1 /* 2 * Copyright (c) 1998, 2010, 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 */ 24 25 #ifndef _JAVA_JVMTIEXPORT_H_ 26 #define _JAVA_JVMTIEXPORT_H_ 27 28 // Forward declarations 29 30 class JvmtiEventControllerPrivate; 31 class JvmtiManageCapabilities; 32 class JvmtiEnv; 33 class JvmtiThreadState; 34 class AttachOperation; 35 36 #ifndef JVMTI_KERNEL 37 #define JVMTI_SUPPORT_FLAG(key) \ 38 private: \ 39 static bool _##key; \ 40 public: \ 41 inline static void set_##key(bool on) { _##key = (on != 0); } \ 42 inline static bool key() { return _##key; } 43 #else // JVMTI_KERNEL 44 #define JVMTI_SUPPORT_FLAG(key) \ 45 private: \ 46 const static bool _##key = false; \ 47 public: \ 48 inline static void set_##key(bool on) { report_unsupported(on); } \ 49 inline static bool key() { return _##key; } 50 #endif // JVMTI_KERNEL 51 52 53 // This class contains the JVMTI interface for the rest of hotspot. 54 // 55 class JvmtiExport : public AllStatic { 56 private: 57 static int _field_access_count; 58 static int _field_modification_count; 59 60 static bool _can_access_local_variables; 61 static bool _can_hotswap_or_post_breakpoint; 62 static bool _can_modify_any_class; 63 static bool _can_walk_any_space; 64 65 JVMTI_SUPPORT_FLAG(can_get_source_debug_extension) 66 JVMTI_SUPPORT_FLAG(can_maintain_original_method_order) 67 JVMTI_SUPPORT_FLAG(can_post_interpreter_events) 68 JVMTI_SUPPORT_FLAG(can_post_on_exceptions) 69 JVMTI_SUPPORT_FLAG(can_post_breakpoint) 70 JVMTI_SUPPORT_FLAG(can_post_field_access) 71 JVMTI_SUPPORT_FLAG(can_post_field_modification) 72 JVMTI_SUPPORT_FLAG(can_post_method_entry) 73 JVMTI_SUPPORT_FLAG(can_post_method_exit) 74 JVMTI_SUPPORT_FLAG(can_pop_frame) 75 JVMTI_SUPPORT_FLAG(can_force_early_return) 76 77 friend class JvmtiEventControllerPrivate; // should only modify these flags 78 JVMTI_SUPPORT_FLAG(should_post_single_step) 79 JVMTI_SUPPORT_FLAG(should_post_field_access) 80 JVMTI_SUPPORT_FLAG(should_post_field_modification) 81 JVMTI_SUPPORT_FLAG(should_post_class_load) 82 JVMTI_SUPPORT_FLAG(should_post_class_prepare) 83 JVMTI_SUPPORT_FLAG(should_post_class_unload) 84 JVMTI_SUPPORT_FLAG(should_post_native_method_bind) 85 JVMTI_SUPPORT_FLAG(should_post_compiled_method_load) 86 JVMTI_SUPPORT_FLAG(should_post_compiled_method_unload) 87 JVMTI_SUPPORT_FLAG(should_post_dynamic_code_generated) 88 JVMTI_SUPPORT_FLAG(should_post_monitor_contended_enter) 89 JVMTI_SUPPORT_FLAG(should_post_monitor_contended_entered) 90 JVMTI_SUPPORT_FLAG(should_post_monitor_wait) 91 JVMTI_SUPPORT_FLAG(should_post_monitor_waited) 92 JVMTI_SUPPORT_FLAG(should_post_data_dump) 93 JVMTI_SUPPORT_FLAG(should_post_garbage_collection_start) 94 JVMTI_SUPPORT_FLAG(should_post_garbage_collection_finish) 95 JVMTI_SUPPORT_FLAG(should_post_on_exceptions) 96 97 // ------ the below maybe don't have to be (but are for now) 98 // fixed conditions here ------------ 99 // any events can be enabled 100 JVMTI_SUPPORT_FLAG(should_post_thread_life) 101 JVMTI_SUPPORT_FLAG(should_post_object_free) 102 JVMTI_SUPPORT_FLAG(should_post_resource_exhausted) 103 104 // we are holding objects on the heap - need to talk to GC - e.g. 105 // breakpoint info 106 JVMTI_SUPPORT_FLAG(should_clean_up_heap_objects) 107 JVMTI_SUPPORT_FLAG(should_post_vm_object_alloc) 108 109 // If flag cannot be implemented, give an error if on=true 110 static void report_unsupported(bool on); 111 112 // these should only be called by the friend class 113 friend class JvmtiManageCapabilities; 114 inline static void set_can_modify_any_class(bool on) { _can_modify_any_class = (on != 0); } 115 inline static void set_can_access_local_variables(bool on) { _can_access_local_variables = (on != 0); } 116 inline static void set_can_hotswap_or_post_breakpoint(bool on) { _can_hotswap_or_post_breakpoint = (on != 0); } 117 inline static void set_can_walk_any_space(bool on) { _can_walk_any_space = (on != 0); } 118 119 enum { 120 JVMTI_VERSION_MASK = 0x70000000, 121 JVMTI_VERSION_VALUE = 0x30000000, 122 JVMDI_VERSION_VALUE = 0x20000000 123 }; 124 125 static void post_field_modification(JavaThread *thread, methodOop method, address location, 126 KlassHandle field_klass, Handle object, jfieldID field, 127 char sig_type, jvalue *value); 128 129 130 private: 131 // CompiledMethodUnload events are reported from the VM thread so they 132 // are collected in lists (of jmethodID/addresses) and the events are posted later 133 // from threads posting CompieldMethodLoad or DynamicCodeGenerated events. 134 static bool _have_pending_compiled_method_unload_events; 135 static GrowableArray<jmethodID>* _pending_compiled_method_unload_method_ids; 136 static GrowableArray<const void *>* _pending_compiled_method_unload_code_begins; 137 static JavaThread* _current_poster; 138 139 // tests if there are CompiledMethodUnload events pending 140 inline static bool have_pending_compiled_method_unload_events() { 141 return _have_pending_compiled_method_unload_events; 142 } 143 144 // posts any pending CompiledMethodUnload events. 145 static void post_pending_compiled_method_unload_events(); 146 147 // Perform the actual notification to interested JvmtiEnvs. 148 static void post_compiled_method_unload_internal(JavaThread* self, jmethodID mid, const void* code_begin); 149 150 // posts a DynamicCodeGenerated event (internal/private implementation). 151 // The public post_dynamic_code_generated* functions make use of the 152 // internal implementation. 153 static void post_dynamic_code_generated_internal(const char *name, const void *code_begin, const void *code_end) KERNEL_RETURN; 154 155 156 // GenerateEvents support to allow posting of CompiledMethodLoad and 157 // DynamicCodeGenerated events for a given environment. 158 friend class JvmtiCodeBlobEvents; 159 160 static void post_compiled_method_load(JvmtiEnv* env, const jmethodID method, const jint length, 161 const void *code_begin, const jint map_length, 162 const jvmtiAddrLocationMap* map) KERNEL_RETURN; 163 static void post_dynamic_code_generated(JvmtiEnv* env, const char *name, const void *code_begin, 164 const void *code_end) KERNEL_RETURN; 165 166 // The RedefineClasses() API breaks some invariants in the "regular" 167 // system. For example, there are sanity checks when GC'ing nmethods 168 // that require the containing class to be unloading. However, when a 169 // method is redefined, the old method and nmethod can become GC'able 170 // without the containing class unloading. The state of becoming 171 // GC'able can be asynchronous to the RedefineClasses() call since 172 // the old method may still be running and cannot be GC'ed until 173 // after all old invocations have finished. Additionally, a method 174 // that has not been redefined may have an nmethod that depends on 175 // the redefined method. The dependent nmethod will get deopted in 176 // this case and may also be GC'able without the containing class 177 // being unloaded. 178 // 179 // This flag indicates whether RedefineClasses() has ever redefined 180 // one or more classes during the lifetime of the VM. The flag should 181 // only be set by the friend class and can be queried by other sub 182 // systems as needed to relax invariant checks. 