Carl Shapiro | 69759ea | 2011-07-21 18:13:35 -0700 | [diff] [blame] | 1 | // Copyright 2011 Google Inc. All Rights Reserved. |
Carl Shapiro | 69759ea | 2011-07-21 18:13:35 -0700 | [diff] [blame] | 2 | |
Brian Carlstrom | 578bbdc | 2011-07-21 14:07:47 -0700 | [diff] [blame] | 3 | #include "mark_sweep.h" |
Carl Shapiro | 69759ea | 2011-07-21 18:13:35 -0700 | [diff] [blame] | 4 | |
Carl Shapiro | 58551df | 2011-07-24 03:09:51 -0700 | [diff] [blame] | 5 | #include <climits> |
| 6 | #include <vector> |
| 7 | |
| 8 | #include "heap.h" |
Brian Carlstrom | 578bbdc | 2011-07-21 14:07:47 -0700 | [diff] [blame] | 9 | #include "logging.h" |
| 10 | #include "macros.h" |
| 11 | #include "mark_stack.h" |
| 12 | #include "object.h" |
Brian Carlstrom | 1f87008 | 2011-08-23 16:02:11 -0700 | [diff] [blame] | 13 | #include "class_loader.h" |
| 14 | #include "runtime.h" |
Carl Shapiro | 58551df | 2011-07-24 03:09:51 -0700 | [diff] [blame] | 15 | #include "space.h" |
Brian Carlstrom | 578bbdc | 2011-07-21 14:07:47 -0700 | [diff] [blame] | 16 | #include "thread.h" |
Carl Shapiro | 69759ea | 2011-07-21 18:13:35 -0700 | [diff] [blame] | 17 | |
Carl Shapiro | 69759ea | 2011-07-21 18:13:35 -0700 | [diff] [blame] | 18 | namespace art { |
| 19 | |
Carl Shapiro | 58551df | 2011-07-24 03:09:51 -0700 | [diff] [blame] | 20 | bool MarkSweep::Init() { |
Brian Carlstrom | 4a289ed | 2011-08-16 17:17:49 -0700 | [diff] [blame] | 21 | mark_stack_ = MarkStack::Create(); |
Carl Shapiro | 58551df | 2011-07-24 03:09:51 -0700 | [diff] [blame] | 22 | if (mark_stack_ == NULL) { |
| 23 | return false; |
| 24 | } |
| 25 | |
| 26 | mark_bitmap_ = Heap::GetMarkBits(); |
| 27 | live_bitmap_ = Heap::GetLiveBits(); |
| 28 | |
| 29 | // TODO: if concurrent, clear the card table. |
| 30 | |
| 31 | // TODO: check that the mark bitmap is entirely clear. |
| 32 | |
| 33 | return true; |
| 34 | } |
| 35 | |
Carl Shapiro | 69759ea | 2011-07-21 18:13:35 -0700 | [diff] [blame] | 36 | void MarkSweep::MarkObject0(const Object* obj, bool check_finger) { |
| 37 | DCHECK(obj != NULL); |
| 38 | if (obj < condemned_) { |
| 39 | DCHECK(IsMarked(obj)); |
| 40 | return; |
| 41 | } |
| 42 | bool is_marked = mark_bitmap_->Test(obj); |
| 43 | // This object was not previously marked. |
| 44 | if (!is_marked) { |
| 45 | mark_bitmap_->Set(obj); |
| 46 | if (check_finger && obj < finger_) { |
| 47 | // The object must be pushed on to the mark stack. |
| 48 | mark_stack_->Push(obj); |
| 49 | } |
| 50 | } |
| 51 | } |
| 52 | |
| 53 | // Used to mark objects when recursing. Recursion is done by moving |
| 54 | // the finger across the bitmaps in address order and marking child |
| 55 | // objects. Any newly-marked objects whose addresses are lower than |
| 56 | // the finger won't be visited by the bitmap scan, so those objects |
| 57 | // need to be added to the mark stack. |
| 58 | void MarkSweep::MarkObject(const Object* obj) { |
| 59 | if (obj != NULL) { |
| 60 | MarkObject0(obj, true); |
| 61 | } |
| 62 | } |
| 63 | |
Elliott Hughes | cf4c6c4 | 2011-09-01 15:16:42 -0700 | [diff] [blame] | 64 | void MarkSweep::MarkObjectVisitor(const Object* root, void* arg) { |
Brian Carlstrom | 1f87008 | 2011-08-23 16:02:11 -0700 | [diff] [blame] | 65 | DCHECK(root != NULL); |
| 66 | DCHECK(arg != NULL); |
