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Implement OSGi Service Loader Mediator Specification
Signed-off-by: Hannes Wellmann <wellmann.hannes1@gmx.net>
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169 changes: 169 additions & 0 deletions
169
...eclipse.osgi/container/src/org/eclipse/osgi/internal/hooks/ServiceLoaderMediatorHook.java
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| Original file line number | Diff line number | Diff line change |
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| @@ -0,0 +1,169 @@ | ||
| package org.eclipse.osgi.internal.hooks; | ||
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| import java.io.FileNotFoundException; | ||
| import java.io.IOException; | ||
| import java.lang.reflect.Method; | ||
| import java.net.URL; | ||
| import java.util.Arrays; | ||
| import java.util.Collections; | ||
| import java.util.Enumeration; | ||
| import java.util.HashSet; | ||
| import java.util.List; | ||
| import java.util.Objects; | ||
| import java.util.Optional; | ||
| import java.util.ServiceLoader; | ||
| import java.util.Set; | ||
| import java.util.function.Function; | ||
| import java.util.function.Supplier; | ||
| import java.util.stream.Collectors; | ||
| import java.util.stream.IntStream; | ||
| import java.util.stream.Stream; | ||
| import org.eclipse.osgi.internal.hookregistry.ClassLoaderHook; | ||
| import org.eclipse.osgi.internal.loader.ModuleClassLoader; | ||
| import org.osgi.framework.Constants; | ||
| import org.osgi.framework.wiring.BundleRequirement; | ||
| import org.osgi.framework.wiring.BundleWire; | ||
| import org.osgi.framework.wiring.BundleWiring; | ||
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| public class ServiceLoaderMediatorHook extends ClassLoaderHook { | ||
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| @SuppressWarnings({ "unchecked", "rawtypes" }) | ||
| private Supplier<Optional<Class<?>>> getCallerClassComputer() { | ||
| try { // The Java-9+ way | ||
| Class<?> stackWalkerClass = Class.forName("java.lang.StackWalker"); //$NON-NLS-1$ | ||
| Class stackWalkerOption = Class.forName("java.lang.StackWalker$Option"); //$NON-NLS-1$ | ||
| Enum<?> retainClassReference = Enum.valueOf(stackWalkerOption, "RETAIN_CLASS_REFERENCE"); //$NON-NLS-1$ | ||
| Object stackWalker = stackWalkerClass.getMethod("getInstance", Set.class, int.class).invoke(null, //$NON-NLS-1$ | ||
| new HashSet<>(Arrays.asList(retainClassReference)), 15); | ||
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| Method stackWalkerWalk = stackWalkerClass.getMethod("walk", Function.class); //$NON-NLS-1$ | ||
| Class<?> stackFrameClass = Class.forName("java.lang.StackWalker$StackFrame"); //$NON-NLS-1$ | ||
| Method stackFrameGetDeclaringClass = stackFrameClass.getMethod("getDeclaringClass"); //$NON-NLS-1$ | ||
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| Function<Stream<?>, Optional<Class<?>>> function = frames -> frames.<Class<?>>map(f -> { | ||
| try { | ||
| return (Class<?>) stackFrameGetDeclaringClass.invoke(f); | ||
| } catch (ReflectiveOperationException e) { | ||
| return null; | ||
| } | ||
| }).filter(Objects::nonNull).limit(15) | ||
| .filter(c -> c == ServiceLoader.class || c.getEnclosingClass() == ServiceLoader.class).findFirst(); | ||
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| return () -> { | ||
| try { | ||
| return (Optional<Class<?>>) stackWalkerWalk.invoke(stackWalker, function); | ||
| } catch (ReflectiveOperationException e) { | ||
| return Optional.empty(); | ||
| } | ||
| }; | ||
| } catch (ReflectiveOperationException e) { // ignore | ||
| } | ||
| try { // Try the Java-1.8 way | ||
| Class<?> reflectionClass = Class.forName("sun.reflect.Reflection"); //$NON-NLS-1$ | ||
| Method getCallerClass = Objects.requireNonNull(reflectionClass.getMethod("getCallerClass", int.class)); //$NON-NLS-1$ | ||
| return () -> IntStream.range(0, 15).<Class<?>>mapToObj(i -> { | ||
| try { | ||
| return (Class<?>) getCallerClass.invoke(null, i); | ||
| } catch (ReflectiveOperationException e) { | ||
| return null; | ||
| } | ||
| }).filter(Objects::nonNull) | ||
| .filter(c -> c == ServiceLoader.class || c.getEnclosingClass() == ServiceLoader.class).findFirst(); | ||
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| } catch (ReflectiveOperationException e) { // ignore an try Java-8 way | ||
| } | ||
| throw new AssertionError("Neither the Java-8 nor the Java-9+ way to obtain the caller class is available"); //$NON-NLS-1$ | ||
| } | ||
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| private static final String SERVICE_NAME_PREFIX = "META-INF/services/"; //$NON-NLS-1$ | ||
