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 ATTRIBUTE_UNUSED) const {
45    if (expected_value == CardTable::kCardDirty) {
46      dirty_cards_->insert(card);
47    }
48  }
49
50 private:
51  RememberedSet::CardSet* const dirty_cards_;
52};
53
54void RememberedSet::ClearCards() {
55  CardTable* card_table = GetHeap()->GetCardTable();
56  RememberedSetCardVisitor card_visitor(&dirty_cards_);
57  // Clear dirty cards in the space and insert them into the dirty card set.
58  card_table->ModifyCardsAtomic(space_->Begin(), space_->End(), AgeCardVisitor(), card_visitor);
59}
60
61class RememberedSetReferenceVisitor {
62 public:
63  RememberedSetReferenceVisitor(space::ContinuousSpace* target_space,
64                                bool* const contains_reference_to_target_space,
65                                collector::GarbageCollector* collector)
66      : collector_(collector), target_space_(target_space),
67        contains_reference_to_target_space_(contains_reference_to_target_space) {}
68
69  void operator()(mirror::Object* obj, MemberOffset offset, bool is_static ATTRIBUTE_UNUSED) const
70      SHARED_REQUIRES(Locks::mutator_lock_) {
71    DCHECK(obj != nullptr);
72    mirror::HeapReference<mirror::Object>* ref_ptr = obj->GetFieldObjectReferenceAddr(offset);
73    if (target_space_->HasAddress(ref_ptr->AsMirrorPtr())) {
74      *contains_reference_to_target_space_ = true;
75      collector_->MarkHeapReference(ref_ptr);
76      DCHECK(!target_space_->HasAddress(ref_ptr->AsMirrorPtr()));
77    }
78  }
79
80  void operator()(mirror::Class* klass, mirror::Reference* ref) const
81      SHARED_REQUIRES(Locks::mutator_lock_) REQUIRES(Locks::heap_bitmap_lock_) {
82    if (target_space_->HasAddress(ref->GetReferent())) {
83      *contains_reference_to_target_space_ = true;
84      collector_->DelayReferenceReferent(klass, ref);
85    }
86  }
87
88  void VisitRootIfNonNull(mirror::CompressedReference<mirror::Object>* root) const
89      SHARED_REQUIRES(Locks::mutator_lock_) {
90    if (!root->IsNull()) {
91      VisitRoot(root);
92    }
93  }
94
95  void VisitRoot(mirror::CompressedReference<mirror::Object>* root) const
96      SHARED_REQUIRES(Locks::mutator_lock_) {
97    if (target_space_->HasAddress(root->AsMirrorPtr())) {
98      *contains_reference_to_target_space_ = true;
99      root->Assign(collector_->MarkObject(root->AsMirrorPtr()));
100      DCHECK(!target_space_->HasAddress(root->AsMirrorPtr()));
101    }
102  }
103
104 private:
105  collector::GarbageCollector* const collector_;
106  space::ContinuousSpace* const target_space_;
107  bool* const contains_reference_to_target_space_;
108};
109
110class RememberedSetObjectVisitor {
111 public:
112  RememberedSetObjectVisitor(space::ContinuousSpace* target_space,
113                             bool* const contains_reference_to_target_space,
114                             collector::GarbageCollector* collector)
115      : collector_(collector), target_space_(target_space),
116        contains_reference_to_target_space_(contains_reference_to_target_space) {}
117
118  void operator()(mirror::Object* obj) const REQUIRES(Locks::heap_bitmap_lock_)
119      SHARED_REQUIRES(Locks::mutator_lock_) {
120    RememberedSetReferenceVisitor visitor(target_space_, contains_reference_to_target_space_,
121                                          collector_);
122    obj->VisitReferences(visitor, visitor);
123  }
124
125 private:
126  collector::GarbageCollector* const collector_;
127  space::ContinuousSpace* const target_space_;
128  bool* const contains_reference_to_target_space_;
129};
130
131void RememberedSet::UpdateAndMarkReferences(space::ContinuousSpace* target_space,
132                                            collector::GarbageCollector* collector) {
133  CardTable* card_table = heap_->GetCardTable();
134  bool contains_reference_to_target_space = false;
135  RememberedSetObjectVisitor obj_visitor(target_space, &contains_reference_to_target_space,
136                                         collector);
137  ContinuousSpaceBitmap* bitmap = space_->GetLiveBitmap();
138  CardSet remove_card_set;
139  for (uint8_t* const card_addr : dirty_cards_) {
140    contains_reference_to_target_space = false;
141    uintptr_t start = reinterpret_cast<uintptr_t>(card_table->AddrFromCard(card_addr));
142    DCHECK(space_->HasAddress(reinterpret_cast<mirror::Object*>(start)));
143    bitmap->VisitMarkedRange(start, start + CardTable::kCardSize, obj_visitor);
144    if (!contains_reference_to_target_space) {
145      // It was in the dirty card set, but it didn't actually contain
146      // a reference to the target space. So, remove it from the dirty
147      // card set so we won't have to scan it again (unless it gets
148      // dirty again.)
149      remove_card_set.insert(card_addr);
150    }
151  }
152
153  // Remove the cards that didn't contain a reference to the target
154  // space from the dirty card set.
155  for (uint8_t* const card_addr : remove_card_set) {
156    DCHECK(dirty_cards_.find(card_addr) != dirty_cards_.end());
157    dirty_cards_.erase(card_addr);
158  }
159}
160
161void RememberedSet::Dump(std::ostream& os) {
162  CardTable* card_table = heap_->GetCardTable();
163  os << "RememberedSet dirty cards: [";
164  for (const uint8_t* card_addr : dirty_cards_) {
165    auto start = reinterpret_cast<uintptr_t>(card_table->AddrFromCard(card_addr));
166    auto end = start + CardTable::kCardSize;
167    os << reinterpret_cast<void*>(start) << "-" << reinterpret_cast<void*>(end) << "\n";
168  }
169  os << "]";
170}
171
172void RememberedSet::AssertAllDirtyCardsAreWithinSpace() const {
173  CardTable* card_table = heap_->GetCardTable();
174  for (const uint8_t* card_addr : dirty_cards_) {
175    auto start = reinterpret_cast<uint8_t*>(card_table->AddrFromCard(card_addr));
176    auto end = start + CardTable::kCardSize;
177    DCHECK_LE(space_->Begin(), start);
178    DCHECK_LE(end, space_->Limit());
179  }
180}
181
182}  // namespace accounting
183}  // namespace gc
184}  // namespace art
185