1 /*
  2  * Copyright (c) 1998, 2021, 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_PRIMS_JVMTIEXPORT_HPP
 26 #define SHARE_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/oopHandle.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 #include "utilities/macros.hpp"
 39 
 40 // Must be included after jvmti.h.
 41 #include "jvmticmlr.h"
 42 
 43 // Forward declarations
 44 
 45 struct JvmtiCachedClassFileData;
 46 class JvmtiEventControllerPrivate;
 47 class JvmtiManageCapabilities;
 48 class JvmtiEnv;
 49 class JvmtiThreadState;
 50 
 51 class OopStorage;
 52 
 53 #define JVMTI_SUPPORT_FLAG(key)                                           \
 54   private:                                                                \
 55   static bool  _##key;                                                    \
 56   public:                                                                 \
 57   inline static void set_##key(bool on) {                                 \
 58     JVMTI_ONLY(_##key = (on != 0));                                       \
 59     NOT_JVMTI(report_unsupported(on));                                    \
 60   }                                                                       \
 61   inline static bool key() {                                              \
 62     JVMTI_ONLY(return _##key);                                            \
 63     NOT_JVMTI(return false);                                              \
 64   }
 65 
 66 
 67 // This class contains the JVMTI interface for the rest of hotspot.
 68 //
 69 class JvmtiExport : public AllStatic {
 70   friend class VMStructs;
 71   friend class CompileReplay;
 72 
 73  private:
 74 
 75 #if INCLUDE_JVMTI
 76   static int         _field_access_count;
 77   static int         _field_modification_count;
 78 
 79   static bool        _can_access_local_variables;
 80   static bool        _can_hotswap_or_post_breakpoint;
 81   static bool        _can_modify_any_class;
 82   static bool        _can_walk_any_space;
 83 #endif // INCLUDE_JVMTI
 84 
 85   JVMTI_SUPPORT_FLAG(can_get_source_debug_extension)
 86   JVMTI_SUPPORT_FLAG(can_maintain_original_method_order)
 87   JVMTI_SUPPORT_FLAG(can_post_interpreter_events)
 88   JVMTI_SUPPORT_FLAG(can_post_on_exceptions)
 89   JVMTI_SUPPORT_FLAG(can_post_breakpoint)
 90   JVMTI_SUPPORT_FLAG(can_post_field_access)
 91   JVMTI_SUPPORT_FLAG(can_post_field_modification)
 92   JVMTI_SUPPORT_FLAG(can_post_method_entry)
 93   JVMTI_SUPPORT_FLAG(can_post_method_exit)
 94   JVMTI_SUPPORT_FLAG(can_pop_frame)
 95   JVMTI_SUPPORT_FLAG(can_force_early_return)
 96 
 97   JVMTI_SUPPORT_FLAG(early_vmstart_recorded)
 98   JVMTI_SUPPORT_FLAG(can_get_owned_monitor_info) // includes can_get_owned_monitor_stack_depth_info
 99 
100   friend class JvmtiEventControllerPrivate;  // should only modify these flags
101   JVMTI_SUPPORT_FLAG(should_post_single_step)
102   JVMTI_SUPPORT_FLAG(should_post_field_access)
103   JVMTI_SUPPORT_FLAG(should_post_field_modification)
104   JVMTI_SUPPORT_FLAG(should_post_class_load)
105   JVMTI_SUPPORT_FLAG(should_post_class_prepare)
106   JVMTI_SUPPORT_FLAG(should_post_class_unload)
107   JVMTI_SUPPORT_FLAG(should_post_native_method_bind)
108   JVMTI_SUPPORT_FLAG(should_post_compiled_method_load)
109   JVMTI_SUPPORT_FLAG(should_post_compiled_method_unload)
110   JVMTI_SUPPORT_FLAG(should_post_dynamic_code_generated)
111   JVMTI_SUPPORT_FLAG(should_post_monitor_contended_enter)
112   JVMTI_SUPPORT_FLAG(should_post_monitor_contended_entered)
113   JVMTI_SUPPORT_FLAG(should_post_monitor_wait)
114   JVMTI_SUPPORT_FLAG(should_post_monitor_waited)
115   JVMTI_SUPPORT_FLAG(should_post_data_dump)
116   JVMTI_SUPPORT_FLAG(should_post_garbage_collection_start)
117   JVMTI_SUPPORT_FLAG(should_post_garbage_collection_finish)
118   JVMTI_SUPPORT_FLAG(should_post_on_exceptions)
119 
120   // ------ the below maybe don't have to be (but are for now)
121   // fixed conditions here ------------
122   // any events can be enabled
123   JVMTI_SUPPORT_FLAG(should_post_thread_life)
124   JVMTI_SUPPORT_FLAG(should_post_object_free)
125   JVMTI_SUPPORT_FLAG(should_post_resource_exhausted)
126 
127   // we are holding objects on the heap - need to talk to GC - e.g.
