1 /* 2 * Copyright (c) 2005, 2006, 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. Oracle designates this 8 * particular file as subject to the "Classpath" exception as provided 9 * by Oracle in the LICENSE file that accompanied this code. 10 * 11 * This code is distributed in the hope that it will be useful, but WITHOUT 12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14 * version 2 for more details (a copy is included in the LICENSE file that 15 * accompanied this code). 16 * 17 * You should have received a copy of the GNU General Public License version 18 * 2 along with this work; if not, write to the Free Software Foundation, 19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 20 * 21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 22 * or visit www.oracle.com if you need additional information or have any 23 * questions. 24 */ 25 26 package com.sun.tools.attach; 27 28 import com.sun.tools.attach.spi.AttachProvider; 29 import java.util.ArrayList; 30 import java.util.List; 31 import java.util.Properties; 32 import java.io.IOException; 33 34 35 /** 36 * A Java virtual machine. 37 * 38 * <p> A <code>VirtualMachine</code> represents a Java virtual machine to which this 39 * Java virtual machine has attached. The Java virtual machine to which it is 40 * attached is sometimes called the <i>target virtual machine</i>, or <i>target VM</i>. 41 * An application (typically a tool such as a managemet console or profiler) uses a 42 * VirtualMachine to load an agent into the target VM. For example, a profiler tool 43 * written in the Java Language might attach to a running application and load its 44 * profiler agent to profile the running application. </p> 45 * 46 * <p> A VirtualMachine is obtained by invoking the {@link #attach(String) attach} method 47 * with an identifier that identifies the target virtual machine. The identifier is 48 * implementation-dependent but is typically the process identifier (or pid) in 49 * environments where each Java virtual machine runs in its own operating system process. 50 * Alternatively, a <code>VirtualMachine</code> instance is obtained by invoking the 51 * {@link #attach(VirtualMachineDescriptor) attach} method with a {@link 52 * com.sun.tools.attach.VirtualMachineDescriptor VirtualMachineDescriptor} obtained 53 * from the list of virtual machine descriptors returned by the {@link #list list} method. 54 * Once a reference to a virtual machine is obtained, the {@link #loadAgent loadAgent}, 55 * {@link #loadAgentLibrary loadAgentLibrary}, and {@link #loadAgentPath loadAgentPath} 56 * methods are used to load agents into target virtual machine. The {@link 57 * #loadAgent loadAgent} method is used to load agents that are written in the Java 58 * Language and deployed in a {@link java.util.jar.JarFile JAR file}. (See 59 * {@link java.lang.instrument} for a detailed description on how these agents 60 * are loaded and started). The {@link #loadAgentLibrary loadAgentLibrary} and 61 * {@link #loadAgentPath loadAgentPath} methods are used to load agents that 62 * are deployed in a dynamic library and make use of the <a 63 * href="../../../../../../../../technotes/guides/jvmti/index.html">JVM Tools 64 * Interface</a>. </p> 65 * 66 * <p> In addition to loading agents a VirtualMachine provides read access to the 67 * {@link java.lang.System#getProperties() system properties} in the target VM. 68 * This can be useful in some environments where properties such as 69 * <code>java.home</code>, <code>os.name</code>, or <code>os.arch</code> are 70 * used to construct the path to agent that will be loaded into the target VM. 71 * 72 * <p> The following example demonstrates how VirtualMachine may be used:</p> 73 * 74 * <pre> 75 * 76 * // attach to target VM 77 * VirtualMachine vm = VirtualMachine.attach("2177"); 78 * 79 * // get system properties in target VM 80 * Properties props = vm.getSystemProperties(); 81 * 82 * // construct path to management agent 83 * String home = props.getProperty("java.home"); 84 * String agent = home + File.separator + "lib" + File.separator 85 * + "management-agent.jar"; 86 * 87 * // load agent into target