1 /* 2 * Copyright (c) 2014, 2016, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 */ 23 package jdk.vm.ci.services; 24 25 import java.lang.reflect.InvocationTargetException; 26 import java.lang.reflect.Method; 27 import java.util.Formatter; 28 import java.util.Iterator; 29 import java.util.ServiceConfigurationError; 30 import java.util.ServiceLoader; 31 32 /** 33 * A mechanism for accessing service providers via JVMCI. 34 */ 35 public final class Services { 36 37 private Services() { 38 } 39 40 private static int getJavaSpecificationVersion() { 41 String value = System.getProperty("java.specification.version"); 42 if (value.startsWith("1.")) { 43 value = value.substring(2); 44 } 45 return Integer.parseInt(value); 46 } 47 48 /** 49 * The integer value corresponding to the value of the {@code java.specification.version} system 50 * property after any leading {@code "1."} has been stripped. 51 */ 52 public static final int JAVA_SPECIFICATION_VERSION = getJavaSpecificationVersion(); 53 54 // Use reflection so that this compiles on Java 8 55 private static final Method getModule; 56 private static final Method getPackages; 57 private static final Method addUses; 58 private static final Method isExported; 59 private static final Method addExports; 60 61 static { 62 if (JAVA_SPECIFICATION_VERSION >= 9) { 63 try { 64 getModule = Class.class.getMethod("getModule"); 65 Class<?> moduleClass = getModule.getReturnType(); 66 getPackages = moduleClass.getMethod("getPackages"); 67 addUses = moduleClass.getMethod("addUses", Class.class); 68 isExported = moduleClass.getMethod("isExported", String.class, moduleClass); 69 addExports = moduleClass.getMethod("addExports", String.class, moduleClass); 70 } catch (NoSuchMethodException | SecurityException e) { 71 throw new InternalError(e); 72 } 73 } else { 74 getModule = null; 75 getPackages = null; 76 addUses = null; 77 isExported = null; 78 addExports = null; 79 } 80 } 81 82 @SuppressWarnings("unchecked") 83 static <T> T invoke(Method method, Object receiver, Object... args) { 84 try { 85 return (T) method.invoke(receiver, args); 86 } catch (IllegalAccessException | IllegalArgumentException | InvocationTargetException e) { 87 throw new InternalError(e); 88 } 89 } 90 91 /** 92 * Performs any required security checks and dynamic reconfiguration to allow the module of a 93 * given class to access the classes in the JVMCI module. 94 * 95 * Note: This API uses {@link Class} instead of {@code Module} to provide backwards 96 * compatibility for JVMCI clients compiled against a JDK release earlier than 9. 97 * 98 * @param requestor a class requesting access to the JVMCI module for its module 99 * @throws SecurityException if a security manager is present and it denies 100 * {@link JVMCIPermission} 101 */ 102 public static void exportJVMCITo(Class<?> requestor) { 103 SecurityManager sm = System.getSecurityManager(); 104 if (sm != null) { 105 sm.checkPermission(new JVMCIPermission()); 106 } 107 if (JAVA_SPECIFICATION_VERSION >= 9) { 108 Object jvmci = invoke(getModule, Services.class); 109 Object requestorModule = invoke(getModule, requestor); 110 if (jvmci != requestorModule) { 111 String[] packages = invoke(getPackages, jvmci); 112 for (String pkg : packages) { 113 // Export all JVMCI packages dynamically instead 114 // of requiring a long list of --add-exports 115 // options on the JVM command line. 116 boolean exported = invoke(isExported, jvmci, pkg, requestorModule); 117 if (!exported) { 118 invoke(addExports, jvmci, pkg, requestorModule); 119 } 120 } 121 } 122 } 123 } 124 125 /** 126 * Gets an {@link Iterable} of the JVMCI providers available for a given service. 127 * 128 * @throws SecurityException if a security manager is present and it denies 129 * {@link JVMCIPermission} 130 */ 131 public static <S> Iterable<S> load(Class<S> service) { 132 SecurityManager sm = System.getSecurityManager(); 133 if (sm != null) { 134 sm.checkPermission(new JVMCIPermission()); 135 } 136 if (JAVA_SPECIFICATION_VERSION >= 9) { 137 Object jvmci = invoke(getModule, Services.class); 138 invoke(addUses, jvmci, service); 139 } 140 141 // Restrict JVMCI clients to be on the class path or module path 142 return ServiceLoader.load(service, ClassLoader.getSystemClassLoader()); 143 } 144 145 /** 146 * Gets the JVMCI provider for a given service for which at most one provider must be available. 147 * 148 * @param service the service whose provider is being requested 149 * @param required specifies if an {@link InternalError} should be thrown if no provider of 150 * {@code service} is available 151 * @throws SecurityException if a security manager is present and it denies 152 * {@link JVMCIPermission} 153 */ 154 public static <S> S loadSingle(Class<S> service, boolean required) { 155 SecurityManager sm = System.getSecurityManager(); 156 if (sm != null) { 157 sm.checkPermission(new JVMCIPermission()); 158 } 159 if (JAVA_SPECIFICATION_VERSION >= 9) { 160 Object jvmci = invoke(getModule, Services.class); 161 invoke(addUses, jvmci, service); 162 } 163 // Restrict JVMCI clients to be on the class path or module path 164 Iterable<S> providers = ServiceLoader.load(service, ClassLoader.getSystemClassLoader()); 165 S singleProvider = null; 166 try { 167 for (Iterator<S> it = providers.iterator(); it.hasNext();) { 168 singleProvider = it.next(); 169 if (it.hasNext()) { 170 throw new InternalError(String.format("Multiple %s providers found", service.getName())); 171 } 172 } 173 } catch (ServiceConfigurationError e) { 174 // If the service is required we will bail out below. 175 } 176 if (singleProvider == null && required) { 177 String javaHome = System.getProperty("java.home"); 178 String vmName = System.getProperty("java.vm.name"); 179 Formatter errorMessage = new Formatter(); 180 errorMessage.format("The VM does not expose required service %s.%n", service.getName()); 181 errorMessage.format("Currently used Java home directory is %s.%n", javaHome); 182 errorMessage.format("Currently used VM configuration is: %s", vmName); 183 throw new UnsupportedOperationException(errorMessage.toString()); 184 } 185 return singleProvider; 186 } 187 }