128   // breakpoint info
129   JVMTI_SUPPORT_FLAG(should_clean_up_heap_objects)
130   JVMTI_SUPPORT_FLAG(should_post_vm_object_alloc)
131   JVMTI_SUPPORT_FLAG(should_post_sampled_object_alloc)
132 
133   // If flag cannot be implemented, give an error if on=true
134   static void report_unsupported(bool on);
135 
136   // these should only be called by the friend class
137   friend class JvmtiManageCapabilities;
138   inline static void set_can_modify_any_class(bool on) {
139     JVMTI_ONLY(_can_modify_any_class = (on != 0);)
140   }
141   inline static void set_can_access_local_variables(bool on) {
142     JVMTI_ONLY(_can_access_local_variables = (on != 0);)
143   }
144   inline static void set_can_hotswap_or_post_breakpoint(bool on) {
145     JVMTI_ONLY(_can_hotswap_or_post_breakpoint = (on != 0);)
146   }
147   inline static void set_can_walk_any_space(bool on) {
148     JVMTI_ONLY(_can_walk_any_space = (on != 0);)
149   }
150 
151   enum {
152     JVMTI_VERSION_MASK   = 0x70000000,
153     JVMTI_VERSION_VALUE  = 0x30000000,
154     JVMDI_VERSION_VALUE  = 0x20000000
155   };
156 
157   static void post_field_modification(JavaThread *thread, Method* method, address location,
158                                       Klass* field_klass, Handle object, jfieldID field,
159                                       char sig_type, jvalue *value);
160 
161 
162   // posts a DynamicCodeGenerated event (internal/private implementation).
163   // The public post_dynamic_code_generated* functions make use of the
164   // internal implementation.  Also called from JvmtiDeferredEvent::post()
165   static void post_dynamic_code_generated_internal(const char *name, const void *code_begin, const void *code_end) NOT_JVMTI_RETURN;
166 
167   static void post_class_unload_internal(const char *name) NOT_JVMTI_RETURN;
168 
169   static void initialize_oop_storage() NOT_JVMTI_RETURN;
170   static OopStorage* jvmti_oop_storage();
171   static OopStorage* weak_tag_storage();
172  private:
173 
174   // GenerateEvents support to allow posting of CompiledMethodLoad and
175   // DynamicCodeGenerated events for a given environment.
176   friend class JvmtiCodeBlobEvents;
177 
178   static void post_dynamic_code_generated(JvmtiEnv* env, const char *name, const void *code_begin,
179                                           const void *code_end) NOT_JVMTI_RETURN;
180 
181   // This flag indicates whether RedefineClasses() has ever redefined
182   // one or more classes during the lifetime of the VM. The flag should
183   // only be set by the friend class and can be queried by other sub
184   // systems as needed to relax invariant checks.
185   static uint64_t _redefinition_count;
186   friend class VM_RedefineClasses;
187   inline static void increment_redefinition_count() {
188     JVMTI_ONLY(_redefinition_count++;)
189   }
190   // Flag to indicate if the compiler has recorded all dependencies. When the
191   // can_redefine_classes capability is enabled in the OnLoad phase then the compiler
192   // records all dependencies from startup. However if the capability is first
193   // enabled some time later then the dependencies recorded by the compiler
194   // are incomplete. This flag is used by RedefineClasses to know if the
195   // dependency information is complete or not.
