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      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/art_field-inl.h"
     30 #include "mirror/object-inl.h"
     31 #include "mirror/class-inl.h"
     32 #include "mirror/object_array-inl.h"
     33 #include "space_bitmap-inl.h"
     34 #include "thread.h"
     35 
     36 namespace art {
     37 namespace gc {
     38 namespace accounting {
     39 
     40 class RememberedSetCardVisitor {
     41  public:
     42   explicit RememberedSetCardVisitor(RememberedSet::CardSet* const dirty_cards)
     43       : dirty_cards_(dirty_cards) {}
     44 
     45   void operator()(byte* card, byte expected_value, byte new_value) const {
     46     if (expected_value == CardTable::kCardDirty) {
     47       dirty_cards_->insert(card);
     48     }
     49   }
     50 
     51  private:
     52   RememberedSet::CardSet* const dirty_cards_;
     53 };
     54 
     55 void 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 
     62 class 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 
     99 class 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 
    123 void 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 (byte* 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 (byte* 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 
    154 void RememberedSet::Dump(std::ostream& os) {
    155   CardTable* card_table = heap_->GetCardTable();
    156   os << "RememberedSet dirty cards: [";
    157   for (const byte* 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 
    165 void RememberedSet::AssertAllDirtyCardsAreWithinSpace() const {
    166   CardTable* card_table = heap_->GetCardTable();
    167   for (const byte* card_addr : dirty_cards_) {
    168     auto start = reinterpret_cast<byte*>(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