--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/share/vm/prims/jvmtiExport.hpp	Sat Dec 01 00:00:00 2007 +0000
@@ -0,0 +1,553 @@
+/*
+ * Copyright 1998-2006 Sun Microsystems, Inc.  All Rights Reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ *
+ */
+
+#ifndef _JAVA_JVMTIEXPORT_H_
+#define _JAVA_JVMTIEXPORT_H_
+
+// Forward declarations
+
+class JvmtiEventControllerPrivate;
+class JvmtiManageCapabilities;
+class JvmtiEnv;
+class JvmtiThreadState;
+class AttachOperation;
+
+#ifndef JVMTI_KERNEL
+#define JVMTI_SUPPORT_FLAG(key)                                         \
+  private:                                                              \
+  static bool  _##key;                                                  \
+  public:                                                               \
+  inline static void set_##key(bool on)       { _##key = (on != 0); }   \
+  inline static bool key()                    { return _##key; }
+#else  // JVMTI_KERNEL
+#define JVMTI_SUPPORT_FLAG(key)                                           \
+  private:                                                                \
+  const static bool _##key = false;                                       \
+  public:                                                                 \
+  inline static void set_##key(bool on)       { report_unsupported(on); } \
+  inline static bool key()                    { return _##key; }
+#endif // JVMTI_KERNEL
+
+
+// This class contains the JVMTI interface for the rest of hotspot.
+//
+class JvmtiExport : public AllStatic {
+ private:
+  static int         _field_access_count;
+  static int         _field_modification_count;
+
+  static bool        _can_access_local_variables;
+  static bool        _can_examine_or_deopt_anywhere;
+  static bool        _can_hotswap_or_post_breakpoint;
+  static bool        _can_modify_any_class;
+  static bool        _can_walk_any_space;
+
+  JVMTI_SUPPORT_FLAG(can_get_source_debug_extension)
+  JVMTI_SUPPORT_FLAG(can_maintain_original_method_order)
+  JVMTI_SUPPORT_FLAG(can_post_interpreter_events)
+  JVMTI_SUPPORT_FLAG(can_post_exceptions)
+  JVMTI_SUPPORT_FLAG(can_post_breakpoint)
+  JVMTI_SUPPORT_FLAG(can_post_field_access)
+  JVMTI_SUPPORT_FLAG(can_post_field_modification)
+  JVMTI_SUPPORT_FLAG(can_post_method_entry)
+  JVMTI_SUPPORT_FLAG(can_post_method_exit)
+  JVMTI_SUPPORT_FLAG(can_pop_frame)
+  JVMTI_SUPPORT_FLAG(can_force_early_return)
+
+  friend class JvmtiEventControllerPrivate;  // should only modify these flags
+  JVMTI_SUPPORT_FLAG(should_post_single_step)
+  JVMTI_SUPPORT_FLAG(should_post_field_access)
+  JVMTI_SUPPORT_FLAG(should_post_field_modification)
+  JVMTI_SUPPORT_FLAG(should_post_class_load)
+  JVMTI_SUPPORT_FLAG(should_post_class_prepare)
+  JVMTI_SUPPORT_FLAG(should_post_class_unload)
+  JVMTI_SUPPORT_FLAG(should_post_native_method_bind)
+  JVMTI_SUPPORT_FLAG(should_post_compiled_method_load)
+  JVMTI_SUPPORT_FLAG(should_post_compiled_method_unload)
+  JVMTI_SUPPORT_FLAG(should_post_dynamic_code_generated)
+  JVMTI_SUPPORT_FLAG(should_post_monitor_contended_enter)
+  JVMTI_SUPPORT_FLAG(should_post_monitor_contended_entered)
+  JVMTI_SUPPORT_FLAG(should_post_monitor_wait)
+  JVMTI_SUPPORT_FLAG(should_post_monitor_waited)
+  JVMTI_SUPPORT_FLAG(should_post_data_dump)
+  JVMTI_SUPPORT_FLAG(should_post_garbage_collection_start)
+  JVMTI_SUPPORT_FLAG(should_post_garbage_collection_finish)
+
+  // ------ the below maybe don't have to be (but are for now)
+  // fixed conditions here ------------
+  // any events can be enabled
+  JVMTI_SUPPORT_FLAG(should_post_thread_life)
+  JVMTI_SUPPORT_FLAG(should_post_object_free)
+  JVMTI_SUPPORT_FLAG(should_post_resource_exhausted)
+
+  // we are holding objects on the heap - need to talk to GC - e.g.
