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 SHARE_VM_PRIMS_JVMTIEXPORT_HPP
26 #define SHARE_VM_PRIMS_JVMTIEXPORT_HPP
27
28 #include "code/jvmticmlr.h"
29 #include "jvmtifiles/jvmti.h"
30 #include "memory/allocation.hpp"
31 #include "memory/iterator.hpp"
32 #include "oops/oop.hpp"
33 #include "oops/oopsHierarchy.hpp"
34 #include "runtime/frame.hpp"
35 #include "runtime/handles.hpp"
36 #include "utilities/globalDefinitions.hpp"
37 #include "utilities/growableArray.hpp"
38
39 // Forward declarations
40
41 class JvmtiEventControllerPrivate;
42 class JvmtiManageCapabilities;
43 class JvmtiEnv;
44 class JvmtiThreadState;
45 class AttachOperation;
46
47 #ifndef JVMTI_KERNEL
48 #define JVMTI_SUPPORT_FLAG(key) \
49 private: \
50 static bool _##key; \
51 public: \
52 inline static void set_##key(bool on) { _##key = (on != 0); } \
53 inline static bool key() { return _##key; }
54 #else // JVMTI_KERNEL
55 #define JVMTI_SUPPORT_FLAG(key) \
56 private: \
57 const static bool _##key = false; \
58 public: \
59 inline static void set_##key(bool on) { report_unsupported(on); } \
60 inline static bool key() { return _##key; }
61 #endif // JVMTI_KERNEL
62
63
64 // This class contains the JVMTI interface for the rest of hotspot.
65 //
66 class JvmtiExport : public AllStatic {
67 private:
68 static int _field_access_count;
69 static int _field_modification_count;
70
71 static bool _can_access_local_variables;
72 static bool _can_hotswap_or_post_breakpoint;
73 static bool _can_modify_any_class;
74 static bool _can_walk_any_space;
75
76 JVMTI_SUPPORT_FLAG(can_get_source_debug_extension)
77 JVMTI_SUPPORT_FLAG(can_maintain_original_method_order)
78 JVMTI_SUPPORT_FLAG(can_post_interpreter_events)
79 JVMTI_SUPPORT_FLAG(can_post_on_exceptions)
80 JVMTI_SUPPORT_FLAG(can_post_breakpoint)
81 JVMTI_SUPPORT_FLAG(can_post_field_access)
82 JVMTI_SUPPORT_FLAG(can_post_field_modification)
83 JVMTI_SUPPORT_FLAG(can_post_method_entry)
84 JVMTI_SUPPORT_FLAG(can_post_method_exit)
85 JVMTI_SUPPORT_FLAG(can_pop_frame)
86 JVMTI_SUPPORT_FLAG(can_force_early_return)
87
88 friend class JvmtiEventControllerPrivate; // should only modify these flags
89 JVMTI_SUPPORT_FLAG(should_post_single_step)
90 JVMTI_SUPPORT_FLAG(should_post_field_access)
91 JVMTI_SUPPORT_FLAG(should_post_field_modification)
92 JVMTI_SUPPORT_FLAG(should_post_class_load)
93 JVMTI_SUPPORT_FLAG(should_post_class_prepare)
94 JVMTI_SUPPORT_FLAG(should_post_class_unload)
95 JVMTI_SUPPORT_FLAG(should_post_native_method_bind)
96 JVMTI_SUPPORT_FLAG(should_post_compiled_method_load)
97 JVMTI_SUPPORT_FLAG(should_post_compiled_method_unload)
98 JVMTI_SUPPORT_FLAG(should_post_dynamic_code_generated)
99 JVMTI_SUPPORT_FLAG(should_post_monitor_contended_enter)
100 JVMTI_SUPPORT_FLAG(should_post_monitor_contended_entered)
101 JVMTI_SUPPORT_FLAG(should_post_monitor_wait)
102 JVMTI_SUPPORT_FLAG(should_post_monitor_waited)
103 JVMTI_SUPPORT_FLAG(should_post_data_dump)
104 JVMTI_SUPPORT_FLAG(should_post_garbage_collection_start)
105 JVMTI_SUPPORT_FLAG(should_post_garbage_collection_finish)
106 JVMTI_SUPPORT_FLAG(should_post_on_exceptions)
107
108 // ------ the below maybe don't have to be (but are for now)
109 // fixed conditions here ------------
110 // any events can be enabled
111 JVMTI_SUPPORT_FLAG(should_post_thread_life)
112 JVMTI_SUPPORT_FLAG(should_post_object_free)
113 JVMTI_SUPPORT_FLAG(should_post_resource_exhausted)
114
115 // we are holding objects on the heap - need to talk to GC - e.g.
