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/*
* 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 ART_RUNTIME_GC_COLLECTOR_MARK_SWEEP_H_
#define ART_RUNTIME_GC_COLLECTOR_MARK_SWEEP_H_
#include <memory>
#include "base/atomic.h"
#include "barrier.h"
#include "base/macros.h"
#include "base/mutex.h"
#include "garbage_collector.h"
#include "gc/accounting/heap_bitmap.h"
#include "gc_root.h"
#include "immune_spaces.h"
#include "offsets.h"
namespace art {
namespace mirror {
class Class;
class Object;
class Reference;
} // namespace mirror
class Thread;
enum VisitRootFlags : uint8_t;
namespace gc {
class Heap;
namespace accounting {
template<typename T> class AtomicStack;
using ObjectStack = AtomicStack<mirror::Object>;
} // namespace accounting
namespace collector {
class MarkSweep : public GarbageCollector {
public:
MarkSweep(Heap* heap, bool is_concurrent, const std::string& name_prefix = "");
~MarkSweep() {}
void RunPhases() override REQUIRES(!mark_stack_lock_);
void InitializePhase();
void MarkingPhase() REQUIRES(!mark_stack_lock_) REQUIRES_SHARED(Locks::mutator_lock_);
void PausePhase() REQUIRES(Locks::mutator_lock_) REQUIRES(!mark_stack_lock_);
void ReclaimPhase() REQUIRES(!mark_stack_lock_) REQUIRES_SHARED(Locks::mutator_lock_);
void FinishPhase();
virtual void MarkReachableObjects()
REQUIRES(Locks::heap_bitmap_lock_)
REQUIRES(!mark_stack_lock_)
REQUIRES_SHARED(Locks::mutator_lock_);
bool IsConcurrent() const {
return is_concurrent_;
}
GcType GetGcType() const override {
return kGcTypeFull;
}
CollectorType GetCollectorType() const override {
return is_concurrent_ ? kCollectorTypeCMS : kCollectorTypeMS;
}
// Initializes internal structures.
void Init();
// Find the default mark bitmap.
void FindDefaultSpaceBitmap() REQUIRES_SHARED(Locks::mutator_lock_);
// Marks all objects in the root set at the start of a garbage collection.
void MarkRoots(Thread* self)
REQUIRES(Locks::heap_bitmap_lock_)
REQUIRES(!mark_stack_lock_)
REQUIRES_SHARED(Locks::mutator_lock_);
void MarkNonThreadRoots()
REQUIRES(Locks::heap_bitmap_lock_)
REQUIRES(!mark_stack_lock_)
REQUIRES_SHARED(Locks::mutator_lock_);
virtual void MarkConcurrentRoots(VisitRootFlags flags)
REQUIRES(Locks::heap_bitmap_lock_)
REQUIRES(!mark_stack_lock_)
REQUIRES_SHARED(Locks::mutator_lock_);
void MarkRootsCheckpoint(Thread* self, bool revoke_ros_alloc_thread_local_buffers_at_checkpoint)
REQUIRES(Locks::heap_bitmap_lock_)
REQUIRES(!mark_stack_lock_)
REQUIRES_SHARED(Locks::mutator_lock_);
// Builds a mark stack and recursively mark until it empties.
void RecursiveMark()
REQUIRES(Locks::heap_bitmap_lock_)
REQUIRES(!mark_stack_lock_)
REQUIRES_SHARED(Locks::mutator_lock_);
// Bind the live bits to the mark bits of bitmaps for spaces that are never collected, ie
// the image. Mark that portion of the heap as immune.
virtual void BindBitmaps() REQUIRES_SHARED(Locks::mutator_lock_);
// Builds a mark stack with objects on dirty cards and recursively mark until it empties.
void RecursiveMarkDirtyObjects(bool paused, uint8_t minimum_age)
REQUIRES(Locks::heap_bitmap_lock_)
REQUIRES(!mark_stack_lock_)
REQUIRES_SHARED(Locks::mutator_lock_);
// Remarks the root set after completing the concurrent mark.
void ReMarkRoots()
REQUIRES(Locks::heap_bitmap_lock_)
REQUIRES(!mark_stack_lock_)
REQUIRES_SHARED(Locks::mutator_lock_);
void ProcessReferences(Thread* self)
REQUIRES(!mark_stack_lock_)
REQUIRES_SHARED(Locks::mutator_lock_);
// Update and mark references from immune spaces.
