Document code

Author: olpaw

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

@@ -210,6 +210,10 @@ private static Stream<String> extractRequiredModuleNames(Module m) {
     }
 
     private ModuleLayer synthesizeRuntimeBootLayer(ImageClassLoader cl, Set<String> reachableModules, Set<Module> syntheticModules) {
+        /**
+         * For consistent module lookup we reuse the {@link ModuleFinder}s defined and used in
+         * {@link NativeImageClassLoaderSupportJDK11OrLater}.
+         */
         NativeImageClassLoaderSupportJDK11OrLater classLoaderSupport = (NativeImageClassLoaderSupportJDK11OrLater) cl.classLoaderSupport;
         ModuleFinder beforeFinder = classLoaderSupport.modulepathModuleFinder;
         ModuleFinder afterFinder = classLoaderSupport.upgradeAndSystemModuleFinder;

substratevm/src/com.oracle.svm.hosted.jdk11/src/com/oracle/svm/hosted/jdk/NativeImageClassLoaderSupportJDK11OrLater.java

@@ -37,6 +37,7 @@
 import java.util.ArrayDeque;
 import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.Collection;
 import java.util.Collections;
 import java.util.Deque;
 import java.util.HashSet;
@@ -97,6 +98,13 @@ private ModuleLayer createModuleLayer(Path[] modulePaths, ClassLoader parent) {
         ModuleFinder modulePathsFinder = ModuleFinder.of(modulePaths);
         Set<String> moduleNames = modulePathsFinder.findAll().stream().map(moduleReference -> moduleReference.descriptor().name()).collect(Collectors.toSet());
 
+        /**
+         * When building a moduleLayer for the module-path passed to native-image we need to be able
+         * to resolve against system modules that are not used by the moduleLayer in which the
+         * image-builder got loaded into. To do so we use {@link upgradeAndSystemModuleFinder} as
+         * {@code ModuleFinder after} in
+         * {@link Configuration#resolve(ModuleFinder, ModuleFinder, Collection)}.
+         */
         Configuration configuration = ModuleLayer.boot().configuration().resolve(modulePathsFinder, upgradeAndSystemModuleFinder, moduleNames);
         /**
          * For the modules we want to build an image for, a ModuleLayer is needed that can be
@@ -106,7 +114,8 @@ private ModuleLayer createModuleLayer(Path[] modulePaths, ClassLoader parent) {
     }
 
     /**
-     * Gets a finder that locates the upgrade modules and the system modules, in that order.
+     * Gets a finder that locates the upgrade modules and the system modules, in that order. Upgrade
+     * modules are used when mx environment variable {@code MX_BUILD_EXPLODED=true} is used.
      */
     private static ModuleFinder createUpgradeAndSystemModuleFinder() {
         ModuleFinder finder = ModuleFinder.ofSystem();

substratevm/src/com.oracle.svm.hosted/src/com/oracle/svm/hosted/FallbackFeature.java

@@ -125,12 +125,15 @@ void trackMethod(AnalysisMetaAccess metaAccess) {
         void apply(BytecodePosition invokeLocation) {
             Class<?> javaClass = ((AnalysisMethod) invokeLocation.getMethod()).getDeclaringClass().getJavaClass();
             if (systemModuleDescriptors.contains(ModuleSupport.getModuleDescriptor(javaClass))) {
+                /* Ensure all JDK system modules are excluded from reporting reflection use. */
                 return;
             }
             ClassLoader classLoader = javaClass.getClassLoader();
             if (!NativeImageSystemClassLoader.singleton().isNativeImageClassLoader(classLoader)) {
+                /* Classes not loaded by NativeImageClassLoader are also excluded. */
                 return;
             }
+            /* Collect reflection use in application classes. */
             checker.check(this, invokeLocation);
         }