116 // breakpoint info
117 JVMTI_SUPPORT_FLAG(should_clean_up_heap_objects)
118 JVMTI_SUPPORT_FLAG(should_post_vm_object_alloc)
119
120 // If flag cannot be implemented, give an error if on=true
121 static void report_unsupported(bool on);
122
123 // these should only be called by the friend class
124 friend class JvmtiManageCapabilities;
125 inline static void set_can_modify_any_class(bool on) { _can_modify_any_class = (on != 0); }
126 inline static void set_can_access_local_variables(bool on) { _can_access_local_variables = (on != 0); }
127 inline static void set_can_hotswap_or_post_breakpoint(bool on) { _can_hotswap_or_post_breakpoint = (on != 0); }
128 inline static void set_can_walk_any_space(bool on) { _can_walk_any_space = (on != 0); }
129
130 enum {
131 JVMTI_VERSION_MASK = 0x70000000,
132 JVMTI_VERSION_VALUE = 0x30000000,
133 JVMDI_VERSION_VALUE = 0x20000000
134 };
135
136 static void post_field_modification(JavaThread *thread, methodOop method, address location,
137 KlassHandle field_klass, Handle object, jfieldID field,
138 char sig_type, jvalue *value);
139
140
141 private:
142 // CompiledMethodUnload events are reported from the VM thread so they
143 // are collected in lists (of jmethodID/addresses) and the events are posted later
144 // from threads posting CompieldMethodLoad or DynamicCodeGenerated events.
145 static bool _have_pending_compiled_method_unload_events;
146 static GrowableArray<jmethodID>* _pending_compiled_method_unload_method_ids;
147 static GrowableArray<const void *>* _pending_compiled_method_unload_code_begins;
148 static JavaThread* _current_poster;
149
150 // tests if there are CompiledMethodUnload events pending
151 inline static bool have_pending_compiled_method_unload_events() {
152 return _have_pending_compiled_method_unload_events;
153 }
154
155 // posts any pending CompiledMethodUnload events.
156 static void post_pending_compiled_method_unload_events();
157
158 // Perform the actual notification to interested JvmtiEnvs.
159 static void post_compiled_method_unload_internal(JavaThread* self, jmethodID mid, const void* code_begin);
160
161 // posts a DynamicCodeGenerated event (internal/private implementation).
162 // The public post_dynamic_code_generated* functions make use of the
163 // internal implementation.
164 static void post_dynamic_code_generated_internal(const char *name, const void *code_begin, const void *code_end) KERNEL_RETURN;
165
166
167 // GenerateEvents support to allow posting of CompiledMethodLoad and
168 // DynamicCodeGenerated events for a given environment.
169 friend class JvmtiCodeBlobEvents;
170
171 static void post_compiled_method_load(JvmtiEnv* env, const jmethodID method, const jint length,
172 const void *code_begin, const jint map_length,
173 const jvmtiAddrLocationMap* map) KERNEL_RETURN;
174 static void post_dynamic_code_generated(JvmtiEnv* env, const char *name, const void *code_begin,
175 const void *code_end) KERNEL_RETURN;
176
177 // The RedefineClasses() API breaks some invariants in the "regular"
178 // system. For example, there are sanity checks when GC'ing nmethods
179 // that require the containing class to be unloading. However, when a
180 // method is redefined, the old method and nmethod can become GC'able
181 // without the containing class unloading. The state of becoming
182 // GC'able can be asynchronous to the RedefineClasses() call since
183 // the old method may still be running and cannot be GC'ed until
184 // after all old invocations have finished. Additionally, a method
185 // that has not been redefined may have an nmethod that depends on
186 // the redefined method. The dependent nmethod will get deopted in
187 // this case and may also be GC'able without the containing class
188 // being unloaded.