| 67 | MarkSweep* mark_sweep = reinterpret_cast<MarkSweep*>(arg); |
| 68 | mark_sweep->MarkObject0(root, true); |
| 69 | } |
| 70 | |
Carl Shapiro | 69759ea | 2011-07-21 18:13:35 -0700 | [diff] [blame] | 71 | // Marks all objects in the root set. |
| 72 | void MarkSweep::MarkRoots() { |
Brian Carlstrom | 1f87008 | 2011-08-23 16:02:11 -0700 | [diff] [blame] | 73 | Runtime::Current()->VisitRoots(MarkObjectVisitor, this); |
Carl Shapiro | 69759ea | 2011-07-21 18:13:35 -0700 | [diff] [blame] | 74 | } |
| 75 | |
Carl Shapiro | 58551df | 2011-07-24 03:09:51 -0700 | [diff] [blame] | 76 | void MarkSweep::ScanBitmapCallback(Object* obj, void* finger, void* arg) { |
| 77 | MarkSweep* mark_sweep = reinterpret_cast<MarkSweep*>(arg); |
| 78 | mark_sweep->finger_ = reinterpret_cast<Object*>(finger); |
| 79 | mark_sweep->ScanObject(obj); |
| 80 | } |
| 81 | |
| 82 | // Populates the mark stack based on the set of marked objects and |
| 83 | // recursively marks until the mark stack is emptied. |
| 84 | void MarkSweep::RecursiveMark() { |
Brian Carlstrom | 1f87008 | 2011-08-23 16:02:11 -0700 | [diff] [blame] | 85 | |
| 86 | // RecursiveMark will build the lists of known instances of the Reference classes. |
| 87 | // See DelayReferenceReferent for details. |
| 88 | CHECK(soft_reference_list_ == NULL); |
| 89 | CHECK(weak_reference_list_ == NULL); |
| 90 | CHECK(finalizer_reference_list_ == NULL); |
| 91 | CHECK(phantom_reference_list_ == NULL); |
| 92 | CHECK(cleared_reference_list_ == NULL); |
| 93 | |
Carl Shapiro | 58551df | 2011-07-24 03:09:51 -0700 | [diff] [blame] | 94 | void* arg = reinterpret_cast<void*>(this); |
| 95 | const std::vector<Space*>& spaces = Heap::GetSpaces(); |
| 96 | for (size_t i = 0; i < spaces.size(); ++i) { |
| 97 | if (spaces[i]->IsCondemned()) { |
| 98 | uintptr_t base = reinterpret_cast<uintptr_t>(spaces[i]->GetBase()); |
Brian Carlstrom | 1f87008 | 2011-08-23 16:02:11 -0700 | [diff] [blame] | 99 | mark_bitmap_->ScanWalk(base, &MarkSweep::ScanBitmapCallback, arg); |
Carl Shapiro | 58551df | 2011-07-24 03:09:51 -0700 | [diff] [blame] | 100 | } |
| 101 | } |
| 102 | finger_ = reinterpret_cast<Object*>(~0); |
| 103 | ProcessMarkStack(); |
| 104 | } |
| 105 | |
| 106 | void MarkSweep::ReMarkRoots() { |
Elliott Hughes | 53b6131 | 2011-08-12 18:28:20 -0700 | [diff] [blame] | 107 | UNIMPLEMENTED(FATAL); |
Carl Shapiro | 69759ea | 2011-07-21 18:13:35 -0700 | [diff] [blame] | 108 | } |
| 109 | |
Carl Shapiro | 58551df | 2011-07-24 03:09:51 -0700 | [diff] [blame] | 110 | void MarkSweep::SweepSystemWeaks() { |
Elliott Hughes | cf4c6c4 | 2011-09-01 15:16:42 -0700 | [diff] [blame] | 111 | //Runtime::Current()->GetInternTable().RemoveWeakIf(isUnmarkedObject); |
Elliott Hughes | 53b6131 | 2011-08-12 18:28:20 -0700 | [diff] [blame] | 112 | UNIMPLEMENTED(FATAL); |
Elliott Hughes | cf4c6c4 | 2011-09-01 15:16:42 -0700 | [diff] [blame] | 113 | //dvmSweepMonitorList(&gDvm.monitorList, isUnmarkedObject); |
| 114 | //sweepWeakJniGlobals(); |
Carl Shapiro | 58551df | 2011-07-24 03:09:51 -0700 | [diff] [blame] | 115 | } |
| 116 | |
| 117 | void MarkSweep::SweepCallback(size_t num_ptrs, void **ptrs, void *arg) { |
| 118 | // TODO, lock heap if concurrent |
| 119 | Space* space = static_cast<Space*>(arg); |