VM 88 * vm.loadAgent(agent, "com.sun.management.jmxremote.port=5000"); 89 * 90 * // detach 91 * vm.detach(); 92 * 93 * </pre> 94 * 95 * <p> In this example we attach to a Java virtual machine that is identified by 96 * the process identifier <code>2177</code>. The system properties from the target 97 * VM are then used to construct the path to a <i>management agent</i> which is then 98 * loaded into the target VM. Once loaded the client detaches from the target VM. </p> 99 * 100 * <p> A VirtualMachine is safe for use by multiple concurrent threads. </p> 101 * 102 * @since 1.6 103 */ 104 105 public abstract class VirtualMachine { 106 private AttachProvider provider; 107 private String id; 108 private volatile int hash; // 0 => not computed 109 110 /** 111 * Initializes a new instance of this class. 112 * 113 * @param provider 114 * The attach provider creating this class. 115 * @param id 116 * The abstract identifier that identifies the Java virtual machine. 117 * 118 * @throws NullPointerException 119 * If <code>provider</code> or <code>id</code> is <code>null</code>. 120 */ 121 protected VirtualMachine(AttachProvider provider, String id) { 122 if (provider == null) { 123 throw new NullPointerException("provider cannot be null"); 124 } 125 if (id == null) { 126 throw new NullPointerException("id cannot be null"); 127 } 128 this.provider = provider; 129 this.id = id; 130 } 131 132 /** 133 * Return a list of Java virtual machines. 134 * 135 * <p> This method returns a list of Java {@link 136 * com.sun.tools.attach.VirtualMachineDescriptor} elements. 137 * The list is an aggregation of the virtual machine 138 * descriptor lists obtained by invoking the {@link 139 * com.sun.tools.attach.spi.AttachProvider#listVirtualMachines 140 * listVirtualMachines} method of all installed 141 * {@link com.sun.tools.attach.spi.AttachProvider attach providers}. 142 * If there are no Java virtual machines known to any provider 143 * then an empty list is returned. 144 * 145 * @return The list of virtual machine descriptors. 146 */ 147 public static List<VirtualMachineDescriptor> list() { 148 ArrayList<VirtualMachineDescriptor> l = 149 new ArrayList<VirtualMachineDescriptor>(); 150 List<AttachProvider> providers = AttachProvider.providers(); 151 for (AttachProvider provider: providers) { 152 l.addAll(provider.listVirtualMachines()); 153 } 154 return l; 155 } 156 157 /** 158 * Attaches to a Java virtual machine. 159 * 160 * <p> This method obtains the list of attach providers by invoking the 161 * {@link com.sun.tools.attach.spi.AttachProvider#providers() 162 * AttachProvider.providers()} method. It then iterates overs the list 163 * and invokes each provider's {@link 164 * com.sun.tools.attach.spi.AttachProvider#attachVirtualMachine(java.lang.String) 165 * attachVirtualMachine} method in turn. If a provider successfully 166 * attaches then the iteration terminates, and the VirtualMachine created 167 * by the provider that successfully attached is returned by this method. 168 * If the <code>attachVirtualMachine</code> method of all providers throws 169 * {@link com.sun.tools.attach.AttachNotSupportedException AttachNotSupportedException} 170 * then this method also throws <code>AttachNotSupportedException</code>. 171 * This means that <code>AttachNotSupportedException</code> is thrown when 172 * the identifier provided to this method is invalid, or the identifier 173 * corresponds to a Java virtual machine that does not exist, or none 174 * of the providers can attach to it. This exception is also thrown if 175 * {@link com.sun.tools.attach.spi.AttachProvider#providers() 176 * AttachProvider.providers()} returns an empty list. </p> 177 * 178 * @param id 179 * The abstract identifier that identifies the Java virtual machine. 180 * 181 * @return A VirtualMachine representing the target VM. 182 * 183 * @throws SecurityException 184 * If a security manager has been installed and it denies 185 * {@link com.sun.tools.attach.AttachPermission AttachPermission} 186 * <tt>("attachVirtualMachine")</tt>, or another permission 187 * required by the implementation. 