+  // breakpoint info
+  JVMTI_SUPPORT_FLAG(should_clean_up_heap_objects)
+  JVMTI_SUPPORT_FLAG(should_post_vm_object_alloc)
+
+  // If flag cannot be implemented, give an error if on=true
+  static void report_unsupported(bool on);
+
+  // these should only be called by the friend class
+  friend class JvmtiManageCapabilities;
+  inline static void set_can_examine_or_deopt_anywhere(bool on)        { _can_examine_or_deopt_anywhere = (on != 0); }
+  inline static void set_can_modify_any_class(bool on)                 { _can_modify_any_class = (on != 0); }
+  inline static void set_can_access_local_variables(bool on)           { _can_access_local_variables = (on != 0); }
+  inline static void set_can_hotswap_or_post_breakpoint(bool on)       { _can_hotswap_or_post_breakpoint = (on != 0); }
+  inline static void set_can_walk_any_space(bool on)                   { _can_walk_any_space = (on != 0); }
+
+  enum {
+    JVMTI_VERSION_MASK   = 0x70000000,
+    JVMTI_VERSION_VALUE  = 0x30000000,
+    JVMDI_VERSION_VALUE  = 0x20000000
+  };
+
+  static void post_field_modification(JavaThread *thread, methodOop method, address location,
+                                      KlassHandle field_klass, Handle object, jfieldID field,
+                                      char sig_type, jvalue *value);
+
+
+ private:
+  // CompiledMethodUnload events are reported from the VM thread so they
+  // are collected in lists (of jmethodID/addresses) and the events are posted later
+  // from threads posting CompieldMethodLoad or DynamicCodeGenerated events.
+  static bool _have_pending_compiled_method_unload_events;
+  static GrowableArray<jmethodID>* _pending_compiled_method_unload_method_ids;
+  static GrowableArray<const void *>* _pending_compiled_method_unload_code_begins;
+  static JavaThread* _current_poster;
+
+  // tests if there are CompiledMethodUnload events pending
+  inline static bool have_pending_compiled_method_unload_events() {
+    return _have_pending_compiled_method_unload_events;
+  }
+
+  // posts any pending CompiledMethodUnload events.
+  static void post_pending_compiled_method_unload_events();
+
+  // posts a DynamicCodeGenerated event (internal/private implementation).
+  // The public post_dynamic_code_generated* functions make use of the
+  // internal implementation.
+  static void post_dynamic_code_generated_internal(const char *name, const void *code_begin, const void *code_end) KERNEL_RETURN;
+
+
+  // GenerateEvents support to allow posting of CompiledMethodLoad and
+  // DynamicCodeGenerated events for a given environment.
+  friend class JvmtiCodeBlobEvents;
+
+  static void post_compiled_method_load(JvmtiEnv* env, const jmethodID method, const jint length,
+                                        const void *code_begin, const jint map_length,
+                                        const jvmtiAddrLocationMap* map) KERNEL_RETURN;
+  static void post_dynamic_code_generated(JvmtiEnv* env, const char *name, const void *code_begin,
+                                          const void *code_end) KERNEL_RETURN;
+
+  // The RedefineClasses() API breaks some invariants in the "regular"
+  // system. For example, there are sanity checks when GC'ing nmethods
+  // that require the containing class to be unloading. However, when a
+  // method is redefined, the old method and nmethod can become GC'able
+  // without the containing class unloading. The state of becoming
+  // GC'able can be asynchronous to the RedefineClasses() call since
+  // the old method may still be running and cannot be GC'ed until
+  // after all old invocations have finished. Additionally, a method
+  // that has not been redefined may have an nmethod that depends on
+  // the redefined method. The dependent nmethod will get deopted in
+  // this case and may also be GC'able without the containing class
+  // being unloaded.
+  //
+  // This flag indicates whether RedefineClasses() has ever redefined
+  // one or more classes during the lifetime of the VM. The flag should
+  // only be set by the friend class and can be queried by other sub
+  // systems as needed to relax invariant checks.
