J. Duke | 319a3b9 | 2007-12-01 00:00:00 +0000 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright 1998-2006 Sun Microsystems, Inc. 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. Sun designates this |
| 8 | * particular file as subject to the "Classpath" exception as provided |
| 9 | * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
| 22 | * CA 95054 USA or visit www.sun.com if you need additional information or |
| 23 | * have any questions. |
| 24 | */ |
| 25 | |
| 26 | package com.sun.jdi; |
| 27 | |
| 28 | import java.util.List; |
| 29 | import java.util.Map; |
| 30 | |
| 31 | /** |
| 32 | * An object that currently exists in the target VM. An ObjectReference |
| 33 | * mirrors only the object itself and is not specific to any |
| 34 | * {@link Field} or {@link LocalVariable} to which it is currently |
| 35 | * assigned. An ObjectReference can |
| 36 | * have 0 or more references from field(s) and/or variable(s). |
| 37 | * <p> |
| 38 | * Any method on <code>ObjectReference</code> which directly or |
| 39 | * indirectly takes <code>ObjectReference</code> as an parameter may throw |
| 40 | * {@link com.sun.jdi.VMDisconnectedException} if the target VM is |
| 41 | * disconnected and the {@link com.sun.jdi.event.VMDisconnectEvent} has been or is |
| 42 | * available to be read from the {@link com.sun.jdi.event.EventQueue}. |
| 43 | * <p> |
| 44 | * Any method on <code>ObjectReference</code> which directly or |
| 45 | * indirectly takes <code>ObjectReference</code> as an parameter may throw |
| 46 | * {@link com.sun.jdi.VMOutOfMemoryException} if the target VM has run out of memory. |
| 47 | * <p> |
| 48 | * Any method on <code>ObjectReference</code> or which directly or indirectly takes |
| 49 | * <code>ObjectReference</code> as parameter may throw |
| 50 | * {@link com.sun.jdi.ObjectCollectedException} if the mirrored object has been |
| 51 | * garbage collected. |
| 52 | * |
| 53 | * @author Robert Field |
| 54 | * @author Gordon Hirsch |
| 55 | * @author James McIlree |
| 56 | * @since 1.3 |
| 57 | */ |
| 58 | public interface ObjectReference extends Value |
| 59 | { |
| 60 | /** |
| 61 | * Gets the {@link ReferenceType} that mirrors the type |
| 62 | * of this object. The type may be a subclass or implementor of the |
| 63 | * declared type of any field or variable which currently holds it. |
| 64 | * For example, right after the following statement. |
| 65 | * <p> |
| 66 | * <code>Object obj = new String("Hello, world!");</code> |
| 67 | * <p> |
| 68 | * The ReferenceType of obj will mirror java.lang.String and not |
| 69 | * java.lang.Object. |
| 70 | * <p> |
| 71 | * The type of an object never changes, so this method will |
| 72 | * always return the same ReferenceType over the lifetime of the |
| 73 | * mirrored object. |
| 74 | * <p> |
| 75 | * The returned ReferenceType will be a {@link ClassType} or |
| 76 | * {@link ArrayType} and never an {@link InterfaceType}. |
| 77 | * |
| 78 | * @return the {@link ReferenceType} for this object. |
| 79 | */ |
| 80 | ReferenceType referenceType(); |
| 81 | |
| 82 | /** |
| 83 | * Gets the value of a given instance or static field in this object. |
| 84 | * The Field must be valid for this ObjectReference; |
| 85 | * that is, it must be from |
| 86 | * the mirrored object's class or a superclass of that class. |
| 87 | * |
| 88 | * @param sig the field containing the requested value |
| 89 | * @return the {@link Value} of the instance field. |
| 90 | * @throws java.lang.IllegalArgumentException if the field is not valid for |
| 91 | * this object's class. |
| 92 | */ |
| 93 | Value getValue(Field sig); |
| 94 | |
| 95 | /** |
| 96 | * Gets the value of multiple instance and/or static fields in this object. |
| 97 | * The Fields must be valid for this ObjectReference; |
| 98 | * that is, they must be from |
| 99 | * the mirrored object's class or a superclass of that class. |
| 100 | * |
| 101 | * @param fields a list of {@link Field} objects containing the |
| 102 | * requested values. |
| 103 | * @return a Map of the requested {@link Field} objects with |
| 104 | * their {@link Value}. |
| 105 | * @throws java.lang.IllegalArgumentException if any field is not valid for |
| 106 | * this object's class. |
| 107 | */ |
| 108 | Map<Field,Value> getValues(List<? extends Field> fields); |
| 109 | |
| 110 | /** |
| 111 | * Sets the value of a given instance or static field in this object. |
| 112 | * The {@link Field} must be valid for this ObjectReference; that is, |
| 113 | * it must be from the mirrored object's class or a superclass of that class. |