183 static bool _has_redefined_a_class; 184 friend class VM_RedefineClasses; 185 inline static void set_has_redefined_a_class() { 186 _has_redefined_a_class = true; 187 } 188 189 // Flag to indicate if the compiler has recorded all dependencies. When the 190 // can_redefine_classes capability is enabled in the OnLoad phase then the compiler 191 // records all dependencies from startup. However if the capability is first 192 // enabled some time later then the dependencies recorded by the compiler 193 // are incomplete. This flag is used by RedefineClasses to know if the 194 // dependency information is complete or not. 195 static bool _all_dependencies_are_recorded; 196 197 public: 198 inline static bool has_redefined_a_class() { 199 return _has_redefined_a_class; 200 } 201 202 inline static bool all_dependencies_are_recorded() { 203 return _all_dependencies_are_recorded; 204 } 205 206 inline static void set_all_dependencies_are_recorded(bool on) { 207 _all_dependencies_are_recorded = (on != 0); 208 } 209 210 211 // let JVMTI know that the JVM_OnLoad code is running 212 static void enter_onload_phase(); 213 214 // let JVMTI know that the VM isn't up yet (and JVM_OnLoad code isn't running) 215 static void enter_primordial_phase(); 216 217 // let JVMTI know that the VM isn't up yet but JNI is live 218 static void enter_start_phase(); 219 220 // let JVMTI know that the VM is fully up and running now 221 static void enter_live_phase(); 222 223 // ------ can_* conditions (below) are set at OnLoad and never changed ------------ 224 inline static bool can_modify_any_class() { return _can_modify_any_class; } 225 inline static bool can_access_local_variables() { return _can_access_local_variables; } 226 inline static bool can_hotswap_or_post_breakpoint() { return _can_hotswap_or_post_breakpoint; } 227 inline static bool can_walk_any_space() { return _can_walk_any_space; } 228 229 // field access management 230 static address get_field_access_count_addr(); 231 232 // field modification management 233 static address get_field_modification_count_addr(); 234 235 // ----------------- 236 237 static bool is_jvmti_version(jint version) { return (version & JVMTI_VERSION_MASK) == JVMTI_VERSION_VALUE; } 238 static bool is_jvmdi_version(jint version) { return (version & JVMTI_VERSION_MASK) == JVMDI_VERSION_VALUE; } 239 static jint get_jvmti_interface(JavaVM *jvm, void **penv, jint version); 240 static void decode_version_values(jint version, int * major, int * minor, 241 int * micro); 242 243 // single stepping management methods 244 static void at_single_stepping_point(JavaThread *thread, methodOop method, address location) KERNEL_RETURN; 245 static void expose_single_stepping(JavaThread *thread) KERNEL_RETURN; 246 static bool hide_single_stepping(JavaThread *thread) KERNEL_RETURN_(return false;); 247 248 // Methods that notify the debugger that something interesting has happened in the VM. 249 static void post_vm_start (); 250 static void post_vm_initialized (); 251 static void post_vm_death (); 252 253 static void post_single_step (JavaThread *thread, methodOop method, address location) KERNEL_RETURN; 254 static void post_raw_breakpoint (JavaThread *thread, methodOop method, address location) KERNEL_RETURN; 255 256 static void post_exception_throw (JavaThread *thread, methodOop method, address location, oop exception) KERNEL_RETURN; 257 static void notice_unwind_due_to_exception (JavaThread *thread, methodOop method, address location, oop exception, bool in_handler_frame) KERNEL_RETURN; 258 259 static oop jni_GetField_probe (JavaThread *thread, jobject jobj, 260 oop obj, klassOop klass, jfieldID fieldID, bool is_static) 261 KERNEL_RETURN_(return NULL;); 262 static oop jni_GetField_probe_nh (JavaThread *thread, jobject jobj, 263 oop obj, klassOop klass, jfieldID fieldID, bool is_static) 264 KERNEL_RETURN_(return NULL;); 265 static void post_field_access_by_jni (JavaThread *thread, oop obj, 266 klassOop klass, jfieldID fieldID, bool is_static) KERNEL_RETURN; 267 static void post_field_access (JavaThread *thread, methodOop method, 268 address location, KlassHandle