1 /*
   2  * Copyright (c) 1998, 2017, 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 "jvmticmlr.h"
  41 
  42 // Forward declarations
  43 
  44 class JvmtiEventControllerPrivate;
  45 class JvmtiManageCapabilities;
  46 class JvmtiEnv;
  47 class JvmtiThreadState;
  48 
  49 #define JVMTI_SUPPORT_FLAG(key)                                           \
  50   private:                                                                \
  51   static bool  _##key;                                                    \
  52   public:                                                                 \
  53   inline static void set_##key(bool on) {                                 \
  54     JVMTI_ONLY(_##key = (on != 0));                                       \
  55     NOT_JVMTI(report_unsupported(on));                                    \
  56   }                                                                       \
  57   inline static bool key() {                                              \
  58     JVMTI_ONLY(return _##key);                                            \
  59     NOT_JVMTI(return false);                                              \
  60   }
  61 
  62 
  63 // This class contains the JVMTI interface for the rest of hotspot.
  64 //
  65 class JvmtiExport : public AllStatic {
  66   friend class VMStructs;
  67   friend class CompileReplay;
  68 
  69  private:
  70 
  71 #if INCLUDE_JVMTI
  72   static int         _field_access_count;
  73   static int         _field_modification_count;
  74 
  75   static bool        _can_access_local_variables;
  76   static bool        _can_hotswap_or_post_breakpoint;
  77   static bool        _can_modify_any_class;
  78   static bool        _can_walk_any_space;
  79 #endif // INCLUDE_JVMTI
  80 
  81   JVMTI_SUPPORT_FLAG(can_get_source_debug_extension)
  82   JVMTI_SUPPORT_FLAG(can_maintain_original_method_order)
  83   JVMTI_SUPPORT_FLAG(can_post_interpreter_events)
  84   JVMTI_SUPPORT_FLAG(can_post_on_exceptions)
  85   JVMTI_SUPPORT_FLAG(can_post_breakpoint)
  86   JVMTI_SUPPORT_FLAG(can_post_field_access)
  87   JVMTI_SUPPORT_FLAG(can_post_field_modification)
  88   JVMTI_SUPPORT_FLAG(can_post_method_entry)
  89   JVMTI_SUPPORT_FLAG(can_post_method_exit)
  90   JVMTI_SUPPORT_FLAG(can_pop_frame)
  91   JVMTI_SUPPORT_FLAG(can_force_early_return)
  92 
  93   JVMTI_SUPPORT_FLAG(early_vmstart_recorded)
  94 
  95   friend class JvmtiEventControllerPrivate;  // should only modify these flags
  96   JVMTI_SUPPORT_FLAG(should_post_single_step)
  97   JVMTI_SUPPORT_FLAG(should_post_field_access)
  98   JVMTI_SUPPORT_FLAG(should_post_field_modification)
  99   JVMTI_SUPPORT_FLAG(should_post_class_load)
 100   JVMTI_SUPPORT_FLAG(should_post_class_prepare)
 101   JVMTI_SUPPORT_FLAG(should_post_class_unload)
 102   JVMTI_SUPPORT_FLAG(should_post_native_method_bind)
 103   JVMTI_SUPPORT_FLAG(should_post_compiled_method_load)
 104   JVMTI_SUPPORT_FLAG(should_post_compiled_method_unload)
 105   JVMTI_SUPPORT_FLAG(should_post_dynamic_code_generated)
 106   JVMTI_SUPPORT_FLAG(should_post_monitor_contended_enter)
 107   JVMTI_SUPPORT_FLAG(should_post_monitor_contended_entered)
 108   JVMTI_SUPPORT_FLAG(should_post_monitor_wait)
 109   JVMTI_SUPPORT_FLAG(should_post_monitor_waited)
 110   JVMTI_SUPPORT_FLAG(should_post_data_dump)
 111   JVMTI_SUPPORT_FLAG(should_post_garbage_collection_start)
 112   JVMTI_SUPPORT_FLAG(should_post_garbage_collection_finish)
 113   JVMTI_SUPPORT_FLAG(should_post_on_exceptions)
 114 
 115   // ------ the below maybe don't have to be (but are for now)
 116   // fixed conditions here ------------
 117   // any events can be enabled
 118   JVMTI_SUPPORT_FLAG(should_post_thread_life)
 119   JVMTI_SUPPORT_FLAG(should_post_object_free)
 120   JVMTI_SUPPORT_FLAG(should_post_resource_exhausted)
 121 
 122   // we are holding objects on the heap - need to talk to GC - e.g.