| 114 | * If static, the field must not be final. |
| 115 | * <p> |
| 116 | * Object values must be assignment compatible with the field type |
| 117 | * (This implies that the field type must be loaded through the |
| 118 | * enclosing class's class loader). Primitive values must be |
| 119 | * either assignment compatible with the field type or must be |
| 120 | * convertible to the field type without loss of information. |
| 121 | * See the <a href="http://java.sun.com/docs/books/jls/"> |
| 122 | * Java<sup><font size=-2>TM</font></sup> Language Specification</a>. |
| 123 | * section |
| 124 | * <a href="http://java.sun.com/docs/books/jls/second_edition/html/conversions.doc.html#184206">5.2</a> |
| 125 | * for more information on assignment |
| 126 | * compatibility. |
| 127 | * |
| 128 | * @param field the field containing the requested value |
| 129 | * @param value the new value to assign |
| 130 | * @throws java.lang.IllegalArgumentException if the field is not valid for |
| 131 | * this object's class. |
| 132 | * @throws InvalidTypeException if the value's type does not match |
| 133 | * the field's type. |
| 134 | * @throws ClassNotLoadedException if 'value' is not null, and the field |
| 135 | * type has not yet been loaded through the appropriate class loader. |
| 136 | * @throws VMCannotBeModifiedException if the VirtualMachine is read-only - see {@link VirtualMachine#canBeModified()}. |
| 137 | */ |
| 138 | void setValue(Field field, Value value) |
| 139 | throws InvalidTypeException, ClassNotLoadedException; |
| 140 | |
| 141 | /** Perform method invocation with only the invoking thread resumed */ |
| 142 | static final int INVOKE_SINGLE_THREADED = 0x1; |
| 143 | /** Perform non-virtual method invocation */ |
| 144 | static final int INVOKE_NONVIRTUAL = 0x2; |
| 145 | |
| 146 | /** |
| 147 | * Invokes the specified {@link Method} on this object in the |
| 148 | * target VM. The |
| 149 | * specified method can be defined in this object's class, |
| 150 | * in a superclass of this object's class, or in an interface |
| 151 | * implemented by this object. The method may be a static method |
| 152 | * or an instance method, but not a static initializer or constructor. |
| 153 | * Use {@link ClassType#newInstance} to create a new object and |
| 154 | * run its constructor. |
| 155 | * <p> |
| 156 | * The method invocation will occur in the specified thread. |
| 157 | * Method invocation can occur only if the specified thread |
| 158 | * has been suspended by an event which occurred in that thread. |
| 159 | * Method invocation is not supported |
| 160 | * when the target VM has been suspended through |
| 161 | * {@link VirtualMachine#suspend} or when the specified thread |
| 162 | * is suspended through {@link ThreadReference#suspend}. |
| 163 | * <p> |
| 164 | * The specified method is invoked with the arguments in the specified |
| 165 | * argument list. The method invocation is synchronous; this method |
| 166 | * does not return until the invoked method returns in the target VM. |
| 167 | * If the invoked method throws an exception, this method |
| 168 | * will throw an {@link InvocationException} which contains |
| 169 | * a mirror to the exception object thrown. |
| 170 | * <p> |
| 171 | * Object arguments must be assignment compatible with the argument type |
| 172 | * (This implies that the argument type must be loaded through the |
| 173 | * enclosing class's class loader). Primitive arguments must be |
| 174 | * either assignment compatible with the argument type or must be |
| 175 | * convertible to the argument type without loss of information. |
| 176 | * If the method being called accepts a variable number of arguments, |
| 177 | * then the last argument type is an array of some component type. |
| 178 | * The argument in the matching position can be omitted, or can be null, |
| 179 | * an array of the same component type, or an argument of the |
| 180 | * component type followed by any number of other arguments of the same |
| 181 | * type. If the argument is omitted, then a 0 length array of the |
| 182 | * component type is passed. The component type can be a primitive type. |
| 183 | * Autoboxing is not supported. |
| 184 | * |
| 185 | * See the <a href="http://java.sun.com/docs/books/jls/"> |
| 186 | * Java Language Specification</a>. |
| 187 | * section |
| 188 | * <a href="http://java.sun.com/docs/books/jls/second_edition/html/conversions.doc.html#184206">5.2</a> |
| 189 | * for more information on assignment compatibility. |
| 190 | * <p> |