196   static bool _all_dependencies_are_recorded;
197 
198   static void post_method_exit_inner(JavaThread* thread,
199                                      methodHandle& mh,
200                                      JvmtiThreadState *state,
201                                      bool exception_exit,
202                                      frame current_frame,
203                                      jvalue& value);
204 
205  public:
206   inline static bool has_redefined_a_class() {
207     JVMTI_ONLY(return _redefinition_count != 0);
208     NOT_JVMTI(return false);
209   }
210 
211   // Only set in safepoint, so no memory ordering needed.
212   inline static uint64_t redefinition_count() {
213     JVMTI_ONLY(return _redefinition_count);
214     NOT_JVMTI(return 0);
215   }
216 
217   inline static bool all_dependencies_are_recorded() {
218     return _all_dependencies_are_recorded;
219   }
220 
221   inline static void set_all_dependencies_are_recorded(bool on) {
222     _all_dependencies_are_recorded = (on != 0);
223   }
224 
225   // Add read edges to the unnamed modules of the bootstrap and app class loaders
226   static void add_default_read_edges(Handle h_module, TRAPS) NOT_JVMTI_RETURN;
227 
228   // Add a read edge to the module
229   static jvmtiError add_module_reads(Handle module, Handle to_module, TRAPS);
230 
231   // Updates a module to export a package
232   static jvmtiError add_module_exports(Handle module, Handle pkg_name, Handle to_module, TRAPS);
233 
234   // Updates a module to open a package
235   static jvmtiError add_module_opens(Handle module, Handle pkg_name, Handle to_module, TRAPS);
236 
237   // Add a used service to the module
238   static jvmtiError add_module_uses(Handle module, Handle service, TRAPS);
239 
240   // Add a service provider to the module
241   static jvmtiError add_module_provides(Handle module, Handle service, Handle impl_class, TRAPS);
242 
243   // let JVMTI know that the JVM_OnLoad code is running
244   static void enter_onload_phase() NOT_JVMTI_RETURN;
245 
246   // let JVMTI know that the VM isn't up yet (and JVM_OnLoad code isn't running)
247   static void enter_primordial_phase() NOT_JVMTI_RETURN;
248 
249   // let JVMTI know that the VM isn't up yet but JNI is live
250   static void enter_early_start_phase() NOT_JVMTI_RETURN;
251   static void enter_start_phase() NOT_JVMTI_RETURN;
252 
253   // let JVMTI know that the VM is fully up and running now
254   static void enter_live_phase() NOT_JVMTI_RETURN;
255 
256   // ------ can_* conditions (below) are set at OnLoad and never changed ------------
257   inline static bool can_modify_any_class()                       {
258     JVMTI_ONLY(return _can_modify_any_class);
259     NOT_JVMTI(return false);
260   }
261   inline static bool can_access_local_variables()                 {
262     JVMTI_ONLY(return _can_access_local_variables);
263     NOT_JVMTI(return false);
264   }
265   inline static bool can_hotswap_or_post_breakpoint()             {
266     JVMTI_ONLY(return _can_hotswap_or_post_breakpoint);
267     NOT_JVMTI(return false);
268   }
269   inline static bool can_walk_any_space()                         {
270     JVMTI_ONLY(return _can_walk_any_space);
271     NOT_JVMTI(return false);
272   }
273 
274   // field access management
275   static address  get_field_access_count_addr() NOT_JVMTI_RETURN_(0);
276 
277   // field modification management
278   static address  get_field_modification_count_addr() NOT_JVMTI_RETURN_(0);
279 
280   // -----------------
281 
282   static bool is_jvmti_version(jint version)                      {
283     JVMTI_ONLY(return (version & JVMTI_VERSION_MASK) == JVMTI_VERSION_VALUE);
284     NOT_JVMTI(return false);
285   }
286   static bool is_jvmdi_version(jint version)                      {
287     JVMTI_ONLY(return (version & JVMTI_VERSION_MASK) == JVMDI_VERSION_VALUE);
288     NOT_JVMTI(return false);
289   }
290   static jint get_jvmti_interface(JavaVM *jvm, void **penv, jint version) NOT_JVMTI_RETURN_(0);
291   static void decode_version_values(jint version, int * major, int * minor,
292                                     int * micro) NOT_JVMTI_RETURN;
293 
294   // single stepping management methods
295   static void at_single_stepping_point(JavaThread *thread, Method* method, address location) NOT_JVMTI_RETURN;
296   static void expose_single_stepping(JavaThread *thread) NOT_JVMTI_RETURN;
297   static bool hide_single_stepping(JavaThread *thread) NOT_JVMTI_RETURN_(false);
298 
299   // Methods that notify the debugger that something interesting has happened in the VM.
