         "This project has not been recognized as a Spring Boot"
-                                + " application because a main class could not be found."
-                                + " Hilla services will not be available.");
+                                + " application because a main class could not be found.");
             }
             return mainClass;
         } catch (NoClassDefFoundError e) {
@@ -102,19 +101,23 @@ private static Path generateAotArtifacts(
         var argsFile = engineConfiguration.getBuildDir()
                 .resolve("hilla-aot-args.txt");
         Files.write(argsFile, settings);
-
+        var report = engineConfiguration.getBuildDir()
+                .resolve("hilla-aot-report.txt");
         var javaExecutable = ProcessHandle.current().info().command()
                 .orElse(Path.of(System.getProperty("java.home"), "bin", "java")
                         .toString());
 
         // Runs the SpringApplicationAotProcessor to generate the
         // reflect-config.json file. This comes from the `process-aot` goal.
-        int exitCode = new ProcessBuilder().inheritIO()
-                .command(javaExecutable, "@" + argsFile).start().waitFor();
+        var process = new ProcessBuilder().inheritIO()
+                .command(javaExecutable, "@" + argsFile)
+                .redirectOutput(report.toFile()).redirectErrorStream(true)
+                .start();
+        int exitCode = process.waitFor();
 
         if (exitCode != 0) {
-            LOGGER.error(
-                    SPRING_AOT_PROCESSOR + " exited with code: " + exitCode);
+            LOGGER.debug(SPRING_AOT_PROCESSOR + " exited with code " + exitCode
+                    + ". The output of the process is available in " + report);
         }
 
         var json = aotOutput.resolve(Path.of("resources", "META-INF",

packages/java/engine-core/src/main/java/com/vaadin/hilla/engine/EngineConfiguration.java

@@ -16,6 +16,7 @@
 
 import com.vaadin.flow.server.ExecutionFailedException;
 import com.vaadin.flow.server.frontend.FrontendUtils;
+import com.vaadin.flow.server.frontend.scanner.ClassFinder;
 
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -42,6 +43,7 @@ public class EngineConfiguration {
     private BrowserCallableFinder browserCallableFinder;
     private boolean productionMode = false;
     private String nodeCommand = "node";
+    private ClassFinder classFinder;
 
     private EngineConfiguration() {
         baseDir = Path.of(System.getProperty("user.dir"));
@@ -107,6 +109,10 @@ public String getNodeCommand() {
         return nodeCommand;
     }
 
+    public ClassFinder getClassFinder() {
+        return classFinder;
+    }
+
     public List<Class<? extends Annotation>> getEndpointAnnotations() {
         return parser.getEndpointAnnotations();
     }
@@ -129,8 +135,17 @@ public BrowserCallableFinder getBrowserCallableFinder() {
         return () -> {
             try {
                 return AotBrowserCallableFinder.findEndpointClasses(this);
-            } catch (IOException | InterruptedException e) {
-                throw new ExecutionFailedException(e);
+            } catch (Exception e) {
+                if (classFinder != null) {
+                    LOGGER.info(
+                            "AOT-based detection of browser-callable classes failed."
+                                    + " Falling back to classpath scan."
+                                    + " Enable debug logging for more information.");
+                    return LookupBrowserCallableFinder
+                            .findEndpointClasses(classFinder, this);
+                } else {
+                    throw new ExecutionFailedException(e);
+                }
             }
         };
     }
@@ -168,6 +183,7 @@ public Builder(EngineConfiguration configuration) {
             this.configuration.browserCallableFinder = configuration.browserCallableFinder;
             this.configuration.productionMode = configuration.productionMode;
             this.configuration.nodeCommand = configuration.nodeCommand;
+            this.configuration.classFinder = configuration.classFinder;
             this.configuration.parser.setEndpointAnnotations(
                     configuration.getEndpointAnnotations());
             this.configuration.parser.setEndpointExposedAnnotations(
@@ -253,6 +269,11 @@ public Builder nodeCommand(String value) {
             return this;
         }
 
