src/share/vm/prims/jvmtiExport.hpp

Mon, 01 Feb 2010 17:35:05 -0700

author
dcubed
date
Mon, 01 Feb 2010 17:35:05 -0700
changeset 1648
6deeaebad47a
parent 1556
98cd9901c161
child 1832
b4776199210f
permissions
-rw-r--r--

6902182: 4/4 Starting with jdwp agent should not incur performance penalty
Summary: Rename can_post_exceptions support to can_post_on_exceptions. Add support for should_post_on_exceptions flag to permit per JavaThread optimizations.
Reviewed-by: never, kvn, dcubed
Contributed-by: tom.deneau@amd.com

     1 /*
     2  * Copyright 1998-2010 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  */
    25 #ifndef _JAVA_JVMTIEXPORT_H_
    26 #define _JAVA_JVMTIEXPORT_H_
    28 // Forward declarations
    30 class JvmtiEventControllerPrivate;
    31 class JvmtiManageCapabilities;
    32 class JvmtiEnv;
    33 class JvmtiThreadState;
    34 class AttachOperation;
    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
    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;
    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;
    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_on_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)
    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   JVMTI_SUPPORT_FLAG(should_post_on_exceptions)
    98   // ------ the below maybe don't have to be (but are for now)
    99   // fixed conditions here ------------
   100   // any events can be enabled
   101   JVMTI_SUPPORT_FLAG(should_post_thread_life)
   102   JVMTI_SUPPORT_FLAG(should_post_object_free)
   103   JVMTI_SUPPORT_FLAG(should_post_resource_exhausted)
   105   // we are holding objects on the heap - need to talk to GC - e.g.
   106   // breakpoint info
   107   JVMTI_SUPPORT_FLAG(should_clean_up_heap_objects)
   108   JVMTI_SUPPORT_FLAG(should_post_vm_object_alloc)
   110   // If flag cannot be implemented, give an error if on=true
   111   static void report_unsupported(bool on);
   113   // these should only be called by the friend class
   114   friend class JvmtiManageCapabilities;
   115   inline static void set_can_examine_or_deopt_anywhere(bool on)        { _can_examine_or_deopt_anywhere = (on != 0); }
   116   inline static void set_can_modify_any_class(bool on)                 { _can_modify_any_class = (on != 0); }
   117   inline static void set_can_access_local_variables(bool on)           { _can_access_local_variables = (on != 0); }
   118   inline static void set_can_hotswap_or_post_breakpoint(bool on)       { _can_hotswap_or_post_breakpoint = (on != 0); }
   119   inline static void set_can_walk_any_space(bool on)                   { _can_walk_any_space = (on != 0); }
   121   enum {
   122     JVMTI_VERSION_MASK   = 0x70000000,
   123     JVMTI_VERSION_VALUE  = 0x30000000,
   124     JVMDI_VERSION_VALUE  = 0x20000000
   125   };
   127   static void post_field_modification(JavaThread *thread, methodOop method, address location,
   128                                       KlassHandle field_klass, Handle object, jfieldID field,
   129                                       char sig_type, jvalue *value);
   132  private:
   133   // CompiledMethodUnload events are reported from the VM thread so they
   134   // are collected in lists (of jmethodID/addresses) and the events are posted later
   135   // from threads posting CompieldMethodLoad or DynamicCodeGenerated events.
   136   static bool _have_pending_compiled_method_unload_events;
   137   static GrowableArray<jmethodID>* _pending_compiled_method_unload_method_ids;
   138   static GrowableArray<const void *>* _pending_compiled_method_unload_code_begins;
   139   static JavaThread* _current_poster;
   141   // tests if there are CompiledMethodUnload events pending
   142   inline static bool have_pending_compiled_method_unload_events() {
   143     return _have_pending_compiled_method_unload_events;
   144   }
   146   // posts any pending CompiledMethodUnload events.
   147   static void post_pending_compiled_method_unload_events();
   149   // posts a DynamicCodeGenerated event (internal/private implementation).
   150   // The public post_dynamic_code_generated* functions make use of the
   151   // internal implementation.
   152   static void post_dynamic_code_generated_internal(const char *name, const void *code_begin, const void *code_end) KERNEL_RETURN;
   155   // GenerateEvents support to allow posting of CompiledMethodLoad and
   156   // DynamicCodeGenerated events for a given environment.