| 120 | for (size_t i = 0; i < num_ptrs; ++i) { |
| 121 | Object* obj = static_cast<Object*>(ptrs[i]); |
| 122 | space->Free(obj); |
| 123 | } |
| 124 | // TODO, unlock heap if concurrent |
| 125 | } |
| 126 | |
| 127 | void MarkSweep::Sweep() { |
| 128 | const std::vector<Space*>& spaces = Heap::GetSpaces(); |
| 129 | for (size_t i = 0; i < spaces.size(); ++i) { |
| 130 | if (spaces[i]->IsCondemned()) { |
| 131 | uintptr_t base = reinterpret_cast<uintptr_t>(spaces[i]->GetBase()); |
| 132 | uintptr_t limit = reinterpret_cast<uintptr_t>(spaces[i]->GetLimit()); |
| 133 | void* arg = static_cast<void*>(spaces[i]); |
| 134 | HeapBitmap::SweepWalk(*live_bitmap_, *mark_bitmap_, base, limit, |
| 135 | &MarkSweep::SweepCallback, arg); |
| 136 | } |
| 137 | } |
| 138 | } |
| 139 | |
Carl Shapiro | 69759ea | 2011-07-21 18:13:35 -0700 | [diff] [blame] | 140 | // Scans instance fields. |
| 141 | void MarkSweep::ScanInstanceFields(const Object* obj) { |
| 142 | DCHECK(obj != NULL); |
Brian Carlstrom | 4873d46 | 2011-08-21 15:23:39 -0700 | [diff] [blame] | 143 | Class* klass = obj->GetClass(); |
| 144 | DCHECK(klass != NULL); |
| 145 | ScanFields(obj, |
| 146 | klass->GetReferenceInstanceOffsets(), |
| 147 | false); |
| 148 | } |
| 149 | |
| 150 | // Scans static storage on a Class. |
| 151 | void MarkSweep::ScanStaticFields(const Class* klass) { |
| 152 | DCHECK(klass != NULL); |
| 153 | ScanFields(klass, |
| 154 | klass->GetReferenceStaticOffsets(), |
| 155 | true); |
| 156 | } |
| 157 | |
| 158 | void MarkSweep::ScanFields(const Object* obj, |
| 159 | uint32_t ref_offsets, |
| 160 | bool is_static) { |
Carl Shapiro | 69759ea | 2011-07-21 18:13:35 -0700 | [diff] [blame] | 161 | if (ref_offsets != CLASS_WALK_SUPER) { |
| 162 | // Found a reference offset bitmap. Mark the specified offsets. |
| 163 | while (ref_offsets != 0) { |
| 164 | size_t right_shift = CLZ(ref_offsets); |
| 165 | size_t byte_offset = CLASS_OFFSET_FROM_CLZ(right_shift); |
| 166 | const Object* ref = obj->GetFieldObject(byte_offset); |
| 167 | MarkObject(ref); |
| 168 | ref_offsets &= ~(CLASS_HIGH_BIT >> right_shift); |
| 169 | } |
| 170 | } else { |
Brian Carlstrom | 4873d46 | 2011-08-21 15:23:39 -0700 | [diff] [blame] | 171 | // There is no reference offset bitmap. In the non-static case, |
| 172 | // walk up the class inheritance hierarchy and find reference |
| 173 | // offsets the hard way. In the static case, just consider this |
| 174 | // class. |
| 175 | for (const Class* klass = is_static ? obj->AsClass() : obj->GetClass(); |
Carl Shapiro | 69759ea | 2011-07-21 18:13:35 -0700 | [diff] [blame] | 176 | klass != NULL; |
Brian Carlstrom | 4873d46 | 2011-08-21 15:23:39 -0700 | [diff] [blame] | 177 | klass = is_static ? NULL : klass->GetSuperClass()) { |
| 178 | size_t num_reference_fields = (is_static |
| 179 | ? klass->NumReferenceStaticFields() |
| 180 | : klass->NumReferenceInstanceFields()); |
| 181 | for (size_t i = 0; i < num_reference_fields; ++i) { |
| 182 | Field* field = (is_static |
| 183 | ? klass->GetStaticField(i) |
| 184 | : klass->GetInstanceField(i)); |
| 185 | size_t field_offset = field->GetOffset(); |
Carl Shapiro | 69759ea | 2011-07-21 18:13:35 -0700 | [diff] [blame] | 186 | const Object* ref = obj->GetFieldObject(field_offset); |
| 187 | MarkObject(ref); |