+  static bool _has_redefined_a_class;
+  friend class VM_RedefineClasses;
+  inline static void set_has_redefined_a_class() {
+    _has_redefined_a_class = true;
+  }
+
+  // Flag to indicate if the compiler has recorded all dependencies. When the
+  // can_redefine_classes capability is enabled in the OnLoad phase then the compiler
+  // records all dependencies from startup. However if the capability is first
+  // enabled some time later then the dependencies recorded by the compiler
+  // are incomplete. This flag is used by RedefineClasses to know if the
+  // dependency information is complete or not.
+  static bool _all_dependencies_are_recorded;
+
+ public:
+  inline static bool has_redefined_a_class() {
+    return _has_redefined_a_class;
+  }
+
+  inline static bool all_dependencies_are_recorded() {
+    return _all_dependencies_are_recorded;
+  }
+
+  inline static void set_all_dependencies_are_recorded(bool on) {
+    _all_dependencies_are_recorded = (on != 0);
+  }
+
+
+  // let JVMTI know that the JVM_OnLoad code is running
+  static void enter_onload_phase();
+
+  // let JVMTI know that the VM isn't up yet (and JVM_OnLoad code isn't running)
+  static void enter_primordial_phase();
+
+  // let JVMTI know that the VM isn't up yet but JNI is live
+  static void enter_start_phase();
+
+  // let JVMTI know that the VM is fully up and running now
+  static void enter_live_phase();
+
+  // ------ can_* conditions (below) are set at OnLoad and never changed ------------
+  inline static bool can_examine_or_deopt_anywhere()              { return _can_examine_or_deopt_anywhere; }
+  inline static bool can_modify_any_class()                       { return _can_modify_any_class; }
+  inline static bool can_access_local_variables()                 { return _can_access_local_variables; }
+  inline static bool can_hotswap_or_post_breakpoint()             { return _can_hotswap_or_post_breakpoint; }
+  inline static bool can_walk_any_space()                         { return _can_walk_any_space; }
+
+  // field access management
+  static address  get_field_access_count_addr();
+
+  // field modification management
+  static address  get_field_modification_count_addr();
+
+  // -----------------
+
+  static bool is_jvmti_version(jint version)                      { return (version & JVMTI_VERSION_MASK) == JVMTI_VERSION_VALUE; }
+  static bool is_jvmdi_version(jint version)                      { return (version & JVMTI_VERSION_MASK) == JVMDI_VERSION_VALUE; }
+  static jint get_jvmti_interface(JavaVM *jvm, void **penv, jint version);
+
+  // single stepping management methods
+  static void at_single_stepping_point(JavaThread *thread, methodOop method, address location) KERNEL_RETURN;
+  static void expose_single_stepping(JavaThread *thread) KERNEL_RETURN;
+  static bool hide_single_stepping(JavaThread *thread) KERNEL_RETURN_(return false;);
+
+  // Methods that notify the debugger that something interesting has happened in the VM.