+        public Builder classFinder(ClassFinder value) {
+            configuration.classFinder = value;
+            return this;
+        }
+
         public Builder endpointAnnotations(
                 Class<? extends Annotation>... value) {
             configuration.parser.setEndpointAnnotations(Arrays.asList(value));

packages/java/engine-core/src/main/java/com/vaadin/hilla/engine/LookupBrowserCallableFinder.java

@@ -0,0 +1,17 @@
+package com.vaadin.hilla.engine;
+
+import java.util.List;
+import java.util.Set;
+
+import com.vaadin.flow.server.frontend.scanner.ClassFinder;
+
+class LookupBrowserCallableFinder {
+
+    static List<Class<?>> findEndpointClasses(ClassFinder classFinder,
+            EngineConfiguration engineConfiguration) {
+        return engineConfiguration.getEndpointAnnotations().stream()
+                .map(classFinder::getAnnotatedClasses).flatMap(Set::stream)
+                .distinct().toList();
+    }
+
+}

packages/java/engine-core/src/test/java/com/vaadin/hilla/engine/EngineConfigurationTest.java

@@ -0,0 +1,61 @@
+package com.vaadin.hilla.engine;
+
+import org.junit.jupiter.api.Test;
+
+import java.lang.annotation.Annotation;
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+import java.util.List;
+import java.util.Set;
+
+import static org.junit.jupiter.api.Assertions.*;
+import static org.mockito.Mockito.*;
+
+import com.vaadin.flow.server.frontend.scanner.ClassFinder;
+
+public class EngineConfigurationTest {
+    @Target(ElementType.TYPE)
+    @Retention(RetentionPolicy.RUNTIME)
+    public @interface BrowserCallableEndpoint {
+    }
+
+    private static class EndpointFromAot {
+    }
+
+    private static class EndpointFromClassFinder {
+    }
+
+    @Test
+    public void shouldUseAot() throws Exception {
+        var classFinder = mock(ClassFinder.class);
+        when(classFinder
+                .getAnnotatedClasses((Class<? extends Annotation>) any()))
+                .thenThrow(RuntimeException.class);
+        var conf = new EngineConfiguration.Builder().classFinder(classFinder)
+                .build();
+        try (var aotMock = mockStatic(AotBrowserCallableFinder.class)) {
+            when(AotBrowserCallableFinder.findEndpointClasses(conf))
+                    .thenReturn(List.of(EndpointFromAot.class));
+            assertEquals(List.of(EndpointFromAot.class),
+                    conf.getBrowserCallableFinder().findBrowserCallables());
+        }
+    }
+
+    @Test
+    public void shouldFallbackToClassFinder() throws Exception {
+        var classFinder = mock(ClassFinder.class);
+        when(classFinder
+                .getAnnotatedClasses((Class<? extends Annotation>) any()))
+                .thenReturn(Set.of(EndpointFromClassFinder.class));
+        var conf = new EngineConfiguration.Builder().classFinder(classFinder)
+                .endpointAnnotations(BrowserCallableEndpoint.class).build();
+        try (var aotMock = mockStatic(AotBrowserCallableFinder.class)) {
+            when(AotBrowserCallableFinder.findEndpointClasses(conf))
+                    .thenThrow(ParserException.class);
+            assertEquals(List.of(EndpointFromClassFinder.class),
+                    conf.getBrowserCallableFinder().findBrowserCallables());
+        }
+    }
+}

packages/java/engine-runtime/src/main/java/com/vaadin/hilla/internal/EndpointGeneratorTaskFactoryImpl.java

@@ -97,6 +97,7 @@ private static EngineConfiguration configureFromOptions(Options options) {
                 .buildDir(options.getBuildDirectoryName())
                 .outputDir(options.getFrontendGeneratedFolder().toPath())
                 .nodeCommand(buildTools(options).getNodeExecutable())
+                .classFinder(options.getClassFinder())
                 .productionMode(options.isProductionMode())
                 .withDefaultAnnotations().build();
     }