189 //
190 // This flag indicates whether RedefineClasses() has ever redefined
191 // one or more classes during the lifetime of the VM. The flag should
192 // only be set by the friend class and can be queried by other sub
193 // systems as needed to relax invariant checks.
194 static bool _has_redefined_a_class;
195 friend class VM_RedefineClasses;
196 inline static void set_has_redefined_a_class() {
197 _has_redefined_a_class = true;
198 }
199
200 // Flag to indicate if the compiler has recorded all dependencies. When the
201 // can_redefine_classes capability is enabled in the OnLoad phase then the compiler
202 // records all dependencies from startup. However if the capability is first
203 // enabled some time later then the dependencies recorded by the compiler
204 // are incomplete. This flag is used by RedefineClasses to know if the
205 // dependency information is complete or not.
206 static bool _all_dependencies_are_recorded;
207
208 public:
209 inline static bool has_redefined_a_class() {
210 return _has_redefined_a_class;
211 }
212
213 inline static bool all_dependencies_are_recorded() {
214 return _all_dependencies_are_recorded;
215 }
216
217 inline static void set_all_dependencies_are_recorded(bool on) {
218 _all_dependencies_are_recorded = (on != 0);
219 }
220
221
222 // let JVMTI know that the JVM_OnLoad code is running
223 static void enter_onload_phase();
224
225 // let JVMTI know that the VM isn't up yet (and JVM_OnLoad code isn't running)
226 static void enter_primordial_phase();
227
228 // let JVMTI know that the VM isn't up yet but JNI is live
229 static void enter_start_phase();
230
231 // let JVMTI know that the VM is fully up and running now
232 static void enter_live_phase();
233
234 // ------ can_* conditions (below) are set at OnLoad and never changed ------------
235 inline static bool can_modify_any_class() { return _can_modify_any_class; }
236 inline static bool can_access_local_variables() { return _can_access_local_variables; }
237 inline static bool can_hotswap_or_post_breakpoint() { return _can_hotswap_or_post_breakpoint; }
238 inline static bool can_walk_any_space() { return _can_walk_any_space; }
239
240 // field access management
241 static address get_field_access_count_addr();
242
243 // field modification management
244 static address get_field_modification_count_addr();
245
246 // -----------------
247
248 static bool is_jvmti_version(jint version) { return (version & JVMTI_VERSION_MASK) == JVMTI_VERSION_VALUE; }
249 static bool is_jvmdi_version(jint version) { return (version & JVMTI_VERSION_MASK) == JVMDI_VERSION_VALUE; }
250 static jint get_jvmti_interface(JavaVM *jvm, void **penv, jint version);
251 static void decode_version_values(jint version, int * major, int * minor,
252 int * micro);
253
254 // single stepping management methods
255 static void at_single_stepping_point(JavaThread *thread, methodOop method, address location) KERNEL_RETURN;
256 static void expose_single_stepping(JavaThread *thread) KERNEL_RETURN;
257 static bool hide_single_stepping(JavaThread *thread) KERNEL_RETURN_(return false;);
258
259 // Methods that notify the debugger that something interesting has happened in the VM.
