1 /*

     2  * Copyright 1998-2006 Sun Microsystems, Inc.  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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

    20  * CA 95054 USA or visit www.sun.com if you need additional information or

    21  * have any questions.

    22  *

    23  */

    24 

    25 #ifndef _JAVA_JVMTIEXPORT_H_

    26 #define _JAVA_JVMTIEXPORT_H_

    27 

    28 // Forward declarations

    29 

    30 class JvmtiEventControllerPrivate;

    31 class JvmtiManageCapabilities;

    32 class JvmtiEnv;

    33 class JvmtiThreadState;

    34 class AttachOperation;

    35 

    36 #ifndef JVMTI_KERNEL

    37 #define JVMTI_SUPPORT_FLAG(key)                                         \

    38   private:                                                              \

    39   static bool  _##key;                                                  \

    40   public:                                                               \

    41   inline static void set_##key(bool on)       { _##key = (on != 0); }   \

    42   inline static bool key()                    { return _##key; }

    43 #else  // JVMTI_KERNEL

    44 #define JVMTI_SUPPORT_FLAG(key)                                           \

    45   private:                                                                \

    46   const static bool _##key = false;                                       \

    47   public:                                                                 \

    48   inline static void set_##key(bool on)       { report_unsupported(on); } \

    49   inline static bool key()                    { return _##key; }

    50 #endif // JVMTI_KERNEL

    51 

    52 

    53 // This class contains the JVMTI interface for the rest of hotspot.

    54 //

    55 class JvmtiExport : public AllStatic {

    56  private:

    57   static int         _field_access_count;

    58   static int         _field_modification_count;

    59 

    60   static bool        _can_access_local_variables;

    61   static bool        _can_examine_or_deopt_anywhere;

    62   static bool        _can_hotswap_or_post_breakpoint;

    63   static bool        _can_modify_any_class;

    64   static bool        _can_walk_any_space;

    65 

    66   JVMTI_SUPPORT_FLAG(can_get_source_debug_extension)

    67   JVMTI_SUPPORT_FLAG(can_maintain_original_method_order)

    68   JVMTI_SUPPORT_FLAG(can_post_interpreter_events)

    69   JVMTI_SUPPORT_FLAG(can_post_exceptions)

    70   JVMTI_SUPPORT_FLAG(can_post_breakpoint)

    71   JVMTI_SUPPORT_FLAG(can_post_field_access)

    72   JVMTI_SUPPORT_FLAG(can_post_field_modification)

    73   JVMTI_SUPPORT_FLAG(can_post_method_entry)

    74   JVMTI_SUPPORT_FLAG(can_post_method_exit)

    75   JVMTI_SUPPORT_FLAG(can_pop_frame)

    76   JVMTI_SUPPORT_FLAG(can_force_early_return)

    77 

    78   friend class JvmtiEventControllerPrivate;  // should only modify these flags

    79   JVMTI_SUPPORT_FLAG(should_post_single_step)

    80   JVMTI_SUPPORT_FLAG(should_post_field_access)

    81   JVMTI_SUPPORT_FLAG(should_post_field_modification)

    82   JVMTI_SUPPORT_FLAG(should_post_class_load)

    83   JVMTI_SUPPORT_FLAG(should_post_class_prepare)

    84   JVMTI_SUPPORT_FLAG(should_post_class_unload)

    85   JVMTI_SUPPORT_FLAG(should_post_native_method_bind)

    86   JVMTI_SUPPORT_FLAG(should_post_compiled_method_load)

    87   JVMTI_SUPPORT_FLAG(should_post_compiled_method_unload)

    88   JVMTI_SUPPORT_FLAG(should_post_dynamic_code_generated)

    89   JVMTI_SUPPORT_FLAG(should_post_monitor_contended_enter)

    90   JVMTI_SUPPORT_FLAG(should_post_monitor_contended_entered)

    91   JVMTI_SUPPORT_FLAG(should_post_monitor_wait)

    92   JVMTI_SUPPORT_FLAG(should_post_monitor_waited)

    93   JVMTI_SUPPORT_FLAG(should_post_data_dump)

    94   JVMTI_SUPPORT_FLAG(should_post_garbage_collection_start)

    95   JVMTI_SUPPORT_FLAG(should_post_garbage_collection_finish)

    96 

    97   // ------ the below maybe don't have to be (but are for now)

