1 /*
2 * Copyright (c) 1998, 2016, 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 "jvmtifiles/jvmti.h"
29 #include "memory/allocation.hpp"
30 #include "memory/iterator.hpp"
31 #include "oops/oop.hpp"
32 #include "oops/oopsHierarchy.hpp"
33 #include "runtime/frame.hpp"
34 #include "runtime/handles.hpp"
35 #include "utilities/globalDefinitions.hpp"
36 #include "utilities/growableArray.hpp"
37 #include "utilities/macros.hpp"
38
39 // Must be included after jvmti.h.
40 #include "code/jvmticmlr.h"
41
42 // Forward declarations
43
44 class JvmtiEventControllerPrivate;
45 class JvmtiManageCapabilities;
46 class JvmtiEnv;
47 class JvmtiThreadState;
48 class AttachOperation;
49
50 #define JVMTI_SUPPORT_FLAG(key) \
51 private: \
52 static bool _##key; \
53 public: \
54 inline static void set_##key(bool on) { \
55 JVMTI_ONLY(_##key = (on != 0)); \
56 NOT_JVMTI(report_unsupported(on)); \
57 } \
58 inline static bool key() { \
59 JVMTI_ONLY(return _##key); \
60 NOT_JVMTI(return false); \
61 }
62
63
64 // This class contains the JVMTI interface for the rest of hotspot.
65 //
66 class JvmtiExport : public AllStatic {
67 friend class VMStructs;
68 friend class CompileReplay;
69
70 private:
71
72 #if INCLUDE_JVMTI
73 static int _field_access_count;
74 static int _field_modification_count;
75
76 static bool _can_access_local_variables;
77 static bool _can_hotswap_or_post_breakpoint;
78 static bool _can_modify_any_class;
79 static bool _can_walk_any_space;
80 #endif // INCLUDE_JVMTI
81
82 JVMTI_SUPPORT_FLAG(can_get_source_debug_extension)
83 JVMTI_SUPPORT_FLAG(can_maintain_original_method_order)
84 JVMTI_SUPPORT_FLAG(can_post_interpreter_events)
85 JVMTI_SUPPORT_FLAG(can_post_on_exceptions)
86 JVMTI_SUPPORT_FLAG(can_post_breakpoint)
87 JVMTI_SUPPORT_FLAG(can_post_field_access)
88 JVMTI_SUPPORT_FLAG(can_post_field_modification)
89 JVMTI_SUPPORT_FLAG(can_post_method_entry)
90 JVMTI_SUPPORT_FLAG(can_post_method_exit)
91 JVMTI_SUPPORT_FLAG(can_pop_frame)
92 JVMTI_SUPPORT_FLAG(can_force_early_return)
93
94 JVMTI_SUPPORT_FLAG(early_vmstart_recorded)
95
96 friend class JvmtiEventControllerPrivate; // should only modify these flags
97 JVMTI_SUPPORT_FLAG(should_post_single_step)
98 JVMTI_SUPPORT_FLAG(should_post_field_access)
99 JVMTI_SUPPORT_FLAG(should_post_field_modification)
100 JVMTI_SUPPORT_FLAG(should_post_class_load)
101 JVMTI_SUPPORT_FLAG(should_post_class_prepare)
102 JVMTI_SUPPORT_FLAG(should_post_class_unload)
103 JVMTI_SUPPORT_FLAG(should_post_native_method_bind)
104 JVMTI_SUPPORT_FLAG(should_post_compiled_method_load)
105 JVMTI_SUPPORT_FLAG(should_post_compiled_method_unload)
106 JVMTI_SUPPORT_FLAG(should_post_dynamic_code_generated)
107 JVMTI_SUPPORT_FLAG(should_post_monitor_contended_enter)
108 JVMTI_SUPPORT_FLAG(should_post_monitor_contended_entered)
109 JVMTI_SUPPORT_FLAG(should_post_monitor_wait)
110 JVMTI_SUPPORT_FLAG(should_post_monitor_waited)
111 JVMTI_SUPPORT_FLAG(should_post_data_dump)
112 JVMTI_SUPPORT_FLAG(should_post_garbage_collection_start)
113 JVMTI_SUPPORT_FLAG(should_post_garbage_collection_finish)
114 JVMTI_SUPPORT_FLAG(should_post_on_exceptions)
115
116 // ------ the below maybe don't have to be (but are for now)
117 // fixed conditions here ------------
118 // any events can be enabled
119 JVMTI_SUPPORT_FLAG(should_post_thread_life)
120 JVMTI_SUPPORT_FLAG(should_post_object_free)
121 JVMTI_SUPPORT_FLAG(should_post_resource_exhausted)
122
123 // we are holding objects on the heap - need to talk to GC - e.g.
