view src/share/vm/gc_implementation/g1/g1SATBCardTableModRefBS.cpp @ 364:919e7959392a

6742641: G1: NullPointerException during GCOld Summary: An update buffer is not processed correctly, which causes roots into the collection set not to be scanned and, hence, for the heap to be corrupted. The cause is that an object is accessed after it has been explicitly deleted, which causes a race. Reviewed-by: jcoomes, ysr
author tonyp
date Mon, 22 Sep 2008 09:56:49 -0400
parents 37f87013dfd8
children df6caf649ff7
line wrap: on
line source

/*
 * Copyright 2001-2007 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.
 *
 */

#include "incls/_precompiled.incl"
#include "incls/_g1SATBCardTableModRefBS.cpp.incl"

G1SATBCardTableModRefBS::G1SATBCardTableModRefBS(MemRegion whole_heap,
                                                 int max_covered_regions) :
    CardTableModRefBSForCTRS(whole_heap, max_covered_regions)
{
  _kind = G1SATBCT;
}


void G1SATBCardTableModRefBS::enqueue(oop pre_val) {
  if (!JavaThread::satb_mark_queue_set().active()) return;
  Thread* thr = Thread::current();
  if (thr->is_Java_thread()) {
    JavaThread* jt = (JavaThread*)thr;
    jt->satb_mark_queue().enqueue(pre_val);
  } else {
    MutexLocker x(Shared_SATB_Q_lock);
    JavaThread::satb_mark_queue_set().shared_satb_queue()->enqueue(pre_val);
  }
}

// When we know the current java thread:
void
G1SATBCardTableModRefBS::write_ref_field_pre_static(void* field,
                                                    oop newVal,
                                                    JavaThread* jt) {
  if (!JavaThread::satb_mark_queue_set().active()) return;
  assert(!UseCompressedOops, "Else will need to modify this to deal with narrowOop");
  oop preVal = *(oop*)field;
  if (preVal != NULL) {
    jt->satb_mark_queue().enqueue(preVal);
  }
}

void
G1SATBCardTableModRefBS::write_ref_array_pre(MemRegion mr) {
  if (!JavaThread::satb_mark_queue_set().active()) return;
  assert(!UseCompressedOops, "Else will need to modify this to deal with narrowOop");
  oop* elem_ptr = (oop*)mr.start();
  while ((HeapWord*)elem_ptr < mr.end()) {
    oop elem = *elem_ptr;
    if (elem != NULL) enqueue(elem);
    elem_ptr++;
  }
}



G1SATBCardTableLoggingModRefBS::
G1SATBCardTableLoggingModRefBS(MemRegion whole_heap,
                               int max_covered_regions) :
  G1SATBCardTableModRefBS(whole_heap, max_covered_regions),
  _dcqs(JavaThread::dirty_card_queue_set())
{
  _kind = G1SATBCTLogging;
}

void
G1SATBCardTableLoggingModRefBS::write_ref_field_work(void* field,
                                                     oop new_val) {
  jbyte* byte = byte_for(field);
  if (*byte != dirty_card) {
    *byte = dirty_card;
    Thread* thr = Thread::current();
    if (thr->is_Java_thread()) {
      JavaThread* jt = (JavaThread*)thr;
      jt->dirty_card_queue().enqueue(byte);
    } else {
      MutexLockerEx x(Shared_DirtyCardQ_lock,
                      Mutex::_no_safepoint_check_flag);
      _dcqs.shared_dirty_card_queue()->enqueue(byte);
    }
  }
}

void
G1SATBCardTableLoggingModRefBS::write_ref_field_static(void* field,
                                                       oop new_val) {
  uintptr_t field_uint = (uintptr_t)field;
  uintptr_t new_val_uint = (uintptr_t)new_val;
  uintptr_t comb = field_uint ^ new_val_uint;
  comb = comb >> HeapRegion::LogOfHRGrainBytes;
  if (comb == 0) return;
  if (new_val == NULL) return;
  // Otherwise, log it.
  G1SATBCardTableLoggingModRefBS* g1_bs =
    (G1SATBCardTableLoggingModRefBS*)Universe::heap()->barrier_set();
  g1_bs->write_ref_field_work(field, new_val);
}

void
G1SATBCardTableLoggingModRefBS::invalidate(MemRegion mr, bool whole_heap) {
  jbyte* byte = byte_for(mr.start());
  jbyte* last_byte = byte_for(mr.last());
  Thread* thr = Thread::current();
  if (whole_heap) {
    while (byte <= last_byte) {
      *byte = dirty_card;
      byte++;
    }
  } else {
    // Enqueue if necessary.
    if (thr->is_Java_thread()) {
      JavaThread* jt = (JavaThread*)thr;
      while (byte <= last_byte) {
        if (*byte != dirty_card) {
          *byte = dirty_card;
          jt->dirty_card_queue().enqueue(byte);
        }
        byte++;
      }
    } else {
      MutexLockerEx x(Shared_DirtyCardQ_lock,
                      Mutex::_no_safepoint_check_flag);
      while (byte <= last_byte) {
        if (*byte != dirty_card) {
          *byte = dirty_card;
          _dcqs.shared_dirty_card_queue()->enqueue(byte);
        }
        byte++;
      }
    }
  }
}