| 188 | } |
| 189 | } |
| 190 | } |
| 191 | } |
| 192 | |
Carl Shapiro | 69759ea | 2011-07-21 18:13:35 -0700 | [diff] [blame] | 193 | void MarkSweep::ScanInterfaces(const Class* klass) { |
| 194 | DCHECK(klass != NULL); |
| 195 | for (size_t i = 0; i < klass->NumInterfaces(); ++i) { |
| 196 | MarkObject(klass->GetInterface(i)); |
| 197 | } |
| 198 | } |
| 199 | |
| 200 | // Scans the header, static field references, and interface pointers |
| 201 | // of a class object. |
| 202 | void MarkSweep::ScanClass(const Object* obj) { |
| 203 | DCHECK(obj != NULL); |
| 204 | DCHECK(obj->IsClass()); |
| 205 | const Class* klass = obj->AsClass(); |
| 206 | MarkObject(klass->GetClass()); |
Brian Carlstrom | b63ec39 | 2011-08-27 17:38:27 -0700 | [diff] [blame] | 207 | if (klass->IsArrayClass()) { |
Carl Shapiro | 69759ea | 2011-07-21 18:13:35 -0700 | [diff] [blame] | 208 | MarkObject(klass->GetComponentType()); |
| 209 | } |
| 210 | if (klass->IsLoaded()) { |
| 211 | MarkObject(klass->GetSuperClass()); |
| 212 | } |
| 213 | MarkObject(klass->GetClassLoader()); |
| 214 | ScanInstanceFields(obj); |
| 215 | ScanStaticFields(klass); |
| 216 | // TODO: scan methods |
| 217 | // TODO: scan instance fields |
| 218 | if (klass->IsLoaded()) { |
| 219 | ScanInterfaces(klass); |
| 220 | } |
| 221 | } |
| 222 | |
| 223 | // Scans the header of all array objects. If the array object is |
| 224 | // specialized to a reference type, scans the array data as well. |
Brian Carlstrom | 4873d46 | 2011-08-21 15:23:39 -0700 | [diff] [blame] | 225 | void MarkSweep::ScanArray(const Object* obj) { |
Carl Shapiro | 69759ea | 2011-07-21 18:13:35 -0700 | [diff] [blame] | 226 | DCHECK(obj != NULL); |
| 227 | DCHECK(obj->GetClass() != NULL); |
| 228 | MarkObject(obj->GetClass()); |
| 229 | if (obj->IsObjectArray()) { |
Brian Carlstrom | db4d540 | 2011-08-09 12:18:28 -0700 | [diff] [blame] | 230 | const ObjectArray<Object>* array = obj->AsObjectArray<Object>(); |
Elliott Hughes | d8ddfd5 | 2011-08-15 14:32:53 -0700 | [diff] [blame] | 231 | for (int32_t i = 0; i < array->GetLength(); ++i) { |
Carl Shapiro | 69759ea | 2011-07-21 18:13:35 -0700 | [diff] [blame] | 232 | const Object* element = array->Get(i); |
| 233 | MarkObject(element); |
| 234 | } |
| 235 | } |
| 236 | } |
| 237 | |
| 238 | void MarkSweep::EnqueuePendingReference(Object* ref, Object** list) { |
| 239 | DCHECK(ref != NULL); |
| 240 | DCHECK(list != NULL); |
Brian Carlstrom | 1f87008 | 2011-08-23 16:02:11 -0700 | [diff] [blame] | 241 | size_t offset = Heap::GetReferencePendingNextOffset(); |
Carl Shapiro | 69759ea | 2011-07-21 18:13:35 -0700 | [diff] [blame] | 242 | if (*list == NULL) { |
| 243 | ref->SetFieldObject(offset, ref); |
| 244 | *list = ref; |
| 245 | } else { |
Brian Carlstrom | 4873d46 | 2011-08-21 15:23:39 -0700 | [diff] [blame] | 246 | Object* head = (*list)->GetFieldObject(offset); |
Carl Shapiro | 69759ea | 2011-07-21 18:13:35 -0700 | [diff] [blame] | 247 | ref->SetFieldObject(offset, head); |
| 248 | (*list)->SetFieldObject(offset, ref); |
| 249 | } |
| 250 | } |
| 251 | |
| 252 | Object* MarkSweep::DequeuePendingReference(Object** list) { |
| 253 | DCHECK(list != NULL); |
| 254 | DCHECK(*list != NULL); |
Brian Carlstrom | 1f87008 | 2011-08-23 16:02:11 -0700 | [diff] [blame] | 255 | size_t offset = Heap::GetReferencePendingNextOffset(); |
