mark_compact.h revision cb535da36915f9d10bec3880b46f1de1f7a69f22 
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#ifndef ART_RUNTIME_GC_COLLECTOR_MARK_COMPACT_H_
18#define ART_RUNTIME_GC_COLLECTOR_MARK_COMPACT_H_
19
20#include <deque>
21#include <memory>  // For unique_ptr.
22
23#include "atomic.h"
24#include "base/macros.h"
25#include "base/mutex.h"
26#include "garbage_collector.h"
27#include "gc_root.h"
28#include "gc/accounting/heap_bitmap.h"
29#include "immune_region.h"
30#include "lock_word.h"
31#include "object_callbacks.h"
32#include "offsets.h"
33
34namespace art {
35
36class Thread;
37
38namespace mirror {
39  class Class;
40  class Object;
41}  // namespace mirror
42
43namespace gc {
44
45class Heap;
46
47namespace accounting {
48  template <typename T> class AtomicStack;
49  typedef AtomicStack<mirror::Object> ObjectStack;
50}  // namespace accounting
51
52namespace space {
53  class BumpPointerSpace;
54  class ContinuousMemMapAllocSpace;
55  class ContinuousSpace;
56}  // namespace space
57
58namespace collector {
59
60class MarkCompact : public GarbageCollector {
61 public:
62  explicit MarkCompact(Heap* heap, const std::string& name_prefix = "");
63  ~MarkCompact() {}
64
65  virtual void RunPhases() OVERRIDE NO_THREAD_SAFETY_ANALYSIS;
66  void InitializePhase();
67  void MarkingPhase() EXCLUSIVE_LOCKS_REQUIRED(Locks::mutator_lock_)
68      LOCKS_EXCLUDED(Locks::heap_bitmap_lock_);
69  void ReclaimPhase() EXCLUSIVE_LOCKS_REQUIRED(Locks::mutator_lock_)
70      LOCKS_EXCLUDED(Locks::heap_bitmap_lock_);
71  void FinishPhase() EXCLUSIVE_LOCKS_REQUIRED(Locks::mutator_lock_);
72  void MarkReachableObjects()
73      EXCLUSIVE_LOCKS_REQUIRED(Locks::mutator_lock_, Locks::heap_bitmap_lock_);
74  virtual GcType GetGcType() const OVERRIDE {
75    return kGcTypePartial;
76  }
77  virtual CollectorType GetCollectorType() const OVERRIDE {
78    return kCollectorTypeMC;
79  }
80
81  // Sets which space we will be copying objects in.
82  void SetSpace(space::BumpPointerSpace* space);
83
84  // Initializes internal structures.
85  void Init();
86
87  // Find the default mark bitmap.
88  void FindDefaultMarkBitmap();
89
90  void ScanObject(mirror::Object* obj)
91      EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_, Locks::mutator_lock_);
92
93  // Marks the root set at the start of a garbage collection.
94  void MarkRoots()
95      EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_, Locks::mutator_lock_);
96
97  // Bind the live bits to the mark bits of bitmaps for spaces that are never collected, ie
98  // the image. Mark that portion of the heap as immune.
99  void BindBitmaps() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_)
100      LOCKS_EXCLUDED(Locks::heap_bitmap_lock_);
101
102  void UnBindBitmaps()
103      EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_);
104
105  void ProcessReferences(Thread* self) EXCLUSIVE_LOCKS_REQUIRED(Locks::mutator_lock_)
106      EXCLUSIVE_LOCKS_REQUIRED(Locks::mutator_lock_);
107
108  // Sweeps unmarked objects to complete the garbage collection.
109  void Sweep(bool swap_bitmaps) EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_);
110
111  // Sweeps unmarked objects to complete the garbage collection.
112  void SweepLargeObjects(bool swap_bitmaps) EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_);
113
114  void SweepSystemWeaks()
115      SHARED_LOCKS_REQUIRED(Locks::heap_bitmap_lock_, Locks::mutator_lock_);
116
117  static void MarkRootCallback(mirror::Object** root, void* arg, const RootInfo& root_info)
118      EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_, Locks::mutator_lock_);
119
120  static mirror::Object* MarkObjectCallback(mirror::Object* root, void* arg)
121      EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_, Locks::mutator_lock_);
122
123  static void MarkHeapReferenceCallback(mirror::HeapReference<mirror::Object>* obj_ptr, void* arg)
124      EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_, Locks::mutator_lock_);
125
126  static bool HeapReferenceMarkedCallback(mirror::HeapReference<mirror::Object>* ref_ptr,
127                                          void* arg)
128      EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_, Locks::mutator_lock_);
129
130  static void ProcessMarkStackCallback(void* arg)
131      EXCLUSIVE_LOCKS_REQUIRED(Locks::mutator_lock_, Locks::heap_bitmap_lock_);
132
133  static void DelayReferenceReferentCallback(mirror::Class* klass, mirror::Reference* ref,
134                                             void* arg)
135      SHARED_LOCKS_REQUIRED(Locks::heap_bitmap_lock_, Locks::mutator_lock_);
136
137  // Schedules an unmarked object for reference processing.
138  void DelayReferenceReferent(mirror::Class* klass, mirror::Reference* reference)
139      SHARED_LOCKS_REQUIRED(Locks::heap_bitmap_lock_, Locks::mutator_lock_);
140
141 protected:
142  // Returns null if the object is not marked, otherwise returns the forwarding address (same as
143  // object for non movable things).