260 static void post_vm_start ();
261 static void post_vm_initialized ();
262 static void post_vm_death ();
263
264 static void post_single_step (JavaThread *thread, methodOop method, address location) KERNEL_RETURN;
265 static void post_raw_breakpoint (JavaThread *thread, methodOop method, address location) KERNEL_RETURN;
266
267 static void post_exception_throw (JavaThread *thread, methodOop method, address location, oop exception) KERNEL_RETURN;
268 static void notice_unwind_due_to_exception (JavaThread *thread, methodOop method, address location, oop exception, bool in_handler_frame) KERNEL_RETURN;
269
270 static oop jni_GetField_probe (JavaThread *thread, jobject jobj,
271 oop obj, klassOop klass, jfieldID fieldID, bool is_static)
272 KERNEL_RETURN_(return NULL;);
273 static oop jni_GetField_probe_nh (JavaThread *thread, jobject jobj,
274 oop obj, klassOop klass, jfieldID fieldID, bool is_static)
275 KERNEL_RETURN_(return NULL;);
276 static void post_field_access_by_jni (JavaThread *thread, oop obj,
277 klassOop klass, jfieldID fieldID, bool is_static) KERNEL_RETURN;
278 static void post_field_access (JavaThread *thread, methodOop method,
279 address location, KlassHandle field_klass, Handle object, jfieldID field) KERNEL_RETURN;
280 static oop jni_SetField_probe (JavaThread *thread, jobject jobj,
281 oop obj, klassOop klass, jfieldID fieldID, bool is_static, char sig_type,
282 jvalue *value) KERNEL_RETURN_(return NULL;);
283 static oop jni_SetField_probe_nh (JavaThread *thread, jobject jobj,
284 oop obj, klassOop klass, jfieldID fieldID, bool is_static, char sig_type,
285 jvalue *value) KERNEL_RETURN_(return NULL;);
286 static void post_field_modification_by_jni(JavaThread *thread, oop obj,
287 klassOop klass, jfieldID fieldID, bool is_static, char sig_type,
288 jvalue *value);
289 static void post_raw_field_modification(JavaThread *thread, methodOop method,
290 address location, KlassHandle field_klass, Handle object, jfieldID field,
291 char sig_type, jvalue *value) KERNEL_RETURN;
292
293 static void post_method_entry (JavaThread *thread, methodOop method, frame current_frame) KERNEL_RETURN;
294 static void post_method_exit (JavaThread *thread, methodOop method, frame current_frame) KERNEL_RETURN;
295
296 static void post_class_load (JavaThread *thread, klassOop klass) KERNEL_RETURN;
297 static void post_class_unload (klassOop klass) KERNEL_RETURN;
298 static void post_class_prepare (JavaThread *thread, klassOop klass) KERNEL_RETURN;
299
300 static void post_thread_start (JavaThread *thread) KERNEL_RETURN;
301 static void post_thread_end (JavaThread *thread) KERNEL_RETURN;
302
303 // Support for java.lang.instrument agent loading.
304 static bool _should_post_class_file_load_hook;
305 inline static void set_should_post_class_file_load_hook(bool on) { _should_post_class_file_load_hook = on; }
306 inline static bool should_post_class_file_load_hook() { return _should_post_class_file_load_hook; }
307 static void post_class_file_load_hook(symbolHandle h_name, Handle class_loader,
308 Handle h_protection_domain,
309 unsigned char **data_ptr, unsigned char **end_ptr,
310 unsigned char **cached_data_ptr,
311 jint *cached_length_ptr);
312 static void post_native_method_bind(methodOop method, address* function_ptr) KERNEL_RETURN;
313 static void post_compiled_method_load(nmethod *nm) KERNEL_RETURN;
314 static void post_dynamic_code_generated(const char *name, const void *code_begin, const void *code_end) KERNEL_RETURN;
315
316 // used to post a CompiledMethodUnload event
317 static void post_compiled_method_unload(jmethodID mid, const void *code_begin) KERNEL_RETURN;
318
319 // similiar to post_dynamic_code_generated except that it can be used to
320 // post a DynamicCodeGenerated event while holding locks in the VM. Any event
321 // posted using this function is recorded by the enclosing event collector
322 // -- JvmtiDynamicCodeEventCollector.
323 static void post_dynamic_code_generated_while_holding_locks(const char* name, address code_begin, address code_end) KERNEL_RETURN;
324
325 static void post_garbage_collection_finish() KERNEL_RETURN;
326 static void post_garbage_collection_start() KERNEL_RETURN;
327 static void post_data_dump() KERNEL_RETURN;
328 static void post_monitor_contended_enter(JavaThread *thread, ObjectMonitor *obj_mntr) KERNEL_RETURN;
329 static void post_monitor_contended_entered(JavaThread *thread, ObjectMonitor *obj_mntr) KERNEL_RETURN;
330 static void post_monitor_wait(JavaThread *thread, oop obj, jlong timeout) KERNEL_RETURN;
331 static void post_monitor_waited(JavaThread *thread, ObjectMonitor *obj_mntr, jboolean timed_out) KERNEL_RETURN;
332 static void post_object_free(JvmtiEnv* env, jlong tag) KERNEL_RETURN;
333 static void post_resource_exhausted(jint resource_exhausted_flags, const char* detail) KERNEL_RETURN;
334 static void record_vm_internal_object_allocation(oop object) KERNEL_RETURN;
335 // Post objects collected by vm_object_alloc_event_collector.