Carl Shapiro | 69759ea | 2011-07-21 18:13:35 -0700 | [diff] [blame] | 256 | Object* head = (*list)->GetFieldObject(offset); |
| 257 | Object* ref; |
| 258 | if (*list == head) { |
| 259 | ref = *list; |
| 260 | *list = NULL; |
| 261 | } else { |
Brian Carlstrom | 4873d46 | 2011-08-21 15:23:39 -0700 | [diff] [blame] | 262 | Object* next = head->GetFieldObject(offset); |
Carl Shapiro | 69759ea | 2011-07-21 18:13:35 -0700 | [diff] [blame] | 263 | (*list)->SetFieldObject(offset, next); |
| 264 | ref = head; |
| 265 | } |
| 266 | ref->SetFieldObject(offset, NULL); |
| 267 | return ref; |
| 268 | } |
| 269 | |
| 270 | // Process the "referent" field in a java.lang.ref.Reference. If the |
| 271 | // referent has not yet been marked, put it on the appropriate list in |
| 272 | // the gcHeap for later processing. |
| 273 | void MarkSweep::DelayReferenceReferent(Object* obj) { |
| 274 | DCHECK(obj != NULL); |
Brian Carlstrom | 1f87008 | 2011-08-23 16:02:11 -0700 | [diff] [blame] | 275 | Class* klass = obj->GetClass(); |
| 276 | DCHECK(klass != NULL); |
| 277 | DCHECK(klass->IsReference()); |
| 278 | Object* pending = obj->GetFieldObject(Heap::GetReferencePendingNextOffset()); |
| 279 | Object* referent = obj->GetFieldObject(Heap::GetReferenceReferentOffset()); |
Carl Shapiro | 69759ea | 2011-07-21 18:13:35 -0700 | [diff] [blame] | 280 | if (pending == NULL && referent != NULL && !IsMarked(referent)) { |
Brian Carlstrom | 4873d46 | 2011-08-21 15:23:39 -0700 | [diff] [blame] | 281 | Object** list = NULL; |
Brian Carlstrom | 1f87008 | 2011-08-23 16:02:11 -0700 | [diff] [blame] | 282 | if (klass->IsSoftReference()) { |
Carl Shapiro | 69759ea | 2011-07-21 18:13:35 -0700 | [diff] [blame] | 283 | list = &soft_reference_list_; |
Brian Carlstrom | 1f87008 | 2011-08-23 16:02:11 -0700 | [diff] [blame] | 284 | } else if (klass->IsWeakReference()) { |
Carl Shapiro | 69759ea | 2011-07-21 18:13:35 -0700 | [diff] [blame] | 285 | list = &weak_reference_list_; |
Brian Carlstrom | 1f87008 | 2011-08-23 16:02:11 -0700 | [diff] [blame] | 286 | } else if (klass->IsFinalizerReference()) { |
Carl Shapiro | 69759ea | 2011-07-21 18:13:35 -0700 | [diff] [blame] | 287 | list = &finalizer_reference_list_; |
Brian Carlstrom | 1f87008 | 2011-08-23 16:02:11 -0700 | [diff] [blame] | 288 | } else if (klass->IsPhantomReference()) { |
Carl Shapiro | 69759ea | 2011-07-21 18:13:35 -0700 | [diff] [blame] | 289 | list = &phantom_reference_list_; |
| 290 | } |
| 291 | DCHECK(list != NULL); |
| 292 | EnqueuePendingReference(obj, list); |
| 293 | } |
| 294 | } |
| 295 | |
| 296 | // Scans the header and field references of a data object. If the |
| 297 | // scanned object is a reference subclass, it is scheduled for later |
| 298 | // processing |
Carl Shapiro | 58551df | 2011-07-24 03:09:51 -0700 | [diff] [blame] | 299 | void MarkSweep::ScanOther(const Object* obj) { |
Carl Shapiro | 69759ea | 2011-07-21 18:13:35 -0700 | [diff] [blame] | 300 | DCHECK(obj != NULL); |
Brian Carlstrom | 1f87008 | 2011-08-23 16:02:11 -0700 | [diff] [blame] | 301 | Class* klass = obj->GetClass(); |
| 302 | DCHECK(klass != NULL); |
| 303 | MarkObject(klass); |
Carl Shapiro | 69759ea | 2011-07-21 18:13:35 -0700 | [diff] [blame] | 304 | ScanInstanceFields(obj); |