124 // breakpoint info
125 JVMTI_SUPPORT_FLAG(should_clean_up_heap_objects)
126 JVMTI_SUPPORT_FLAG(should_post_vm_object_alloc)
127
128 // If flag cannot be implemented, give an error if on=true
129 static void report_unsupported(bool on);
130
131 // these should only be called by the friend class
132 friend class JvmtiManageCapabilities;
133 inline static void set_can_modify_any_class(bool on) {
134 JVMTI_ONLY(_can_modify_any_class = (on != 0);)
135 }
136 inline static void set_can_access_local_variables(bool on) {
137 JVMTI_ONLY(_can_access_local_variables = (on != 0);)
138 }
139 inline static void set_can_hotswap_or_post_breakpoint(bool on) {
140 JVMTI_ONLY(_can_hotswap_or_post_breakpoint = (on != 0);)
141 }
142 inline static void set_can_walk_any_space(bool on) {
143 JVMTI_ONLY(_can_walk_any_space = (on != 0);)
144 }
145
146 enum {
147 JVMTI_VERSION_MASK = 0x70000000,
148 JVMTI_VERSION_VALUE = 0x30000000,
149 JVMDI_VERSION_VALUE = 0x20000000
150 };
151
152 static void post_field_modification(JavaThread *thread, Method* method, address location,
153 KlassHandle field_klass, Handle object, jfieldID field,
154 char sig_type, jvalue *value);
155
156
157 // posts a DynamicCodeGenerated event (internal/private implementation).
158 // The public post_dynamic_code_generated* functions make use of the
159 // internal implementation. Also called from JvmtiDeferredEvent::post()
160 static void post_dynamic_code_generated_internal(const char *name, const void *code_begin, const void *code_end) NOT_JVMTI_RETURN;
161
162 private:
163
164 // GenerateEvents support to allow posting of CompiledMethodLoad and
165 // DynamicCodeGenerated events for a given environment.
166 friend class JvmtiCodeBlobEvents;
167
168 static void post_compiled_method_load(JvmtiEnv* env, const jmethodID method, const jint length,
169 const void *code_begin, const jint map_length,
170 const jvmtiAddrLocationMap* map) NOT_JVMTI_RETURN;
171 static void post_dynamic_code_generated(JvmtiEnv* env, const char *name, const void *code_begin,
172 const void *code_end) NOT_JVMTI_RETURN;
173
174 // The RedefineClasses() API breaks some invariants in the "regular"
175 // system. For example, there are sanity checks when GC'ing nmethods
176 // that require the containing class to be unloading. However, when a
177 // method is redefined, the old method and nmethod can become GC'able
178 // without the containing class unloading. The state of becoming
179 // GC'able can be asynchronous to the RedefineClasses() call since
180 // the old method may still be running and cannot be GC'ed until
181 // after all old invocations have finished. Additionally, a method
182 // that has not been redefined may have an nmethod that depends on
183 // the redefined method. The dependent nmethod will get deopted in
184 // this case and may also be GC'able without the containing class
185 // being unloaded.
186 //
187 // This flag indicates whether RedefineClasses() has ever redefined
188 // one or more classes during the lifetime of the VM. The flag should
189 // only be set by the friend class and can be queried by other sub
190 // systems as needed to relax invariant checks.
191 static bool _has_redefined_a_class;
192 friend class VM_RedefineClasses;
193 inline static void set_has_redefined_a_class() {
194 JVMTI_ONLY(_has_redefined_a_class = true;)
195 }
196 // Flag to indicate if the compiler has recorded all dependencies. When the
197 // can_redefine_classes capability is enabled in the OnLoad phase then the compiler
198 // records all dependencies from startup. However if the capability is first
199 // enabled some time later then the dependencies recorded by the compiler
200 // are incomplete. This flag is used by RedefineClasses to know if the
201 // dependency information is complete or not.