336 static void post_vm_object_alloc(JavaThread *thread, oop object) KERNEL_RETURN;
337 // Collects vm internal objects for later event posting.
338 inline static void vm_object_alloc_event_collector(oop object) {
339 if (should_post_vm_object_alloc()) {
340 record_vm_internal_object_allocation(object);
341 }
342 }
343
344 static void cleanup_thread (JavaThread* thread) KERNEL_RETURN;
345
346 static void oops_do(OopClosure* f) KERNEL_RETURN;
347
348 static void transition_pending_onload_raw_monitors() KERNEL_RETURN;
349
350 #ifndef SERVICES_KERNEL
351 // attach support
352 static jint load_agent_library(AttachOperation* op, outputStream* out);
353 #endif // SERVICES_KERNEL
354
355 // SetNativeMethodPrefix support
356 static char** get_all_native_method_prefixes(int* count_ptr);
357
358 // call after CMS has completed referencing processing
359 static void cms_ref_processing_epilogue() KERNEL_RETURN;
360 };
361
362 // Support class used by JvmtiDynamicCodeEventCollector and others. It
363 // describes a single code blob by name and address range.
364 class JvmtiCodeBlobDesc : public CHeapObj {
365 private:
366 char _name[64];
367 address _code_begin;
368 address _code_end;
369
370 public:
371 JvmtiCodeBlobDesc(const char *name, address code_begin, address code_end) {
372 assert(name != NULL, "all code blobs must be named");
373 strncpy(_name, name, sizeof(_name));
374 _name[sizeof(_name)-1] = '\0';
375 _code_begin = code_begin;
376 _code_end = code_end;
377 }
378 char* name() { return _name; }
379 address code_begin() { return _code_begin; }
380 address code_end() { return _code_end; }
381 };
382
383 // JvmtiEventCollector is a helper class to setup thread for
384 // event collection.
385 class JvmtiEventCollector : public StackObj {
386 private:
387 JvmtiEventCollector* _prev; // Save previous one to support nested event collector.
388
389 public:
390 void setup_jvmti_thread_state(); // Set this collector in current thread.
391 void unset_jvmti_thread_state(); // Reset previous collector in current thread.
392 virtual bool is_dynamic_code_event() { return false; }
393 virtual bool is_vm_object_alloc_event(){ return false; }
394 JvmtiEventCollector *get_prev() { return _prev; }
395 };
396
397 // A JvmtiDynamicCodeEventCollector is a helper class for the JvmtiExport
398 // interface. It collects "dynamic code generated" events that are posted
399 // while holding locks. When the event collector goes out of scope the
400 // events will be posted.
401 //
402 // Usage :-
403 //
404 // {
405 // JvmtiDynamicCodeEventCollector event_collector;
406 // :
407 // { MutexLocker ml(...)
408 // :
409 // JvmtiExport::post_dynamic_code_generated_while_holding_locks(...)
410 // }
411 // // event collector goes out of scope => post events to profiler.
412 // }
413
414 class JvmtiDynamicCodeEventCollector : public JvmtiEventCollector {
415 private:
416 GrowableArray<JvmtiCodeBlobDesc*>* _code_blobs; // collected code blob events
417
418 friend class JvmtiExport;
419 void register_stub(const char* name, address start, address end);
420
421 public:
422 JvmtiDynamicCodeEventCollector() KERNEL_RETURN;
423 ~JvmtiDynamicCodeEventCollector() KERNEL_RETURN;
424 bool is_dynamic_code_event() { return true; }
425
426 };
427
428 // Used to record vm internally allocated object oops and post
429 // vm object alloc event for objects visible to java world.
430 // Constructor enables JvmtiThreadState flag and all vm allocated
431 // objects are recorded in a growable array. When destructor is
432 // called the vm object alloc event is posted for each objects
433 // visible to java world.
434 // See jvm.cpp file for its usage.
435 //
436 class JvmtiVMObjectAllocEventCollector : public JvmtiEventCollector {
437 private:
438 GrowableArray<oop>* _allocated; // field to record vm internally allocated object oop.
439 bool _enable; // This flag is enabled in constructor and disabled
440 // in destructor before posting event. To avoid
441 // collection of objects allocated while running java code inside
442 // agent post_vm_object_alloc() event handler.