Brian Carlstrom | 1f87008 | 2011-08-23 16:02:11 -0700 | [diff] [blame] | 305 | if (klass->IsReference()) { |
Carl Shapiro | 69759ea | 2011-07-21 18:13:35 -0700 | [diff] [blame] | 306 | DelayReferenceReferent(const_cast<Object*>(obj)); |
| 307 | } |
| 308 | } |
| 309 | |
| 310 | // Scans an object reference. Determines the type of the reference |
| 311 | // and dispatches to a specialized scanning routine. |
| 312 | void MarkSweep::ScanObject(const Object* obj) { |
| 313 | DCHECK(obj != NULL); |
| 314 | DCHECK(obj->GetClass() != NULL); |
| 315 | DCHECK(IsMarked(obj)); |
| 316 | if (obj->IsClass()) { |
| 317 | ScanClass(obj); |
Brian Carlstrom | b63ec39 | 2011-08-27 17:38:27 -0700 | [diff] [blame] | 318 | } else if (obj->IsArrayInstance()) { |
Carl Shapiro | 69759ea | 2011-07-21 18:13:35 -0700 | [diff] [blame] | 319 | ScanArray(obj); |
| 320 | } else { |
Carl Shapiro | 58551df | 2011-07-24 03:09:51 -0700 | [diff] [blame] | 321 | ScanOther(obj); |
Carl Shapiro | 69759ea | 2011-07-21 18:13:35 -0700 | [diff] [blame] | 322 | } |
| 323 | } |
| 324 | |
| 325 | // Scan anything that's on the mark stack. We can't use the bitmaps |
| 326 | // anymore, so use a finger that points past the end of them. |
| 327 | void MarkSweep::ProcessMarkStack() { |
| 328 | while (!mark_stack_->IsEmpty()) { |
Brian Carlstrom | 4873d46 | 2011-08-21 15:23:39 -0700 | [diff] [blame] | 329 | const Object* obj = mark_stack_->Pop(); |
Carl Shapiro | 69759ea | 2011-07-21 18:13:35 -0700 | [diff] [blame] | 330 | ScanObject(obj); |
| 331 | } |
| 332 | } |
| 333 | |
| 334 | void MarkSweep::ScanDirtyObjects() { |
| 335 | ProcessMarkStack(); |
| 336 | } |
| 337 | |
| 338 | void MarkSweep::ClearReference(Object* ref) { |
| 339 | DCHECK(ref != NULL); |
Brian Carlstrom | 1f87008 | 2011-08-23 16:02:11 -0700 | [diff] [blame] | 340 | ref->SetFieldObject(Heap::GetReferenceReferentOffset(), NULL); |
Carl Shapiro | 69759ea | 2011-07-21 18:13:35 -0700 | [diff] [blame] | 341 | } |
| 342 | |
| 343 | bool MarkSweep::IsEnqueuable(const Object* ref) { |
| 344 | DCHECK(ref != NULL); |
Brian Carlstrom | 1f87008 | 2011-08-23 16:02:11 -0700 | [diff] [blame] | 345 | const Object* queue = ref->GetFieldObject(Heap::GetReferenceQueueOffset()); |
| 346 | const Object* queue_next = ref->GetFieldObject(Heap::GetReferenceQueueNextOffset()); |
Carl Shapiro | 69759ea | 2011-07-21 18:13:35 -0700 | [diff] [blame] | 347 | return (queue != NULL) && (queue_next == NULL); |
| 348 | } |
| 349 | |
| 350 | void MarkSweep::EnqueueReference(Object* ref) { |
| 351 | DCHECK(ref != NULL); |
Brian Carlstrom | 1f87008 | 2011-08-23 16:02:11 -0700 | [diff] [blame] | 352 | CHECK(ref->GetFieldObject(Heap::GetReferenceQueueOffset()) != NULL); |
| 353 | CHECK(ref->GetFieldObject(Heap::GetReferenceQueueNextOffset()) == NULL); |
Carl Shapiro | 69759ea | 2011-07-21 18:13:35 -0700 | [diff] [blame] | 354 | EnqueuePendingReference(ref, &cleared_reference_list_); |
| 355 | } |
| 356 | |
| 357 | // Walks the reference list marking any references subject to the |
| 358 | // reference clearing policy. References with a black referent are |
| 359 | // removed from the list. References with white referents biased |
| 360 | // toward saving are blackened and also removed from the list. |