300   static void post_early_vm_start        () NOT_JVMTI_RETURN;
301   static void post_vm_start              () NOT_JVMTI_RETURN;
302   static void post_vm_initialized        () NOT_JVMTI_RETURN;
303   static void post_vm_death              () NOT_JVMTI_RETURN;
304 
305   static void post_single_step           (JavaThread *thread, Method* method, address location) NOT_JVMTI_RETURN;
306   static void post_raw_breakpoint        (JavaThread *thread, Method* method, address location) NOT_JVMTI_RETURN;
307 
308   static void post_exception_throw       (JavaThread *thread, Method* method, address location, oop exception) NOT_JVMTI_RETURN;
309   static void notice_unwind_due_to_exception (JavaThread *thread, Method* method, address location, oop exception, bool in_handler_frame) NOT_JVMTI_RETURN;
310 
311   static oop jni_GetField_probe          (JavaThread *thread, jobject jobj,
312     oop obj, Klass* klass, jfieldID fieldID, bool is_static)
313     NOT_JVMTI_RETURN_(NULL);
314   static void post_field_access_by_jni   (JavaThread *thread, oop obj,
315     Klass* klass, jfieldID fieldID, bool is_static) NOT_JVMTI_RETURN;
316   static void post_field_access          (JavaThread *thread, Method* method,
317     address location, Klass* field_klass, Handle object, jfieldID field) NOT_JVMTI_RETURN;
318   static oop jni_SetField_probe          (JavaThread *thread, jobject jobj,
319     oop obj, Klass* klass, jfieldID fieldID, bool is_static, char sig_type,
320     jvalue *value) NOT_JVMTI_RETURN_(NULL);
321   static void post_field_modification_by_jni(JavaThread *thread, oop obj,
322     Klass* klass, jfieldID fieldID, bool is_static, char sig_type,
323     jvalue *value);
324   static void post_raw_field_modification(JavaThread *thread, Method* method,
325     address location, Klass* field_klass, Handle object, jfieldID field,
326     char sig_type, jvalue *value) NOT_JVMTI_RETURN;
327 
328   static void post_method_entry          (JavaThread *thread, Method* method, frame current_frame) NOT_JVMTI_RETURN;
329   static void post_method_exit           (JavaThread *thread, Method* method, frame current_frame) NOT_JVMTI_RETURN;
330 
331   static void post_class_load            (JavaThread *thread, Klass* klass) NOT_JVMTI_RETURN;
332   static void post_class_unload          (Klass* klass) NOT_JVMTI_RETURN;
333   static void post_class_prepare         (JavaThread *thread, Klass* klass) NOT_JVMTI_RETURN;
334 
335   static void post_thread_start          (JavaThread *thread) NOT_JVMTI_RETURN;
336   static void post_thread_end            (JavaThread *thread) NOT_JVMTI_RETURN;
337 
338   // Support for java.lang.instrument agent loading.
339   static bool _should_post_class_file_load_hook;
340   inline static void set_should_post_class_file_load_hook(bool on)     { _should_post_class_file_load_hook = on;  }
341   inline static bool should_post_class_file_load_hook()           {
342     JVMTI_ONLY(return _should_post_class_file_load_hook);
343     NOT_JVMTI(return false;)
344   }
345   static bool is_early_phase() NOT_JVMTI_RETURN_(false);
346   static bool has_early_class_hook_env() NOT_JVMTI_RETURN_(false);
347   // Return true if the class was modified by the hook.
