1/*
2 * Copyright (C) 2014 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#include "remembered_set.h"
18
19#include <memory>
20
21#include "base/stl_util.h"
22#include "card_table-inl.h"
23#include "heap_bitmap.h"
24#include "gc/collector/mark_sweep.h"
25#include "gc/collector/mark_sweep-inl.h"
26#include "gc/collector/semi_space.h"
27#include "gc/heap.h"
28#include "gc/space/space.h"
29#include "mirror/object-inl.h"
30#include "mirror/class-inl.h"
31#include "mirror/object_array-inl.h"
32#include "space_bitmap-inl.h"
33#include "thread.h"
34
35namespace art {
36namespace gc {
37namespace accounting {
38
39class RememberedSetCardVisitor {
40 public:
41  explicit RememberedSetCardVisitor(RememberedSet::CardSet* const dirty_cards)
42      : dirty_cards_(dirty_cards) {}
43
44  void operator()(uint8_t* card, uint8_t expected_value, uint8_t new_value) const {
45    UNUSED(new_value);
46    if (expected_value == CardTable::kCardDirty) {
47      dirty_cards_->insert(card);
48    }
49  }
50
51 private:
52  RememberedSet::CardSet* const dirty_cards_;
53};
54
55void RememberedSet::ClearCards() {
56  CardTable* card_table = GetHeap()->GetCardTable();
57  RememberedSetCardVisitor card_visitor(&dirty_cards_);
58  // Clear dirty cards in the space and insert them into the dirty card set.
59  card_table->ModifyCardsAtomic(space_->Begin(), space_->End(), AgeCardVisitor(), card_visitor);
60}
61
62class RememberedSetReferenceVisitor {
63 public:
64  RememberedSetReferenceVisitor(MarkHeapReferenceCallback* callback,
65                                DelayReferenceReferentCallback* ref_callback,
66                                space::ContinuousSpace* target_space,
67                                bool* const contains_reference_to_target_space, void* arg)
68      : callback_(callback), ref_callback_(ref_callback), target_space_(target_space), arg_(arg),
69        contains_reference_to_target_space_(contains_reference_to_target_space) {}
70
71  void operator()(mirror::Object* obj, MemberOffset offset, bool /* is_static */) const
72      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
73    DCHECK(obj != nullptr);
74    mirror::HeapReference<mirror::Object>* ref_ptr = obj->GetFieldObjectReferenceAddr(offset);
75    if (target_space_->HasAddress(ref_ptr->AsMirrorPtr())) {
76      *contains_reference_to_target_space_ = true;
77      callback_(ref_ptr, arg_);
78      DCHECK(!target_space_->HasAddress(ref_ptr->AsMirrorPtr()));
79    }
80  }
81
82  void operator()(mirror::Class* klass, mirror::Reference* ref) const
83      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_)
84      EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_) {
85    if (target_space_->HasAddress(ref->GetReferent())) {
86      *contains_reference_to_target_space_ = true;
87      ref_callback_(klass, ref, arg_);
88    }
89  }
90
91 private:
92  MarkHeapReferenceCallback* const callback_;
93  DelayReferenceReferentCallback* const ref_callback_;
94  space::ContinuousSpace* const target_space_;
95  void* const arg_;
96  bool* const contains_reference_to_target_space_;
97};
98
99class RememberedSetObjectVisitor {
100 public:
101  RememberedSetObjectVisitor(MarkHeapReferenceCallback* callback,
102                             DelayReferenceReferentCallback* ref_callback,
103                             space::ContinuousSpace* target_space,
104                             bool* const contains_reference_to_target_space, void* arg)
105      : callback_(callback), ref_callback_(ref_callback), target_space_(target_space), arg_(arg),
106        contains_reference_to_target_space_(contains_reference_to_target_space) {}
107
108  void operator()(mirror::Object* obj) const EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_)
109      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
110    RememberedSetReferenceVisitor visitor(callback_, ref_callback_, target_space_,
111                                          contains_reference_to_target_space_, arg_);
112    obj->VisitReferences<kMovingClasses>(visitor, visitor);
113  }
114
115 private:
116  MarkHeapReferenceCallback* const callback_;
117  DelayReferenceReferentCallback* const ref_callback_;
118  space::ContinuousSpace* const target_space_;
119  void* const arg_;
120  bool* const contains_reference_to_target_space_;
121};
122
123void RememberedSet::UpdateAndMarkReferences(MarkHeapReferenceCallback* callback,
124                                            DelayReferenceReferentCallback* ref_callback,
125                                            space::ContinuousSpace* target_space, void* arg) {
126  CardTable* card_table = heap_->GetCardTable();
127  bool contains_reference_to_target_space = false;
128  RememberedSetObjectVisitor obj_visitor(callback, ref_callback, target_space,
129                                         &contains_reference_to_target_space, arg);
130  ContinuousSpaceBitmap* bitmap = space_->GetLiveBitmap();
131  CardSet remove_card_set;
132  for (uint8_t* const card_addr : dirty_cards_) {
133    contains_reference_to_target_space = false;
134    uintptr_t start = reinterpret_cast<uintptr_t>(card_table->AddrFromCard(card_addr));
135    DCHECK(space_->HasAddress(reinterpret_cast<mirror::Object*>(start)));
136    bitmap->VisitMarkedRange(start, start + CardTable::kCardSize, obj_visitor);
137    if (!contains_reference_to_target_space) {
138      // It was in the dirty card set, but it didn't actually contain
139      // a reference to the target space. So, remove it from the dirty
140      // card set so we won't have to scan it again (unless it gets
141      // dirty again.)
142      remove_card_set.insert(card_addr);
143    }
144  }
145
146  // Remove the cards that didn't contain a reference to the target
147  // space from the dirty card set.
148  for (uint8_t* const card_addr : remove_card_set) {
149    DCHECK(dirty_cards_.find(card_addr) != dirty_cards_.end());
150    dirty_cards_.erase(card_addr);
151  }
152}
153
154void RememberedSet::Dump(std::ostream& os) {
155  CardTable* card_table = heap_->GetCardTable();
156  os << "RememberedSet dirty cards: [";
157  for (const uint8_t* card_addr : dirty_cards_) {
158    auto start = reinterpret_cast<uintptr_t>(card_table->AddrFromCard(card_addr));
159    auto end = start + CardTable::kCardSize;
160    os << reinterpret_cast<void*>(start) << "-" << reinterpret_cast<void*>(end) << "\n";
161  }
162  os << "]";
163}
164
165void RememberedSet::AssertAllDirtyCardsAreWithinSpace() const {
166  CardTable* card_table = heap_->GetCardTable();
167  for (const uint8_t* card_addr : dirty_cards_) {
168    auto start = reinterpret_cast<uint8_t*>(card_table->AddrFromCard(card_addr));
169    auto end = start + CardTable::kCardSize;
170    DCHECK_LE(space_->Begin(), start);
171    DCHECK_LE(end, space_->Limit());
172  }
173}
174
175}  // namespace accounting
176}  // namespace gc
177}  // namespace art
178