Propagate the cause of the failure from loadClass

If currently the bundle can not be resolved the method Bundle#loadClass
fails with a quite generic exception that it hard to understand as it
does not contain the name of the class to load nor the actual root cause
that the bundle is unable to resolve.

This now move the actual logging out of the place of fetching and
resolving method to the loadCLass method that allows to also throw a
proper exception message here.

Author: laeubi

bundles/org.eclipse.osgi/container/src/org/eclipse/osgi/internal/framework/EquinoxBundle.java

@@ -614,7 +614,7 @@ public URL getResource(String name) {
 			return null;
 		}
 
-		ModuleClassLoader classLoader = getModuleClassLoader(false);
+		ModuleClassLoader classLoader = getModuleClassLoader().moduleClassLoader;
 		if (classLoader != null) {
 			return classLoader.getResource(name);
 		}
@@ -644,13 +644,23 @@ public Class<?> loadClass(String name) throws ClassNotFoundException {
 		if (isFragment()) {
 			throw new ClassNotFoundException("Can not load a class from a fragment bundle: " + this); //$NON-NLS-1$
 		}
+		ResolvedModuleClassLoader resolvedClassLoader = getModuleClassLoader();
+		ModuleClassLoader classLoader = resolvedClassLoader.moduleClassLoader;
+		if (classLoader == null) {
+			ResolutionReport report = resolvedClassLoader.report;
+			if (report != null) {
+				String reportMessage = report.getResolutionReportMessage(module.getCurrentRevision());
+				BundleException bundleException = new BundleException(reportMessage, BundleException.RESOLVE_ERROR);
+				equinoxContainer.getEventPublisher().publishFrameworkEvent(FrameworkEvent.ERROR, this, bundleException);
+				throw new ClassNotFoundException(name, bundleException);
+			}
+			throw new ClassNotFoundException("No class loader available for the bundle: " + this); //$NON-NLS-1$
+		}
 		try {
-			ModuleClassLoader classLoader = getModuleClassLoader(true);
-			if (classLoader != null) {
-				if (name.length() > 0 && name.charAt(0) == '[')
-					return Class.forName(name, false, classLoader);
-				return classLoader.loadClass(name);
+			if (name.length() > 0 && name.charAt(0) == '[') {
+				return Class.forName(name, false, classLoader);
 			}
+			return classLoader.loadClass(name);
 		} catch (ClassNotFoundException e) {
 			// This is an equinox-ism, check compatibility flag
 			boolean compatibilityLazyTrigger = equinoxContainer.getConfiguration().compatibilityLazyTriggerOnFailLoad;
@@ -665,17 +675,11 @@ public Class<?> loadClass(String name) throws ClassNotFoundException {
 			}
 			throw e;
 		}
-		throw new ClassNotFoundException("No class loader available for the bundle: " + this); //$NON-NLS-1$
 	}
 
-	private ModuleClassLoader getModuleClassLoader(boolean logResolveError) {
+	private ResolvedModuleClassLoader getModuleClassLoader() {
 		ResolutionReport report = resolve();
-		if (logResolveError && !Module.RESOLVED_SET.contains(module.getState())) {
-			String reportMessage = report.getResolutionReportMessage(module.getCurrentRevision());
-			equinoxContainer.getEventPublisher().publishFrameworkEvent(FrameworkEvent.ERROR, this,
-					new BundleException(reportMessage, BundleException.RESOLVE_ERROR));
-		}
-		return AccessController.doPrivileged(new PrivilegedAction<ModuleClassLoader>() {
+		ModuleClassLoader cl = AccessController.doPrivileged(new PrivilegedAction<ModuleClassLoader>() {
 			@Override
 			public ModuleClassLoader run() {
 				ModuleWiring wiring = getModule().getCurrentRevision().getWiring();
@@ -688,6 +692,7 @@ public ModuleClassLoader run() {
 				return null;
 			}
 		});
+		return new ResolvedModuleClassLoader(cl, report);
 	}
 
 	@Override
@@ -701,7 +706,7 @@ public Enumeration<URL> getResources(String name) throws IOException {
 		if (isFragment()) {
 			return null;
 		}
-		ModuleClassLoader classLoader = getModuleClassLoader(false);
+		ModuleClassLoader classLoader = getModuleClassLoader().moduleClassLoader;
 		Enumeration<URL> result = null;
 		if (classLoader != null) {
 			result = classLoader.getResources(name);
@@ -1121,4 +1126,16 @@ public String toString() {
 			name = "unknown"; //$NON-NLS-1$
 		return (name + '_' + getVersion() + " [" + getBundleId() + "]"); //$NON-NLS-1$ //$NON-NLS-2$
 	}
+
+	static class ResolvedModuleClassLoader {
+
+		final ModuleClassLoader moduleClassLoader;
+		final ResolutionReport report;
+
+		public ResolvedModuleClassLoader(ModuleClassLoader moduleClassLoader, ResolutionReport report) {
+			this.moduleClassLoader = moduleClassLoader;
+			this.report = report;
+		}
+
+	}
 }