202 static bool _all_dependencies_are_recorded;
203
204 public:
205 inline static bool has_redefined_a_class() {
206 JVMTI_ONLY(return _has_redefined_a_class);
207 NOT_JVMTI(return false);
208 }
209
210 inline static bool all_dependencies_are_recorded() {
211 return _all_dependencies_are_recorded;
212 }
213
214 inline static void set_all_dependencies_are_recorded(bool on) {
215 _all_dependencies_are_recorded = (on != 0);
216 }
217
218 // Add read edges to the unnamed modules of the bootstrap and app class loaders
219 static void add_default_read_edges(Handle h_module, TRAPS) NOT_JVMTI_RETURN;
220
221 // let JVMTI know that the JVM_OnLoad code is running
222 static void enter_onload_phase() NOT_JVMTI_RETURN;
223
224 // let JVMTI know that the VM isn't up yet (and JVM_OnLoad code isn't running)
225 static void enter_primordial_phase() NOT_JVMTI_RETURN;
226
227 // let JVMTI know that the VM isn't up yet but JNI is live
228 static void enter_early_start_phase() NOT_JVMTI_RETURN;
229 static void enter_start_phase() NOT_JVMTI_RETURN;
230
231 // let JVMTI know that the VM is fully up and running now
232 static void enter_live_phase() NOT_JVMTI_RETURN;
233
234 // ------ can_* conditions (below) are set at OnLoad and never changed ------------
235 inline static bool can_modify_any_class() {
236 JVMTI_ONLY(return _can_modify_any_class);
237 NOT_JVMTI(return false);
238 }
239 inline static bool can_access_local_variables() {
240 JVMTI_ONLY(return _can_access_local_variables);
241 NOT_JVMTI(return false);
242 }
243 inline static bool can_hotswap_or_post_breakpoint() {
244 JVMTI_ONLY(return _can_hotswap_or_post_breakpoint);
245 NOT_JVMTI(return false);
246 }
247 inline static bool can_walk_any_space() {
248 JVMTI_ONLY(return _can_walk_any_space);
249 NOT_JVMTI(return false);
250 }
251
252 // field access management
253 static address get_field_access_count_addr() NOT_JVMTI_RETURN_(0);
254
255 // field modification management
256 static address get_field_modification_count_addr() NOT_JVMTI_RETURN_(0);
257
258 // -----------------
259
260 static bool is_jvmti_version(jint version) {
261 JVMTI_ONLY(return (version & JVMTI_VERSION_MASK) == JVMTI_VERSION_VALUE);
262 NOT_JVMTI(return false);
263 }
264 static bool is_jvmdi_version(jint version) {
265 JVMTI_ONLY(return (version & JVMTI_VERSION_MASK) == JVMDI_VERSION_VALUE);
266 NOT_JVMTI(return false);
267 }
268 static jint get_jvmti_interface(JavaVM *jvm, void **penv, jint version) NOT_JVMTI_RETURN_(0);
269 static void decode_version_values(jint version, int * major, int * minor,
270 int * micro) NOT_JVMTI_RETURN;
271
272 // single stepping management methods
273 static void at_single_stepping_point(JavaThread *thread, Method* method, address location) NOT_JVMTI_RETURN;
274 static void expose_single_stepping(JavaThread *thread) NOT_JVMTI_RETURN;
275 static bool hide_single_stepping(JavaThread *thread) NOT_JVMTI_RETURN_(false);
276
277 // Methods that notify the debugger that something interesting has happened in the VM.