| 361 | void MarkSweep::PreserveSomeSoftReferences(Object** list) { |
| 362 | DCHECK(list != NULL); |
| 363 | Object* clear = NULL; |
| 364 | size_t counter = 0; |
| 365 | while (*list != NULL) { |
| 366 | Object* ref = DequeuePendingReference(list); |
Brian Carlstrom | 1f87008 | 2011-08-23 16:02:11 -0700 | [diff] [blame] | 367 | Object* referent = ref->GetFieldObject(Heap::GetReferenceReferentOffset()); |
Carl Shapiro | 69759ea | 2011-07-21 18:13:35 -0700 | [diff] [blame] | 368 | if (referent == NULL) { |
| 369 | // Referent was cleared by the user during marking. |
| 370 | continue; |
| 371 | } |
| 372 | bool is_marked = IsMarked(referent); |
| 373 | if (!is_marked && ((++counter) & 1)) { |
| 374 | // Referent is white and biased toward saving, mark it. |
| 375 | MarkObject(referent); |
| 376 | is_marked = true; |
| 377 | } |
| 378 | if (!is_marked) { |
| 379 | // Referent is white, queue it for clearing. |
| 380 | EnqueuePendingReference(ref, &clear); |
| 381 | } |
| 382 | } |
| 383 | *list = clear; |
| 384 | // Restart the mark with the newly black references added to the |
| 385 | // root set. |
| 386 | ProcessMarkStack(); |
| 387 | } |
| 388 | |
| 389 | // Unlink the reference list clearing references objects with white |
| 390 | // referents. Cleared references registered to a reference queue are |
| 391 | // scheduled for appending by the heap worker thread. |
| 392 | void MarkSweep::ClearWhiteReferences(Object** list) { |
| 393 | DCHECK(list != NULL); |
Brian Carlstrom | 1f87008 | 2011-08-23 16:02:11 -0700 | [diff] [blame] | 394 | size_t offset = Heap::GetReferenceReferentOffset(); |
Carl Shapiro | 69759ea | 2011-07-21 18:13:35 -0700 | [diff] [blame] | 395 | while (*list != NULL) { |
Brian Carlstrom | 4873d46 | 2011-08-21 15:23:39 -0700 | [diff] [blame] | 396 | Object* ref = DequeuePendingReference(list); |
| 397 | Object* referent = ref->GetFieldObject(offset); |
Carl Shapiro | 69759ea | 2011-07-21 18:13:35 -0700 | [diff] [blame] | 398 | if (referent != NULL && !IsMarked(referent)) { |
| 399 | // Referent is white, clear it. |
| 400 | ClearReference(ref); |
| 401 | if (IsEnqueuable(ref)) { |
| 402 | EnqueueReference(ref); |
| 403 | } |
| 404 | } |
| 405 | } |
| 406 | DCHECK(*list == NULL); |
| 407 | } |
| 408 | |
| 409 | // Enqueues finalizer references with white referents. White |
| 410 | // referents are blackened, moved to the zombie field, and the |
| 411 | // referent field is cleared. |
| 412 | void MarkSweep::EnqueueFinalizerReferences(Object** list) { |
| 413 | DCHECK(list != NULL); |
Brian Carlstrom | 1f87008 | 2011-08-23 16:02:11 -0700 | [diff] [blame] | 414 | size_t referent_offset = Heap::GetReferenceReferentOffset(); |
| 415 | size_t zombie_offset = Heap::GetFinalizerReferenceZombieOffset(); |
Carl Shapiro | 69759ea | 2011-07-21 18:13:35 -0700 | [diff] [blame] | 416 | bool has_enqueued = false; |
| 417 | while (*list != NULL) { |
| 418 | Object* ref = DequeuePendingReference(list); |
| 419 | Object* referent = ref->GetFieldObject(referent_offset); |
| 420 | if (referent != NULL && !IsMarked(referent)) { |
| 421 | MarkObject(referent); |
| 422 | // If the referent is non-null the reference must queuable. |
| 423 | DCHECK(IsEnqueuable(ref)); |
| 424 | ref->SetFieldObject(zombie_offset, referent); |
