Synchronize defineModule0 checks

Author: ivan-ristovic

substratevm/src/com.oracle.svm.core.jdk11/src/com/oracle/svm/core/jdk/Target_java_lang_Module.java

@@ -97,25 +97,28 @@ private static void defineModule0(Module module, boolean isOpen, String version,
             }
         }
 
-        // TODO (ivan-ristovic) is synchronization necessary?
-        Package existingPackage = null;
-        boolean moduleAlreadyExists = false;
-        for (String pn : pns) {
-            existingPackage = loader.getDefinedPackage(pn);
-            if (Objects.nonNull(existingPackage)) {
-                moduleAlreadyExists = ModuleUtil.moduleAlreadyExists(module);
-                break;
+        Package definedPackage = null;
+        Module definedModule = null;
+        //noinspection CheckStyle
+        synchronized (ModuleUtil.moduleLock) {
+            for (String pn : pns) {
+                definedPackage = loader.getDefinedPackage(pn);
+                if (Objects.nonNull(definedPackage)) {
+                    definedModule = ModuleUtil.getDefinedModule(module.getName());
+                    break;
+                }
             }
         }
-        if (moduleAlreadyExists) {
+
+        if (Objects.nonNull(definedModule)) {
             throw new IllegalStateException("Module " + module.getName() + " is already defined");
-        } else if (Objects.nonNull(existingPackage)) {
-            Target_java_lang_NamedPackage namedPackage = SubstrateUtil.cast(existingPackage, Target_java_lang_NamedPackage.class);
+        } else if (Objects.nonNull(definedPackage)) {
+            Target_java_lang_NamedPackage namedPackage = SubstrateUtil.cast(definedPackage, Target_java_lang_NamedPackage.class);
             if (namedPackage.module.isNamed()) {
-                throw new IllegalStateException("Package " + existingPackage.getName() + " is already in another module, "
+                throw new IllegalStateException("Package " + definedPackage.getName() + " is already in another module, "
                         + namedPackage.module.getName() + ", defined to the class loader");
             } else {
-                throw new IllegalStateException("Package " + existingPackage.getName()
+                throw new IllegalStateException("Package " + definedPackage.getName()
                         + " is already in the unnamed module defined to the class loader");
             }
         }
@@ -160,6 +163,9 @@ private static final class Target_java_lang_Module_ReflectionData {
 }
 
 class ModuleUtil {
+
+    static final Object moduleLock = new Object();
+
     static void checkFromModuleAndPackageNullability(Module from, String pn) {
         if (Objects.isNull(from)) {
             throw new NullPointerException("from_module is null");
@@ -182,7 +188,7 @@ static void checkIsPackageContainedInModule(String pn, Module module) {
             }
         }
 
-        if (module.getPackages().stream().noneMatch(p -> p.equals(pn))) {
+        if (!module.getPackages().contains(pn)) {
             throw new IllegalArgumentException("Package " + pn + " not found in from_module " + module.getName());
         }
     }
@@ -201,9 +207,9 @@ static boolean isValidPackageName(String pn) {
         return Objects.nonNull(pn) && SourceVersion.isName(pn);
     }
 
-    static boolean moduleAlreadyExists(Module module) {
+    static Module getDefinedModule(String moduleName) {
         // TODO (ivan-ristovic)
-        return false;
+        return null;
     }
 
     public static boolean bootLayerContainsModule(String name) {

substratevm/src/com.oracle.svm.hosted.jdk11/src/com/oracle/svm/hosted/ModuleLayerFeature.java

@@ -123,8 +123,9 @@ public void duringAnalysis(DuringAnalysisAccess access) {
                 .stream()
                 .filter(t -> t.isReachable() && !t.isArray())
                 .map(t -> t.getJavaClass().getModule())
+                .distinct()
                 .filter(m -> m.isNamed() && !m.getDescriptor().modifiers().contains(ModuleDescriptor.Modifier.SYNTHETIC))
-                .collect(Collectors.toMap(Module::getName, m -> m, (m1, m2) -> m1));
+                .collect(Collectors.toMap(Module::getName, m -> m));
 
         ModuleLayer runtimeBootLayer = synthesizeRuntimeBootLayer(accessImpl.imageClassLoader, reachableModules);
         BootModuleLayerSupport.instance().setBootLayer(runtimeBootLayer);