 123   // breakpoint info
 124   JVMTI_SUPPORT_FLAG(should_clean_up_heap_objects)
 125   JVMTI_SUPPORT_FLAG(should_post_vm_object_alloc)
 126 
 127   // If flag cannot be implemented, give an error if on=true
 128   static void report_unsupported(bool on);
 129 
 130   // these should only be called by the friend class
 131   friend class JvmtiManageCapabilities;
 132   inline static void set_can_modify_any_class(bool on) {
 133     JVMTI_ONLY(_can_modify_any_class = (on != 0);)
 134   }
 135   inline static void set_can_access_local_variables(bool on) {
 136     JVMTI_ONLY(_can_access_local_variables = (on != 0);)
 137   }
 138   inline static void set_can_hotswap_or_post_breakpoint(bool on) {
 139     JVMTI_ONLY(_can_hotswap_or_post_breakpoint = (on != 0);)
 140   }
 141   inline static void set_can_walk_any_space(bool on) {
 142     JVMTI_ONLY(_can_walk_any_space = (on != 0);)
 143   }
 144 
 145   enum {
 146     JVMTI_VERSION_MASK   = 0x70000000,
 147     JVMTI_VERSION_VALUE  = 0x30000000,
 148     JVMDI_VERSION_VALUE  = 0x20000000
 149   };
 150 
 151   static void post_field_modification(JavaThread *thread, Method* method, address location,
 152                                       Klass* field_klass, Handle object, jfieldID field,
 153                                       char sig_type, jvalue *value);
 154 
 155 
 156   // posts a DynamicCodeGenerated event (internal/private implementation).
 157   // The public post_dynamic_code_generated* functions make use of the
 158   // internal implementation.  Also called from JvmtiDeferredEvent::post()
 159   static void post_dynamic_code_generated_internal(const char *name, const void *code_begin, const void *code_end) NOT_JVMTI_RETURN;
 160 
 161  private:
 162 
 163   // GenerateEvents support to allow posting of CompiledMethodLoad and
 164   // DynamicCodeGenerated events for a given environment.
 165   friend class JvmtiCodeBlobEvents;
 166 
 167   static void post_compiled_method_load(JvmtiEnv* env, const jmethodID method, const jint length,
 168                                         const void *code_begin, const jint map_length,
 169                                         const jvmtiAddrLocationMap* map) NOT_JVMTI_RETURN;
 170   static void post_dynamic_code_generated(JvmtiEnv* env, const char *name, const void *code_begin,
 171                                           const void *code_end) NOT_JVMTI_RETURN;
 172 
 173   // The RedefineClasses() API breaks some invariants in the "regular"
 174   // system. For example, there are sanity checks when GC'ing nmethods
 175   // that require the containing class to be unloading. However, when a
 176   // method is redefined, the old method and nmethod can become GC'able
 177   // without the containing class unloading. The state of becoming
 178   // GC'able can be asynchronous to the RedefineClasses() call since
 179   // the old method may still be running and cannot be GC'ed until
 180   // after all old invocations have finished. Additionally, a method
 181   // that has not been redefined may have an nmethod that depends on
 182   // the redefined method. The dependent nmethod will get deopted in
 183   // this case and may also be GC'able without the containing class
 184   // being unloaded.
 185   //
 186   // This flag indicates whether RedefineClasses() has ever redefined
 187   // one or more classes during the lifetime of the VM. The flag should
 188   // only be set by the friend class and can be queried by other sub
 189   // systems as needed to relax invariant checks.