188 * 189 * @throws AttachNotSupportedException 190 * If the <code>attachVirtualmachine</code> method of all installed 191 * providers throws <code>AttachNotSupportedException</code>, or 192 * there aren't any providers installed. 193 * 194 * @throws IOException 195 * If an I/O error occurs 196 * 197 * @throws NullPointerException 198 * If <code>id</code> is <code>null</code>. 199 */ 200 public static VirtualMachine attach(String id) 201 throws AttachNotSupportedException, IOException 202 { 203 if (id == null) { 204 throw new NullPointerException("id cannot be null"); 205 } 206 List<AttachProvider> providers = AttachProvider.providers(); 207 if (providers.size() == 0) { 208 throw new AttachNotSupportedException("no providers installed"); 209 } 210 AttachNotSupportedException lastExc = null; 211 for (AttachProvider provider: providers) { 212 try { 213 return provider.attachVirtualMachine(id); 214 } catch (AttachNotSupportedException x) { 215 lastExc = x; 216 } 217 } 218 throw lastExc; 219 } 220 221 /** 222 * Attaches to a Java virtual machine. 223 * 224 * <p> This method first invokes the {@link 225 * com.sun.tools.attach.VirtualMachineDescriptor#provider() provider()} method 226 * of the given virtual machine descriptor to obtain the attach provider. It 227 * then invokes the attach provider's {@link 228 * com.sun.tools.attach.spi.AttachProvider#attachVirtualMachine(VirtualMachineDescriptor) 229 * attachVirtualMachine} to attach to the target VM. 230 * 231 * @param vmd 232 * The virtual machine descriptor. 233 * 234 * @return A VirtualMachine representing the target VM. 235 * 236 * @throws SecurityException 237 * If a security manager has been installed and it denies 238 * {@link com.sun.tools.attach.AttachPermission AttachPermission} 239 * <tt>("attachVirtualMachine")</tt>, or another permission 240 * required by the implementation. 241 * 242 * @throws AttachNotSupportedException 243 * If the attach provider's <code>attachVirtualmachine</code> 244 * throws <code>AttachNotSupportedException</code>. 245 * 246 * @throws IOException 247 * If an I/O error occurs 248 * 249 * @throws NullPointerException 250 * If <code>vmd</code> is <code>null</code>. 251 */ 252 public static VirtualMachine attach(VirtualMachineDescriptor vmd) 253 throws AttachNotSupportedException, IOException 254 { 255 return vmd.provider().attachVirtualMachine(vmd); 256 } 257 258 /** 259 * Detach from the virtual machine. 260 * 261 * <p> After detaching from the virtual machine, any further attempt to invoke 262 * operations on that virtual machine will cause an {@link java.io.IOException 263 * IOException} to be thrown. If an operation (such as {@link #loadAgent 264 * loadAgent} for example) is in progress when this method is invoked then 265 * the behaviour is implementation dependent. In other words, it is 266 * implementation specific if the operation completes or throws 267 * <tt>IOException</tt>. 268 * 269 * <p> If already detached from the virtual machine then invoking this 270 * method has no effect. </p> 271 * 272 * @throws IOException 273 * If an I/O error occurs 274 */ 275 public abstract void detach() throws IOException; 276 277 /** 278 * Returns the provider that created this virtual machine. 279 * 280 * @return The provider that created this virtual machine. 281 */ 282 public final AttachProvider provider() { 283 return provider; 284 } 285 286 /** 287 * Returns the identifier for this Java virtual machine. 288 * 289 * @return The identifier for this Java virtual machine. 290 */ 291 public final String id() { 292 return id; 293 } 294 295 /** 296 * Loads an agent library. 297 * 298 * <p> A <a href="../../../../../../../../technotes/guides/jvmti/index.html">JVM 299 * TI</a> client is called an <i>agent</i>. It is developed in a native language. 300 * A JVM TI agent is deployed in a platform specific manner but it is typically the 301 * platform equivalent of a dynamic library. This method causes the given agent 302 * library to be loaded into the target VM (if not already loaded). 