278 static void post_early_vm_start () NOT_JVMTI_RETURN;
279 static void post_vm_start () NOT_JVMTI_RETURN;
280 static void post_vm_initialized () NOT_JVMTI_RETURN;
281 static void post_vm_death () NOT_JVMTI_RETURN;
282
283 static void post_single_step (JavaThread *thread, Method* method, address location) NOT_JVMTI_RETURN;
284 static void post_raw_breakpoint (JavaThread *thread, Method* method, address location) NOT_JVMTI_RETURN;
285
286 static void post_exception_throw (JavaThread *thread, Method* method, address location, oop exception) NOT_JVMTI_RETURN;
287 static void notice_unwind_due_to_exception (JavaThread *thread, Method* method, address location, oop exception, bool in_handler_frame) NOT_JVMTI_RETURN;
288
289 static oop jni_GetField_probe (JavaThread *thread, jobject jobj,
290 oop obj, Klass* klass, jfieldID fieldID, bool is_static)
291 NOT_JVMTI_RETURN_(NULL);
292 static oop jni_GetField_probe_nh (JavaThread *thread, jobject jobj,
293 oop obj, Klass* klass, jfieldID fieldID, bool is_static)
294 NOT_JVMTI_RETURN_(NULL);
295 static void post_field_access_by_jni (JavaThread *thread, oop obj,
296 Klass* klass, jfieldID fieldID, bool is_static) NOT_JVMTI_RETURN;
297 static void post_field_access (JavaThread *thread, Method* method,
298 address location, KlassHandle field_klass, Handle object, jfieldID field) NOT_JVMTI_RETURN;
299 static oop jni_SetField_probe (JavaThread *thread, jobject jobj,
300 oop obj, Klass* klass, jfieldID fieldID, bool is_static, char sig_type,
301 jvalue *value) NOT_JVMTI_RETURN_(NULL);
302 static oop jni_SetField_probe_nh (JavaThread *thread, jobject jobj,
303 oop obj, Klass* klass, jfieldID fieldID, bool is_static, char sig_type,
304 jvalue *value) NOT_JVMTI_RETURN_(NULL);
305 static void post_field_modification_by_jni(JavaThread *thread, oop obj,
306 Klass* klass, jfieldID fieldID, bool is_static, char sig_type,
307 jvalue *value);
308 static void post_raw_field_modification(JavaThread *thread, Method* method,
309 address location, KlassHandle field_klass, Handle object, jfieldID field,
310 char sig_type, jvalue *value) NOT_JVMTI_RETURN;
311
312 static void post_method_entry (JavaThread *thread, Method* method, frame current_frame) NOT_JVMTI_RETURN;
313 static void post_method_exit (JavaThread *thread, Method* method, frame current_frame) NOT_JVMTI_RETURN;
314
315 static void post_class_load (JavaThread *thread, Klass* klass) NOT_JVMTI_RETURN;
316 static void post_class_unload (Klass* klass) NOT_JVMTI_RETURN;
317 static void post_class_prepare (JavaThread *thread, Klass* klass) NOT_JVMTI_RETURN;
318
319 static void post_thread_start (JavaThread *thread) NOT_JVMTI_RETURN;
320 static void post_thread_end (JavaThread *thread) NOT_JVMTI_RETURN;
321
322 // Support for java.lang.instrument agent loading.
323 static bool _should_post_class_file_load_hook;
324 inline static void set_should_post_class_file_load_hook(bool on) { _should_post_class_file_load_hook = on; }
325 inline static bool should_post_class_file_load_hook() {
326 JVMTI_ONLY(return _should_post_class_file_load_hook);
327 NOT_JVMTI(return false;)
328 }
329 // Return true if the class was modified by the hook.
330 static bool post_class_file_load_hook(Symbol* h_name, Handle class_loader,
331 Handle h_protection_domain,
332 unsigned char **data_ptr, unsigned char **end_ptr,
333 JvmtiCachedClassFileData **cache_ptr) NOT_JVMTI_RETURN_(false);
334 static void post_native_method_bind(Method* method, address* function_ptr) NOT_JVMTI_RETURN;
335 static void post_compiled_method_load(nmethod *nm) NOT_JVMTI_RETURN;
336 static void post_dynamic_code_generated(const char *name, const void *code_begin, const void *code_end) NOT_JVMTI_RETURN;
337
338 // used to post a CompiledMethodUnload event
339 static void post_compiled_method_unload(jmethodID mid, const void *code_begin) NOT_JVMTI_RETURN;
340
341 // similiar to post_dynamic_code_generated except that it can be used to
342 // post a DynamicCodeGenerated event while holding locks in the VM. Any event
343 // posted using this function is recorded by the enclosing event collector
344 // -- JvmtiDynamicCodeEventCollector.