 190   static bool _has_redefined_a_class;
 191   friend class VM_RedefineClasses;
 192   inline static void set_has_redefined_a_class() {
 193     JVMTI_ONLY(_has_redefined_a_class = true;)
 194   }
 195   // Flag to indicate if the compiler has recorded all dependencies. When the
 196   // can_redefine_classes capability is enabled in the OnLoad phase then the compiler
 197   // records all dependencies from startup. However if the capability is first
 198   // enabled some time later then the dependencies recorded by the compiler
 199   // are incomplete. This flag is used by RedefineClasses to know if the
 200   // dependency information is complete or not.
 201   static bool _all_dependencies_are_recorded;
 202 
 203  public:
 204   inline static bool has_redefined_a_class() {
 205     JVMTI_ONLY(return _has_redefined_a_class);
 206     NOT_JVMTI(return false);
 207   }
 208 
 209   inline static bool all_dependencies_are_recorded() {
 210     return _all_dependencies_are_recorded;
 211   }
 212 
 213   inline static void set_all_dependencies_are_recorded(bool on) {
 214     _all_dependencies_are_recorded = (on != 0);
 215   }
 216 
 217   // Add read edges to the unnamed modules of the bootstrap and app class loaders
 218   static void add_default_read_edges(Handle h_module, TRAPS) NOT_JVMTI_RETURN;
 219 
 220   // Add a read edge to the module
 221   static jvmtiError add_module_reads(Handle module, Handle to_module, TRAPS);
 222 
 223   // Updates a module to export a package
 224   static jvmtiError add_module_exports(Handle module, Handle pkg_name, Handle to_module, TRAPS);
 225 
 226   // Updates a module to open a package
 227   static jvmtiError add_module_opens(Handle module, Handle pkg_name, Handle to_module, TRAPS);
 228 
 229   // Add a used service to the module
 230   static jvmtiError add_module_uses(Handle module, Handle service, TRAPS);
 231 
 232   // Add a service provider to the module
 233   static jvmtiError add_module_provides(Handle module, Handle service, Handle impl_class, TRAPS);
 234 
 235   // let JVMTI know that the JVM_OnLoad code is running
 236   static void enter_onload_phase() NOT_JVMTI_RETURN;
 237 
 238   // let JVMTI know that the VM isn't up yet (and JVM_OnLoad code isn't running)
 239   static void enter_primordial_phase() NOT_JVMTI_RETURN;
 240 
 241   // let JVMTI know that the VM isn't up yet but JNI is live
 242   static void enter_early_start_phase() NOT_JVMTI_RETURN;
 243   static void enter_start_phase() NOT_JVMTI_RETURN;
 244 
 245   // let JVMTI know that the VM is fully up and running now
 246   static void enter_live_phase() NOT_JVMTI_RETURN;
 247 
 248   // ------ can_* conditions (below) are set at OnLoad and never changed ------------
 249   inline static bool can_modify_any_class()                       {
 250     JVMTI_ONLY(return _can_modify_any_class);
 251     NOT_JVMTI(return false);
 252   }
 253   inline static bool can_access_local_variables()                 {
 254     JVMTI_ONLY(return _can_access_local_variables);
 255     NOT_JVMTI(return false);
 256   }
 257   inline static bool can_hotswap_or_post_breakpoint()             {
 258     JVMTI_ONLY(return _can_hotswap_or_post_breakpoint);
 259     NOT_JVMTI(return false);
 260   }
 261   inline static bool can_walk_any_space()                         {
 262     JVMTI_ONLY(return _can_walk_any_space);
 263     NOT_JVMTI(return false);
 264   }
 265 
 266   // field access management
 267   static address  get_field_access_count_addr() NOT_JVMTI_RETURN_(0);
 268 
 269   // field modification management
 270   static address  get_field_modification_count_addr() NOT_JVMTI_RETURN_(0);
 271 
 272   // -----------------
 273 
 274   static bool is_jvmti_version(jint version)                      {
 275     JVMTI_ONLY(return (version & JVMTI_VERSION_MASK) == JVMTI_VERSION_VALUE);
 276     NOT_JVMTI(return false);
 277   }
 278   static bool is_jvmdi_version(jint version)                      {
 279     JVMTI_ONLY(return (version & JVMTI_VERSION_MASK) == JVMDI_VERSION_VALUE);
 280     NOT_JVMTI(return false);
 281   }
 282   static jint get_jvmti_interface(JavaVM *jvm, void **penv, jint version) NOT_JVMTI_RETURN_(0);
 283   static void decode_version_values(jint version, int * major, int * minor,
 284                                     int * micro) NOT_JVMTI_RETURN;
 285 
 286   // single stepping management methods
 287   static void at_single_stepping_point(JavaThread *thread, Method* method, address location) NOT_JVMTI_RETURN;
 288   static void expose_single_stepping(JavaThread *thread) NOT_JVMTI_RETURN;
 289   static bool hide_single_stepping(JavaThread *thread) NOT_JVMTI_RETURN_(false);
 290 
 291   // Methods that notify the debugger that something interesting has happened in the VM.