443
444 //GC support
445 void oops_do(OopClosure* f);
446
447 friend class JvmtiExport;
448 // Record vm allocated object oop.
449 inline void record_allocation(oop obj);
450
451 //GC support
452 static void oops_do_for_all_threads(OopClosure* f);
453
454 public:
455 JvmtiVMObjectAllocEventCollector() KERNEL_RETURN;
456 ~JvmtiVMObjectAllocEventCollector() KERNEL_RETURN;
457 bool is_vm_object_alloc_event() { return true; }
458
459 bool is_enabled() { return _enable; }
460 void set_enabled(bool on) { _enable = on; }
461 };
462
463
464
465 // Marker class to disable the posting of VMObjectAlloc events
466 // within its scope.
467 //
468 // Usage :-
469 //
470 // {
471 // NoJvmtiVMObjectAllocMark njm;
472 // :
473 // // VMObjAlloc event will not be posted
474 // JvmtiExport::vm_object_alloc_event_collector(obj);
475 // :
476 // }
477
478 class NoJvmtiVMObjectAllocMark : public StackObj {
479 private:
480 // enclosing collector if enabled, NULL otherwise
481 JvmtiVMObjectAllocEventCollector *_collector;
482
483 bool was_enabled() { return _collector != NULL; }
484
485 public:
486 NoJvmtiVMObjectAllocMark() KERNEL_RETURN;
487 ~NoJvmtiVMObjectAllocMark() KERNEL_RETURN;
488 };
489
490
491 // Base class for reporting GC events to JVMTI.
492 class JvmtiGCMarker : public StackObj {
493 private:
494 bool _full; // marks a "full" GC
495 unsigned int _invocation_count; // GC invocation count
496 protected:
497 JvmtiGCMarker(bool full) KERNEL_RETURN; // protected
498 ~JvmtiGCMarker() KERNEL_RETURN; // protected
499 };
500
501
502 // Support class used to report GC events to JVMTI. The class is stack
503 // allocated and should be placed in the doit() implementation of all
504 // vm operations that do a stop-the-world GC for failed allocation.
505 //
506 // Usage :-
507 //
508 // void VM_GenCollectForAllocation::doit() {
509 // JvmtiGCForAllocationMarker jgcm;
510 // :
511 // }
512 //
513 // If jvmti is not enabled the constructor and destructor is essentially
514 // a no-op (no overhead).
515 //
516 class JvmtiGCForAllocationMarker : public JvmtiGCMarker {
517 public:
518 JvmtiGCForAllocationMarker() : JvmtiGCMarker(false) {
519 }
520 };
521
522 // Support class used to report GC events to JVMTI. The class is stack
523 // allocated and should be placed in the doit() implementation of all
524 // vm operations that do a "full" stop-the-world GC. This class differs
525 // from JvmtiGCForAllocationMarker in that this class assumes that a
526 // "full" GC will happen.
527 //
528 // Usage :-
529 //
530 // void VM_GenCollectFull::doit() {
531 // JvmtiGCFullMarker jgcm;
532 // :
533 // }
534 //
535 class JvmtiGCFullMarker : public JvmtiGCMarker {
536 public:
537 JvmtiGCFullMarker() : JvmtiGCMarker(true) {
538 }
539 };
540
541
542 // JvmtiHideSingleStepping is a helper class for hiding
543 // internal single step events.
544 class JvmtiHideSingleStepping : public StackObj {
545 private:
546 bool _single_step_hidden;
547 JavaThread * _thread;
548
549 public:
550 JvmtiHideSingleStepping(JavaThread * thread) {
551 assert(thread != NULL, "sanity check");
552
553 _single_step_hidden = false;
554 _thread = thread;
555 if (JvmtiExport::should_post_single_step()) {
556 _single_step_hidden = JvmtiExport::hide_single_stepping(_thread);
557 }
558 }
559
560 ~JvmtiHideSingleStepping() {
561 if (_single_step_hidden) {
562 JvmtiExport::expose_single_stepping(_thread);
563 }
564 }
565 };
566
567 #endif // SHARE_VM_PRIMS_JVMTIEXPORT_HPP