    98   // fixed conditions here ------------

    99   // any events can be enabled

   100   JVMTI_SUPPORT_FLAG(should_post_thread_life)

   101   JVMTI_SUPPORT_FLAG(should_post_object_free)

   102   JVMTI_SUPPORT_FLAG(should_post_resource_exhausted)

   103 

   104   // we are holding objects on the heap - need to talk to GC - e.g.

   105   // breakpoint info

   106   JVMTI_SUPPORT_FLAG(should_clean_up_heap_objects)

   107   JVMTI_SUPPORT_FLAG(should_post_vm_object_alloc)

   108 

   109   // If flag cannot be implemented, give an error if on=true

   110   static void report_unsupported(bool on);

   111 

   112   // these should only be called by the friend class

   113   friend class JvmtiManageCapabilities;

   114   inline static void set_can_examine_or_deopt_anywhere(bool on)        { _can_examine_or_deopt_anywhere = (on != 0); }

   115   inline static void set_can_modify_any_class(bool on)                 { _can_modify_any_class = (on != 0); }

   116   inline static void set_can_access_local_variables(bool on)           { _can_access_local_variables = (on != 0); }

   117   inline static void set_can_hotswap_or_post_breakpoint(bool on)       { _can_hotswap_or_post_breakpoint = (on != 0); }

   118   inline static void set_can_walk_any_space(bool on)                   { _can_walk_any_space = (on != 0); }

   119 

   120   enum {

   121     JVMTI_VERSION_MASK   = 0x70000000,

   122     JVMTI_VERSION_VALUE  = 0x30000000,

   123     JVMDI_VERSION_VALUE  = 0x20000000

   124   };

   125 

   126   static void post_field_modification(JavaThread *thread, methodOop method, address location,

   127                                       KlassHandle field_klass, Handle object, jfieldID field,

   128                                       char sig_type, jvalue *value);

   129 

   130 

   131  private:

   132   // CompiledMethodUnload events are reported from the VM thread so they

   133   // are collected in lists (of jmethodID/addresses) and the events are posted later

   134   // from threads posting CompieldMethodLoad or DynamicCodeGenerated events.

   135   static bool _have_pending_compiled_method_unload_events;

   136   static GrowableArray<jmethodID>* _pending_compiled_method_unload_method_ids;

   137   static GrowableArray<const void *>* _pending_compiled_method_unload_code_begins;

   138   static JavaThread* _current_poster;

   139 

   140   // tests if there are CompiledMethodUnload events pending

   141   inline static bool have_pending_compiled_method_unload_events() {

   142     return _have_pending_compiled_method_unload_events;

   143   }

   144 

   145   // posts any pending CompiledMethodUnload events.

   146   static void post_pending_compiled_method_unload_events();

   147 

   148   // posts a DynamicCodeGenerated event (internal/private implementation).

   149   // The public post_dynamic_code_generated* functions make use of the

   150   // internal implementation.

   151   static void post_dynamic_code_generated_internal(const char *name, const void *code_begin, const void *code_end) KERNEL_RETURN;

   152 

   153 

   154   // GenerateEvents support to allow posting of CompiledMethodLoad and

   155   // DynamicCodeGenerated events for a given environment.