 292   static void post_early_vm_start        () NOT_JVMTI_RETURN;
 293   static void post_vm_start              () NOT_JVMTI_RETURN;
 294   static void post_vm_initialized        () NOT_JVMTI_RETURN;
 295   static void post_vm_death              () NOT_JVMTI_RETURN;
 296 
 297   static void post_single_step           (JavaThread *thread, Method* method, address location) NOT_JVMTI_RETURN;
 298   static void post_raw_breakpoint        (JavaThread *thread, Method* method, address location) NOT_JVMTI_RETURN;
 299 
 300   static void post_exception_throw       (JavaThread *thread, Method* method, address location, oop exception) NOT_JVMTI_RETURN;
 301   static void notice_unwind_due_to_exception (JavaThread *thread, Method* method, address location, oop exception, bool in_handler_frame) NOT_JVMTI_RETURN;
 302 
 303   static oop jni_GetField_probe          (JavaThread *thread, jobject jobj,
 304     oop obj, Klass* klass, jfieldID fieldID, bool is_static)
 305     NOT_JVMTI_RETURN_(NULL);
 306   static oop jni_GetField_probe_nh       (JavaThread *thread, jobject jobj,
 307     oop obj, Klass* klass, jfieldID fieldID, bool is_static)
 308     NOT_JVMTI_RETURN_(NULL);
 309   static void post_field_access_by_jni   (JavaThread *thread, oop obj,
 310     Klass* klass, jfieldID fieldID, bool is_static) NOT_JVMTI_RETURN;
 311   static void post_field_access          (JavaThread *thread, Method* method,
 312     address location, Klass* field_klass, Handle object, jfieldID field) NOT_JVMTI_RETURN;
 313   static oop jni_SetField_probe          (JavaThread *thread, jobject jobj,
 314     oop obj, Klass* klass, jfieldID fieldID, bool is_static, char sig_type,
 315     jvalue *value) NOT_JVMTI_RETURN_(NULL);
 316   static oop jni_SetField_probe_nh       (JavaThread *thread, jobject jobj,
 317     oop obj, Klass* klass, jfieldID fieldID, bool is_static, char sig_type,
 318     jvalue *value) NOT_JVMTI_RETURN_(NULL);
 319   static void post_field_modification_by_jni(JavaThread *thread, oop obj,
 320     Klass* klass, jfieldID fieldID, bool is_static, char sig_type,
 321     jvalue *value);
 322   static void post_raw_field_modification(JavaThread *thread, Method* method,
 323     address location, Klass* field_klass, Handle object, jfieldID field,
 324     char sig_type, jvalue *value) NOT_JVMTI_RETURN;
 325 
 326   static void post_method_entry          (JavaThread *thread, Method* method, frame current_frame) NOT_JVMTI_RETURN;
 327   static void post_method_exit           (JavaThread *thread, Method* method, frame current_frame) NOT_JVMTI_RETURN;
 328 
 329   static void post_class_load            (JavaThread *thread, Klass* klass) NOT_JVMTI_RETURN;
 330   static void post_class_unload          (Klass* klass) NOT_JVMTI_RETURN;
 331   static void post_class_prepare         (JavaThread *thread, Klass* klass) NOT_JVMTI_RETURN;
 332 
 333   static void post_thread_start          (JavaThread *thread) NOT_JVMTI_RETURN;
 334   static void post_thread_end            (JavaThread *thread) NOT_JVMTI_RETURN;
 335 
 336   // Support for java.lang.instrument agent loading.