field_klass, Handle object, jfieldID field) KERNEL_RETURN; 269 static oop jni_SetField_probe (JavaThread *thread, jobject jobj, 270 oop obj, klassOop klass, jfieldID fieldID, bool is_static, char sig_type, 271 jvalue *value) KERNEL_RETURN_(return NULL;); 272 static oop jni_SetField_probe_nh (JavaThread *thread, jobject jobj, 273 oop obj, klassOop klass, jfieldID fieldID, bool is_static, char sig_type, 274 jvalue *value) KERNEL_RETURN_(return NULL;); 275 static void post_field_modification_by_jni(JavaThread *thread, oop obj, 276 klassOop klass, jfieldID fieldID, bool is_static, char sig_type, 277 jvalue *value); 278 static void post_raw_field_modification(JavaThread *thread, methodOop method, 279 address location, KlassHandle field_klass, Handle object, jfieldID field, 280 char sig_type, jvalue *value) KERNEL_RETURN; 281 282 static void post_method_entry (JavaThread *thread, methodOop method, frame current_frame) KERNEL_RETURN; 283 static void post_method_exit (JavaThread *thread, methodOop method, frame current_frame) KERNEL_RETURN; 284 285 static void post_class_load (JavaThread *thread, klassOop klass) KERNEL_RETURN; 286 static void post_class_unload (klassOop klass) KERNEL_RETURN; 287 static void post_class_prepare (JavaThread *thread, klassOop klass) KERNEL_RETURN; 288 289 static void post_thread_start (JavaThread *thread) KERNEL_RETURN; 290 static void post_thread_end (JavaThread *thread) KERNEL_RETURN; 291 292 // Support for java.lang.instrument agent loading. 293 static bool _should_post_class_file_load_hook; 294 inline static void set_should_post_class_file_load_hook(bool on) { _should_post_class_file_load_hook = on; } 295 inline static bool should_post_class_file_load_hook() { return _should_post_class_file_load_hook; } 296 static void post_class_file_load_hook(symbolHandle h_name, Handle class_loader, 297 Handle h_protection_domain, 298 unsigned char **data_ptr, unsigned char **end_ptr, 299 unsigned char **cached_data_ptr, 300 jint *cached_length_ptr); 301 static void post_native_method_bind(methodOop method, address* function_ptr) KERNEL_RETURN; 302 static void post_compiled_method_load(nmethod *nm) KERNEL_RETURN; 303 static void post_dynamic_code_generated(const char *name, const void *code_begin, const void *code_end) KERNEL_RETURN; 304 305 // used to post a CompiledMethodUnload event 306 static void post_compiled_method_unload(jmethodID mid, const void *code_begin) KERNEL_RETURN; 307 308 // similiar to post_dynamic_code_generated except that it can be used to 309 // post a DynamicCodeGenerated event while holding locks in the VM. Any event 310 // posted using this function is recorded by the enclosing event collector 311 // -- JvmtiDynamicCodeEventCollector. 312 static void post_dynamic_code_generated_while_holding_locks(const char* name, address code_begin, address code_end) KERNEL_RETURN; 313 314 static void post_garbage_collection_finish() KERNEL_RETURN; 315 static void post_garbage_collection_start() KERNEL_RETURN; 316 static void post_data_dump() KERNEL_RETURN; 317 static void post_monitor_contended_enter(JavaThread *thread, ObjectMonitor *obj_mntr) KERNEL_RETURN; 318 static void post_monitor_contended_entered(JavaThread *thread, ObjectMonitor *obj_mntr) KERNEL_RETURN; 319 static void post_monitor_wait(JavaThread *thread, oop obj, jlong timeout) KERNEL_RETURN; 320 static void post_monitor_waited(JavaThread *thread, ObjectMonitor *obj_mntr, jboolean timed_out) KERNEL_RETURN; 321 static void post_object_free(JvmtiEnv* env, jlong tag) KERNEL_RETURN; 322 static void post_resource_exhausted(jint resource_exhausted_flags, const char* detail) KERNEL_RETURN; 323 static void record_vm_internal_object_allocation(oop object) KERNEL_RETURN; 324 // Post objects collected by vm_object_alloc_event_collector. 