1 /* 2 * Copyright (c) 2014, 2019, 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.io.ByteArrayInputStream; 26 import java.io.ByteArrayOutputStream; 27 import java.io.DataInputStream; 28 import java.io.DataOutputStream; 29 import java.io.IOException; 30 import java.util.ArrayList; 31 import java.util.Collections; 32 import java.util.Formatter; 33 import java.util.HashMap; 34 import java.util.List; 35 import java.util.Map; 36 import java.util.Properties; 37 import java.util.ServiceLoader; 38 import java.util.Set; 39 40 import jdk.internal.misc.VM; 41 import jdk.internal.reflect.Reflection; 42 43 /** 44 * Provides utilities needed by JVMCI clients. 45 */ 46 public final class Services { 47 48 // This class must be compilable and executable on JDK 8 since it's used in annotation 49 // processors while building JDK 9 so use of API added in JDK 9 is made via reflection. 50 51 /** 52 * Guards code that should be run when building an JVMCI shared library but should be excluded 53 * from (being compiled into) the library. Such code must be directly guarded by an {@code if} 54 * statement on this field - the guard cannot be behind a method call. 55 */ 56 public static final boolean IS_BUILDING_NATIVE_IMAGE = Boolean.parseBoolean(VM.getSavedProperty("jdk.vm.ci.services.aot")); 57 58 /** 59 * Guards code that should only be run in a JVMCI shared library. Such code must be directly 60 * guarded by an {@code if} statement on this field - the guard cannot be behind a method call. 61 * 62 * The value of this field in a JVMCI shared library runtime must be {@code true}. 63 */ 64 public static final boolean IS_IN_NATIVE_IMAGE; 65 static { 66 /* 67 * Prevents javac from constant folding use of this field. It is set to true by the process 68 * that builds the shared library. 69 */ 70 IS_IN_NATIVE_IMAGE = false; 71 } 72 73 private Services() { 74 } 75 76 private static volatile Map<String, String> savedProperties = VM.getSavedProperties(); 77 static final boolean JVMCI_ENABLED = Boolean.parseBoolean(savedProperties.get("jdk.internal.vm.ci.enabled")); 78 79 /** 80 * Checks that JVMCI is enabled in the VM and throws an error if it isn't. 81 */ 82 static void checkJVMCIEnabled() { 83 if (!JVMCI_ENABLED) { 84 throw new Error("The EnableJVMCI VM option must be true (i.e., -XX:+EnableJVMCI) to use JVMCI"); 85 } 86 } 87 88 /** 89 * Gets an unmodifiable copy of the system properties saved when {@link System} is initialized. 90 */ 91 public static Map<String, String> getSavedProperties() { 92 checkJVMCIEnabled(); 93 SecurityManager sm = System.getSecurityManager(); 94 if (sm != null) { 95 sm.checkPermission(new JVMCIPermission()); 96 } 97 return savedProperties; 98 } 99 100 /** 101 * Helper method equivalent to {@link #getSavedProperties()}{@code .getOrDefault(name, def)}. 102 */ 103 public static String getSavedProperty(String name, String def) { 104 return Services.getSavedProperties().getOrDefault(name, def); 105 } 106 107 /** 108 * Helper method equivalent to {@link #getSavedProperties()}{@code .get(name)}. 109 */ 110 public static String getSavedProperty(String name) { 111 return Services.getSavedProperties().get(name); 112 } 113 114 /** 115 * Causes the JVMCI subsystem to be initialized if it isn't already initialized. 