 337   static bool _should_post_class_file_load_hook;
 338   inline static void set_should_post_class_file_load_hook(bool on)     { _should_post_class_file_load_hook = on;  }
 339   inline static bool should_post_class_file_load_hook()           {
 340     JVMTI_ONLY(return _should_post_class_file_load_hook);
 341     NOT_JVMTI(return false;)
 342   }
 343   // Return true if the class was modified by the hook.
 344   static bool post_class_file_load_hook(Symbol* h_name, Handle class_loader,
 345                                         Handle h_protection_domain,
 346                                         unsigned char **data_ptr, unsigned char **end_ptr,
 347                                         JvmtiCachedClassFileData **cache_ptr) NOT_JVMTI_RETURN_(false);
 348   static void post_native_method_bind(Method* method, address* function_ptr) NOT_JVMTI_RETURN;
 349   static void post_compiled_method_load(nmethod *nm) NOT_JVMTI_RETURN;
 350   static void post_dynamic_code_generated(const char *name, const void *code_begin, const void *code_end) NOT_JVMTI_RETURN;
 351 
 352   // used to post a CompiledMethodUnload event
 353   static void post_compiled_method_unload(jmethodID mid, const void *code_begin) NOT_JVMTI_RETURN;
 354 
 355   // similiar to post_dynamic_code_generated except that it can be used to
 356   // post a DynamicCodeGenerated event while holding locks in the VM. Any event
 357   // posted using this function is recorded by the enclosing event collector
 358   // -- JvmtiDynamicCodeEventCollector.
 359   static void post_dynamic_code_generated_while_holding_locks(const char* name, address code_begin, address code_end) NOT_JVMTI_RETURN;
 360 
 361   static void post_garbage_collection_finish() NOT_JVMTI_RETURN;
 362   static void post_garbage_collection_start() NOT_JVMTI_RETURN;
 363   static void post_data_dump() NOT_JVMTI_RETURN;
 364   static void post_monitor_contended_enter(JavaThread *thread, ObjectMonitor *obj_mntr) NOT_JVMTI_RETURN;
 365   static void post_monitor_contended_entered(JavaThread *thread, ObjectMonitor *obj_mntr) NOT_JVMTI_RETURN;
 366   static void post_monitor_wait(JavaThread *thread, oop obj, jlong timeout) NOT_JVMTI_RETURN;
 367   static void post_monitor_waited(JavaThread *thread, ObjectMonitor *obj_mntr, jboolean timed_out) NOT_JVMTI_RETURN;
 368   static void post_object_free(JvmtiEnv* env, jlong tag) NOT_JVMTI_RETURN;
 369   static void post_resource_exhausted(jint resource_exhausted_flags, const char* detail) NOT_JVMTI_RETURN;
 370   static void record_vm_internal_object_allocation(oop object) NOT_JVMTI_RETURN;
 371   // Post objects collected by vm_object_alloc_event_collector.
 372   static void post_vm_object_alloc(JavaThread *thread, oop object) NOT_JVMTI_RETURN;
 373   // Collects vm internal objects for later event posting.