   156   friend class JvmtiCodeBlobEvents;

   157 

   158   static void post_compiled_method_load(JvmtiEnv* env, const jmethodID method, const jint length,

   159                                         const void *code_begin, const jint map_length,

   160                                         const jvmtiAddrLocationMap* map) KERNEL_RETURN;

   161   static void post_dynamic_code_generated(JvmtiEnv* env, const char *name, const void *code_begin,

   162                                           const void *code_end) KERNEL_RETURN;

   163 

   164   // The RedefineClasses() API breaks some invariants in the "regular"

   165   // system. For example, there are sanity checks when GC'ing nmethods

   166   // that require the containing class to be unloading. However, when a

   167   // method is redefined, the old method and nmethod can become GC'able

   168   // without the containing class unloading. The state of becoming

   169   // GC'able can be asynchronous to the RedefineClasses() call since

   170   // the old method may still be running and cannot be GC'ed until

   171   // after all old invocations have finished. Additionally, a method

   172   // that has not been redefined may have an nmethod that depends on

   173   // the redefined method. The dependent nmethod will get deopted in

   174   // this case and may also be GC'able without the containing class

   175   // being unloaded.

   176   //

   177   // This flag indicates whether RedefineClasses() has ever redefined

   178   // one or more classes during the lifetime of the VM. The flag should

   179   // only be set by the friend class and can be queried by other sub

   180   // systems as needed to relax invariant checks.

   181   static bool _has_redefined_a_class;

   182   friend class VM_RedefineClasses;

   183   inline static void set_has_redefined_a_class() {

   184     _has_redefined_a_class = true;

   185   }

   186 

   187   // Flag to indicate if the compiler has recorded all dependencies. When the

   188   // can_redefine_classes capability is enabled in the OnLoad phase then the compiler

   189   // records all dependencies from startup. However if the capability is first

   190   // enabled some time later then the dependencies recorded by the compiler

   191   // are incomplete. This flag is used by RedefineClasses to know if the

   192   // dependency information is complete or not.

   193   static bool _all_dependencies_are_recorded;

   194 

   195  public:

   196   inline static bool has_redefined_a_class() {

   197     return _has_redefined_a_class;

   198   }

   199 

   200   inline static bool all_dependencies_are_recorded() {

   201     return _all_dependencies_are_recorded;

   202   }

   203 

   204   inline static void set_all_dependencies_are_recorded(bool on) {

   205     _all_dependencies_are_recorded = (on != 0);

   206   }

   207 

   208 

   209   // let JVMTI know that the JVM_OnLoad code is running

   210   static void enter_onload_phase();

   211 

   212   // let JVMTI know that the VM isn't up yet (and JVM_OnLoad code isn't running)

   213   static void enter_primordial_phase();

   214 

   215   // let JVMTI know that the VM isn't up yet but JNI is live

   216   static void enter_start_phase();

   217 

   218   // let JVMTI know that the VM is fully up and running now

   219   static void enter_live_phase();

   220 

   221   // ------ can_* conditions (below) are set at OnLoad and never changed ------------

   222   inline static bool can_examine_or_deopt_anywhere()              { return _can_examine_or_deopt_anywhere; }

   223   inline static bool can_modify_any_class()                       { return _can_modify_any_class; }

   224   inline static bool can_access_local_variables()                 { return _can_access_local_variables; }

   225   inline static bool can_hotswap_or_post_breakpoint()             { return _can_hotswap_or_post_breakpoint; }

   226   inline static bool can_walk_any_space()                         { return _can_walk_any_space; }

   227 

   228   // field access management

   229   static address  get_field_access_count_addr();

   230 

   231   // field modification management

   232   static address  get_field_modification_count_addr();

   233 

   234   // -----------------

   235 

   236   static bool is_jvmti_version(jint version)                      { return (version & JVMTI_VERSION_MASK) == JVMTI_VERSION_VALUE; }

   237   static bool is_jvmdi_version(jint version)                      { return (version & JVMTI_VERSION_MASK) == JVMDI_VERSION_VALUE; }

   238   static jint get_jvmti_interface(JavaVM *jvm, void **penv, jint version);

   239 

   240   // single stepping management methods

   241   static void at_single_stepping_point(JavaThread *thread, methodOop method, address location) KERNEL_RETURN;

   242   static void expose_single_stepping(JavaThread *thread) KERNEL_RETURN;

   243   static bool hide_single_stepping(JavaThread *thread) KERNEL_RETURN_(return false;);

   244 

   245   // Methods that notify the debugger that something interesting has happened in the VM.