348   static bool post_class_file_load_hook(Symbol* h_name, Handle class_loader,
349                                         Handle h_protection_domain,
350                                         unsigned char **data_ptr, unsigned char **end_ptr,
351                                         JvmtiCachedClassFileData **cache_ptr) NOT_JVMTI_RETURN_(false);
352   static void post_native_method_bind(Method* method, address* function_ptr) NOT_JVMTI_RETURN;
353   static void post_compiled_method_load(JvmtiEnv* env, nmethod *nm) NOT_JVMTI_RETURN;
354   static void post_compiled_method_load(nmethod *nm) NOT_JVMTI_RETURN;
355   static void post_dynamic_code_generated(const char *name, const void *code_begin, const void *code_end) NOT_JVMTI_RETURN;
356 
357   // used to post a CompiledMethodUnload event
358   static void post_compiled_method_unload(jmethodID mid, const void *code_begin) NOT_JVMTI_RETURN;
359 
360   // similiar to post_dynamic_code_generated except that it can be used to
361   // post a DynamicCodeGenerated event while holding locks in the VM. Any event
362   // posted using this function is recorded by the enclosing event collector
363   // -- JvmtiDynamicCodeEventCollector.
364   static void post_dynamic_code_generated_while_holding_locks(const char* name, address code_begin, address code_end) NOT_JVMTI_RETURN;
365 
366   static void post_garbage_collection_finish() NOT_JVMTI_RETURN;
367   static void post_garbage_collection_start() NOT_JVMTI_RETURN;
368   static void post_data_dump() NOT_JVMTI_RETURN;
369   static void post_monitor_contended_enter(JavaThread *thread, ObjectMonitor *obj_mntr) NOT_JVMTI_RETURN;
370   static void post_monitor_contended_entered(JavaThread *thread, ObjectMonitor *obj_mntr) NOT_JVMTI_RETURN;
371   static void post_monitor_wait(JavaThread *thread, oop obj, jlong timeout) NOT_JVMTI_RETURN;
372   static void post_monitor_waited(JavaThread *thread, ObjectMonitor *obj_mntr, jboolean timed_out) NOT_JVMTI_RETURN;
373   static void post_object_free(JvmtiEnv* env, jlong tag) NOT_JVMTI_RETURN;
374   static void post_resource_exhausted(jint resource_exhausted_flags, const char* detail) NOT_JVMTI_RETURN;
375   static void record_vm_internal_object_allocation(oop object) NOT_JVMTI_RETURN;
376   // Post objects collected by vm_object_alloc_event_collector.
377   static void post_vm_object_alloc(JavaThread *thread, oop object) NOT_JVMTI_RETURN;
378   // Collects vm internal objects for later event posting.
379   inline static void vm_object_alloc_event_collector(oop object) {
380     if (should_post_vm_object_alloc()) {
381       record_vm_internal_object_allocation(object);
382     }
383   }
384 
385   static void record_sampled_internal_object_allocation(oop object) NOT_JVMTI_RETURN;
386   // Post objects collected by sampled_object_alloc_event_collector.
387   static void post_sampled_object_alloc(JavaThread *thread, oop object) NOT_JVMTI_RETURN;
388 
389   // Collects vm internal objects for later event posting.
390   inline static void sampled_object_alloc_event_collector(oop object) {
391     if (should_post_sampled_object_alloc()) {
392       record_sampled_internal_object_allocation(object);
393     }
394   }
395 
396   inline static void post_array_size_exhausted() {
397     if (should_post_resource_exhausted()) {
398       post_resource_exhausted(JVMTI_RESOURCE_EXHAUSTED_OOM_ERROR,
399                               "Requested array size exceeds VM limit");
400     }
401   }
402 
403   static void cleanup_thread             (JavaThread* thread) NOT_JVMTI_RETURN;
404   static void clear_detected_exception   (JavaThread* thread) NOT_JVMTI_RETURN;
405 
406   static void transition_pending_onload_raw_monitors() NOT_JVMTI_RETURN;
407 
408 #if INCLUDE_SERVICES
409   // attach support
410   static jint load_agent_library(const char *agent, const char *absParam, const char *options, outputStream* out) NOT_JVMTI_RETURN_(JNI_ERR);
411 #endif
412 
413   // SetNativeMethodPrefix support
414   static char** get_all_native_method_prefixes(int* count_ptr) NOT_JVMTI_RETURN_(NULL);
415 
416   // JavaThread lifecycle support:
417   static jvmtiError cv_external_thread_to_JavaThread(ThreadsList * t_list,
418                                                      jthread thread,
419                                                      JavaThread ** jt_pp,
420                                                      oop * thread_oop_p);
421   static jvmtiError cv_oop_to_JavaThread(ThreadsList * t_list, oop thread_oop,
422                                          JavaThread ** jt_pp);
423 };
424 
425 // Support class used by JvmtiDynamicCodeEventCollector and others. It
426 // describes a single code blob by name and address range.
