1 /*
2 * Copyright (C) 2012 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 "sticky_mark_sweep.h"
18
19 #include "gc/accounting/atomic_stack.h"
20 #include "gc/accounting/card_table.h"
21 #include "gc/heap.h"
22 #include "gc/space/large_object_space.h"
23 #include "gc/space/space-inl.h"
24 #include "runtime.h"
25 #include "thread-current-inl.h"
26
27 namespace art {
28 namespace gc {
29 namespace collector {
30
StickyMarkSweep(Heap * heap,bool is_concurrent,const std::string & name_prefix)31 StickyMarkSweep::StickyMarkSweep(Heap* heap, bool is_concurrent, const std::string& name_prefix)
32 : PartialMarkSweep(heap, is_concurrent, name_prefix.empty() ? "sticky " : name_prefix) {
33 cumulative_timings_.SetName(GetName());
34 }
35
BindBitmaps()36 void StickyMarkSweep::BindBitmaps() {
37 PartialMarkSweep::BindBitmaps();
38 WriterMutexLock mu(Thread::Current(), *Locks::heap_bitmap_lock_);
39 // For sticky GC, we want to bind the bitmaps of all spaces as the allocation stack lets us
40 // know what was allocated since the last GC. A side-effect of binding the allocation space mark
41 // and live bitmap is that marking the objects will place them in the live bitmap.
42 for (const auto& space : GetHeap()->GetContinuousSpaces()) {
43 if (space->IsContinuousMemMapAllocSpace() &&
44 space->GetGcRetentionPolicy() == space::kGcRetentionPolicyAlwaysCollect) {
45 DCHECK(space->IsContinuousMemMapAllocSpace());
46 space->AsContinuousMemMapAllocSpace()->BindLiveToMarkBitmap();
47 }
48 }
49 for (const auto& space : GetHeap()->GetDiscontinuousSpaces()) {
50 CHECK(space->IsLargeObjectSpace());
51 space->AsLargeObjectSpace()->CopyLiveToMarked();
52 }
53 }
54
MarkReachableObjects()55 void StickyMarkSweep::MarkReachableObjects() {
56 // All reachable objects must be referenced by a root or a dirty card, so we can clear the mark
57 // stack here since all objects in the mark stack will get scanned by the card scanning anyways.
58 // TODO: Not put these objects in the mark stack in the first place.
59 mark_stack_->Reset();
60 RecursiveMarkDirtyObjects(false, accounting::CardTable::kCardDirty - 1);
61 }
62
MarkConcurrentRoots(VisitRootFlags flags)63 void StickyMarkSweep::MarkConcurrentRoots(VisitRootFlags flags) {
64 TimingLogger::ScopedTiming t(__FUNCTION__, GetTimings());
65 // Visit all runtime roots and clear dirty flags including class loader. This is done to prevent
66 // incorrect class unloading since the GC does not card mark when storing the class during
67 // object allocation. Doing this for each allocation would be slow.
68 // Since the card is not dirty, it means the object may not get scanned. This can cause class
69 // unloading to occur even though the class and class loader are reachable through the object's
70 // class.
71 Runtime::Current()->VisitConcurrentRoots(
72 this,
73 static_cast<VisitRootFlags>(flags | kVisitRootFlagClassLoader));
74 }
75
Sweep(bool swap_bitmaps ATTRIBUTE_UNUSED)76 void StickyMarkSweep::Sweep(bool swap_bitmaps ATTRIBUTE_UNUSED) {
77 SweepArray(GetHeap()->GetLiveStack(), false);
78 }
79
80 } // namespace collector
81 } // namespace gc
82 } // namespace art
83