   157   friend class JvmtiCodeBlobEvents;
   159   static void post_compiled_method_load(JvmtiEnv* env, const jmethodID method, const jint length,
   160                                         const void *code_begin, const jint map_length,
   161                                         const jvmtiAddrLocationMap* map) KERNEL_RETURN;
   162   static void post_dynamic_code_generated(JvmtiEnv* env, const char *name, const void *code_begin,
   163                                           const void *code_end) KERNEL_RETURN;
   165   // The RedefineClasses() API breaks some invariants in the "regular"
   166   // system. For example, there are sanity checks when GC'ing nmethods
   167   // that require the containing class to be unloading. However, when a
   168   // method is redefined, the old method and nmethod can become GC'able
   169   // without the containing class unloading. The state of becoming
   170   // GC'able can be asynchronous to the RedefineClasses() call since
   171   // the old method may still be running and cannot be GC'ed until
   172   // after all old invocations have finished. Additionally, a method
   173   // that has not been redefined may have an nmethod that depends on
   174   // the redefined method. The dependent nmethod will get deopted in
   175   // this case and may also be GC'able without the containing class
   176   // being unloaded.
   177   //
   178   // This flag indicates whether RedefineClasses() has ever redefined
   179   // one or more classes during the lifetime of the VM. The flag should
   180   // only be set by the friend class and can be queried by other sub
   181   // systems as needed to relax invariant checks.
   182   static bool _has_redefined_a_class;
   183   friend class VM_RedefineClasses;
   184   inline static void set_has_redefined_a_class() {
   185     _has_redefined_a_class = true;
   186   }
   188   // Flag to indicate if the compiler has recorded all dependencies. When the
   189   // can_redefine_classes capability is enabled in the OnLoad phase then the compiler
   190   // records all dependencies from startup. However if the capability is first
   191   // enabled some time later then the dependencies recorded by the compiler
   192   // are incomplete. This flag is used by RedefineClasses to know if the
   193   // dependency information is complete or not.
   194   static bool _all_dependencies_are_recorded;
   196  public:
   197   inline static bool has_redefined_a_class() {
   198     return _has_redefined_a_class;
   199   }
   201   inline static bool all_dependencies_are_recorded() {
   202     return _all_dependencies_are_recorded;
   203   }
   205   inline static void set_all_dependencies_are_recorded(bool on) {
   206     _all_dependencies_are_recorded = (on != 0);
   207   }
   210   // let JVMTI know that the JVM_OnLoad code is running
   211   static void enter_onload_phase();
   213   // let JVMTI know that the VM isn't up yet (and JVM_OnLoad code isn't running)
   214   static void enter_primordial_phase();
   216   // let JVMTI know that the VM isn't up yet but JNI is live
   217   static void enter_start_phase();
   219   // let JVMTI know that the VM is fully up and running now
   220   static void enter_live_phase();
   222   // ------ can_* conditions (below) are set at OnLoad and never changed ------------
   223   inline static bool can_examine_or_deopt_anywhere()              { return _can_examine_or_deopt_anywhere; }
   224   inline static bool can_modify_any_class()                       { return _can_modify_any_class; }
   225   inline static bool can_access_local_variables()                 { return _can_access_local_variables; }
   226   inline static bool can_hotswap_or_post_breakpoint()             { return _can_hotswap_or_post_breakpoint; }
   227   inline static bool can_walk_any_space()                         { return _can_walk_any_space; }
   229   // field access management
   230   static address  get_field_access_count_addr();
   232   // field modification management
   233   static address  get_field_modification_count_addr();
   235   // -----------------
   237   static bool is_jvmti_version(jint version)                      { return (version & JVMTI_VERSION_MASK) == JVMTI_VERSION_VALUE; }
   238   static bool is_jvmdi_version(jint version)                      { return (version & JVMTI_VERSION_MASK) == JVMDI_VERSION_VALUE; }
   239   static jint get_jvmti_interface(JavaVM *jvm, void **penv, jint version);
   240   static void decode_version_values(jint version, int * major, int * minor,
   241                                     int * micro);
   243   // single stepping management methods
   244   static void at_single_stepping_point(JavaThread *thread, methodOop method, address location) KERNEL_RETURN;
   245   static void expose_single_stepping(JavaThread *thread) KERNEL_RETURN;
   246   static bool hide_single_stepping(JavaThread *thread) KERNEL_RETURN_(return false;);
   248   // Methods that notify the debugger that something interesting has happened in the VM.
