view src/share/vm/prims/jvmtiTagMap.hpp @ 3992:d1bdeef3e3e2

7098282: G1: assert(interval >= 0) failed: Sanity check, referencePolicy.cpp: 76 Summary: There is a race between one thread successfully forwarding and copying the klass mirror for the SoftReference class (including the static master clock) and another thread attempting to use the master clock while attempting to discover a soft reference object. Maintain a shadow copy of the soft reference master clock and use the shadow during reference discovery and reference processing. Reviewed-by: tonyp, brutisso, ysr
author johnc
date Wed, 12 Oct 2011 10:25:51 -0700
parents 1d1603768966
children d2a62e0f25eb
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/*
 * Copyright (c) 2003, 2011, 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.
 *
 */

// JvmtiTagMap

#ifndef SHARE_VM_PRIMS_JVMTITAGMAP_HPP
#define SHARE_VM_PRIMS_JVMTITAGMAP_HPP

#ifndef JVMTI_KERNEL
#include "gc_interface/collectedHeap.hpp"
#include "jvmtifiles/jvmti.h"
#include "jvmtifiles/jvmtiEnv.hpp"
#include "memory/allocation.hpp"
#include "memory/genCollectedHeap.hpp"
#include "memory/universe.hpp"
#endif

// forward references
class JvmtiTagHashmap;
class JvmtiTagHashmapEntry;
class JvmtiTagHashmapEntryClosure;

class JvmtiTagMap :  public CHeapObj {
 private:

  enum{
    max_free_entries = 4096         // maximum number of free entries per env
  };

  JvmtiEnv*             _env;                       // the jvmti environment
  Mutex                 _lock;                      // lock for this tag map
  JvmtiTagHashmap*      _hashmap;                   // the hashmap

  JvmtiTagHashmapEntry* _free_entries;              // free list for this environment
  int _free_entries_count;                          // number of entries on the free list

  // create a tag map
  JvmtiTagMap(JvmtiEnv* env);

  // accessors
  inline Mutex* lock()                      { return &_lock; }
  inline JvmtiEnv* env() const              { return _env; }

  void do_weak_oops(BoolObjectClosure* is_alive, OopClosure* f);

  // iterate over all entries in this tag map
  void entry_iterate(JvmtiTagHashmapEntryClosure* closure);

 public:

  // indicates if this tag map is locked
  bool is_locked()                          { return lock()->is_locked(); }

  JvmtiTagHashmap* hashmap() { return _hashmap; }

  // create/destroy entries
  JvmtiTagHashmapEntry* create_entry(oop ref, jlong tag);
  void destroy_entry(JvmtiTagHashmapEntry* entry);

  // returns true if the hashmaps are empty
  bool is_empty();

  // return tag for the given environment
  static JvmtiTagMap* tag_map_for(JvmtiEnv* env);

  // destroy tag map
  ~JvmtiTagMap();

  // set/get tag
  void set_tag(jobject obj, jlong tag);
  jlong get_tag(jobject obj);

  // deprecated heap iteration functions
  void iterate_over_heap(jvmtiHeapObjectFilter object_filter,
                         KlassHandle klass,
                         jvmtiHeapObjectCallback heap_object_callback,
                         const void* user_data);

  void iterate_over_reachable_objects(jvmtiHeapRootCallback heap_root_callback,
                                      jvmtiStackReferenceCallback stack_ref_callback,
                                      jvmtiObjectReferenceCallback object_ref_callback,
                                      const void* user_data);

  void iterate_over_objects_reachable_from_object(jobject object,
                                                  jvmtiObjectReferenceCallback object_reference_callback,
                                                  const void* user_data);


  // advanced (JVMTI 1.1) heap iteration functions
  void iterate_through_heap(jint heap_filter,
                            KlassHandle klass,
                            const jvmtiHeapCallbacks* callbacks,
                            const void* user_data);

  void follow_references(jint heap_filter,
                         KlassHandle klass,
                         jobject initial_object,
                         const jvmtiHeapCallbacks* callbacks,
                         const void* user_data);

  // get tagged objects
  jvmtiError get_objects_with_tags(const jlong* tags, jint count,
                                   jint* count_ptr, jobject** object_result_ptr,
                                   jlong** tag_result_ptr);

  static void weak_oops_do(
      BoolObjectClosure* is_alive, OopClosure* f) KERNEL_RETURN;
};

#endif // SHARE_VM_PRIMS_JVMTITAGMAP_HPP