+  static void post_vm_start              ();
+  static void post_vm_initialized        ();
+  static void post_vm_death              ();
+
+  static void post_single_step           (JavaThread *thread, methodOop method, address location) KERNEL_RETURN;
+  static void post_raw_breakpoint        (JavaThread *thread, methodOop method, address location) KERNEL_RETURN;
+
+  static void post_exception_throw       (JavaThread *thread, methodOop method, address location, oop exception) KERNEL_RETURN;
+  static void notice_unwind_due_to_exception (JavaThread *thread, methodOop method, address location, oop exception, bool in_handler_frame) KERNEL_RETURN;
+
+  static oop jni_GetField_probe          (JavaThread *thread, jobject jobj,
+    oop obj, klassOop klass, jfieldID fieldID, bool is_static)
+    KERNEL_RETURN_(return NULL;);
+  static oop jni_GetField_probe_nh       (JavaThread *thread, jobject jobj,
+    oop obj, klassOop klass, jfieldID fieldID, bool is_static)
+    KERNEL_RETURN_(return NULL;);
+  static void post_field_access_by_jni   (JavaThread *thread, oop obj,
+    klassOop klass, jfieldID fieldID, bool is_static) KERNEL_RETURN;
+  static void post_field_access          (JavaThread *thread, methodOop method,
+    address location, KlassHandle field_klass, Handle object, jfieldID field) KERNEL_RETURN;
+  static oop jni_SetField_probe          (JavaThread *thread, jobject jobj,
+    oop obj, klassOop klass, jfieldID fieldID, bool is_static, char sig_type,
+    jvalue *value) KERNEL_RETURN_(return NULL;);
+  static oop jni_SetField_probe_nh       (JavaThread *thread, jobject jobj,
+    oop obj, klassOop klass, jfieldID fieldID, bool is_static, char sig_type,
+    jvalue *value) KERNEL_RETURN_(return NULL;);
+  static void post_field_modification_by_jni(JavaThread *thread, oop obj,
+    klassOop klass, jfieldID fieldID, bool is_static, char sig_type,
+    jvalue *value);
+  static void post_raw_field_modification(JavaThread *thread, methodOop method,
+    address location, KlassHandle field_klass, Handle object, jfieldID field,
+    char sig_type, jvalue *value) KERNEL_RETURN;
+
+  static void post_method_entry          (JavaThread *thread, methodOop method, frame current_frame) KERNEL_RETURN;
+  static void post_method_exit           (JavaThread *thread, methodOop method, frame current_frame) KERNEL_RETURN;
+
+  static void post_class_load            (JavaThread *thread, klassOop klass) KERNEL_RETURN;
+  static void post_class_unload          (klassOop klass) KERNEL_RETURN;
+  static void post_class_prepare         (JavaThread *thread, klassOop klass) KERNEL_RETURN;
+
+  static void post_thread_start          (JavaThread *thread) KERNEL_RETURN;
+  static void post_thread_end            (JavaThread *thread) KERNEL_RETURN;
+
+  // Support for java.lang.instrument agent loading.
+  static bool _should_post_class_file_load_hook;
+  inline static void set_should_post_class_file_load_hook(bool on)     { _should_post_class_file_load_hook = on;  }
+  inline static bool should_post_class_file_load_hook()           { return _should_post_class_file_load_hook; }
+  static void post_class_file_load_hook(symbolHandle h_name, Handle class_loader,
+                                        Handle h_protection_domain,
+                                        unsigned char **data_ptr, unsigned char **end_ptr,
+                                        unsigned char **cached_data_ptr,
+                                        jint *cached_length_ptr);
+  static void post_native_method_bind(methodOop method, address* function_ptr) KERNEL_RETURN;
+  static void post_compiled_method_load(nmethod *nm) KERNEL_RETURN;
+  static void post_dynamic_code_generated(const char *name, const void *code_begin, const void *code_end) KERNEL_RETURN;
+
+  // used at a safepoint to post a CompiledMethodUnload event
+  static void post_compiled_method_unload_at_safepoint(jmethodID mid, const void *code_begin) KERNEL_RETURN;
+
+  // similiar to post_dynamic_code_generated except that it can be used to
+  // post a DynamicCodeGenerated event while holding locks in the VM. Any event
+  // posted using this function is recorded by the enclosing event collector
+  // -- JvmtiDynamicCodeEventCollector.
+  static void post_dynamic_code_generated_while_holding_locks(const char* name, address code_begin, address code_end) KERNEL_RETURN;
+
+  static void post_garbage_collection_finish() KERNEL_RETURN;
+  static void post_garbage_collection_start() KERNEL_RETURN;
+  static void post_data_dump() KERNEL_RETURN;
+  static void post_monitor_contended_enter(JavaThread *thread, ObjectMonitor *obj_mntr) KERNEL_RETURN;
+  static void post_monitor_contended_entered(JavaThread *thread, ObjectMonitor *obj_mntr) KERNEL_RETURN;
+  static void post_monitor_wait(JavaThread *thread, oop obj, jlong timeout) KERNEL_RETURN;
+  static void post_monitor_waited(JavaThread *thread, ObjectMonitor *obj_mntr, jboolean timed_out) KERNEL_RETURN;
+  static void post_object_free(JvmtiEnv* env, jlong tag) KERNEL_RETURN;
+  static void post_resource_exhausted(jint resource_exhausted_flags, const char* detail) KERNEL_RETURN;
+  static void record_vm_internal_object_allocation(oop object) KERNEL_RETURN;
+  // Post objects collected by vm_object_alloc_event_collector.