   249   static void post_vm_start              ();
   250   static void post_vm_initialized        ();
   251   static void post_vm_death              ();
   253   static void post_single_step           (JavaThread *thread, methodOop method, address location) KERNEL_RETURN;
   254   static void post_raw_breakpoint        (JavaThread *thread, methodOop method, address location) KERNEL_RETURN;
   256   static void post_exception_throw       (JavaThread *thread, methodOop method, address location, oop exception) KERNEL_RETURN;
   257   static void notice_unwind_due_to_exception (JavaThread *thread, methodOop method, address location, oop exception, bool in_handler_frame) KERNEL_RETURN;
   259   static oop jni_GetField_probe          (JavaThread *thread, jobject jobj,
   260     oop obj, klassOop klass, jfieldID fieldID, bool is_static)
   261     KERNEL_RETURN_(return NULL;);
   262   static oop jni_GetField_probe_nh       (JavaThread *thread, jobject jobj,
   263     oop obj, klassOop klass, jfieldID fieldID, bool is_static)
   264     KERNEL_RETURN_(return NULL;);
   265   static void post_field_access_by_jni   (JavaThread *thread, oop obj,
   266     klassOop klass, jfieldID fieldID, bool is_static) KERNEL_RETURN;
   267   static void post_field_access          (JavaThread *thread, methodOop method,
   268     address location, KlassHandle field_klass, Handle object, jfieldID field) KERNEL_RETURN;
   269   static oop jni_SetField_probe          (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 oop jni_SetField_probe_nh       (JavaThread *thread, jobject jobj,
   273     oop obj, klassOop klass, jfieldID fieldID, bool is_static, char sig_type,
   274     jvalue *value) KERNEL_RETURN_(return NULL;);
   275   static void post_field_modification_by_jni(JavaThread *thread, oop obj,
   276     klassOop klass, jfieldID fieldID, bool is_static, char sig_type,
   277     jvalue *value);
   278   static void post_raw_field_modification(JavaThread *thread, methodOop method,
   279     address location, KlassHandle field_klass, Handle object, jfieldID field,
   280     char sig_type, jvalue *value) KERNEL_RETURN;
   282   static void post_method_entry          (JavaThread *thread, methodOop method, frame current_frame) KERNEL_RETURN;
   283   static void post_method_exit           (JavaThread *thread, methodOop method, frame current_frame) KERNEL_RETURN;
   285   static void post_class_load            (JavaThread *thread, klassOop klass) KERNEL_RETURN;
   286   static void post_class_unload          (klassOop klass) KERNEL_RETURN;
   287   static void post_class_prepare         (JavaThread *thread, klassOop klass) KERNEL_RETURN;
   289   static void post_thread_start          (JavaThread *thread) KERNEL_RETURN;
   290   static void post_thread_end            (JavaThread *thread) KERNEL_RETURN;
   292   // Support for java.lang.instrument agent loading.
   293   static bool _should_post_class_file_load_hook;
   294   inline static void set_should_post_class_file_load_hook(bool on)     { _should_post_class_file_load_hook = on;  }
   295   inline static bool should_post_class_file_load_hook()           { return _should_post_class_file_load_hook; }
   296   static void post_class_file_load_hook(symbolHandle h_name, Handle class_loader,
   297                                         Handle h_protection_domain,
   298                                         unsigned char **data_ptr, unsigned char **end_ptr,
   299                                         unsigned char **cached_data_ptr,
   300                                         jint *cached_length_ptr);
   301   static void post_native_method_bind(methodOop method, address* function_ptr) KERNEL_RETURN;
   302   static void post_compiled_method_load(nmethod *nm) KERNEL_RETURN;
   303   static void post_dynamic_code_generated(const char *name, const void *code_begin, const void *code_end) KERNEL_RETURN;
   305   // used at a safepoint to post a CompiledMethodUnload event
   306   static void post_compiled_method_unload_at_safepoint(jmethodID mid, const void *code_begin) KERNEL_RETURN;
   308   // similiar to post_dynamic_code_generated except that it can be used to
   309   // post a DynamicCodeGenerated event while holding locks in the VM. Any event
   310   // posted using this function is recorded by the enclosing event collector
   311   // -- JvmtiDynamicCodeEventCollector.
   312   static void post_dynamic_code_generated_while_holding_locks(const char* name, address code_begin, address code_end) KERNEL_RETURN;
   314   static void post_garbage_collection_finish() KERNEL_RETURN;
   315   static void post_garbage_collection_start() KERNEL_RETURN;
   316   static void post_data_dump() KERNEL_RETURN;
   317   static void post_monitor_contended_enter(JavaThread *thread, ObjectMonitor *obj_mntr) KERNEL_RETURN;
   318   static void post_monitor_contended_entered(JavaThread *thread, ObjectMonitor *obj_mntr) KERNEL_RETURN;
   319   static void post_monitor_wait(JavaThread *thread, oop obj, jlong timeout) KERNEL_RETURN;
   320   static void post_monitor_waited(JavaThread *thread, ObjectMonitor *obj_mntr, jboolean timed_out) KERNEL_RETURN;
   321   static void post_object_free(JvmtiEnv* env, jlong tag) KERNEL_RETURN;
   322   static void post_resource_exhausted(jint resource_exhausted_flags, const char* detail) KERNEL_RETURN;
   323   static void record_vm_internal_object_allocation(oop object) KERNEL_RETURN;
   324   // Post objects collected by vm_object_alloc_event_collector.