   246   static void post_vm_start              ();

   247   static void post_vm_initialized        ();

   248   static void post_vm_death              ();

   249 

   250   static void post_single_step           (JavaThread *thread, methodOop method, address location) KERNEL_RETURN;

   251   static void post_raw_breakpoint        (JavaThread *thread, methodOop method, address location) KERNEL_RETURN;

   252 

   253   static void post_exception_throw       (JavaThread *thread, methodOop method, address location, oop exception) KERNEL_RETURN;

   254   static void notice_unwind_due_to_exception (JavaThread *thread, methodOop method, address location, oop exception, bool in_handler_frame) KERNEL_RETURN;

   255 

   256   static oop jni_GetField_probe          (JavaThread *thread, jobject jobj,

   257     oop obj, klassOop klass, jfieldID fieldID, bool is_static)

   258     KERNEL_RETURN_(return NULL;);

   259   static oop jni_GetField_probe_nh       (JavaThread *thread, jobject jobj,

   260     oop obj, klassOop klass, jfieldID fieldID, bool is_static)

   261     KERNEL_RETURN_(return NULL;);

   262   static void post_field_access_by_jni   (JavaThread *thread, oop obj,

   263     klassOop klass, jfieldID fieldID, bool is_static) KERNEL_RETURN;

   264   static void post_field_access          (JavaThread *thread, methodOop method,

   265     address location, KlassHandle field_klass, Handle object, jfieldID field) KERNEL_RETURN;

   266   static oop jni_SetField_probe          (JavaThread *thread, jobject jobj,

   267     oop obj, klassOop klass, jfieldID fieldID, bool is_static, char sig_type,

   268     jvalue *value) KERNEL_RETURN_(return NULL;);

   269   static oop jni_SetField_probe_nh       (JavaThread *thread, jobject jobj,

   270     oop obj, klassOop klass, jfieldID fieldID, bool is_static, char sig_type,

   271     jvalue *value) KERNEL_RETURN_(return NULL;);

   272   static void post_field_modification_by_jni(JavaThread *thread, oop obj,

   273     klassOop klass, jfieldID fieldID, bool is_static, char sig_type,

   274     jvalue *value);

   275   static void post_raw_field_modification(JavaThread *thread, methodOop method,

   276     address location, KlassHandle field_klass, Handle object, jfieldID field,

   277     char sig_type, jvalue *value) KERNEL_RETURN;

   278 

   279   static void post_method_entry          (JavaThread *thread, methodOop method, frame current_frame) KERNEL_RETURN;

   280   static void post_method_exit           (JavaThread *thread, methodOop method, frame current_frame) KERNEL_RETURN;

   281 

   282   static void post_class_load            (JavaThread *thread, klassOop klass) KERNEL_RETURN;

   283   static void post_class_unload          (klassOop klass) KERNEL_RETURN;

   284   static void post_class_prepare         (JavaThread *thread, klassOop klass) KERNEL_RETURN;

   285 

   286   static void post_thread_start          (JavaThread *thread) KERNEL_RETURN;

   287   static void post_thread_end            (JavaThread *thread) KERNEL_RETURN;

   288 

   289   // Support for java.lang.instrument agent loading.

