| /* |
| * Copyright (c) 2014, 2016, Oracle and/or its affiliates. All rights reserved. |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. |
| * |
| * This code is distributed in the hope that it will be useful, but WITHOUT |
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| */ |
| package jdk.vm.ci.services; |
| |
| import java.lang.reflect.InvocationTargetException; |
| import java.lang.reflect.Method; |
| import java.util.Formatter; |
| import java.util.Iterator; |
| import java.util.ServiceConfigurationError; |
| import java.util.ServiceLoader; |
| |
| /** |
| * A mechanism for accessing service providers via JVMCI. |
| */ |
| public final class Services { |
| |
| private Services() { |
| } |
| |
| private static int getJavaSpecificationVersion() { |
| String value = System.getProperty("java.specification.version"); |
| if (value.startsWith("1.")) { |
| value = value.substring(2); |
| } |
| return Integer.parseInt(value); |
| } |
| |
| /** |
| * The integer value corresponding to the value of the {@code java.specification.version} system |
| * property after any leading {@code "1."} has been stripped. |
| */ |
| public static final int JAVA_SPECIFICATION_VERSION = getJavaSpecificationVersion(); |
| |
| // Use reflection so that this compiles on Java 8 |
| private static final Method getModule; |
| private static final Method getPackages; |
| private static final Method addUses; |
| private static final Method isExported; |
| private static final Method addExports; |
| |
| static { |
| if (JAVA_SPECIFICATION_VERSION >= 9) { |
| try { |
| getModule = Class.class.getMethod("getModule"); |
| Class<?> moduleClass = getModule.getReturnType(); |
| getPackages = moduleClass.getMethod("getPackages"); |
| addUses = moduleClass.getMethod("addUses", Class.class); |
| isExported = moduleClass.getMethod("isExported", String.class, moduleClass); |
| addExports = moduleClass.getMethod("addExports", String.class, moduleClass); |
| } catch (NoSuchMethodException | SecurityException e) { |
| throw new InternalError(e); |
| } |
| } else { |
| getModule = null; |
| getPackages = null; |
| addUses = null; |
| isExported = null; |
| addExports = null; |
| } |
| } |
| |
| @SuppressWarnings("unchecked") |
| static <T> T invoke(Method method, Object receiver, Object... args) { |
| try { |
| return (T) method.invoke(receiver, args); |
| } catch (IllegalAccessException | IllegalArgumentException | InvocationTargetException e) { |
| throw new InternalError(e); |
| } |
| } |
| |
| /** |
| * Performs any required security checks and dynamic reconfiguration to allow the module of a |
| * given class to access the classes in the JVMCI module. |
| * |
| * Note: This API uses {@link Class} instead of {@code Module} to provide backwards |
| * compatibility for JVMCI clients compiled against a JDK release earlier than 9. |
| * |
| * @param requestor a class requesting access to the JVMCI module for its module |
| * @throws SecurityException if a security manager is present and it denies |
| * {@link JVMCIPermission} |
| */ |
| public static void exportJVMCITo(Class<?> requestor) { |
| SecurityManager sm = System.getSecurityManager(); |
| if (sm != null) { |
| sm.checkPermission(new JVMCIPermission()); |
| } |
| if (JAVA_SPECIFICATION_VERSION >= 9) { |
| Object jvmci = invoke(getModule, Services.class); |
| Object requestorModule = invoke(getModule, requestor); |
| if (jvmci != requestorModule) { |
| String[] packages = invoke(getPackages, jvmci); |
| for (String pkg : packages) { |
| // Export all JVMCI packages dynamically instead |
| // of requiring a long list of --add-exports |
| // options on the JVM command line. |
| boolean exported = invoke(isExported, jvmci, pkg, requestorModule); |
| if (!exported) { |
| invoke(addExports, jvmci, pkg, requestorModule); |
| } |
| } |
| } |
| } |
| } |
| |
| /** |
| * Gets an {@link Iterable} of the JVMCI providers available for a given service. |
| * |
| * @throws SecurityException if a security manager is present and it denies |
| * {@link JVMCIPermission} |
| */ |
| public static <S> Iterable<S> load(Class<S> service) { |
| SecurityManager sm = System.getSecurityManager(); |
| if (sm != null) { |
| sm.checkPermission(new JVMCIPermission()); |
| } |
| if (JAVA_SPECIFICATION_VERSION >= 9) { |
| Object jvmci = invoke(getModule, Services.class); |
| invoke(addUses, jvmci, service); |
| } |
| |
| // Restrict JVMCI clients to be on the class path or module path |
| return ServiceLoader.load(service, ClassLoader.getSystemClassLoader()); |
| } |
| |
| /** |
| * Gets the JVMCI provider for a given service for which at most one provider must be available. |
| * |
| * @param service the service whose provider is being requested |
| * @param required specifies if an {@link InternalError} should be thrown if no provider of |
| * {@code service} is available |
| * @throws SecurityException if a security manager is present and it denies |
| * {@link JVMCIPermission} |
| */ |
| public static <S> S loadSingle(Class<S> service, boolean required) { |
| SecurityManager sm = System.getSecurityManager(); |
| if (sm != null) { |
| sm.checkPermission(new JVMCIPermission()); |
| } |
| if (JAVA_SPECIFICATION_VERSION >= 9) { |
| Object jvmci = invoke(getModule, Services.class); |
| invoke(addUses, jvmci, service); |
| } |
| // Restrict JVMCI clients to be on the class path or module path |
| Iterable<S> providers = ServiceLoader.load(service, ClassLoader.getSystemClassLoader()); |
| S singleProvider = null; |
| try { |
| for (Iterator<S> it = providers.iterator(); it.hasNext();) { |
| singleProvider = it.next(); |
| if (it.hasNext()) { |
| throw new InternalError(String.format("Multiple %s providers found", service.getName())); |
| } |
| } |
| } catch (ServiceConfigurationError e) { |
| // If the service is required we will bail out below. |
| } |
| if (singleProvider == null && required) { |
| String javaHome = System.getProperty("java.home"); |
| String vmName = System.getProperty("java.vm.name"); |
| Formatter errorMessage = new Formatter(); |
| errorMessage.format("The VM does not expose required service %s.%n", service.getName()); |
| errorMessage.format("Currently used Java home directory is %s.%n", javaHome); |
| errorMessage.format("Currently used VM configuration is: %s", vmName); |
| throw new UnsupportedOperationException(errorMessage.toString()); |
| } |
| return singleProvider; |
| } |
| } |