--- /dev/null 2017-01-22 10:16:57.869617664 -0800 +++ new/src/jdk.internal.vm.ci/share/classes/jdk.vm.ci.services/src/jdk/vm/ci/services/Services.java 2017-02-15 16:56:20.669694061 -0800 @@ -0,0 +1,187 @@ +/* + * 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 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 Iterable load(Class 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 loadSingle(Class 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 providers = ServiceLoader.load(service, ClassLoader.getSystemClassLoader()); + S singleProvider = null; + try { + for (Iterator 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; + } +}