303 * It then causes the target VM to invoke the <code>Agent_OnAttach</code> function 304 * as specified in the 305 * <a href="../../../../../../../../technotes/guides/jvmti/index.html"> JVM Tools 306 * Interface</a> specification. Note that the <code>Agent_OnAttach</code> 307 * function is invoked even if the agent library was loaded prior to invoking 308 * this method. 309 * 310 * <p> The agent library provided is the name of the agent library. It is interpreted 311 * in the target virtual machine in an implementation-dependent manner. Typically an 312 * implementation will expand the library name into an operating system specific file 313 * name. For example, on UNIX systems, the name <tt>foo</tt> might be expanded to 314 * <tt>libfoo.so</tt>, and located using the search path specified by the 315 * <tt>LD_LIBRARY_PATH</tt> environment variable.</p> 316 * 317 * <p> If the <code>Agent_OnAttach</code> function in the agent library returns 318 * an error then an {@link com.sun.tools.attach.AgentInitializationException} is 319 * thrown. The return value from the <code>Agent_OnAttach</code> can then be 320 * obtained by invoking the {@link 321 * com.sun.tools.attach.AgentInitializationException#returnValue() returnValue} 322 * method on the exception. </p> 323 * 324 * @param agentLibrary 325 * The name of the agent library. 326 * 327 * @param options 328 * The options to provide to the <code>Agent_OnAttach</code> 329 * function (can be <code>null</code>). 330 * 331 * @throws AgentLoadException 332 * If the agent library does not exist, or cannot be loaded for 333 * another reason. 334 * 335 * @throws AgentInitializationException 336 * If the <code>Agent_OnAttach</code> function returns an error 337 * 338 * @throws IOException 339 * If an I/O error occurs 340 * 341 * @throws NullPointerException 342 * If <code>agentLibrary</code> is <code>null</code>. 343 * 344 * @see com.sun.tools.attach.AgentInitializationException#returnValue() 345 */ 346 public abstract void loadAgentLibrary(String agentLibrary, String options) 347 throws AgentLoadException, AgentInitializationException, IOException; 348 349 /** 350 * Loads an agent library. 351 * 352 * <p> This convenience method works as if by invoking: 353 * 354 * <blockquote><tt> 355 * {@link #loadAgentLibrary(String, String) loadAgentLibrary}(agentLibrary, null); 356 * </tt></blockquote> 357 * 358 * @param agentLibrary 359 * The name of the agent library. 360 * 361 * @throws AgentLoadException 362 * If the agent library does not exist, or cannot be loaded for 363 * another reason. 364 * 365 * @throws AgentInitializationException 366 * If the <code>Agent_OnAttach</code> function returns an error 367 * 368 * @throws IOException 369 * If an I/O error occurs 370 * 371 * @throws NullPointerException 372 * If <code>agentLibrary</code> is <code>null</code>. 373 */ 374 public void loadAgentLibrary(String agentLibrary) 375 throws AgentLoadException, AgentInitializationException, IOException 376 { 377 loadAgentLibrary(agentLibrary, null); 378 } 379 380 /** 381 * Load a native agent library by full pathname. 382 * 383 * <p> A <a href="../../../../../../../../technotes/guides/jvmti/index.html">JVM 384 * TI</a> client is called an <i>agent</i>. It is developed in a native language. 385 * A JVM TI agent is deployed in a platform specific manner but it is typically the 386 * platform equivalent of a dynamic library. This method causes the given agent 387 * library to be loaded into the target VM (if not already loaded). 388 * It then causes the target VM to invoke the <code>Agent_OnAttach</code> function 389 * as specified in the 390 * <a href="../../../../../../../../technotes/guides/jvmti/index.html"> JVM Tools 391 * Interface</a> specification. Note that the <code>Agent_OnAttach</code> 392 * function is invoked even if the agent library was loaded prior to invoking 393 * this method. 394 * 395 * <p> The agent library provided is the absolute path from which to load the 396 * agent library. Unlike {@link #loadAgentLibrary loadAgentLibrary}, the library name 397 * is not expanded in the target virtual machine. </p> 398 * 399 * <p> If the <code>Agent_OnAttach</code> function in the agent library returns 400 * an error then an {@link com.sun.tools.attach.AgentInitializationException} is 401 * thrown. The return value from the <code>Agent_OnAttach</code> can then be 402 * obtained by invoking the {@link 403 * com.sun.tools.attach.AgentInitializationException#returnValue() returnValue} 404 * method on the exception. </p> 405 * 406 * @param agentPath 407 * The full path of the agent library. 