Bug 1280666 - Allow class annotations to set defaults for members when generating Java bindings r=jchen

build/annotationProcessors/utils/GeneratableElementIterator.java

@@ -27,6 +27,7 @@ public class GeneratableElementIterator implements Iterator<AnnotatableEntity> {
     private final Member[] mObjects;
     private AnnotatableEntity mNextReturnValue;
     private int mElementIndex;
+    private AnnotationInfo mClassInfo;
 
     private boolean mIterateEveryEntry;
 
@@ -55,8 +56,8 @@ public class GeneratableElementIterator implements Iterator<AnnotatableEntity> {
 
         // Check for "Wrap ALL the things" flag.
         for (Annotation annotation : aClass.getDeclaredAnnotations()) {
-            final String annotationTypeName = annotation.annotationType().getName();
-            if (annotationTypeName.equals("org.mozilla.gecko.annotation.WrapForJNI")) {
+            mClassInfo = buildAnnotationInfo(aClass, annotation);
+            if (mClassInfo != null) {
                 mIterateEveryEntry = true;
                 break;
             }
@@ -115,19 +116,13 @@ public class GeneratableElementIterator implements Iterator<AnnotatableEntity> {
         return ret;
     }
 
-    /**
-     * Find and cache the next appropriately annotated method, plus the annotation parameter, if
-     * one exists. Otherwise cache null, so hasNext returns false.
-     */
-    private void findNextValue() {
-        while (mElementIndex < mObjects.length) {
-            Member candidateElement = mObjects[mElementIndex];
-            mElementIndex++;
-            for (Annotation annotation : ((AnnotatedElement) candidateElement).getDeclaredAnnotations()) {
-                // WrappedJNIMethod has parameters. Use Reflection to obtain them.
+    private AnnotationInfo buildAnnotationInfo(AnnotatedElement element, Annotation annotation) {
         Class<? extends Annotation> annotationType = annotation.annotationType();
         final String annotationTypeName = annotationType.getName();
-                if (annotationTypeName.equals("org.mozilla.gecko.annotation.WrapForJNI")) {
+        if (!annotationTypeName.equals("org.mozilla.gecko.annotation.WrapForJNI")) {
+            return null;
+        }
+
         String stubName = null;
         boolean isMultithreadedStub = false;
         boolean noThrow = false;
@@ -139,10 +134,16 @@ public class GeneratableElementIterator implements Iterator<AnnotatableEntity> {
             stubNameMethod.setAccessible(true);
             stubName = (String) stubNameMethod.invoke(annotation);
 
+            if (element instanceof Class<?>) {
+                // Make @WrapForJNI always allow multithread by default, individual methods can then
+                // override with their own annotation
+                isMultithreadedStub = true;
+            } else {
                 // Determine if the generated stub is to allow calls from multiple threads.
                 final Method multithreadedStubMethod = annotationType.getDeclaredMethod("allowMultithread");
                 multithreadedStubMethod.setAccessible(true);
                 isMultithreadedStub = (Boolean) multithreadedStubMethod.invoke(annotation);
+            }
 
             // Determine if ignoring exceptions
             final Method noThrowMethod = annotationType.getDeclaredMethod("noThrow");
@@ -175,12 +176,25 @@ public class GeneratableElementIterator implements Iterator<AnnotatableEntity> {
 
         // If the method name was not explicitly given in the annotation generate one...
         if (stubName.isEmpty()) {
-                        stubName = Utils.getNativeName(candidateElement);
+            stubName = Utils.getNativeName(element);
         }
 
-                    AnnotationInfo annotationInfo = new AnnotationInfo(
+        return new AnnotationInfo(
             stubName, isMultithreadedStub, noThrow, narrowChars, catchException);
-                    mNextReturnValue = new AnnotatableEntity(candidateElement, annotationInfo);
+    }
+
+    /**
+     * Find and cache the next appropriately annotated method, plus the annotation parameter, if
+     * one exists. Otherwise cache null, so hasNext returns false.
+     */
+    private void findNextValue() {
+        while (mElementIndex < mObjects.length) {
+            Member candidateElement = mObjects[mElementIndex];
+            mElementIndex++;
+            for (Annotation annotation : ((AnnotatedElement) candidateElement).getDeclaredAnnotations()) {
+                AnnotationInfo info = buildAnnotationInfo((AnnotatedElement)candidateElement, annotation);
+                if (info != null) {
+                    mNextReturnValue = new AnnotatableEntity(candidateElement, info);
                     return;
                 }
             }
@@ -190,10 +204,10 @@ public class GeneratableElementIterator implements Iterator<AnnotatableEntity> {
             if (mIterateEveryEntry) {
                 AnnotationInfo annotationInfo = new AnnotationInfo(
                     Utils.getNativeName(candidateElement),
-                    /* multithreaded */ true,
-                    /* noThrow */ false,
-                    /* narrowChars */ false,
-                    /* catchException */ false);
+                    mClassInfo.isMultithreaded,
+                    mClassInfo.noThrow,
+                    mClassInfo.narrowChars,
+                    mClassInfo.catchException);
                 mNextReturnValue = new AnnotatableEntity(candidateElement, annotationInfo);
                 return;
             }

build/annotationProcessors/utils/Utils.java

@@ -6,6 +6,7 @@ package org.mozilla.gecko.annotationProcessors.utils;
 
 import org.mozilla.gecko.annotationProcessors.AnnotationInfo;
 
+import java.lang.reflect.AnnotatedElement;
 import java.lang.reflect.Constructor;
 import java.lang.reflect.Field;
 import java.lang.reflect.Member;
@@ -212,6 +213,33 @@ public class Utils {
         return name.substring(0, 1).toUpperCase() + name.substring(1);
     }
 
+    /**
+     * Get the C++ name for a member.
+     *
+     * @param member Member to get the name for.
+     * @return JNI name as a string
+     */
+    public static String getNativeName(Class<?> clz) {
+        final String name = clz.getName();
+        return name.substring(0, 1).toUpperCase() + name.substring(1);
+    }
+
+    /**
+     * Get the C++ name for a member.
+     *
+     * @param member Member to get the name for.
+     * @return JNI name as a string
+     */
+    public static String getNativeName(AnnotatedElement element) {
+        if (element instanceof Class<?>) {
+            return getNativeName((Class<?>)element);
+        } else if (element instanceof Member) {
+            return getNativeName((Member)element);
+        } else {
+            return null;
+        }
+    }
+
     /**
      * Get the JNI name for a member.
      *

mobile/android/base/java/org/mozilla/gecko/annotation/WrapForJNI.java

@@ -31,9 +31,8 @@ public @interface WrapForJNI {
 
     /**
      * If set, the generated method stub will support being called from any thread via the use of
-     * GetEnvForThread. This is rarely useful, at time of writing, as well as possibly risky.
-     *
-     * Did I mention use of this function is discouraged?
+     * GetEnvForThread. This is forced to 'true' when the annotation is used on a class, but can
+     * be overridden for individual methods.
      */
     boolean allowMultithread() default false;