| 191 | * By default, the method is invoked using dynamic lookup as |
| 192 | * documented in the |
| 193 | * <a href="http://java.sun.com/docs/books/jls/"> |
| 194 | * Java Language Specification</a> |
| 195 | * second edition, section |
| 196 | * <a href="http://java.sun.com/docs/books/jls/second_edition/html/expressions.doc.html#45606">15.12.4.4</a>; |
| 197 | * in particular, overriding based on the runtime type of the object |
| 198 | * mirrored by this {@link ObjectReference} will occur. This |
| 199 | * behavior can be changed by specifying the |
| 200 | * {@link #INVOKE_NONVIRTUAL} bit flag in the <code>options</code> |
| 201 | * argument. If this flag is set, the specified method is invoked |
| 202 | * whether or not it is overridden for this object's runtime type. |
| 203 | * The method, in this case, must not belong to an interface and |
| 204 | * must not be abstract. This option is useful for performing method |
| 205 | * invocations like those done with the <code>super</code> keyword in |
| 206 | * the Java programming language. |
| 207 | * <p> |
| 208 | * By default, all threads in the target VM are resumed while |
| 209 | * the method is being invoked if they were previously |
| 210 | * suspended by an event or by {@link VirtualMachine#suspend} or |
| 211 | * {@link ThreadReference#suspend}. This is done to prevent the deadlocks |
| 212 | * that will occur if any of the threads own monitors |
| 213 | * that will be needed by the invoked method. |
| 214 | * Note, however, that this implicit resume acts exactly like |
| 215 | * {@link ThreadReference#resume}, so if the thread's suspend |
| 216 | * count is greater than 1, it will remain in a suspended state |
| 217 | * during the invocation and thus a deadlock could still occur. |
| 218 | * By default, when the invocation completes, |
| 219 | * all threads in the target VM are suspended, regardless their state |
| 220 | * before the invocation. |
| 221 | * It is possible that |
| 222 | * breakpoints or other events might occur during the invocation. |
| 223 | * This can cause deadlocks as described above. It can also cause a deadlock |
| 224 | * if invokeMethod is called from the client's event handler thread. In this |
| 225 | * case, this thread will be waiting for the invokeMethod to complete and |
| 226 | * won't read the EventSet that comes in for the new event. If this |
| 227 | * new EventSet is SUSPEND_ALL, then a deadlock will occur because no |
| 228 | * one will resume the EventSet. To avoid this, all EventRequests should |
| 229 | * be disabled before doing the invokeMethod, or the invokeMethod should |
| 230 | * not be done from the client's event handler thread. |
| 231 | * <p> |
| 232 | * The resumption of other threads during the invocation can be prevented |
| 233 | * by specifying the {@link #INVOKE_SINGLE_THREADED} |
| 234 | * bit flag in the <code>options</code> argument; however, |
| 235 | * there is no protection against or recovery from the deadlocks |
| 236 | * described above, so this option should be used with great caution. |
| 237 | * Only the specified thread will be resumed (as described for all |
| 238 | * threads above). Upon completion of a single threaded invoke, the invoking thread |
| 239 | * will be suspended once again. Note that any threads started during |
| 240 | * the single threaded invocation will not be suspended when the |
| 241 | * invocation completes. |
| 242 | * <p> |
| 243 | * If the target VM is disconnected during the invoke (for example, through |
| 244 | * {@link VirtualMachine#dispose}) the method invocation continues. |
| 245 | * |
| 246 | * @param thread the thread in which to invoke. |
| 247 | * @param method the {@link Method} to invoke. |
| 248 | * @param arguments the list of {@link Value} arguments bound to the |
| 249 | * invoked method. Values from the list are assigned to arguments |
| 250 | * in the order they appear in the method signature. |
| 251 | * @param options the integer bit flag options. |
| 252 | * @return a {@link Value} mirror of the invoked method's return value. |
| 253 | * @throws java.lang.IllegalArgumentException if the method is not |
| 254 | * a member of this object's class, if the size of the argument list |
| 255 | * does not match the number of declared arguemnts for the method, |
| 256 | * if the method is a constructor or static intializer, or |
| 257 | * if {@link #INVOKE_NONVIRTUAL} is specified and the method is |
| 258 | * either abstract or an interface member. |
| 259 | * @throws {@link InvalidTypeException} if any argument in the |