116 */ 117 public static void initializeJVMCI() { 118 checkJVMCIEnabled(); 119 try { 120 Class.forName("jdk.vm.ci.runtime.JVMCI"); 121 } catch (ClassNotFoundException e) { 122 throw new InternalError(e); 123 } 124 } 125 126 private static boolean jvmciEnabled = true; 127 128 /** 129 * When {@code -XX:-UseJVMCIClassLoader} is in use, JVMCI classes are loaded via the boot class 130 * loader. When {@code null} is the second argument to 131 * {@link ServiceLoader#load(Class, ClassLoader)}, service lookup will use the system class 132 * loader and thus find application classes which violates the API of {@link #load} and 133 * {@link #loadSingle}. To avoid this, a class loader that simply delegates to the boot class 134 * loader is used. 135 */ 136 static class LazyBootClassPath { 137 static final ClassLoader bootClassPath = new ClassLoader(null) { 138 }; 139 } 140 141 private static ClassLoader findBootClassLoaderChild(ClassLoader start) { 142 ClassLoader cl = start; 143 while (cl.getParent() != null) { 144 cl = cl.getParent(); 145 } 146 return cl; 147 } 148 149 private static final Map<Class<?>, List<?>> servicesCache = IS_BUILDING_NATIVE_IMAGE ? new HashMap<>() : null; 150 151 @SuppressWarnings("unchecked") 152 private static <S> Iterable<S> load0(Class<S> service) { 153 if (IS_IN_NATIVE_IMAGE || IS_BUILDING_NATIVE_IMAGE) { 154 List<?> list = servicesCache.get(service); 155 if (list != null) { 156 return (Iterable<S>) list; 157 } 158 if (IS_IN_NATIVE_IMAGE) { 159 throw new InternalError(String.format("No %s providers found when building native image", service.getName())); 160 } 161 } 162 163 Iterable<S> providers = Collections.emptyList(); 164 if (jvmciEnabled) { 165 ClassLoader cl = null; 166 try { 167 cl = getJVMCIClassLoader(); 168 if (cl == null) { 169 cl = LazyBootClassPath.bootClassPath; 170 // JVMCI classes are loaded via the boot class loader. 171 // If we use null as the second argument to ServiceLoader.load, 172 // service loading will use the system class loader 173 // and find classes on the application class path. Since we 174 // don't want this, we use a loader that is as close to the 175 // boot class loader as possible (since it is impossible 176 // to force service loading to use only the boot class loader). 177 cl = findBootClassLoaderChild(ClassLoader.getSystemClassLoader()); 178 } 179 providers = ServiceLoader.load(service, cl); 180 } catch (UnsatisfiedLinkError e) { 181 jvmciEnabled = false; 182 } catch (InternalError e) { 183 if (e.getMessage().equals("JVMCI is not enabled")) { 184 jvmciEnabled = false; 185 } else { 186 throw e; 187 } 188 } 189 } 190 if (IS_BUILDING_NATIVE_IMAGE) { 191 synchronized (servicesCache) { 192 ArrayList<S> providersList = new ArrayList<>(); 193 for (S provider : providers) { 194 providersList.add(provider); 195 } 196 servicesCache.put(service, providersList); 197 providers = providersList; 198 } 199 } 200 return providers; 201 } 202 203 /** 204 * Opens all JVMCI packages to {@code otherModule}. 205 */ 206 static void openJVMCITo(Module otherModule) { 207 Module jvmci = Services.class.getModule(); 208 if (jvmci != otherModule) { 209 Set<String> packages = jvmci.getPackages(); 210 for (String pkg : packages) { 211 boolean opened = jvmci.isOpen(pkg, otherModule); 212 if (!opened) { 213 jvmci.addOpens(pkg, otherModule); 214 } 215 } 216 } 217 } 218 219 /** 220 * Gets an {@link Iterable} of the JVMCI providers available for a given service. 221 * 222 * @throws SecurityException if a security manager is present and it denies <tt> 223 * {@link RuntimePermission}("jvmci")</tt> 224 */ 225 public static <S> Iterable<S> load(Class<S> service) { 226 SecurityManager sm = System.getSecurityManager(); 227 if (sm != null) { 228 sm.checkPermission(new JVMCIPermission()); 229 } 230 return load0(service); 231 } 232 233 /** 234 * Gets the JVMCI provider for a given service for which at most one provider must be available. 