 374   inline static void vm_object_alloc_event_collector(oop object) {
 375     if (should_post_vm_object_alloc()) {
 376       record_vm_internal_object_allocation(object);
 377     }
 378   }
 379   inline static void post_array_size_exhausted() {
 380     if (should_post_resource_exhausted()) {
 381       post_resource_exhausted(JVMTI_RESOURCE_EXHAUSTED_OOM_ERROR,
 382                               "Requested array size exceeds VM limit");
 383     }
 384   }
 385 
 386   static void cleanup_thread             (JavaThread* thread) NOT_JVMTI_RETURN;
 387   static void clear_detected_exception   (JavaThread* thread) NOT_JVMTI_RETURN;
 388 
 389   static void oops_do(OopClosure* f) NOT_JVMTI_RETURN;
 390   static void weak_oops_do(BoolObjectClosure* b, OopClosure* f) NOT_JVMTI_RETURN;
 391   static void gc_epilogue() NOT_JVMTI_RETURN;
 392 
 393   static void transition_pending_onload_raw_monitors() NOT_JVMTI_RETURN;
 394 
 395 #if INCLUDE_SERVICES
 396   // attach support
 397   static jint load_agent_library(const char *agent, const char *absParam, const char *options, outputStream* out) NOT_JVMTI_RETURN_(JNI_ERR);
 398 #endif
 399 
 400   // SetNativeMethodPrefix support
 401   static char** get_all_native_method_prefixes(int* count_ptr) NOT_JVMTI_RETURN_(NULL);
 402 
 403   // JavaThread lifecycle support:
 404   static jvmtiError cv_external_thread_to_JavaThread(ThreadsList * t_list,
 405                                                      jthread thread,
 406                                                      JavaThread ** jt_pp,
 407                                                      oop * thread_oop_p);
 408   static jvmtiError cv_oop_to_JavaThread(ThreadsList * t_list, oop thread_oop,
 409                                          JavaThread ** jt_pp);
 410 };
 411 
 412 // Support class used by JvmtiDynamicCodeEventCollector and others. It
 413 // describes a single code blob by name and address range.
 414 class JvmtiCodeBlobDesc : public CHeapObj<mtInternal> {
 415  private:
 416   char _name[64];
 417   address _code_begin;
 418   address _code_end;
 419 
 420  public:
 421   JvmtiCodeBlobDesc(const char *name, address code_begin, address code_end) {
 422     assert(name != NULL, "all code blobs must be named");
 423     strncpy(_name, name, sizeof(_name));
 424     _name[sizeof(_name)-1] = '\0';
 425     _code_begin = code_begin;
 426     _code_end = code_end;
 427   }
 428   char* name()                  { return _name; }
 429   address code_begin()          { return _code_begin; }
 430   address code_end()            { return _code_end; }
 431 };
 432 
 433 // JvmtiEventCollector is a helper class to setup thread for
 434 // event collection.
 435 class JvmtiEventCollector : public StackObj {
 436  private:
 437   JvmtiEventCollector* _prev;  // Save previous one to support nested event collector.
 438 
 439  public:
 440   void setup_jvmti_thread_state(); // Set this collector in current thread.
 441   void unset_jvmti_thread_state(); // Reset previous collector in current thread.
 442   virtual bool is_dynamic_code_event()   { return false; }
 443   virtual bool is_vm_object_alloc_event(){ return false; }
 444   JvmtiEventCollector *get_prev()        { return _prev; }
 445 };
 446 
 447 // A JvmtiDynamicCodeEventCollector is a helper class for the JvmtiExport
 448 // interface. It collects "dynamic code generated" events that are posted
 449 // while holding locks. When the event collector goes out of scope the
 450 // events will be posted.
 451 //
 452 // Usage :-
 453 //
 454 // {
 455 //   JvmtiDynamicCodeEventCollector event_collector;
 456 //   :
 457 //   { MutexLocker ml(...)
 458 //     :
 459 //     JvmtiExport::post_dynamic_code_generated_while_holding_locks(...)
 460 //   }
 461 //   // event collector goes out of scope => post events to profiler.