+  static void post_vm_object_alloc(JavaThread *thread, oop object) KERNEL_RETURN;
+  // Collects vm internal objects for later event posting.
+  inline static void vm_object_alloc_event_collector(oop object) {
+    if (should_post_vm_object_alloc()) {
+      record_vm_internal_object_allocation(object);
+    }
+  }
+
+  static void cleanup_thread             (JavaThread* thread) KERNEL_RETURN;
+
+  static void oops_do(OopClosure* f) KERNEL_RETURN;
+
+  static void transition_pending_onload_raw_monitors() KERNEL_RETURN;
+
+#ifndef SERVICES_KERNEL
+  // attach support
+  static jint load_agent_library(AttachOperation* op, outputStream* out);
+#endif // SERVICES_KERNEL
+
+  // SetNativeMethodPrefix support
+  static char** get_all_native_method_prefixes(int* count_ptr);
+
+  // call after CMS has completed referencing processing
+  static void cms_ref_processing_epilogue() KERNEL_RETURN;
+};
+
+// Support class used by JvmtiDynamicCodeEventCollector and others. It
+// describes a single code blob by name and address range.
+class JvmtiCodeBlobDesc : public CHeapObj {
+ private:
+  char _name[64];
+  address _code_begin;
+  address _code_end;
+
+ public:
+  JvmtiCodeBlobDesc(const char *name, address code_begin, address code_end) {
+    assert(name != NULL, "all code blobs must be named");
+    strncpy(_name, name, sizeof(_name));
+    _name[sizeof(_name)-1] = '\0';
+    _code_begin = code_begin;
+    _code_end = code_end;
+  }
+  char* name()                  { return _name; }
+  address code_begin()          { return _code_begin; }
+  address code_end()            { return _code_end; }
+};
+
+// JvmtiEventCollector is a helper class to setup thread for
+// event collection.
+class JvmtiEventCollector : public StackObj {
+ private:
+  JvmtiEventCollector* _prev;  // Save previous one to support nested event collector.
+
+ public:
+  void setup_jvmti_thread_state(); // Set this collector in current thread.
+  void unset_jvmti_thread_state(); // Reset previous collector in current thread.
+  virtual bool is_dynamic_code_event()   { return false; }
+  virtual bool is_vm_object_alloc_event(){ return false; }
+  JvmtiEventCollector *get_prev()        { return _prev; }
+};
+
+// A JvmtiDynamicCodeEventCollector is a helper class for the JvmtiExport
+// interface. It collects "dynamic code generated" events that are posted
+// while holding locks. When the event collector goes out of scope the
+// events will be posted.
+//
+// Usage :-
+//
+// {
+//   JvmtiDynamicCodeEventCollector event_collector;
+//   :
+//   { MutexLocker ml(...)
+//     :
+//     JvmtiExport::post_dynamic_code_generated_while_holding_locks(...)
+//   }
+//   // event collector goes out of scope => post events to profiler.
+// }
+
+class JvmtiDynamicCodeEventCollector : public JvmtiEventCollector {
+ private:
+  GrowableArray<JvmtiCodeBlobDesc*>* _code_blobs;           // collected code blob events
+
+  friend class JvmtiExport;
+  void register_stub(const char* name, address start, address end);
+
+ public:
+  JvmtiDynamicCodeEventCollector()  KERNEL_RETURN;
+  ~JvmtiDynamicCodeEventCollector() KERNEL_RETURN;
+  bool is_dynamic_code_event()   { return true; }
+
+};
+
+// Used to record vm internally allocated object oops and post
+// vm object alloc event for objects visible to java world.
+// Constructor enables JvmtiThreadState flag and all vm allocated
+// objects are recorded in a growable array. When destructor is
+// called the vm object alloc event is posted for each objects
+// visible to java world.
+// See jvm.cpp file for its usage.
+//
+class JvmtiVMObjectAllocEventCollector : public JvmtiEventCollector {
+ private:
+  GrowableArray<oop>* _allocated; // field to record vm internally allocated object oop.
