1 /*
   2  * Copyright (c) 2019, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "gc/g1/g1DirtyCardQueue.hpp"
  27 #include "gc/g1/g1SharedDirtyCardQueue.hpp"
  28 #include "gc/shared/ptrQueue.hpp"
  29 #include "runtime/mutex.hpp"
  30 #include "runtime/mutexLocker.inline.hpp"
  31 
  32 G1SharedDirtyCardQueue::G1SharedDirtyCardQueue(G1DirtyCardQueueSet* qset) :
  33   _qset(qset),
  34   _buffer(NULL),
  35   _index(0)
  36 {}
  37 
  38 G1SharedDirtyCardQueue::~G1SharedDirtyCardQueue() {
  39   flush();
  40 }
  41 
  42 void G1SharedDirtyCardQueue::enqueue(void* card_ptr) {
  43   MutexLocker ml(Shared_DirtyCardQ_lock, Mutex::_no_safepoint_check_flag);
  44   if (_index == 0) {
  45     flush();
  46     _buffer = _qset->allocate_buffer();
  47     _index = _qset->buffer_size();
  48     assert(_index != 0, "invariant");
  49   }
  50   _buffer[--_index] = card_ptr;
  51 }
  52 
  53 void G1SharedDirtyCardQueue::flush() {
  54   if (_buffer != NULL) {
  55     BufferNode* node = BufferNode::make_node_from_buffer(_buffer, _index);
  56     _buffer = NULL;
  57     _index = 0;
  58     if (node->index() == _qset->buffer_size()) {
  59       _qset->deallocate_buffer(node);
  60     } else {
  61       _qset->enqueue_completed_buffer(node);
  62     }
  63   }
  64   assert(_index == 0, "invariant");
  65 }
  66 
  67 void G1SharedDirtyCardQueue::reset() {
  68   if (_buffer == NULL) {
  69     _index = 0;
  70   } else {
  71     _index = _qset->buffer_size();
  72   }
  73 }