345 static void post_dynamic_code_generated_while_holding_locks(const char* name, address code_begin, address code_end) NOT_JVMTI_RETURN;
346
347 static void post_garbage_collection_finish() NOT_JVMTI_RETURN;
348 static void post_garbage_collection_start() NOT_JVMTI_RETURN;
349 static void post_data_dump() NOT_JVMTI_RETURN;
350 static void post_monitor_contended_enter(JavaThread *thread, ObjectMonitor *obj_mntr) NOT_JVMTI_RETURN;
351 static void post_monitor_contended_entered(JavaThread *thread, ObjectMonitor *obj_mntr) NOT_JVMTI_RETURN;
352 static void post_monitor_wait(JavaThread *thread, oop obj, jlong timeout) NOT_JVMTI_RETURN;
353 static void post_monitor_waited(JavaThread *thread, ObjectMonitor *obj_mntr, jboolean timed_out) NOT_JVMTI_RETURN;
354 static void post_object_free(JvmtiEnv* env, jlong tag) NOT_JVMTI_RETURN;
355 static void post_resource_exhausted(jint resource_exhausted_flags, const char* detail) NOT_JVMTI_RETURN;
356 static void record_vm_internal_object_allocation(oop object) NOT_JVMTI_RETURN;
357 // Post objects collected by vm_object_alloc_event_collector.
358 static void post_vm_object_alloc(JavaThread *thread, oop object) NOT_JVMTI_RETURN;
359 // Collects vm internal objects for later event posting.
360 inline static void vm_object_alloc_event_collector(oop object) {
361 if (should_post_vm_object_alloc()) {
362 record_vm_internal_object_allocation(object);
363 }
364 }
365 inline static void post_array_size_exhausted() {
366 if (should_post_resource_exhausted()) {
367 post_resource_exhausted(JVMTI_RESOURCE_EXHAUSTED_OOM_ERROR,
368 "Requested array size exceeds VM limit");
369 }
370 }
371
372 static void cleanup_thread (JavaThread* thread) NOT_JVMTI_RETURN;
373 static void clear_detected_exception (JavaThread* thread) NOT_JVMTI_RETURN;
374
375 static void oops_do(OopClosure* f) NOT_JVMTI_RETURN;
376 static void weak_oops_do(BoolObjectClosure* b, OopClosure* f) NOT_JVMTI_RETURN;
377 static void gc_epilogue() NOT_JVMTI_RETURN;
378
379 static void transition_pending_onload_raw_monitors() NOT_JVMTI_RETURN;
380
381 #if INCLUDE_SERVICES
382 // attach support
383 static jint load_agent_library(const char *agent, const char *absParam, const char *options, outputStream* out) NOT_JVMTI_RETURN_(JNI_ERR);
384 static jint load_agent_library(AttachOperation* op, outputStream* out) NOT_JVMTI_RETURN_(JNI_ERR);
385 #endif
386
387 // SetNativeMethodPrefix support
388 static char** get_all_native_method_prefixes(int* count_ptr) NOT_JVMTI_RETURN_(NULL);
389 };
390
391 // Support class used by JvmtiDynamicCodeEventCollector and others. It
392 // describes a single code blob by name and address range.
393 class JvmtiCodeBlobDesc : public CHeapObj<mtInternal> {
394 private:
395 char _name[64];
396 address _code_begin;
397 address _code_end;
398
399 public:
400 JvmtiCodeBlobDesc(const char *name, address code_begin, address code_end) {
401 assert(name != NULL, "all code blobs must be named");
402 strncpy(_name, name, sizeof(_name));
403 _name[sizeof(_name)-1] = '\0';
404 _code_begin = code_begin;
405 _code_end = code_end;
406 }
407 char* name() { return _name; }
408 address code_begin() { return _code_begin; }
409 address code_end() { return _code_end; }
410 };
411
412 // JvmtiEventCollector is a helper class to setup thread for
413 // event collection.
414 class JvmtiEventCollector : public StackObj {
415 private:
416 JvmtiEventCollector* _prev; // Save previous one to support nested event collector.
417
418 public:
419 void setup_jvmti_thread_state(); // Set this collector in current thread.
420 void unset_jvmti_thread_state(); // Reset previous collector in current thread.
421 virtual bool is_dynamic_code_event() { return false; }
422 virtual bool is_vm_object_alloc_event(){ return false; }
423 JvmtiEventCollector *get_prev() { return _prev; }
424 };
425
426 // A JvmtiDynamicCodeEventCollector is a helper class for the JvmtiExport
427 // interface. It collects "dynamic code generated" events that are posted
428 // while holding locks. When the event collector goes out of scope the
429 // events will be posted.