427 class JvmtiCodeBlobDesc : public CHeapObj<mtInternal> {
428  private:
429   char _name[64];
430   address _code_begin;
431   address _code_end;
432 
433  public:
434   JvmtiCodeBlobDesc(const char *name, address code_begin, address code_end) {
435     assert(name != NULL, "all code blobs must be named");
436     strncpy(_name, name, sizeof(_name) - 1);
437     _name[sizeof(_name)-1] = '\0';
438     _code_begin = code_begin;
439     _code_end = code_end;
440   }
441   char* name()                  { return _name; }
442   address code_begin()          { return _code_begin; }
443   address code_end()            { return _code_end; }
444 };
445 
446 // JvmtiEventCollector is a helper class to setup thread for
447 // event collection.
448 class JvmtiEventCollector : public StackObj {
449  private:
450   JvmtiEventCollector* _prev;  // Save previous one to support nested event collector.
451   bool _unset_jvmti_thread_state;
452 
453  public:
454   JvmtiEventCollector() : _prev(NULL), _unset_jvmti_thread_state(false) {}
455 
456   void setup_jvmti_thread_state(); // Set this collector in current thread, returns if success.
457   void unset_jvmti_thread_state(); // Reset previous collector in current thread.
458   virtual bool is_dynamic_code_event()   { return false; }
459   virtual bool is_vm_object_alloc_event(){ return false; }
460   virtual bool is_sampled_object_alloc_event(){ return false; }
461   JvmtiEventCollector *get_prev()        { return _prev; }
462 };
463 
464 // A JvmtiDynamicCodeEventCollector is a helper class for the JvmtiExport
465 // interface. It collects "dynamic code generated" events that are posted
466 // while holding locks. When the event collector goes out of scope the
467 // events will be posted.
468 //
469 // Usage :-
470 //
471 // {
472 //   JvmtiDynamicCodeEventCollector event_collector;
473 //   :
474 //   { MutexLocker ml(...)
475 //     :
476 //     JvmtiExport::post_dynamic_code_generated_while_holding_locks(...)
477 //   }
478 //   // event collector goes out of scope => post events to profiler.
479 // }
480 
481 class JvmtiDynamicCodeEventCollector : public JvmtiEventCollector {
482  private:
483   GrowableArray<JvmtiCodeBlobDesc*>* _code_blobs;           // collected code blob events
484 
485   friend class JvmtiExport;
486   void register_stub(const char* name, address start, address end);
487 
488  public:
489   JvmtiDynamicCodeEventCollector()  NOT_JVMTI_RETURN;
490   ~JvmtiDynamicCodeEventCollector() NOT_JVMTI_RETURN;
491   bool is_dynamic_code_event()   { return true; }
492 
493 };
494 
495 // Used as a base class for object allocation collection and then posting
496 // the allocations to any event notification callbacks.
497 //
498 class JvmtiObjectAllocEventCollector : public JvmtiEventCollector {
499  protected:
500   GrowableArray<OopHandle>* _allocated;      // field to record collected allocated object oop.
501   bool _enable;                   // This flag is enabled in constructor if set up in the thread state
502                                   // and disabled in destructor before posting event. To avoid
503                                   // collection of objects allocated while running java code inside
504                                   // agent post_X_object_alloc() event handler.