235 * 236 * @param service the service whose provider is being requested 237 * @param required specifies if an {@link InternalError} should be thrown if no provider of 238 * {@code service} is available 239 * @throws SecurityException if a security manager is present and it denies <tt> 240 * {@link RuntimePermission}("jvmci")</tt> 241 */ 242 public static <S> S loadSingle(Class<S> service, boolean required) { 243 SecurityManager sm = System.getSecurityManager(); 244 if (sm != null) { 245 sm.checkPermission(new JVMCIPermission()); 246 } 247 Iterable<S> providers = load0(service); 248 249 S singleProvider = null; 250 for (S provider : providers) { 251 if (singleProvider != null) { 252 throw new InternalError(String.format("Multiple %s providers found: %s, %s", service.getName(), singleProvider.getClass().getName(), provider.getClass().getName())); 253 } 254 singleProvider = provider; 255 } 256 if (singleProvider == null && required) { 257 String javaHome = Services.getSavedProperty("java.home"); 258 String vmName = Services.getSavedProperty("java.vm.name"); 259 Formatter errorMessage = new Formatter(); 260 errorMessage.format("The VM does not expose required service %s.%n", service.getName()); 261 errorMessage.format("Currently used Java home directory is %s.%n", javaHome); 262 errorMessage.format("Currently used VM configuration is: %s", vmName); 263 throw new UnsupportedOperationException(errorMessage.toString()); 264 } 265 return singleProvider; 266 } 267 268 static { 269 Reflection.registerMethodsToFilter(Services.class, Set.of("getJVMCIClassLoader")); 270 } 271 272 /** 273 * Gets the JVMCI class loader. 274 * 275 * @throws InternalError with the {@linkplain Throwable#getMessage() message} 276 * {@code "JVMCI is not enabled"} iff JVMCI is not enabled 277 */ 278 private static ClassLoader getJVMCIClassLoader() { 279 if (IS_IN_NATIVE_IMAGE) { 280 return null; 281 } 282 return ClassLoader.getSystemClassLoader(); 283 } 284 285 /** 286 * Serializes the {@linkplain #getSavedProperties() saved system properties} to a byte array for 287 * the purpose of {@linkplain #initializeSavedProperties(byte[]) initializing} the initial 288 * properties in the JVMCI shared library. 289 */ 290 @VMEntryPoint 291 private static byte[] serializeSavedProperties() throws IOException { 292 if (IS_IN_NATIVE_IMAGE) { 293 throw new InternalError("Can only serialize saved properties in HotSpot runtime"); 294 } 295 Map<String, String> props = Services.getSavedProperties(); 296 297 // Compute size of output on the assumption that 298 // all system properties have ASCII names and values 299 int estimate = 4; 300 for (Map.Entry<String, String> e : props.entrySet()) { 301 String name = e.getKey(); 302 String value = e.getValue(); 303 estimate += (2 + (name.length())) + (2 + (value.length())); 304 } 305 306 ByteArrayOutputStream baos = new ByteArrayOutputStream(estimate); 307 DataOutputStream out = new DataOutputStream(baos); 308 out.writeInt(props.size()); 309 for (Map.Entry<String, String> e : props.entrySet()) { 310 String name = e.getKey(); 311 String value = e.getValue(); 312 out.writeUTF(name); 313 out.writeUTF(value); 314 } 315 return baos.toByteArray(); 316 } 317 318 /** 319 * Initialized the {@linkplain #getSavedProperties() saved system properties} in the JVMCI 320 * shared library from the {@linkplain #serializeSavedProperties() serialized saved properties} 321 * in the HotSpot runtime. 322 */ 323 @VMEntryPoint 324 private static void initializeSavedProperties(byte[] serializedProperties) throws IOException { 325 if (!IS_IN_NATIVE_IMAGE) { 326 throw new InternalError("Can only initialize saved properties in JVMCI shared library runtime"); 327 } 328 DataInputStream in = new DataInputStream(new ByteArrayInputStream(serializedProperties)); 329 Map<String, String> props = new HashMap<>(in.readInt()); 330 while (in.available() != 0) { 331 String name = in.readUTF(); 332 String value = in.readUTF(); 333 props.put(name, value); 334 } 335 savedProperties = Collections.unmodifiableMap(props); 336 } 337 }