| /* |
| * Copyright (C) 2011 The Android Open Source Project |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| #ifndef DALVIK_ALLOC_CARDTABLE_H_ |
| #define DALVIK_ALLOC_CARDTABLE_H_ |
| |
| #include "globals.h" |
| #include "logging.h" |
| #include "mem_map.h" |
| #include "UniquePtr.h" |
| |
| namespace art { |
| |
| class Object; |
| |
| #define GC_CARD_SHIFT 7 |
| #define GC_CARD_SIZE (1 << GC_CARD_SHIFT) |
| #define GC_CARD_CLEAN 0 |
| #define GC_CARD_DIRTY 0x70 |
| |
| // Maintain a card table from the the write barrier. All writes of |
| // non-NULL values to heap addresses should go through an entry in |
| // WriteBarrier, and from there to here. |
| class CardTable { |
| public: |
| |
| static CardTable* Create(const byte* heap_begin, size_t heap_capacity); |
| |
| // Set the card associated with the given address to GC_CARD_DIRTY. |
| void MarkCard(const void *addr) { |
| byte* cardAddr = CardFromAddr(addr); |
| *cardAddr = GC_CARD_DIRTY; |
| } |
| |
| // Is the object on a dirty card? |
| bool IsDirty(const Object* obj) const { |
| return *CardFromAddr(obj) == GC_CARD_DIRTY; |
| } |
| |
| // Returns a value that when added to a heap address >> GC_CARD_SHIFT will address the appropriate |
| // card table byte. For convenience this value is cached in every Thread |
| byte* GetBiasedBegin() const { |
| return biased_begin_; |
| } |
| |
| // For every dirty card between begin and end invoke the visitor with the specified argument |
| typedef void Callback(Object* obj, void* arg); |
| void Scan(byte* begin, byte* end, Callback* visitor, void* arg) const; |
| |
| |
| // Assertion used to check the given address is covered by the card table |
| void CheckAddrIsInCardTable(const byte* addr) const; |
| |
| private: |
| |
| CardTable(MemMap* begin, byte* biased_begin, size_t offset) : |
| mem_map_(begin), biased_begin_(biased_begin), offset_(offset) {} |
| |
| // Resets all of the bytes in the card table to clean. |
| void ClearCardTable(); |
| |
| // Returns the address of the relevant byte in the card table, given an address on the heap. |
| byte* CardFromAddr(const void *addr) const { |
| byte *cardAddr = biased_begin_ + ((uintptr_t)addr >> GC_CARD_SHIFT); |
| // Sanity check the caller was asking for address covered by the card table |
| DCHECK(IsValidCard(cardAddr)) << "addr: " << addr |
| << " cardAddr: " << reinterpret_cast<void*>(cardAddr); |
| return cardAddr; |
| } |
| |
| // Returns the first address in the heap which maps to this card. |
| void* AddrFromCard(const byte *cardAddr) const { |
| DCHECK(IsValidCard(cardAddr)); |
| uintptr_t offset = cardAddr - biased_begin_; |
| return reinterpret_cast<void*>(offset << GC_CARD_SHIFT); |
| } |
| |
| // Returns true iff the card table address is within the bounds of the card table. |
| bool IsValidCard(const byte* cardAddr) const { |
| byte* begin = mem_map_->Begin() + offset_; |
| byte* end = mem_map_->End(); |
| return cardAddr >= begin && cardAddr < end; |
| } |
| |
| // Verifies that all gray objects are on a dirty card. |
| void VerifyCardTable(); |
| |
| // Mmapped pages for the card table |
| UniquePtr<MemMap> mem_map_; |
| // Value used to compute card table addresses from object addresses, see GetBiasedBegin |
| byte* const biased_begin_; |
| // Card table doesn't begin at the beginning of the mem_map_, instead it is displaced by offset |
| // to allow the byte value of biased_begin_ to equal GC_CARD_DIRTY |
| const size_t offset_; |
| }; |
| |
| } // namespace art |
| #endif // DALVIK_ALLOC_CARDTABLE_H_ |