| 260 | * argument list is not assignable to the corresponding method argument |
| 261 | * type. |
| 262 | * @throws ClassNotLoadedException if any argument type has not yet been loaded |
| 263 | * through the appropriate class loader. |
| 264 | * @throws IncompatibleThreadStateException if the specified thread has not |
| 265 | * been suspended by an event. |
| 266 | * @throws InvocationException if the method invocation resulted in |
| 267 | * an exception in the target VM. |
| 268 | * @throws InvalidTypeException If the arguments do not meet this requirement -- |
| 269 | * Object arguments must be assignment compatible with the argument |
| 270 | * type. This implies that the argument type must be |
| 271 | * loaded through the enclosing class's class loader. |
| 272 | * Primitive arguments must be either assignment compatible with the |
| 273 | * argument type or must be convertible to the argument type without loss |
| 274 | * of information. See JLS section 5.2 for more information on assignment |
| 275 | * compatibility. |
| 276 | * @throws VMCannotBeModifiedException if the VirtualMachine is read-only - see {@link VirtualMachine#canBeModified()}. |
| 277 | */ |
| 278 | Value invokeMethod(ThreadReference thread, Method method, |
| 279 | List<? extends Value> arguments, int options) |
| 280 | throws InvalidTypeException, |
| 281 | ClassNotLoadedException, |
| 282 | IncompatibleThreadStateException, |
| 283 | InvocationException; |
| 284 | |
| 285 | /** |
| 286 | * Prevents garbage collection for this object. By default all |
| 287 | * {@link ObjectReference} values returned by JDI may be collected |
| 288 | * at any time the target VM is running. A call to this method |
| 289 | * guarantees that the object will not be collected. |
| 290 | * {@link #enableCollection} can be used to allow collection once |
| 291 | * again. |
| 292 | * <p> |
| 293 | * Calls to this method are counted. Every call to this method |
| 294 | * requires a corresponding call to {@link #enableCollection} before |
| 295 | * garbage collection is re-enabled. |
| 296 | * <p> |
| 297 | * Note that while the target VM is suspended, no garbage collection |
| 298 | * will occur because all threads are suspended. The typical |
| 299 | * examination of variables, fields, and arrays during the suspension |
| 300 | * is safe without explicitly disabling garbage collection. |
| 301 | * <p> |
| 302 | * This method should be used sparingly, as it alters the |
| 303 | * pattern of garbage collection in the target VM and, |
| 304 | * consequently, may result in application behavior under the |
| 305 | * debugger that differs from its non-debugged behavior. |
| 306 | * @throws VMCannotBeModifiedException if the VirtualMachine is read-only |
| 307 | * -see {@link VirtualMachine#canBeModified()}. |
| 308 | */ |
| 309 | void disableCollection(); |
| 310 | |
| 311 | /** |
| 312 | * Permits garbage collection for this object. By default all |
| 313 | * {@link ObjectReference} values returned by JDI may be collected |
| 314 | * at any time the target VM is running. A call to this method |
| 315 | * is necessary only if garbage collection was previously disabled |
| 316 | * with {@link #disableCollection}. |
| 317 | * @throws VMCannotBeModifiedException if the VirtualMachine is read-only |
| 318 | * -see {@link VirtualMachine#canBeModified()}. |
| 319 | */ |
| 320 | void enableCollection(); |
| 321 | |
| 322 | /** |
| 323 | * Determines if this object has been garbage collected in the target |
| 324 | * VM. |
| 325 | * |
| 326 | * @return <code>true</code> if this {@link ObjectReference} has been collected; |
| 327 | * <code>false</code> otherwise. |
| 328 | * @throws VMCannotBeModifiedException if the VirtualMachine is read-only |
| 329 | * -see {@link VirtualMachine#canBeModified()}. |
| 330 | */ |
| 331 | boolean isCollected(); |
| 332 | |
| 333 | /** |
| 334 | * Returns a unique identifier for this ObjectReference. |
| 335 | * It is guaranteed to be unique among all |
| 336 | * ObjectReferences from the same VM that have not yet been disposed. |
| 337 | * The guarantee applies as long |
| 338 | * as this ObjectReference has not yet been disposed. |
| 339 | * |
| 340 | * @return a long unique ID |
| 341 | */ |
| 342 | long uniqueID(); |
| 343 | |
| 344 | /** |
| 345 | * Returns a List containing a {@link ThreadReference} for |
| 346 | * each thread currently waiting for this object's monitor. |
| 347 | * See {@link ThreadReference#currentContendedMonitor} for |
| 348 | * information about when a thread is considered to be waiting |
| 349 | * for a monitor. |