325 static void post_vm_object_alloc(JavaThread *thread, oop object) KERNEL_RETURN; 326 // Collects vm internal objects for later event posting. 327 inline static void vm_object_alloc_event_collector(oop object) { 328 if (should_post_vm_object_alloc()) { 329 record_vm_internal_object_allocation(object); 330 } 331 } 332 333 static void cleanup_thread (JavaThread* thread) KERNEL_RETURN; 334 335 static void oops_do(OopClosure* f) KERNEL_RETURN; 336 337 static void transition_pending_onload_raw_monitors() KERNEL_RETURN; 338 339 #ifndef SERVICES_KERNEL 340 // attach support 341 static jint load_agent_library(AttachOperation* op, outputStream* out); 342 #endif // SERVICES_KERNEL 343 344 // SetNativeMethodPrefix support 345 static char** get_all_native_method_prefixes(int* count_ptr); 346 347 // call after CMS has completed referencing processing 348 static void cms_ref_processing_epilogue() KERNEL_RETURN; 349 }; 350 351 // Support class used by JvmtiDynamicCodeEventCollector and others. It 352 // describes a single code blob by name and address range. 353 class JvmtiCodeBlobDesc : public CHeapObj { 354 private: 355 char _name[64]; 356 address _code_begin; 357 address _code_end; 358 359 public: 360 JvmtiCodeBlobDesc(const char *name, address code_begin, address code_end) { 361 assert(name != NULL, "all code blobs must be named"); 362 strncpy(_name, name, sizeof(_name)); 363 _name[sizeof(_name)-1] = '\0'; 364 _code_begin = code_begin; 365 _code_end = code_end; 366 } 367 char* name() { return _name; } 368 address code_begin() { return _code_begin; } 369 address code_end() { return _code_end; } 370 }; 371 372 // JvmtiEventCollector is a helper class to setup thread for 373 // event collection. 374 class JvmtiEventCollector : public StackObj { 375 private: 376 JvmtiEventCollector* _prev; // Save previous one to support nested event collector. 377 378 public: 379 void setup_jvmti_thread_state(); // Set this collector in current thread. 380 void unset_jvmti_thread_state(); // Reset previous collector in current thread. 381 virtual bool is_dynamic_code_event() { return false; } 382 virtual bool is_vm_object_alloc_event(){ return false; } 383 JvmtiEventCollector *get_prev() { return _prev; } 384 }; 385 386 // A JvmtiDynamicCodeEventCollector is a helper class for the JvmtiExport 387 // interface. It collects "dynamic code generated" events that are posted 388 // while holding locks. When the event collector goes out of scope the 389 // events will be posted. 390 // 391 // Usage :- 392 // 393 // { 394 // JvmtiDynamicCodeEventCollector event_collector; 395 // : 396 // { MutexLocker ml(...) 397 // : 398 // JvmtiExport::post_dynamic_code_generated_while_holding_locks(...) 399 // } 400 // // event collector goes out of scope => post events to profiler. 401 // } 402 403 class JvmtiDynamicCodeEventCollector : public JvmtiEventCollector { 404 private: 405 GrowableArray<JvmtiCodeBlobDesc*>* _code_blobs; // collected code blob events 406 407 friend class JvmtiExport; 408 void register_stub(const char* name, address start, address end); 409 410 public: 411 JvmtiDynamicCodeEventCollector() KERNEL_RETURN; 412 ~JvmtiDynamicCodeEventCollector() KERNEL_RETURN; 413 bool is_dynamic_code_event() { return true; } 414 415 }; 416 417 // Used to record vm internally allocated object oops and post 418 // vm object alloc event for objects visible to java world. 419 // Constructor enables JvmtiThreadState flag and all vm allocated 420 // objects are recorded in a growable array. When destructor is 421 // called the vm object alloc event is posted for each objects 422 // visible to java world. 423 // See jvm.cpp file for its usage. 