408 * 409 * @param options 410 * The options to provide to the <code>Agent_OnAttach</code> 411 * function (can be <code>null</code>). 412 * 413 * @throws AgentLoadException 414 * If the agent library does not exist, or cannot be loaded for 415 * another reason. 416 * 417 * @throws AgentInitializationException 418 * If the <code>Agent_OnAttach</code> function returns an error 419 * 420 * @throws IOException 421 * If an I/O error occurs 422 * 423 * @throws NullPointerException 424 * If <code>agentPath</code> is <code>null</code>. 425 * 426 * @see com.sun.tools.attach.AgentInitializationException#returnValue() 427 */ 428 public abstract void loadAgentPath(String agentPath, String options) 429 throws AgentLoadException, AgentInitializationException, IOException; 430 431 /** 432 * Load a native agent library by full pathname. 433 * 434 * <p> This convenience method works as if by invoking: 435 * 436 * <blockquote><tt> 437 * {@link #loadAgentPath(String, String) loadAgentPath}(agentLibrary, null); 438 * </tt></blockquote> 439 * 440 * @param agentPath 441 * The full path to the agent library. 442 * 443 * @throws AgentLoadException 444 * If the agent library does not exist, or cannot be loaded for 445 * another reason. 446 * 447 * @throws AgentInitializationException 448 * If the <code>Agent_OnAttach</code> function returns an error 449 * 450 * @throws IOException 451 * If an I/O error occurs 452 * 453 * @throws NullPointerException 454 * If <code>agentPath</code> is <code>null</code>. 455 */ 456 public void loadAgentPath(String agentPath) 457 throws AgentLoadException, AgentInitializationException, IOException 458 { 459 loadAgentPath(agentPath, null); 460 } 461 462 463 /** 464 * Loads an agent. 465 * 466 * <p> The agent provided to this method is a path name to a JAR file on the file 467 * system of the target virtual machine. This path is passed to the target virtual 468 * machine where it is interpreted. The target virtual machine attempts to start 469 * the agent as specified by the {@link java.lang.instrument} specification. 470 * That is, the specified JAR file is added to the system class path (of the target 471 * virtual machine), and the <code>agentmain</code> method of the agent class, specified 472 * by the <code>Agent-Class</code> attribute in the JAR manifest, is invoked. This 473 * method completes when the <code>agentmain</code> method completes. 474 * 475 * @param agent 476 * Path to the JAR file containing the agent. 477 * 478 * @param options 479 * The options to provide to the agent's <code>agentmain</code> 480 * method (can be <code>null</code>). 481 * 482 * @throws AgentLoadException 483 * If the agent does not exist, or cannot be started in the manner 484 * specified in the {@link java.lang.instrument} specification. 485 * 486 * @throws AgentInitializationException 487 * If the <code>agentmain</code> throws an exception 488 * 489 * @throws IOException 490 * If an I/O error occurs 491 * 492 * @throws NullPointerException 493 * If <code>agent</code> is <code>null</code>. 494 */ 495 public abstract void loadAgent(String agent, String options) 496 throws AgentLoadException, AgentInitializationException, IOException; 497 498 /** 499 * Loads an agent. 500 * 501 * <p> This convenience method works as if by invoking: 502 * 503 * <blockquote><tt> 504 * {@link #loadAgent(String, String) loadAgent}(agent, null); 505 * </tt></blockquote> 506 * 507 * @param agent 508 * Path to the JAR file containing the agent. 509 * 510 * @throws AgentLoadException 511 * If the agent does not exist, or cannot be started in the manner 512 * specified in the {@link java.lang.instrument} specification. 513 * 514 * @throws AgentInitializationException 515 * If the <code>agentmain</code> throws an exception 516 * 517 * @throws IOException 518 * If an I/O error occurs 519 * 520 * @throws NullPointerException 521 * If <code>agent</code> is <code>null</code>. 