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/g1RedirtyCardsQueue.hpp"

    27 #include "runtime/atomic.hpp"

    28 #include "utilities/debug.hpp"

    29 #include "utilities/macros.hpp"

    30 

    31 // G1RedirtyCardsBufferList

    32 

    33 G1RedirtyCardsBufferList::G1RedirtyCardsBufferList() :

    34   _head(NULL), _tail(NULL), _count(0) {}

    35 

    36 G1RedirtyCardsBufferList::G1RedirtyCardsBufferList(BufferNode* head,

    37                                                    BufferNode* tail,

    38                                                    size_t count) :

    39   _head(head), _tail(tail), _count(count)

    40 {

    41   assert((_head == NULL) == (_tail == NULL), "invariant");

    42   assert((_head == NULL) == (_count == 0), "invariant");

    43 }

    44 

    45 // G1RedirtyCardsQueueBase::LocalQSet

    46 

    47 G1RedirtyCardsQueueBase::LocalQSet::LocalQSet(G1RedirtyCardsQueueSet* shared_qset) :

    48   PtrQueueSet(),

    49   _shared_qset(shared_qset),

    50   _buffers()

    51 {

    52   PtrQueueSet::initialize(_shared_qset->allocator());

    53 }

    54 

    55 G1RedirtyCardsQueueBase::LocalQSet::~LocalQSet() {

    56   assert(_buffers._head == NULL, "unflushed qset");

    57   assert(_buffers._tail == NULL, "invariant");

    58   assert(_buffers._count == 0, "invariant");

    59 }

    60 

    61 void G1RedirtyCardsQueueBase::LocalQSet::enqueue_completed_buffer(BufferNode* node) {

    62   ++_buffers._count;

    63   node->set_next(_buffers._head);

    64   _buffers._head = node;

    65   if (_buffers._tail == NULL) {

    66     _buffers._tail = node;

    67   }

    68 }

    69 

    70 G1RedirtyCardsBufferList

    71 G1RedirtyCardsQueueBase::LocalQSet::take_all_completed_buffers() {

    72   G1RedirtyCardsBufferList result = _buffers;

    73   _buffers = G1RedirtyCardsBufferList();

    74   return result;

    75 }

    76 

    77 void G1RedirtyCardsQueueBase::LocalQSet::flush() {

    78   _shared_qset->merge_bufferlist(this);

    79 }

    80 

    81 // G1RedirtyCardsQueue

    82 

    83 G1RedirtyCardsQueue::G1RedirtyCardsQueue(G1RedirtyCardsQueueSet* qset) :

    84   G1RedirtyCardsQueueBase(qset), // Init _local_qset before passing to PtrQueue.

    85   PtrQueue(&_local_qset, true /* active (always) */)

    86 {}

    87 

    88 G1RedirtyCardsQueue::~G1RedirtyCardsQueue() {

    89   flush();

    90 }

    91 

    92 void G1RedirtyCardsQueue::handle_completed_buffer() {

    93   enqueue_completed_buffer();

    94 }

    95 

    96 void G1RedirtyCardsQueue::flush() {

    97   flush_impl();

    98   _local_qset.flush();

    99 }

   100 

   101 // G1RedirtyCardsQueueSet

   102 

   103 G1RedirtyCardsQueueSet::G1RedirtyCardsQueueSet() :

   104   PtrQueueSet(),

   105   _list(),

   106   _count(0),

   107   _tail(NULL)

   108   DEBUG_ONLY(COMMA _collecting(true))

   109 {}

   110 

   111 G1RedirtyCardsQueueSet::~G1RedirtyCardsQueueSet() {

   112   verify_empty();

   113 }

   114 

   115 #ifdef ASSERT

   116 void G1RedirtyCardsQueueSet::verify_empty() const {

   117   assert(_list.empty(), "precondition");

   118   assert(_tail == NULL, "invariant");

   119   assert(_count == 0, "invariant");

   120 }

   121 #endif // ASSERT

   122 

   123 BufferNode* G1RedirtyCardsQueueSet::all_completed_buffers() const {

   124   DEBUG_ONLY(_collecting = false;)

   125   return _list.top();

   126 }

   127 

   128 G1RedirtyCardsBufferList G1RedirtyCardsQueueSet::take_all_completed_buffers() {

   129   DEBUG_ONLY(_collecting = false;)

   130   G1RedirtyCardsBufferList result(_list.pop_all(), _tail, _count);

   131   _tail = NULL;

   132   _count = 0;

   133   DEBUG_ONLY(_collecting = true;)

   134   return result;

   135 }

   136 

   137 void G1RedirtyCardsQueueSet::update_tail(BufferNode* node) {

   138   // Node is the tail of a (possibly single element) list just prepended to

   139   // _list.  If, after that prepend, node's follower is NULL, then node is

   140   // also the tail of _list, so record it as such.

   141   if (node->next() == NULL) {

   142     assert(_tail == NULL, "invariant");

   143     _tail = node;

   144   }

   145 }

   146 

   147 void G1RedirtyCardsQueueSet::enqueue_completed_buffer(BufferNode* node) {

   148   assert(_collecting, "precondition");

   149   Atomic::inc(&_count);

   150   _list.push(*node);

   151   update_tail(node);

   152 }

   153 

   154 void G1RedirtyCardsQueueSet::merge_bufferlist(LocalQSet* src) {

   155   assert(_collecting, "precondition");

   156   const G1RedirtyCardsBufferList from = src->take_all_completed_buffers();

   157   if (from._head != NULL) {

   158     assert(from._tail != NULL, "invariant");

   159     Atomic::add(from._count, &_count);

   160     _list.prepend(*from._head, *from._tail);

   161     update_tail(from._tail);

   162   }

   163 }