view src/share/vm/prims/jvmtiEnvThreadState.hpp @ 1716:be3f9c242c9d

6948538: CMS: BOT walkers can fall into object allocation and initialization cracks Summary: GC workers now recognize an intermediate transient state of blocks which are allocated but have not yet completed initialization. blk_start() calls do not attempt to determine the size of a block in the transient state, rather waiting for the block to become initialized so that it is safe to query its size. Audited and ensured the order of initialization of object fields (klass, free bit and size) to respect block state transition protocol. Also included some new assertion checking code enabled in debug mode. Reviewed-by: chrisphi, johnc, poonam
author ysr
date Mon, 16 Aug 2010 15:58:42 -0700
parents 126ea7725993
children f95d63e2154a
line wrap: on
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/*
 * Copyright (c) 2003, 2006, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 *
 */
#ifndef _JAVA_JVMTIENVTHREADSTATE_H_
#define _JAVA_JVMTIENVTHREADSTATE_H_

class JvmtiEnv;

///////////////////////////////////////////////////////////////
//
// class JvmtiFramePop
// Used by              : JvmtiFramePops
// Used by JVMTI methods: none directly.
//
// Wrapper class for FramePop, used in the JvmtiFramePops class.
//
// Two problems: 1) this isn't being used as a ValueObj class, in
// several places there are constructors for it. 2) It seems like
// overkill as a means to get an assert and name the geater than
// operator.  I'm trying to to rewrite everything.

class JvmtiFramePop VALUE_OBJ_CLASS_SPEC {
 private:
  // Frame number counting from BOTTOM (oldest) frame;
  // bottom frame == #0
  int _frame_number;
 public:
  JvmtiFramePop() {}
  JvmtiFramePop(int frame_number) {
    assert(frame_number >= 0, "invalid frame number");
    _frame_number = frame_number;
  }

  int frame_number() { return _frame_number; }
  int above_on_stack(JvmtiFramePop& other) { return _frame_number > other._frame_number; }
  void print() PRODUCT_RETURN;
};


///////////////////////////////////////////////////////////////
//
// class JvmtiFramePops
// Used by              : JvmtiThreadState
// Used by JVMTI methods: none directly.
//
// A collection of JvmtiFramePop.
// It records what frames on a threads stack should post frame_pop events when they're exited.
//

class JvmtiFramePops : public CHeapObj {
 private:
  GrowableArray<int>* _pops;

  // should only be used by JvmtiEventControllerPrivate
  // to insure they only occur at safepoints.
  // Todo: add checks for safepoint
  friend class JvmtiEventControllerPrivate;
  void set(JvmtiFramePop& fp);
  void clear(JvmtiFramePop& fp);
  int clear_to(JvmtiFramePop& fp);

 public:
  JvmtiFramePops();
  ~JvmtiFramePops();

  bool contains(JvmtiFramePop& fp) { return _pops->contains(fp.frame_number()); }
  int length() { return _pops->length(); }
  void print() PRODUCT_RETURN;
};


///////////////////////////////////////////////////////////////
//
// class JvmtiEnvThreadState
//
// 2. Cache of pending frame_pop_events, created by NotifyFramePop
//    and lazily initialized.
// 3: Location of last executed instruction, used to filter out duplicate
//    events due to instruction rewriting.

class JvmtiEnvThreadState : public CHeapObj {
private:
  friend class JvmtiEnv;
  JavaThread        *_thread;
  JvmtiEnv          *_env;
  JvmtiEnvThreadState *_next;
  jmethodID         _current_method_id;
  int               _current_bci;
  bool              _breakpoint_posted;
  bool              _single_stepping_posted;
  JvmtiEnvThreadEventEnable _event_enable;
  void              *_agent_thread_local_storage_data; // per env and per thread agent allocated data.

  // Class used to store pending framepops.
  // lazily initialized by get_frame_pops();
  JvmtiFramePops *_frame_pops;

  inline void set_current_location(jmethodID method_id, int bci) {
    _current_method_id = method_id;
    _current_bci  = bci;
  }

  friend class JvmtiEnvThreadStateIterator;
  JvmtiEnvThreadState* next() { return _next; }

  friend class JvmtiThreadState;
  void set_next(JvmtiEnvThreadState* link) { _next = link; }

public:
  JvmtiEnvThreadState(JavaThread *thread, JvmtiEnvBase *env);
  ~JvmtiEnvThreadState();

  bool is_enabled(jvmtiEvent event_type) { return _event_enable.is_enabled(event_type); }

  JvmtiEnvThreadEventEnable *event_enable() { return &_event_enable; }
  void *get_agent_thread_local_storage_data() { return _agent_thread_local_storage_data; }
  void set_agent_thread_local_storage_data (void *data) { _agent_thread_local_storage_data = data; }


  // If the thread is in the given method at the given
  // location just return.  Otherwise, reset the current location
  // and reset _breakpoint_posted and _single_stepping_posted.
  // _breakpoint_posted and _single_stepping_posted are only cleared
  // here.
  void compare_and_set_current_location(methodOop method, address location, jvmtiEvent event);

  void clear_current_location() { set_current_location((jmethodID)NULL, 0); }

  void reset_current_location(jvmtiEvent event, bool enabled);

  inline void set_breakpoint_posted()  { _breakpoint_posted = true; }
  inline void set_single_stepping_posted() {
    _single_stepping_posted = true;
  }
  inline bool breakpoint_posted() { return _breakpoint_posted; }
  inline bool single_stepping_posted() {
    return _single_stepping_posted;
  }

  inline JavaThread *get_thread() { return _thread; }
  inline JvmtiEnv *get_env() { return _env; }

  // lazily initialize _frame_pops
  JvmtiFramePops* get_frame_pops();

  bool has_frame_pops();

  // quickly test whether we should deliver a frame pop event on return from sp
  bool is_frame_pop(int cur_stack_depth);

  void set_frame_pop(int frame_number);
  void clear_frame_pop(int frame_number);
  void clear_to_frame_pop(int frame_number);

};

#endif   /* _JAVA_JVMTIENVTHREADSTATE_H_ */