内存空间添加

(1) 如果space是连续的，则添加到continuous_spaces_数组。
(2) continuous_spaces_按照起始地址排序
(3) 内存不连续的，则添加到discontinuous_spaces_
(4) 对于可分配内存的space,添加到alloc_spaces_
(5) 将RegionSpace的live_bitmap,mark_bitmap添加到Heap的live_bitmap_,mark_bitmap_的continuous_space_bitmaps_。
(6) DiscontinuousSpace的live_bitmap,mark_bitmap添加到Heap的的live_bitmap_,mark_bitmap_的large_object_bitmaps_,

void Heap::AddSpace(space::Space* space) {
  WriterMutexLock mu(Thread::Current(), *Locks::heap_bitmap_lock_);
  if (space->IsContinuousSpace()) {
    space::ContinuousSpace* continuous_space = space->AsContinuousSpace();
    // Continuous spaces don't necessarily have bitmaps.
    accounting::ContinuousSpaceBitmap* live_bitmap = continuous_space->GetLiveBitmap();
    accounting::ContinuousSpaceBitmap* mark_bitmap = continuous_space->GetMarkBitmap();
    // The region space bitmap is not added since VisitObjects visits the region space objects with
    // special handling.
    if (live_bitmap != nullptr && !space->IsRegionSpace()) {
//(5)
      live_bitmap_->AddContinuousSpaceBitmap(live_bitmap);
      mark_bitmap_->AddContinuousSpaceBitmap(mark_bitmap);
    }
//(1)
    continuous_spaces_.push_back(continuous_space);
    // Ensure that spaces remain sorted in increasing order of start address.
//(2)
    std::sort(continuous_spaces_.begin(), continuous_spaces_.end(),
              [](const space::ContinuousSpace* a, const space::ContinuousSpace* b) {
      return a->Begin() < b->Begin();
    });
  } else {
    space::DiscontinuousSpace* discontinuous_space = space->AsDiscontinuousSpace();
//(6)
    live_bitmap_->AddLargeObjectBitmap(discontinuous_space->GetLiveBitmap());
    mark_bitmap_->AddLargeObjectBitmap(discontinuous_space->GetMarkBitmap());
//(3)
    discontinuous_spaces_.push_back(discontinuous_space);
  }
  if (space->IsAllocSpace()) {
//(4)
    alloc_spaces_.push_back(space->AsAllocSpace());
  }
}

内存空间移除

void Heap::RemoveSpace(space::Space* space) {
  WriterMutexLock mu(Thread::Current(), *Locks::heap_bitmap_lock_);
  if (space->IsContinuousSpace()) {
    space::ContinuousSpace* continuous_space = space->AsContinuousSpace();
    // Continuous spaces don't necessarily have bitmaps.
    accounting::ContinuousSpaceBitmap* live_bitmap = continuous_space->GetLiveBitmap();
    accounting::ContinuousSpaceBitmap* mark_bitmap = continuous_space->GetMarkBitmap();
    if (live_bitmap != nullptr && !space->IsRegionSpace()) {
      DCHECK(mark_bitmap != nullptr);
      live_bitmap_->RemoveContinuousSpaceBitmap(live_bitmap);
      mark_bitmap_->RemoveContinuousSpaceBitmap(mark_bitmap);
    }
    auto it = std::find(continuous_spaces_.begin(), continuous_spaces_.end(), continuous_space);
    DCHECK(it != continuous_spaces_.end());
    continuous_spaces_.erase(it);
  } else {
    DCHECK(space->IsDiscontinuousSpace());
    space::DiscontinuousSpace* discontinuous_space = space->AsDiscontinuousSpace();
    live_bitmap_->RemoveLargeObjectBitmap(discontinuous_space->GetLiveBitmap());
    mark_bitmap_->RemoveLargeObjectBitmap(discontinuous_space->GetMarkBitmap());
    auto it = std::find(discontinuous_spaces_.begin(), discontinuous_spaces_.end(),
                        discontinuous_space);
    DCHECK(it != discontinuous_spaces_.end());
    discontinuous_spaces_.erase(it);
  }
  if (space->IsAllocSpace()) {
    auto it = std::find(alloc_spaces_.begin(), alloc_spaces_.end(), space->AsAllocSpace());
    DCHECK(it != alloc_spaces_.end());
    alloc_spaces_.erase(it);
  }
}

android java对象在堆上分配，具体保存在某个space上。art虚拟机并没有具体的数据结构表示老年代和新生代，一般情况下将ImageSpace和ZyogoteSpace作为老年代。