1 /*
   2  * Copyright (c) 2016, 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/shared/preservedMarks.inline.hpp"
  27 #include "gc/shared/workgroup.hpp"
  28 #include "memory/allocation.inline.hpp"
  29 #include "memory/resourceArea.hpp"
  30 #include "utilities/macros.hpp"
  31 
  32 void PreservedMarks::restore() {
  33   while (!_stack.is_empty()) {
  34     const OopAndMarkOop elem = _stack.pop();
  35     elem.set_mark();
  36   }
  37   assert_empty();
  38 }
  39 
  40 void PreservedMarks::restore_and_increment(volatile size_t* const total_size_addr) {
  41   const size_t stack_size = size();
  42   restore();
  43   // Only do the atomic add if the size is > 0.
  44   if (stack_size > 0) {
  45     Atomic::add(stack_size, total_size_addr);
  46   }
  47 }
  48 
  49 #ifndef PRODUCT
  50 void PreservedMarks::assert_empty() {
  51   assert(_stack.is_empty(), "stack expected to be empty, size = "SIZE_FORMAT,
  52          _stack.size());
  53   assert(_stack.cache_size() == 0,
  54          "stack expected to have no cached segments, cache size = "SIZE_FORMAT,
  55          _stack.cache_size());
  56 }
  57 #endif // ndef PRODUCT
  58 
  59 void RemoveForwardedPointerClosure::do_object(oop obj) {
  60   if (obj->is_forwarded()) {
  61     PreservedMarks::init_forwarded_mark(obj);
  62   }
  63 }
  64 
  65 void PreservedMarksSet::init(uint num) {
  66   assert(_stacks == NULL && _num == 0, "do not re-initialize");
  67   assert(num > 0, "pre-condition");
  68   if (_in_c_heap) {
  69     _stacks = NEW_C_HEAP_ARRAY(Padded<PreservedMarks>, num, mtGC);
  70   } else {
  71     _stacks = NEW_RESOURCE_ARRAY(Padded<PreservedMarks>, num);
  72   }
  73   for (uint i = 0; i < num; i += 1) {
  74     ::new (_stacks + i) PreservedMarks();
  75   }
  76   _num = num;
  77 
  78   assert_empty();
  79 }
  80 
  81 class ParRestoreTask : public AbstractGangTask {
  82 private:
  83   PreservedMarksSet* const _preserved_marks_set;
  84   SequentialSubTasksDone _sub_tasks;
  85   volatile size_t* const _total_size_addr;
  86 
  87 public:
  88   virtual void work(uint worker_id) {
  89     uint task_id = 0;
  90     while (!_sub_tasks.is_task_claimed(/* reference */ task_id)) {
  91       _preserved_marks_set->get(task_id)->restore_and_increment(_total_size_addr);
  92     }
  93     _sub_tasks.all_tasks_completed();
  94   }
  95 
  96   ParRestoreTask(uint worker_num,
  97                  PreservedMarksSet* preserved_marks_set,
  98                  volatile size_t* total_size_addr)
  99       : AbstractGangTask("Parallel Preserved Mark Restoration"),
 100         _preserved_marks_set(preserved_marks_set),
 101         _total_size_addr(total_size_addr) {
 102     _sub_tasks.set_n_threads(worker_num);
 103     _sub_tasks.set_n_tasks(preserved_marks_set->num());
 104   }
 105 };
 106 
 107 
 108 void PreservedMarksSet::reclaim() {
 109   assert_empty();
 110 
 111   for (uint i = 0; i < _num; i += 1) {
 112     _stacks[i].~Padded<PreservedMarks>();
 113   }
 114 
 115   if (_in_c_heap) {
 116     FREE_C_HEAP_ARRAY(Padded<PreservedMarks>, _stacks);
 117   } else {
 118     // the array was resource-allocated, so nothing to do
 119   }
 120   _stacks = NULL;
 121   _num = 0;
 122 }
 123 
 124 #ifndef PRODUCT
 125 void PreservedMarksSet::assert_empty() {
 126   assert(_stacks != NULL && _num > 0, "should have been initialized");
 127   for (uint i = 0; i < _num; i += 1) {
 128     get(i)->assert_empty();
 129   }
 130 }
 131 #endif // ndef PRODUCT
 132 
 133 void SharedRestorePreservedMarksTaskExecutor::restore(PreservedMarksSet* preserved_marks_set,
 134                                                volatile size_t* total_size_addr) {
 135   if (_workers == NULL) {
 136     for (uint i = 0; i < preserved_marks_set->num(); i += 1) {
 137       total_size_addr += preserved_marks_set->get(i)->size();
 138       preserved_marks_set->get(i)->restore();
 139     }
 140   } else {
 141     ParRestoreTask task(_workers->active_workers(), preserved_marks_set, total_size_addr);
 142     _workers->run_task(&task);
 143   }
 144 }