| 350 | * <p> |
| 351 | * Not all target VMs support this operation. See |
| 352 | * VirtualMachine#canGetMonitorInfo to determine if the |
| 353 | * operation is supported. |
| 354 | * |
| 355 | * @return a List of {@link ThreadReference} objects. The list |
| 356 | * has zero length if no threads are waiting for the monitor. |
| 357 | * @throws java.lang.UnsupportedOperationException if the |
| 358 | * target VM does not support this operation. |
| 359 | * @throws IncompatibleThreadStateException if any |
| 360 | * waiting thread is not suspended |
| 361 | * in the target VM |
| 362 | */ |
| 363 | List<ThreadReference> waitingThreads() |
| 364 | throws IncompatibleThreadStateException; |
| 365 | |
| 366 | /** |
| 367 | * Returns an {@link ThreadReference} for the thread, if any, |
| 368 | * which currently owns this object's monitor. |
| 369 | * See {@link ThreadReference#ownedMonitors} for a definition |
| 370 | * of ownership. |
| 371 | * <p> |
| 372 | * Not all target VMs support this operation. See |
| 373 | * VirtualMachine#canGetMonitorInfo to determine if the |
| 374 | * operation is supported. |
| 375 | * |
| 376 | * @return the {@link ThreadReference} which currently owns the |
| 377 | * monitor, or null if it is unowned. |
| 378 | * |
| 379 | * @throws java.lang.UnsupportedOperationException if the |
| 380 | * target VM does not support this operation. |
| 381 | * @throws IncompatibleThreadStateException if the owning thread is |
| 382 | * not suspended in the target VM |
| 383 | */ |
| 384 | ThreadReference owningThread() throws IncompatibleThreadStateException; |
| 385 | |
| 386 | /** |
| 387 | * Returns the number times this object's monitor has been |
| 388 | * entered by the current owning thread. |
| 389 | * See {@link ThreadReference#ownedMonitors} for a definition |
| 390 | * of ownership. |
| 391 | * <p> |
| 392 | * Not all target VMs support this operation. See |
| 393 | * VirtualMachine#canGetMonitorInfo to determine if the |
| 394 | * operation is supported. |
| 395 | * |
| 396 | * @see #owningThread |
| 397 | * @return the integer count of the number of entries. |
| 398 | * |
| 399 | * @throws java.lang.UnsupportedOperationException if the |
| 400 | * target VM does not support this operation. |
| 401 | * @throws IncompatibleThreadStateException if the owning thread is |
| 402 | * not suspended in the target VM |
| 403 | */ |
| 404 | int entryCount() throws IncompatibleThreadStateException; |
| 405 | |
| 406 | /** |
| 407 | * Returns objects that directly reference this object. |
| 408 | * Only objects that are reachable for the purposes of garbage collection |
| 409 | * are returned. Note that an object can also be referenced in other ways, |
| 410 | * such as from a local variable in a stack frame, or from a JNI global |
| 411 | * reference. Such non-object referrers are not returned by this method. |
| 412 | * <p> |
| 413 | * Not all target virtual machines support this operation. |
| 414 | * Use {@link VirtualMachine#canGetInstanceInfo()} |
| 415 | * to determine if the operation is supported. |
| 416 | * |
| 417 | * @see VirtualMachine#instanceCounts(List) |
| 418 | * @see ReferenceType#instances(long) |
| 419 | |
| 420 | * @param maxReferrers The maximum number of referring objects to return. |
| 421 | * Must be non-negative. If zero, all referring |
| 422 | * objects are returned. |
| 423 | * @return a of List of {@link ObjectReference} objects. If there are |
| 424 | * no objects that reference this object, a zero-length list is returned.. |
| 425 | * @throws java.lang.UnsupportedOperationException if |
| 426 | * the target virtual machine does not support this |
| 427 | * operation - see |
| 428 | * {@link VirtualMachine#canGetInstanceInfo() canGetInstanceInfo()} |
| 429 | * @throws java.lang.IllegalArgumentException if maxReferrers is less |
| 430 | * than zero. |
| 431 | * @since 1.6 |
| 432 | */ |
| 433 | List<ObjectReference> referringObjects(long maxReferrers); |
| 434 | |
| 435 | |
| 436 | /** |
| 437 | * Compares the specified Object with this ObjectReference for equality. |
| 438 | * |
| 439 | * @return true if the Object is an ObjectReference, if the |
| 440 | * ObjectReferences belong to the same VM, and if applying the |
| 441 | * "==" operator on the mirrored objects in that VM evaluates to true. |
| 442 | */ |
| 443 | boolean equals(Object obj); |
| 444 | |
| 445 | /** |
| 446 | * Returns the hash code value for this ObjectReference. |
| 447 | * |
| 448 | * @return the integer hash code |
| 449 | */ |
| 450 | int hashCode(); |
| 451 | } |