 462 // }
 463 
 464 class JvmtiDynamicCodeEventCollector : public JvmtiEventCollector {
 465  private:
 466   GrowableArray<JvmtiCodeBlobDesc*>* _code_blobs;           // collected code blob events
 467 
 468   friend class JvmtiExport;
 469   void register_stub(const char* name, address start, address end);
 470 
 471  public:
 472   JvmtiDynamicCodeEventCollector()  NOT_JVMTI_RETURN;
 473   ~JvmtiDynamicCodeEventCollector() NOT_JVMTI_RETURN;
 474   bool is_dynamic_code_event()   { return true; }
 475 
 476 };
 477 
 478 // Used to record vm internally allocated object oops and post
 479 // vm object alloc event for objects visible to java world.
 480 // Constructor enables JvmtiThreadState flag and all vm allocated
 481 // objects are recorded in a growable array. When destructor is
 482 // called the vm object alloc event is posted for each objects
 483 // visible to java world.
 484 // See jvm.cpp file for its usage.
 485 //
 486 class JvmtiVMObjectAllocEventCollector : public JvmtiEventCollector {
 487  private:
 488   GrowableArray<oop>* _allocated; // field to record vm internally allocated object oop.
 489   bool _enable;                   // This flag is enabled in constructor and disabled
 490                                   // in destructor before posting event. To avoid
 491                                   // collection of objects allocated while running java code inside
 492                                   // agent post_vm_object_alloc() event handler.
 493 
 494   //GC support
 495   void oops_do(OopClosure* f);
 496 
 497   friend class JvmtiExport;
 498   // Record vm allocated object oop.
 499   inline void record_allocation(oop obj);
 500 
 501   //GC support
 502   static void oops_do_for_all_threads(OopClosure* f);
 503 
 504  public:
 505   JvmtiVMObjectAllocEventCollector()  NOT_JVMTI_RETURN;
 506   ~JvmtiVMObjectAllocEventCollector() NOT_JVMTI_RETURN;
 507   bool is_vm_object_alloc_event()   { return true; }
 508 
 509   bool is_enabled()                 { return _enable; }
 510   void set_enabled(bool on)         { _enable = on; }
 511 };
 512 
 513 
 514 
 515 // Marker class to disable the posting of VMObjectAlloc events
 516 // within its scope.
 517 //
 518 // Usage :-
 519 //
 520 // {
 521 //   NoJvmtiVMObjectAllocMark njm;
 522 //   :
 523 //   // VMObjAlloc event will not be posted
 524 //   JvmtiExport::vm_object_alloc_event_collector(obj);
 525 //   :
 526 // }
 527 
 528 class NoJvmtiVMObjectAllocMark : public StackObj {
 529  private:
 530   // enclosing collector if enabled, NULL otherwise
 531   JvmtiVMObjectAllocEventCollector *_collector;
 532 
 533   bool was_enabled()    { return _collector != NULL; }
 534 
 535  public:
 536   NoJvmtiVMObjectAllocMark() NOT_JVMTI_RETURN;
 537   ~NoJvmtiVMObjectAllocMark() NOT_JVMTI_RETURN;
 538 };
 539 
 540 
 541 // Base class for reporting GC events to JVMTI.
 542 class JvmtiGCMarker : public StackObj {
 543  public:
 544   JvmtiGCMarker() NOT_JVMTI_RETURN;
 545   ~JvmtiGCMarker() NOT_JVMTI_RETURN;
 546 };
 547 
 548 // JvmtiHideSingleStepping is a helper class for hiding
 549 // internal single step events.
 550 class JvmtiHideSingleStepping : public StackObj {
 551  private:
 552   bool         _single_step_hidden;
 553   JavaThread * _thread;
 554 
 555  public:
 556   JvmtiHideSingleStepping(JavaThread * thread) {
 557     assert(thread != NULL, "sanity check");
 558 
 559     _single_step_hidden = false;
 560     _thread = thread;
 561     if (JvmtiExport::should_post_single_step()) {
 562       _single_step_hidden = JvmtiExport::hide_single_stepping(_thread);
 563     }
 564   }
 565 
 566   ~JvmtiHideSingleStepping() {
 567     if (_single_step_hidden) {
 568       JvmtiExport::expose_single_stepping(_thread);
 569     }
 570   }
 571 };
 572 
 573 #endif // SHARE_VM_PRIMS_JVMTIEXPORT_HPP