144  mirror::Object* GetMarkedForwardAddress(mirror::Object* object) const
145      EXCLUSIVE_LOCKS_REQUIRED(Locks::mutator_lock_)
146      SHARED_LOCKS_REQUIRED(Locks::heap_bitmap_lock_);
147
148  static mirror::Object* MarkedForwardingAddressCallback(mirror::Object* object, void* arg)
149      EXCLUSIVE_LOCKS_REQUIRED(Locks::mutator_lock_)
150      SHARED_LOCKS_REQUIRED(Locks::heap_bitmap_lock_);
151
152  // Marks or unmarks a large object based on whether or not set is true. If set is true, then we
153  // mark, otherwise we unmark.
154  bool MarkLargeObject(const mirror::Object* obj)
155      EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_)
156      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
157
158  // Expand mark stack to 2x its current size.
159  void ResizeMarkStack(size_t new_size) SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
160
161  // Returns true if we should sweep the space.
162  bool ShouldSweepSpace(space::ContinuousSpace* space) const;
163
164  // Push an object onto the mark stack.
165  void MarkStackPush(mirror::Object* obj) SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
166
167  void UpdateAndMarkModUnion()
168      EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_)
169      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
170
171  // Recursively blackens objects on the mark stack.
172  void ProcessMarkStack()
173      EXCLUSIVE_LOCKS_REQUIRED(Locks::mutator_lock_, Locks::heap_bitmap_lock_);
174
175  // 3 pass mark compact approach.
176  void Compact() EXCLUSIVE_LOCKS_REQUIRED(Locks::mutator_lock_, Locks::heap_bitmap_lock_);
177  // Calculate the forwarding address of objects marked as "live" in the objects_before_forwarding
178  // bitmap.
179  void CalculateObjectForwardingAddresses()
180      EXCLUSIVE_LOCKS_REQUIRED(Locks::mutator_lock_, Locks::heap_bitmap_lock_);
181  // Update the references of objects by using the forwarding addresses.
182  void UpdateReferences() EXCLUSIVE_LOCKS_REQUIRED(Locks::mutator_lock_, Locks::heap_bitmap_lock_);
183  static void UpdateRootCallback(mirror::Object** root, void* arg, const RootInfo& /*root_info*/)
184      EXCLUSIVE_LOCKS_REQUIRED(Locks::mutator_lock_)
185      SHARED_LOCKS_REQUIRED(Locks::heap_bitmap_lock_);
186  // Move objects and restore lock words.
187  void MoveObjects() EXCLUSIVE_LOCKS_REQUIRED(Locks::mutator_lock_);
188  // Move a single object to its forward address.
189  void MoveObject(mirror::Object* obj, size_t len) EXCLUSIVE_LOCKS_REQUIRED(Locks::mutator_lock_);
190  // Mark a single object.
191  void MarkObject(mirror::Object* obj) EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_,
192                                                                Locks::mutator_lock_);
193  bool IsMarked(const mirror::Object* obj) const
194      SHARED_LOCKS_REQUIRED(Locks::heap_bitmap_lock_);
195  static mirror::Object* IsMarkedCallback(mirror::Object* object, void* arg)
196      SHARED_LOCKS_REQUIRED(Locks::heap_bitmap_lock_);
197  void ForwardObject(mirror::Object* obj) EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_,
198                                                                   Locks::mutator_lock_);
199  // Update a single heap reference.
200  void UpdateHeapReference(mirror::HeapReference<mirror::Object>* reference)
201      SHARED_LOCKS_REQUIRED(Locks::heap_bitmap_lock_)
202      EXCLUSIVE_LOCKS_REQUIRED(Locks::mutator_lock_);
203  static void UpdateHeapReferenceCallback(mirror::HeapReference<mirror::Object>* reference,
204                                          void* arg)
205      SHARED_LOCKS_REQUIRED(Locks::heap_bitmap_lock_)
206      EXCLUSIVE_LOCKS_REQUIRED(Locks::mutator_lock_);
207  // Update all of the references of a single object.
208  void UpdateObjectReferences(mirror::Object* obj)
209      SHARED_LOCKS_REQUIRED(Locks::heap_bitmap_lock_)
210      EXCLUSIVE_LOCKS_REQUIRED(Locks::mutator_lock_);
211
212  // Revoke all the thread-local buffers.
213  void RevokeAllThreadLocalBuffers();
214
215  accounting::ObjectStack* mark_stack_;
216
217  // Immune region, every object inside the immune region is assumed to be marked.
218  ImmuneRegion immune_region_;
219
220  // Bump pointer space which we are collecting.
221  space::BumpPointerSpace* space_;
222  // Cached mark bitmap as an optimization.
223  accounting::HeapBitmap* mark_bitmap_;
224
225  // The name of the collector.
226  std::string collector_name_;
227
228  // The bump pointer in the space where the next forwarding address will be.
229  uint8_t* bump_pointer_;
230  // How many live objects we have in the space.
231  size_t live_objects_in_space_;
232
233  // Bitmap which describes which objects we have to move, need to do / 2 so that we can handle
234  // objects which are only 8 bytes.
235  std::unique_ptr<accounting::ContinuousSpaceBitmap> objects_before_forwarding_;
236  // Bitmap which describes which lock words we need to restore.
237  std::unique_ptr<accounting::ContinuousSpaceBitmap> objects_with_lockword_;
238  // Which lock words we need to restore as we are moving objects.
239  std::deque<LockWord> lock_words_to_restore_;
240
241 private:
242  friend class BitmapSetSlowPathVisitor;
243  friend class CalculateObjectForwardingAddressVisitor;
244  friend class MarkCompactMarkObjectVisitor;
245  friend class MoveObjectVisitor;
246  friend class UpdateObjectReferencesVisitor;
247  friend class UpdateReferenceVisitor;
248  DISALLOW_COPY_AND_ASSIGN(MarkCompact);
249};
250
251}  // namespace collector
252}  // namespace gc
253}  // namespace art
254
255#endif  // ART_RUNTIME_GC_COLLECTOR_MARK_COMPACT_H_
256