505   void (*_post_callback)(JavaThread*, oop); // what callback to use when destroying the collector.
506 
507   friend class JvmtiExport;
508 
509   // Record allocated object oop.
510   inline void record_allocation(oop obj);
511 
512  public:
513   JvmtiObjectAllocEventCollector()  NOT_JVMTI_RETURN;
514 
515   void generate_call_for_allocated();
516 
517   bool is_enabled()                 { return _enable; }
518   void set_enabled(bool on)         { _enable = on; }
519 };
520 
521 // Used to record vm internally allocated object oops and post
522 // vm object alloc event for objects visible to java world.
523 // Constructor enables JvmtiThreadState flag and all vm allocated
524 // objects are recorded in a growable array. When destructor is
525 // called the vm object alloc event is posted for each object
526 // visible to java world.
527 // See jvm.cpp file for its usage.
528 //
529 class JvmtiVMObjectAllocEventCollector : public JvmtiObjectAllocEventCollector {
530  public:
531   JvmtiVMObjectAllocEventCollector()  NOT_JVMTI_RETURN;
532   ~JvmtiVMObjectAllocEventCollector()  NOT_JVMTI_RETURN;
533   virtual bool is_vm_object_alloc_event()   { return true; }
534 };
535 
536 // Used to record sampled allocated object oops and post
537 // sampled object alloc event.
538 // Constructor enables JvmtiThreadState flag and all sampled allocated
539 // objects are recorded in a growable array. When destructor is
540 // called the sampled object alloc event is posted for each sampled object.
541 // See jvm.cpp file for its usage.
542 //
543 class JvmtiSampledObjectAllocEventCollector : public JvmtiObjectAllocEventCollector {
544  public:
545   JvmtiSampledObjectAllocEventCollector()  NOT_JVMTI_RETURN;
546   ~JvmtiSampledObjectAllocEventCollector()  NOT_JVMTI_RETURN;
547   bool is_sampled_object_alloc_event()    { return true; }
548   static bool object_alloc_is_safe_to_sample() NOT_JVMTI_RETURN_(false);
549 };
550 
551 // Marker class to disable the posting of VMObjectAlloc events
552 // within its scope.
553 //
554 // Usage :-
555 //
556 // {
557 //   NoJvmtiVMObjectAllocMark njm;
558 //   :
559 //   // VMObjAlloc event will not be posted
560 //   JvmtiExport::vm_object_alloc_event_collector(obj);
561 //   :
562 // }
563 
564 class NoJvmtiVMObjectAllocMark : public StackObj {
565  private:
566   // enclosing collector if enabled, NULL otherwise
567   JvmtiVMObjectAllocEventCollector *_collector;
568 
569   bool was_enabled()    { return _collector != NULL; }
570 
571  public:
572   NoJvmtiVMObjectAllocMark() NOT_JVMTI_RETURN;
573   ~NoJvmtiVMObjectAllocMark() NOT_JVMTI_RETURN;
574 };
575 
576 
577 // Base class for reporting GC events to JVMTI.
578 class JvmtiGCMarker : public StackObj {
579  public:
580   JvmtiGCMarker() NOT_JVMTI_RETURN;
581   ~JvmtiGCMarker() NOT_JVMTI_RETURN;
582 };
583 
584 // JvmtiHideSingleStepping is a helper class for hiding
585 // internal single step events.
586 class JvmtiHideSingleStepping : public StackObj {
587  private:
588   bool         _single_step_hidden;
589   JavaThread * _thread;
590 
591  public:
592   JvmtiHideSingleStepping(JavaThread * thread) {
593     assert(thread != NULL, "sanity check");
594 
595     _single_step_hidden = false;
596     _thread = thread;
597     if (JvmtiExport::should_post_single_step()) {
598       _single_step_hidden = JvmtiExport::hide_single_stepping(_thread);
599     }
600   }
601 
602   ~JvmtiHideSingleStepping() {
603     if (_single_step_hidden) {
604       JvmtiExport::expose_single_stepping(_thread);
605     }
606   }
607 };
608 
609 #endif // SHARE_PRIMS_JVMTIEXPORT_HPP