   325   static void post_vm_object_alloc(JavaThread *thread, oop object) KERNEL_RETURN;
   326   // Collects vm internal objects for later event posting.
   327   inline static void vm_object_alloc_event_collector(oop object) {
   328     if (should_post_vm_object_alloc()) {
   329       record_vm_internal_object_allocation(object);
   330     }
   331   }
   333   static void cleanup_thread             (JavaThread* thread) KERNEL_RETURN;
   335   static void oops_do(OopClosure* f) KERNEL_RETURN;
   337   static void transition_pending_onload_raw_monitors() KERNEL_RETURN;
   339 #ifndef SERVICES_KERNEL
   340   // attach support
   341   static jint load_agent_library(AttachOperation* op, outputStream* out);
   342 #endif // SERVICES_KERNEL
   344   // SetNativeMethodPrefix support
   345   static char** get_all_native_method_prefixes(int* count_ptr);
   347   // call after CMS has completed referencing processing
   348   static void cms_ref_processing_epilogue() KERNEL_RETURN;
   349 };
   351 // Support class used by JvmtiDynamicCodeEventCollector and others. It
   352 // describes a single code blob by name and address range.
   353 class JvmtiCodeBlobDesc : public CHeapObj {
   354  private:
   355   char _name[64];
   356   address _code_begin;
   357   address _code_end;
   359  public:
   360   JvmtiCodeBlobDesc(const char *name, address code_begin, address code_end) {
   361     assert(name != NULL, "all code blobs must be named");
   362     strncpy(_name, name, sizeof(_name));
   363     _name[sizeof(_name)-1] = '\0';
   364     _code_begin = code_begin;
   365     _code_end = code_end;
   366   }
   367   char* name()                  { return _name; }
   368   address code_begin()          { return _code_begin; }
   369   address code_end()            { return _code_end; }
   370 };
   372 // JvmtiEventCollector is a helper class to setup thread for
   373 // event collection.
   374 class JvmtiEventCollector : public StackObj {
   375  private:
   376   JvmtiEventCollector* _prev;  // Save previous one to support nested event collector.
   378  public:
   379   void setup_jvmti_thread_state(); // Set this collector in current thread.
   380   void unset_jvmti_thread_state(); // Reset previous collector in current thread.
   381   virtual bool is_dynamic_code_event()   { return false; }
   382   virtual bool is_vm_object_alloc_event(){ return false; }
   383   JvmtiEventCollector *get_prev()        { return _prev; }
   384 };
   386 // A JvmtiDynamicCodeEventCollector is a helper class for the JvmtiExport
   387 // interface. It collects "dynamic code generated" events that are posted
   388 // while holding locks. When the event collector goes out of scope the
   389 // events will be posted.
   390 //
   391 // Usage :-
   392 //
   393 // {
   394 //   JvmtiDynamicCodeEventCollector event_collector;
   395 //   :
   396 //   { MutexLocker ml(...)
   397 //     :
   398 //     JvmtiExport::post_dynamic_code_generated_while_holding_locks(...)
   399 //   }
   400 //   // event collector goes out of scope => post events to profiler.
   401 // }
   403 class JvmtiDynamicCodeEventCollector : public JvmtiEventCollector {
   404  private:
   405   GrowableArray<JvmtiCodeBlobDesc*>* _code_blobs;           // collected code blob events
   407   friend class JvmtiExport;
   408   void register_stub(const char* name, address start, address end);
   410  public:
   411   JvmtiDynamicCodeEventCollector()  KERNEL_RETURN;
   412   ~JvmtiDynamicCodeEventCollector() KERNEL_RETURN;
   413   bool is_dynamic_code_event()   { return true; }
   415 };
   417 // Used to record vm internally allocated object oops and post
   418 // vm object alloc event for objects visible to java world.
   419 // Constructor enables JvmtiThreadState flag and all vm allocated
   420 // objects are recorded in a growable array. When destructor is
   421 // called the vm object alloc event is posted for each objects
   422 // visible to java world.
   423 // See jvm.cpp file for its usage.