   290   static bool _should_post_class_file_load_hook;

   291   inline static void set_should_post_class_file_load_hook(bool on)     { _should_post_class_file_load_hook = on;  }

   292   inline static bool should_post_class_file_load_hook()           { return _should_post_class_file_load_hook; }

   293   static void post_class_file_load_hook(symbolHandle h_name, Handle class_loader,

   294                                         Handle h_protection_domain,

   295                                         unsigned char **data_ptr, unsigned char **end_ptr,

   296                                         unsigned char **cached_data_ptr,

   297                                         jint *cached_length_ptr);

   298   static void post_native_method_bind(methodOop method, address* function_ptr) KERNEL_RETURN;

   299   static void post_compiled_method_load(nmethod *nm) KERNEL_RETURN;

   300   static void post_dynamic_code_generated(const char *name, const void *code_begin, const void *code_end) KERNEL_RETURN;

   301 

   302   // used at a safepoint to post a CompiledMethodUnload event

   303   static void post_compiled_method_unload_at_safepoint(jmethodID mid, const void *code_begin) KERNEL_RETURN;

   304 

   305   // similiar to post_dynamic_code_generated except that it can be used to

   306   // post a DynamicCodeGenerated event while holding locks in the VM. Any event

   307   // posted using this function is recorded by the enclosing event collector

   308   // -- JvmtiDynamicCodeEventCollector.

   309   static void post_dynamic_code_generated_while_holding_locks(const char* name, address code_begin, address code_end) KERNEL_RETURN;

   310 

   311   static void post_garbage_collection_finish() KERNEL_RETURN;

   312   static void post_garbage_collection_start() KERNEL_RETURN;

   313   static void post_data_dump() KERNEL_RETURN;

   314   static void post_monitor_contended_enter(JavaThread *thread, ObjectMonitor *obj_mntr) KERNEL_RETURN;

   315   static void post_monitor_contended_entered(JavaThread *thread, ObjectMonitor *obj_mntr) KERNEL_RETURN;

   316   static void post_monitor_wait(JavaThread *thread, oop obj, jlong timeout) KERNEL_RETURN;

   317   static void post_monitor_waited(JavaThread *thread, ObjectMonitor *obj_mntr, jboolean timed_out) KERNEL_RETURN;

   318   static void post_object_free(JvmtiEnv* env, jlong tag) KERNEL_RETURN;

   319   static void post_resource_exhausted(jint resource_exhausted_flags, const char* detail) KERNEL_RETURN;

   320   static void record_vm_internal_object_allocation(oop object) KERNEL_RETURN;

   321   // Post objects collected by vm_object_alloc_event_collector.

   322   static void post_vm_object_alloc(JavaThread *thread, oop object) KERNEL_RETURN;

   323   // Collects vm internal objects for later event posting.

   324   inline static void vm_object_alloc_event_collector(oop object) {

   325     if (should_post_vm_object_alloc()) {

   326       record_vm_internal_object_allocation(object);

   327     }

   328   }

   329 

   330   static void cleanup_thread             (JavaThread* thread) KERNEL_RETURN;

   331 

   332   static void oops_do(OopClosure* f) KERNEL_RETURN;

   333 

   334   static void transition_pending_onload_raw_monitors() KERNEL_RETURN;

   335 

   336 #ifndef SERVICES_KERNEL

   337   // attach support

   338   static jint load_agent_library(AttachOperation* op, outputStream* out);

   339 #endif // SERVICES_KERNEL

   340 

   341   // SetNativeMethodPrefix support

   342   static char** get_all_native_method_prefixes(int* count_ptr);

   343 

   344   // call after CMS has completed referencing processing

   345   static void cms_ref_processing_epilogue() KERNEL_RETURN;

   346 };

   347 

   348 // Support class used by JvmtiDynamicCodeEventCollector and others. It

   349 // describes a single code blob by name and address range.

