ppkarwasz commented on a change in pull request #804:
URL: https://github.com/apache/logging-log4j2/pull/804#discussion_r830288798
##########
File path:
log4j-api/src/main/java/org/apache/logging/log4j/util/ServiceLoaderUtil.java
##########
@@ -60,43 +80,48 @@ private ServiceLoaderUtil() {
* @param serviceType The class of the service.
* @return A service of the given type or {@code null} if none is
available.
*/
- public static <T> T getService(final Class<T> serviceType) {
+ public static <T> Optional<T> getService(final Class<T> serviceType) {
+ return getService(serviceType, LoaderUtil.getClassLoaders());
+ }
+
+ public static <T> Optional<T> getService(final Class<T> serviceType,
ClassLoader classLoader) {
+ return getService(serviceType,
LoaderUtil.getClassLoaders(classLoader));
+ }
+
+ private static <T> Optional<T> getService(final Class<T> serviceType,
final ClassLoader[] classLoaders) {
+ final Logger logger = StatusLogger.getLogger();
// 1. Check for a system property with the FQCN of serviceType
- String serviceClassName =
PropertiesUtil.getProperties().getStringProperty(serviceType.getName());
- if (Strings.isNotEmpty(serviceClassName)) {
- try {
- @SuppressWarnings("unchecked")
- final Class<T> serviceClass = (Class<T>)
Class.forName(serviceClassName);
- if (serviceType.isAssignableFrom(serviceClass)) {
- return LoaderUtil.newInstanceOf(serviceClass);
- }
- getLogger().error("Unable to load service {}: it is not of the
required type {}", serviceClass,
- serviceType);
- } catch (ClassNotFoundException | InstantiationException |
IllegalAccessException
- | InvocationTargetException e) {
- getLogger().error("Unable to load service class {}",
serviceClassName, e);
+ try {
+ final T service =
LoaderUtil.newCheckedInstanceOfProperty(serviceType.getName(), serviceType);
+ if (service != null) {
+ return Optional.of(service);
}
+ } catch (ReflectiveOperationException | ClassCastException e) {
+ logger.error("Unable to load service class {}",
serviceType.getName(), e);
}
// 2. Use the ServiceLoader:
- final List<T> services = loadServices(serviceType,
- t -> getLogger().info("Unable to load service class for
service {}", serviceType.getName(), t));
+ final List<T> services = loadServices(serviceType, classLoaders,
true).collect(Collectors.toList());
if (services.size() > 0) {
if (services.size() > 1) {
- getLogger().warn("Multiple versions of service {} are
available on the classpath: {}", serviceType,
+ logger.warn("Multiple versions of service {} are available on
the classpath: {}", serviceType,
services);
}
- return services.get(0);
+ return Optional.of(services.get(0));
}
- return null;
+ return Optional.empty();
}
- static <T> List<T> loadServices(final Class<T> serviceType, final
Consumer<Throwable> logger) {
- final List<T> services = new ArrayList<T>();
- for (final ClassLoader loader : LoaderUtil.getClassLoaders()) {
- addServices(serviceType, loader, logger, services);
- }
+ static <T> Stream<T> loadServices(final Class<T> serviceType,
ClassLoader[] classLoaders, final boolean verbose) {
+ final Stream<T> services = Arrays.stream(classLoaders)
+ .flatMap(classLoader -> loadClassloaderServices(serviceType,
classLoader, verbose));
if (USE_HK2_SERVICE_LOCATOR) {
- addOsgiServices(serviceType, services);
+ try {
+ return Stream.concat(services, loadOsgiServices(serviceType));
+ } catch (Throwable e) {
+ if (verbose) {
+ StatusLogger.getLogger().error("Unable to load OSGI
services for service {}", serviceType, e);
+ }
+ }
}
return services;
Review comment:
I'll go for a single instance per class for now. The `Provider` service
overrides `equals/hashCode`, but the other service does not.
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