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| private final ThreadLocal<String> latestServiceName = new ThreadLocal<>(); | ||
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| private final Supplier<Optional<Class<?>>> callerClass = getCallerClassComputer(); | ||
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| @Override | ||
| public Enumeration<URL> preFindResources(String name, ModuleClassLoader classLoader) throws FileNotFoundException { | ||
| if (name.startsWith(SERVICE_NAME_PREFIX)) { | ||
| Stream<URL> serviceProviderFiles = searchProviders(name, classLoader, cl -> { | ||
| try { | ||
| Enumeration<URL> resources = cl.getResources(name); | ||
| return Collections.list(resources).stream(); | ||
| } catch (IOException e) { | ||
| return Stream.empty(); | ||
| } | ||
| }); | ||
| if (serviceProviderFiles != null) { | ||
| latestServiceName.set(name); | ||
| List<URL> services = serviceProviderFiles.collect(Collectors.toList()); | ||
| return Collections.enumeration(services); | ||
| } | ||
| } | ||
| return null; | ||
| } | ||
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| @Override | ||
| public Class<?> preFindClass(String name, ModuleClassLoader classLoader) throws ClassNotFoundException { | ||
| String serviceName = latestServiceName.get(); // This cannot be removed if subsequent class load other | ||
| // providers for the same service | ||
| if (serviceName != null) { | ||
| Stream<Class<?>> services = searchProviders(serviceName, classLoader, cl -> { | ||
| try { | ||
| return Stream.of(cl.loadClass(name)); | ||
| } catch (ClassNotFoundException | NoClassDefFoundError e) { // ignore | ||
| return Stream.empty(); | ||
| } | ||
| }); | ||
| if (services != null) { | ||
| Optional<Class<?>> findFirst = services.findFirst(); | ||
| return findFirst.orElse(null); | ||
| } | ||
| } | ||
| return null; | ||
| } | ||
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| private <T> Stream<T> searchProviders(String name, ModuleClassLoader classLoader, | ||
| Function<ClassLoader, Stream<T>> mapper) { | ||
| BundleWiring wiring = classLoader.getBundle().adapt(BundleWiring.class); | ||
| if (requiresServiceLoaderProcessor(wiring) && isCalledFromServiceLoader()) { | ||
| return Stream.concat(Stream.of(classLoader), providerClassLoaders(name, wiring)).flatMap(mapper); | ||
| } | ||
| return null; | ||
| } | ||
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| private boolean requiresServiceLoaderProcessor(BundleWiring wiring) { | ||
| List<BundleWire> requiredWires = wiring.getRequiredWires("osgi.extender"); //$NON-NLS-1$ | ||
| if (requiredWires.isEmpty()) { | ||
| return false; | ||
| } | ||
| return requiredWires.stream().anyMatch(w -> w.getRequirement().getDirectives().getOrDefault("filter", "") //$NON-NLS-1$//$NON-NLS-2$ | ||
| .contains("(osgi.extender=osgi.serviceloader.processor)") //$NON-NLS-1$ | ||
| && w.getProvider().getBundle().getBundleId() == Constants.SYSTEM_BUNDLE_ID); | ||
| } | ||
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| private boolean isCalledFromServiceLoader() { | ||
| Optional<Class<?>> caller = callerClass.get(); | ||
| // TODO: If Java-9+ is required one day, just use the following code | ||
| // ClassLoader thisLoader = ServiceLoaderMediatorHook.class.getClassLoader(); | ||
| // Optional<Class<?>> caller = WALKER.walk(frames -> frames.<Class<?>>map(f -> f.getDeclaringClass()) | ||
| // .dropWhile(c -> c.getName().startsWith("org.eclipse.osgi") && c.getClassLoader() == thisLoader) //$NON-NLS-1$ | ||
| // .findFirst()); | ||
| return caller.isPresent() && caller.get().getEnclosingClass() == ServiceLoader.class; | ||
| } | ||
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| private static Stream<ClassLoader> providerClassLoaders(String name, BundleWiring wiring) { | ||
| List<BundleWire> requiredWires = wiring.getRequiredWires("osgi.serviceloader"); //$NON-NLS-1$ | ||
| if (!requiredWires.isEmpty()) { | ||
| String serviceName = name.substring(SERVICE_NAME_PREFIX.length()); | ||
| return requiredWires.stream().filter(wire -> { | ||
| BundleRequirement requirement = wire.getRequirement(); | ||
| String filterDirective = requirement.getDirectives().get("filter"); //$NON-NLS-1$ | ||
| Object serviceLoaderAttribute = wire.getCapability().getAttributes().get("osgi.serviceloader"); //$NON-NLS-1$ | ||
| return serviceName.equals(serviceLoaderAttribute) | ||
| && ("(osgi.serviceloader=" + serviceName + ")").equals(filterDirective); //$NON-NLS-1$ //$NON-NLS-2$ | ||
| }).map(wire -> wire.getProviderWiring().getClassLoader()); | ||
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| } | ||
| return Stream.empty(); | ||
| } | ||
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| } |