   350 class JvmtiCodeBlobDesc : public CHeapObj {

   351  private:

   352   char _name[64];

   353   address _code_begin;

   354   address _code_end;

   355 

   356  public:

   357   JvmtiCodeBlobDesc(const char *name, address code_begin, address code_end) {

   358     assert(name != NULL, "all code blobs must be named");

   359     strncpy(_name, name, sizeof(_name));

   360     _name[sizeof(_name)-1] = '\0';

   361     _code_begin = code_begin;

   362     _code_end = code_end;

   363   }

   364   char* name()                  { return _name; }

   365   address code_begin()          { return _code_begin; }

   366   address code_end()            { return _code_end; }

   367 };

   368 

   369 // JvmtiEventCollector is a helper class to setup thread for

   370 // event collection.

   371 class JvmtiEventCollector : public StackObj {

   372  private:

   373   JvmtiEventCollector* _prev;  // Save previous one to support nested event collector.

   374 

   375  public:

   376   void setup_jvmti_thread_state(); // Set this collector in current thread.

   377   void unset_jvmti_thread_state(); // Reset previous collector in current thread.

   378   virtual bool is_dynamic_code_event()   { return false; }

   379   virtual bool is_vm_object_alloc_event(){ return false; }

   380   JvmtiEventCollector *get_prev()        { return _prev; }

   381 };

   382 

   383 // A JvmtiDynamicCodeEventCollector is a helper class for the JvmtiExport

   384 // interface. It collects "dynamic code generated" events that are posted

   385 // while holding locks. When the event collector goes out of scope the

   386 // events will be posted.

   387 //

   388 // Usage :-

   389 //

   390 // {

   391 //   JvmtiDynamicCodeEventCollector event_collector;

   392 //   :

   393 //   { MutexLocker ml(...)

   394 //     :

   395 //     JvmtiExport::post_dynamic_code_generated_while_holding_locks(...)

   396 //   }

   397 //   // event collector goes out of scope => post events to profiler.

   398 // }

   399 

   400 class JvmtiDynamicCodeEventCollector : public JvmtiEventCollector {

   401  private:

   402   GrowableArray<JvmtiCodeBlobDesc*>* _code_blobs;           // collected code blob events

   403 

   404   friend class JvmtiExport;

   405   void register_stub(const char* name, address start, address end);

   406 

   407  public:

   408   JvmtiDynamicCodeEventCollector()  KERNEL_RETURN;

   409   ~JvmtiDynamicCodeEventCollector() KERNEL_RETURN;

   410   bool is_dynamic_code_event()   { return true; }

   411 

   412 };

   413 

   414 // Used to record vm internally allocated object oops and post

   415 // vm object alloc event for objects visible to java world.

   416 // Constructor enables JvmtiThreadState flag and all vm allocated

   417 // objects are recorded in a growable array. When destructor is

   418 // called the vm object alloc event is posted for each objects

   419 // visible to java world.

   420 // See jvm.cpp file for its usage.

   421 //

   422 class JvmtiVMObjectAllocEventCollector : public JvmtiEventCollector {

   423  private:

   424   GrowableArray<oop>* _allocated; // field to record vm internally allocated object oop.

   425   bool _enable;                   // This flag is enabled in constructor and disabled

   426                                   // in destructor before posting event. To avoid

   427                                   // collection of objects allocated while running java code inside

   428                                   // agent post_vm_object_alloc() event handler.

   429 

   430   //GC support

   431   void oops_do(OopClosure* f);

   432 

   433   friend class JvmtiExport;

   434   // Record vm allocated object oop.

   435   inline void record_allocation(oop obj);

   436 

   437   //GC support

   438   static void oops_do_for_all_threads(OopClosure* f);

   439 

   440  public:

   441   JvmtiVMObjectAllocEventCollector()  KERNEL_RETURN;

   442   ~JvmtiVMObjectAllocEventCollector() KERNEL_RETURN;

   443   bool is_vm_object_alloc_event()   { return true; }

   444 

   445   bool is_enabled()                 { return _enable; }

   446   void set_enabled(bool on)         { _enable = on; }

   447 };

   448 

   449 

   450 

   451 // Marker class to disable the posting of VMObjectAlloc events

   452 // within its scope.