522 */ 523 public void loadAgent(String agent) 524 throws AgentLoadException, AgentInitializationException, IOException 525 { 526 loadAgent(agent, null); 527 } 528 529 /** 530 * Returns the current system properties in the target virtual machine. 531 * 532 * <p> This method returns the system properties in the target virtual 533 * machine. Properties whose key or value is not a <tt>String</tt> are 534 * omitted. The method is approximately equivalent to the invocation of the 535 * method {@link java.lang.System#getProperties System.getProperties} 536 * in the target virtual machine except that properties with a key or 537 * value that is not a <tt>String</tt> are not included. 538 * 539 * <p> This method is typically used to decide which agent to load into 540 * the target virtual machine with {@link #loadAgent loadAgent}, or 541 * {@link #loadAgentLibrary loadAgentLibrary}. For example, the 542 * <code>java.home</code> or <code>user.dir</code> properties might be 543 * use to create the path to the agent library or JAR file. 544 * 545 * @return The system properties 546 * 547 * @throws IOException 548 * If an I/O error occurs 549 * 550 * @see java.lang.System#getProperties 551 * @see #loadAgentLibrary 552 * @see #loadAgent 553 */ 554 public abstract Properties getSystemProperties() throws IOException; 555 556 /** 557 * Returns the current <i>agent properties</i> in the target virtual 558 * machine. 559 * 560 * <p> The target virtual machine can maintain a list of properties on 561 * behalf of agents. The manner in which this is done, the names of the 562 * properties, and the types of values that are allowed, is implementation 563 * specific. Agent properties are typically used to store communication 564 * end-points and other agent configuration details. For example, a debugger 565 * agent might create an agent property for its transport address. 566 * 567 * <p> This method returns the agent properties whose key and value is a 568 * <tt>String</tt>. Properties whose key or value is not a <tt>String</tt> 569 * are omitted. If there are no agent properties maintained in the target 570 * virtual machine then an empty property list is returned. 571 * 572 * @return The agent properties 573 * 574 * @throws IOException 575 * If an I/O error occurs 576 */ 577 public abstract Properties getAgentProperties() throws IOException; 578 579 /** 580 * Returns a hash-code value for this VirtualMachine. The hash 581 * code is based upon the VirtualMachine's components, and satifies 582 * the general contract of the {@link java.lang.Object#hashCode() 583 * Object.hashCode} method. 584 * 585 * @return A hash-code value for this virtual machine 586 */ 587 public int hashCode() { 588 if (hash != 0) { 589 return hash; 590 } 591 hash = provider.hashCode() * 127 + id.hashCode(); 592 return hash; 593 } 594 595 /** 596 * Tests this VirtualMachine for equality with another object. 597 * 598 * <p> If the given object is not a VirtualMachine then this 599 * method returns <tt>false</tt>. For two VirtualMachines to 600 * be considered equal requires that they both reference the same 601 * provider, and their {@link VirtualMachineDescriptor#id() identifiers} are equal. </p> 602 * 603 * <p> This method satisfies the general contract of the {@link 604 * java.lang.Object#equals(Object) Object.equals} method. </p> 605 * 606 * @param ob The object to which this object is to be compared 607 * 608 * @return <tt>true</tt> if, and only if, the given object is 609 * a VirtualMachine that is equal to this 610 * VirtualMachine. 611 */ 612 public boolean equals(Object ob) { 613 if (ob == this) 614 return true; 615 if (!(ob instanceof VirtualMachine)) 616 return false; 617 VirtualMachine other = (VirtualMachine)ob; 618 if (other.provider() != this.provider()) { 619 return false; 620 } 621 if (!other.id().equals(this.id())) { 622 return false; 623 } 624 return true; 625 } 626 627 /** 628 * Returns the string representation of the <code>VirtualMachine</code>. 629 */ 630 public String toString() { 631 return provider.toString() + ": " + id; 632 } 633 }