+  bool _enable;                   // This flag is enabled in constructor and disabled
+                                  // in destructor before posting event. To avoid
+                                  // collection of objects allocated while running java code inside
+                                  // agent post_vm_object_alloc() event handler.
+
+  //GC support
+  void oops_do(OopClosure* f);
+
+  friend class JvmtiExport;
+  // Record vm allocated object oop.
+  inline void record_allocation(oop obj);
+
+  //GC support
+  static void oops_do_for_all_threads(OopClosure* f);
+
+ public:
+  JvmtiVMObjectAllocEventCollector()  KERNEL_RETURN;
+  ~JvmtiVMObjectAllocEventCollector() KERNEL_RETURN;
+  bool is_vm_object_alloc_event()   { return true; }
+
+  bool is_enabled()                 { return _enable; }
+  void set_enabled(bool on)         { _enable = on; }
+};
+
+
+
+// Marker class to disable the posting of VMObjectAlloc events
+// within its scope.
+//
+// Usage :-
+//
+// {
+//   NoJvmtiVMObjectAllocMark njm;
+//   :
+//   // VMObjAlloc event will not be posted
+//   JvmtiExport::vm_object_alloc_event_collector(obj);
+//   :
+// }
+
+class NoJvmtiVMObjectAllocMark : public StackObj {
+ private:
+  // enclosing collector if enabled, NULL otherwise
+  JvmtiVMObjectAllocEventCollector *_collector;
+
+  bool was_enabled()    { return _collector != NULL; }
+
+ public:
+  NoJvmtiVMObjectAllocMark() KERNEL_RETURN;
+  ~NoJvmtiVMObjectAllocMark() KERNEL_RETURN;
+};
+
+
+// Base class for reporting GC events to JVMTI.
+class JvmtiGCMarker : public StackObj {
+ private:
+  bool _full;                           // marks a "full" GC
+  unsigned int _invocation_count;       // GC invocation count
+ protected:
+  JvmtiGCMarker(bool full) KERNEL_RETURN;       // protected
+  ~JvmtiGCMarker() KERNEL_RETURN;               // protected
+};
+
+
+// Support class used to report GC events to JVMTI. The class is stack
+// allocated and should be placed in the doit() implementation of all
+// vm operations that do a stop-the-world GC for failed allocation.
+//
+// Usage :-
+//
+// void VM_GenCollectForAllocation::doit() {
+//   JvmtiGCForAllocationMarker jgcm;
+//   :
+// }
+//
+// If jvmti is not enabled the constructor and destructor is essentially
+// a no-op (no overhead).
+//
+class JvmtiGCForAllocationMarker : public JvmtiGCMarker {
+ public:
+  JvmtiGCForAllocationMarker() : JvmtiGCMarker(false) {
+  }
+};
+
+// Support class used to report GC events to JVMTI. The class is stack
+// allocated and should be placed in the doit() implementation of all
+// vm operations that do a "full" stop-the-world GC. This class differs
+// from JvmtiGCForAllocationMarker in that this class assumes that a
+// "full" GC will happen.
+//
+// Usage :-
+//
+// void VM_GenCollectFull::doit() {
+//   JvmtiGCFullMarker jgcm;
+//   :
+// }
+//
+class JvmtiGCFullMarker : public JvmtiGCMarker {
+ public:
+  JvmtiGCFullMarker() : JvmtiGCMarker(true) {
+  }
+};
+
+
+// JvmtiHideSingleStepping is a helper class for hiding
+// internal single step events.
+class JvmtiHideSingleStepping : public StackObj {
+ private:
+  bool         _single_step_hidden;
+  JavaThread * _thread;
+
+ public:
+  JvmtiHideSingleStepping(JavaThread * thread) {
+    assert(thread != NULL, "sanity check");
+
+    _single_step_hidden = false;
+    _thread = thread;
+    if (JvmtiExport::should_post_single_step()) {
+      _single_step_hidden = JvmtiExport::hide_single_stepping(_thread);
+    }
+  }
+
+  ~JvmtiHideSingleStepping() {
+    if (_single_step_hidden) {
+      JvmtiExport::expose_single_stepping(_thread);
+    }
+  }
+};
+
+#endif   /* _JAVA_JVMTIEXPORT_H_ */