424 // 425 class JvmtiVMObjectAllocEventCollector : public JvmtiEventCollector { 426 private: 427 GrowableArray<oop>* _allocated; // field to record vm internally allocated object oop. 428 bool _enable; // This flag is enabled in constructor and disabled 429 // in destructor before posting event. To avoid 430 // collection of objects allocated while running java code inside 431 // agent post_vm_object_alloc() event handler. 432 433 //GC support 434 void oops_do(OopClosure* f); 435 436 friend class JvmtiExport; 437 // Record vm allocated object oop. 438 inline void record_allocation(oop obj); 439 440 //GC support 441 static void oops_do_for_all_threads(OopClosure* f); 442 443 public: 444 JvmtiVMObjectAllocEventCollector() KERNEL_RETURN; 445 ~JvmtiVMObjectAllocEventCollector() KERNEL_RETURN; 446 bool is_vm_object_alloc_event() { return true; } 447 448 bool is_enabled() { return _enable; } 449 void set_enabled(bool on) { _enable = on; } 450 }; 451 452 453 454 // Marker class to disable the posting of VMObjectAlloc events 455 // within its scope. 456 // 457 // Usage :- 458 // 459 // { 460 // NoJvmtiVMObjectAllocMark njm; 461 // : 462 // // VMObjAlloc event will not be posted 463 // JvmtiExport::vm_object_alloc_event_collector(obj); 464 // : 465 // } 466 467 class NoJvmtiVMObjectAllocMark : public StackObj { 468 private: 469 // enclosing collector if enabled, NULL otherwise 470 JvmtiVMObjectAllocEventCollector *_collector; 471 472 bool was_enabled() { return _collector != NULL; } 473 474 public: 475 NoJvmtiVMObjectAllocMark() KERNEL_RETURN; 476 ~NoJvmtiVMObjectAllocMark() KERNEL_RETURN; 477 }; 478 479 480 // Base class for reporting GC events to JVMTI. 481 class JvmtiGCMarker : public StackObj { 482 private: 483 bool _full; // marks a "full" GC 484 unsigned int _invocation_count; // GC invocation count 485 protected: 486 JvmtiGCMarker(bool full) KERNEL_RETURN; // protected 487 ~JvmtiGCMarker() KERNEL_RETURN; // protected 488 }; 489 490 491 // Support class used to report GC events to JVMTI. The class is stack 492 // allocated and should be placed in the doit() implementation of all 493 // vm operations that do a stop-the-world GC for failed allocation. 494 // 495 // Usage :- 496 // 497 // void VM_GenCollectForAllocation::doit() { 498 // JvmtiGCForAllocationMarker jgcm; 499 // : 500 // } 501 // 502 // If jvmti is not enabled the constructor and destructor is essentially 503 // a no-op (no overhead). 504 // 505 class JvmtiGCForAllocationMarker : public JvmtiGCMarker { 506 public: 507 JvmtiGCForAllocationMarker() : JvmtiGCMarker(false) { 508 } 509 }; 510 511 // Support class used to report GC events to JVMTI. The class is stack 512 // allocated and should be placed in the doit() implementation of all 513 // vm operations that do a "full" stop-the-world GC. This class differs 514 // from JvmtiGCForAllocationMarker in that this class assumes that a 515 // "full" GC will happen. 516 // 517 // Usage :- 518 // 519 // void VM_GenCollectFull::doit() { 520 // JvmtiGCFullMarker jgcm; 521 // : 522 // } 523 // 524 class JvmtiGCFullMarker : public JvmtiGCMarker { 525 public: 526 JvmtiGCFullMarker() : JvmtiGCMarker(true) { 527 } 528 }; 529 530 531 // JvmtiHideSingleStepping is a helper class for hiding 532 // internal single step events. 533 class JvmtiHideSingleStepping : public StackObj { 534 private: 535 bool _single_step_hidden; 536 JavaThread * _thread; 537 538 public: 539 JvmtiHideSingleStepping(JavaThread * thread) { 540 assert(thread != NULL, "sanity check"); 541 542 _single_step_hidden = false; 543 _thread = thread; 544 if (JvmtiExport::should_post_single_step()) { 545 _single_step_hidden = JvmtiExport::hide_single_stepping(_thread); 546 } 547 } 548 549 ~JvmtiHideSingleStepping() { 550 if (_single_step_hidden) { 551 JvmtiExport::expose_single_stepping(_thread); 552 } 553 } 554 }; 555 556 #endif /* _JAVA_JVMTIEXPORT_H_ */