| 425 | ClearReference(ref); |
| 426 | EnqueueReference(ref); |
| 427 | has_enqueued = true; |
| 428 | } |
| 429 | } |
| 430 | if (has_enqueued) { |
| 431 | ProcessMarkStack(); |
| 432 | } |
| 433 | DCHECK(*list == NULL); |
| 434 | } |
| 435 | |
Carl Shapiro | 58551df | 2011-07-24 03:09:51 -0700 | [diff] [blame] | 436 | // Process reference class instances and schedule finalizations. |
Carl Shapiro | 69759ea | 2011-07-21 18:13:35 -0700 | [diff] [blame] | 437 | void MarkSweep::ProcessReferences(Object** soft_references, bool clear_soft, |
| 438 | Object** weak_references, |
| 439 | Object** finalizer_references, |
| 440 | Object** phantom_references) { |
| 441 | DCHECK(soft_references != NULL); |
| 442 | DCHECK(weak_references != NULL); |
| 443 | DCHECK(finalizer_references != NULL); |
| 444 | DCHECK(phantom_references != NULL); |
| 445 | |
| 446 | // Unless we are in the zygote or required to clear soft references |
| 447 | // with white references, preserve some white referents. |
| 448 | if (clear_soft) { |
| 449 | PreserveSomeSoftReferences(soft_references); |
| 450 | } |
| 451 | |
| 452 | // Clear all remaining soft and weak references with white |
| 453 | // referents. |
| 454 | ClearWhiteReferences(soft_references); |
| 455 | ClearWhiteReferences(weak_references); |
| 456 | |
| 457 | // Preserve all white objects with finalize methods and schedule |
| 458 | // them for finalization. |
| 459 | EnqueueFinalizerReferences(finalizer_references); |
| 460 | |
| 461 | // Clear all f-reachable soft and weak references with white |
| 462 | // referents. |
| 463 | ClearWhiteReferences(soft_references); |
| 464 | ClearWhiteReferences(weak_references); |
| 465 | |
| 466 | // Clear all phantom references with white referents. |
| 467 | ClearWhiteReferences(phantom_references); |
| 468 | |
| 469 | // At this point all reference lists should be empty. |
| 470 | DCHECK(*soft_references == NULL); |
| 471 | DCHECK(*weak_references == NULL); |
| 472 | DCHECK(*finalizer_references == NULL); |
| 473 | DCHECK(*phantom_references == NULL); |
| 474 | } |
| 475 | |
| 476 | // Pushes a list of cleared references out to the managed heap. |
| 477 | void MarkSweep::EnqueueClearedReferences(Object** cleared) { |
| 478 | DCHECK(cleared != NULL); |
| 479 | if (*cleared != NULL) { |
| 480 | Thread* self = Thread::Current(); |
| 481 | DCHECK(self != NULL); |
| 482 | // TODO: Method *meth = gDvm.methJavaLangRefReferenceQueueAdd; |
| 483 | // DCHECK(meth != NULL); |
| 484 | // JValue unused; |
Brian Carlstrom | 4873d46 | 2011-08-21 15:23:39 -0700 | [diff] [blame] | 485 | // Object* reference = *cleared; |
Carl Shapiro | 69759ea | 2011-07-21 18:13:35 -0700 | [diff] [blame] | 486 | // TODO: dvmCallMethod(self, meth, NULL, &unused, reference); |
Elliott Hughes | 53b6131 | 2011-08-12 18:28:20 -0700 | [diff] [blame] | 487 | UNIMPLEMENTED(FATAL); |
Carl Shapiro | 69759ea | 2011-07-21 18:13:35 -0700 | [diff] [blame] | 488 | *cleared = NULL; |
| 489 | } |
| 490 | } |
| 491 | |
| 492 | MarkSweep::~MarkSweep() { |
Carl Shapiro | 58551df | 2011-07-24 03:09:51 -0700 | [diff] [blame] | 493 | delete mark_stack_; |
Carl Shapiro | 69759ea | 2011-07-21 18:13:35 -0700 | [diff] [blame] | 494 | mark_bitmap_->Clear(); |
| 495 | } |
| 496 | |
| 497 | } // namespace art |