430 //
431 // Usage :-
432 //
433 // {
434 // JvmtiDynamicCodeEventCollector event_collector;
435 // :
436 // { MutexLocker ml(...)
437 // :
438 // JvmtiExport::post_dynamic_code_generated_while_holding_locks(...)
439 // }
440 // // event collector goes out of scope => post events to profiler.
441 // }
442
443 class JvmtiDynamicCodeEventCollector : public JvmtiEventCollector {
444 private:
445 GrowableArray<JvmtiCodeBlobDesc*>* _code_blobs; // collected code blob events
446
447 friend class JvmtiExport;
448 void register_stub(const char* name, address start, address end);
449
450 public:
451 JvmtiDynamicCodeEventCollector() NOT_JVMTI_RETURN;
452 ~JvmtiDynamicCodeEventCollector() NOT_JVMTI_RETURN;
453 bool is_dynamic_code_event() { return true; }
454
455 };
456
457 // Used to record vm internally allocated object oops and post
458 // vm object alloc event for objects visible to java world.
459 // Constructor enables JvmtiThreadState flag and all vm allocated
460 // objects are recorded in a growable array. When destructor is
461 // called the vm object alloc event is posted for each objects
462 // visible to java world.
463 // See jvm.cpp file for its usage.
464 //
465 class JvmtiVMObjectAllocEventCollector : public JvmtiEventCollector {
466 private:
467 GrowableArray<oop>* _allocated; // field to record vm internally allocated object oop.
468 bool _enable; // This flag is enabled in constructor and disabled
469 // in destructor before posting event. To avoid
470 // collection of objects allocated while running java code inside
471 // agent post_vm_object_alloc() event handler.
472
473 //GC support
474 void oops_do(OopClosure* f);
475
476 friend class JvmtiExport;
477 // Record vm allocated object oop.
478 inline void record_allocation(oop obj);
479
480 //GC support
481 static void oops_do_for_all_threads(OopClosure* f);
482
483 public:
484 JvmtiVMObjectAllocEventCollector() NOT_JVMTI_RETURN;
485 ~JvmtiVMObjectAllocEventCollector() NOT_JVMTI_RETURN;
486 bool is_vm_object_alloc_event() { return true; }
487
488 bool is_enabled() { return _enable; }
489 void set_enabled(bool on) { _enable = on; }
490 };
491
492
493
494 // Marker class to disable the posting of VMObjectAlloc events
495 // within its scope.
496 //
497 // Usage :-
498 //
499 // {
500 // NoJvmtiVMObjectAllocMark njm;
501 // :
502 // // VMObjAlloc event will not be posted
503 // JvmtiExport::vm_object_alloc_event_collector(obj);
504 // :
505 // }
506
507 class NoJvmtiVMObjectAllocMark : public StackObj {
508 private:
509 // enclosing collector if enabled, NULL otherwise
510 JvmtiVMObjectAllocEventCollector *_collector;
511
512 bool was_enabled() { return _collector != NULL; }
513
514 public:
515 NoJvmtiVMObjectAllocMark() NOT_JVMTI_RETURN;
516 ~NoJvmtiVMObjectAllocMark() NOT_JVMTI_RETURN;
517 };
518
519
520 // Base class for reporting GC events to JVMTI.
521 class JvmtiGCMarker : public StackObj {
522 public:
523 JvmtiGCMarker() NOT_JVMTI_RETURN;
524 ~JvmtiGCMarker() NOT_JVMTI_RETURN;
525 };
526
527 // JvmtiHideSingleStepping is a helper class for hiding
528 // internal single step events.
529 class JvmtiHideSingleStepping : public StackObj {
530 private:
531 bool _single_step_hidden;
532 JavaThread * _thread;
533
534 public:
535 JvmtiHideSingleStepping(JavaThread * thread) {
536 assert(thread != NULL, "sanity check");
537
538 _single_step_hidden = false;
539 _thread = thread;
540 if (JvmtiExport::should_post_single_step()) {
541 _single_step_hidden = JvmtiExport::hide_single_stepping(_thread);
542 }
543 }
544
545 ~JvmtiHideSingleStepping() {
546 if (_single_step_hidden) {
547 JvmtiExport::expose_single_stepping(_thread);
548 }
549 }
550 };
551
552 #endif // SHARE_VM_PRIMS_JVMTIEXPORT_HPP