   453 //

   454 // Usage :-

   455 //

   456 // {

   457 //   NoJvmtiVMObjectAllocMark njm;

   458 //   :

   459 //   // VMObjAlloc event will not be posted

   460 //   JvmtiExport::vm_object_alloc_event_collector(obj);

   461 //   :

   462 // }

   463 

   464 class NoJvmtiVMObjectAllocMark : public StackObj {

   465  private:

   466   // enclosing collector if enabled, NULL otherwise

   467   JvmtiVMObjectAllocEventCollector *_collector;

   468 

   469   bool was_enabled()    { return _collector != NULL; }

   470 

   471  public:

   472   NoJvmtiVMObjectAllocMark() KERNEL_RETURN;

   473   ~NoJvmtiVMObjectAllocMark() KERNEL_RETURN;

   474 };

   475 

   476 

   477 // Base class for reporting GC events to JVMTI.

   478 class JvmtiGCMarker : public StackObj {

   479  private:

   480   bool _full;                           // marks a "full" GC

   481   unsigned int _invocation_count;       // GC invocation count

   482  protected:

   483   JvmtiGCMarker(bool full) KERNEL_RETURN;       // protected

   484   ~JvmtiGCMarker() KERNEL_RETURN;               // protected

   485 };

   486 

   487 

   488 // Support class used to report GC events to JVMTI. The class is stack

   489 // allocated and should be placed in the doit() implementation of all

   490 // vm operations that do a stop-the-world GC for failed allocation.

   491 //

   492 // Usage :-

   493 //

   494 // void VM_GenCollectForAllocation::doit() {

   495 //   JvmtiGCForAllocationMarker jgcm;

   496 //   :

   497 // }

   498 //

   499 // If jvmti is not enabled the constructor and destructor is essentially

   500 // a no-op (no overhead).

   501 //

   502 class JvmtiGCForAllocationMarker : public JvmtiGCMarker {

   503  public:

   504   JvmtiGCForAllocationMarker() : JvmtiGCMarker(false) {

   505   }

   506 };

   507 

   508 // Support class used to report GC events to JVMTI. The class is stack

   509 // allocated and should be placed in the doit() implementation of all

   510 // vm operations that do a "full" stop-the-world GC. This class differs

   511 // from JvmtiGCForAllocationMarker in that this class assumes that a

   512 // "full" GC will happen.

   513 //

   514 // Usage :-

   515 //

   516 // void VM_GenCollectFull::doit() {

   517 //   JvmtiGCFullMarker jgcm;

   518 //   :

   519 // }

   520 //

   521 class JvmtiGCFullMarker : public JvmtiGCMarker {

   522  public:

   523   JvmtiGCFullMarker() : JvmtiGCMarker(true) {

   524   }

   525 };

   526 

   527 

   528 // JvmtiHideSingleStepping is a helper class for hiding

   529 // internal single step events.

   530 class JvmtiHideSingleStepping : public StackObj {

   531  private:

   532   bool         _single_step_hidden;

   533   JavaThread * _thread;

   534 

   535  public:

   536   JvmtiHideSingleStepping(JavaThread * thread) {

   537     assert(thread != NULL, "sanity check");

   538 

   539     _single_step_hidden = false;

   540     _thread = thread;

   541     if (JvmtiExport::should_post_single_step()) {

   542       _single_step_hidden = JvmtiExport::hide_single_stepping(_thread);

   543     }

   544   }

   545 

   546   ~JvmtiHideSingleStepping() {

   547     if (_single_step_hidden) {

   548       JvmtiExport::expose_single_stepping(_thread);

   549     }

   550   }

   551 };

   552 

   553 #endif   /* _JAVA_JVMTIEXPORT_H_ */