   424 //
   425 class JvmtiVMObjectAllocEventCollector : public JvmtiEventCollector {
   426  private:
   427   GrowableArray<oop>* _allocated; // field to record vm internally allocated object oop.
   428   bool _enable;                   // This flag is enabled in constructor and disabled
   429                                   // in destructor before posting event. To avoid
   430                                   // collection of objects allocated while running java code inside
   431                                   // agent post_vm_object_alloc() event handler.
   433   //GC support
   434   void oops_do(OopClosure* f);
   436   friend class JvmtiExport;
   437   // Record vm allocated object oop.
   438   inline void record_allocation(oop obj);
   440   //GC support
   441   static void oops_do_for_all_threads(OopClosure* f);
   443  public:
   444   JvmtiVMObjectAllocEventCollector()  KERNEL_RETURN;
   445   ~JvmtiVMObjectAllocEventCollector() KERNEL_RETURN;
   446   bool is_vm_object_alloc_event()   { return true; }
   448   bool is_enabled()                 { return _enable; }
   449   void set_enabled(bool on)         { _enable = on; }
   450 };
   454 // Marker class to disable the posting of VMObjectAlloc events
   455 // within its scope.
   456 //
   457 // Usage :-
   458 //
   459 // {
   460 //   NoJvmtiVMObjectAllocMark njm;
   461 //   :
   462 //   // VMObjAlloc event will not be posted
   463 //   JvmtiExport::vm_object_alloc_event_collector(obj);
   464 //   :
   465 // }
   467 class NoJvmtiVMObjectAllocMark : public StackObj {
   468  private:
   469   // enclosing collector if enabled, NULL otherwise
   470   JvmtiVMObjectAllocEventCollector *_collector;
   472   bool was_enabled()    { return _collector != NULL; }
   474  public:
   475   NoJvmtiVMObjectAllocMark() KERNEL_RETURN;
   476   ~NoJvmtiVMObjectAllocMark() KERNEL_RETURN;
   477 };
   480 // Base class for reporting GC events to JVMTI.
   481 class JvmtiGCMarker : public StackObj {
   482  private:
   483   bool _full;                           // marks a "full" GC
   484   unsigned int _invocation_count;       // GC invocation count
   485  protected:
   486   JvmtiGCMarker(bool full) KERNEL_RETURN;       // protected
   487   ~JvmtiGCMarker() KERNEL_RETURN;               // protected
   488 };
   491 // Support class used to report GC events to JVMTI. The class is stack
   492 // allocated and should be placed in the doit() implementation of all
   493 // vm operations that do a stop-the-world GC for failed allocation.
   494 //
   495 // Usage :-
   496 //
   497 // void VM_GenCollectForAllocation::doit() {
   498 //   JvmtiGCForAllocationMarker jgcm;
   499 //   :
   500 // }
   501 //
   502 // If jvmti is not enabled the constructor and destructor is essentially
   503 // a no-op (no overhead).
   504 //
   505 class JvmtiGCForAllocationMarker : public JvmtiGCMarker {
   506  public:
   507   JvmtiGCForAllocationMarker() : JvmtiGCMarker(false) {
   508   }
   509 };
   511 // Support class used to report GC events to JVMTI. The class is stack
   512 // allocated and should be placed in the doit() implementation of all
   513 // vm operations that do a "full" stop-the-world GC. This class differs
   514 // from JvmtiGCForAllocationMarker in that this class assumes that a
   515 // "full" GC will happen.
   516 //
   517 // Usage :-
   518 //
   519 // void VM_GenCollectFull::doit() {
   520 //   JvmtiGCFullMarker jgcm;
   521 //   :
   522 // }
   523 //
   524 class JvmtiGCFullMarker : public JvmtiGCMarker {
   525  public:
   526   JvmtiGCFullMarker() : JvmtiGCMarker(true) {
   527   }
   528 };
   531 // JvmtiHideSingleStepping is a helper class for hiding
   532 // internal single step events.
   533 class JvmtiHideSingleStepping : public StackObj {
   534  private:
   535   bool         _single_step_hidden;
   536   JavaThread * _thread;
   538  public:
   539   JvmtiHideSingleStepping(JavaThread * thread) {
   540     assert(thread != NULL, "sanity check");
   542     _single_step_hidden = false;
   543     _thread = thread;
   544     if (JvmtiExport::should_post_single_step()) {
   545       _single_step_hidden = JvmtiExport::hide_single_stepping(_thread);
   546     }
   547   }
   549   ~JvmtiHideSingleStepping() {
   550     if (_single_step_hidden) {
   551       JvmtiExport::expose_single_stepping(_thread);
   552     }
   553   }
   554 };
   556 #endif   /* _JAVA_JVMTIEXPORT_H_ */

mercurial