void UpdateAndMarkModUnion()
REQUIRES(!mark_stack_lock_)
REQUIRES_SHARED(Locks::mutator_lock_);
// Pre clean cards to reduce how much work is needed in the pause.
void PreCleanCards()
REQUIRES(Locks::heap_bitmap_lock_)
REQUIRES(!mark_stack_lock_)
REQUIRES_SHARED(Locks::mutator_lock_);
// Sweeps unmarked objects to complete the garbage collection. Virtual as by default it sweeps
// all allocation spaces. Partial and sticky GCs want to just sweep a subset of the heap.
virtual void Sweep(bool swap_bitmaps)
REQUIRES(Locks::heap_bitmap_lock_)
REQUIRES_SHARED(Locks::mutator_lock_);
// Sweeps unmarked objects to complete the garbage collection.
void SweepLargeObjects(bool swap_bitmaps) REQUIRES(Locks::heap_bitmap_lock_);
// Sweep only pointers within an array. WARNING: Trashes objects.
void SweepArray(accounting::ObjectStack* allocation_stack_, bool swap_bitmaps)
REQUIRES(Locks::heap_bitmap_lock_)
REQUIRES_SHARED(Locks::mutator_lock_);
// Blackens an object.
void ScanObject(mirror::Object* obj)
REQUIRES(Locks::heap_bitmap_lock_)
REQUIRES(!mark_stack_lock_)
REQUIRES_SHARED(Locks::mutator_lock_);
// No thread safety analysis due to lambdas.
template<typename MarkVisitor, typename ReferenceVisitor>
void ScanObjectVisit(mirror::Object* obj,
const MarkVisitor& visitor,
const ReferenceVisitor& ref_visitor)
REQUIRES(Locks::heap_bitmap_lock_)
REQUIRES(!mark_stack_lock_)
REQUIRES_SHARED(Locks::mutator_lock_);
void SweepSystemWeaks(Thread* self)
REQUIRES(!Locks::heap_bitmap_lock_)
REQUIRES_SHARED(Locks::mutator_lock_);
static mirror::Object* VerifySystemWeakIsLiveCallback(mirror::Object* obj, void* arg)
REQUIRES_SHARED(Locks::heap_bitmap_lock_, Locks::mutator_lock_);
void VerifySystemWeaks()
REQUIRES(Locks::mutator_lock_) REQUIRES_SHARED(Locks::heap_bitmap_lock_);
// Verify that an object is live, either in a live bitmap or in the allocation stack.
void VerifyIsLive(const mirror::Object* obj)
REQUIRES_SHARED(Locks::mutator_lock_, Locks::heap_bitmap_lock_);
bool IsNullOrMarkedHeapReference(mirror::HeapReference<mirror::Object>* ref,
bool do_atomic_update) override
REQUIRES(Locks::heap_bitmap_lock_)
REQUIRES_SHARED(Locks::mutator_lock_);
void VisitRoots(mirror::Object*** roots, size_t count, const RootInfo& info) override
REQUIRES(Locks::heap_bitmap_lock_)
REQUIRES(!mark_stack_lock_)
REQUIRES_SHARED(Locks::mutator_lock_);
void VisitRoots(mirror::CompressedReference<mirror::Object>** roots,
size_t count,
const RootInfo& info) override
REQUIRES(Locks::heap_bitmap_lock_)
REQUIRES(!mark_stack_lock_)
REQUIRES_SHARED(Locks::mutator_lock_);
// Marks an object.
mirror::Object* MarkObject(mirror::Object* obj) override
REQUIRES(Locks::heap_bitmap_lock_)
REQUIRES(!mark_stack_lock_)
REQUIRES_SHARED(Locks::mutator_lock_);
void MarkObject(mirror::Object* obj, mirror::Object* holder, MemberOffset offset)
REQUIRES(Locks::heap_bitmap_lock_)
REQUIRES(!mark_stack_lock_)
REQUIRES_SHARED(Locks::mutator_lock_);
void MarkHeapReference(mirror::HeapReference<mirror::Object>* ref,
bool do_atomic_update) override
REQUIRES(Locks::heap_bitmap_lock_)
REQUIRES(!mark_stack_lock_)
REQUIRES_SHARED(Locks::mutator_lock_);
Barrier& GetBarrier() {
return *gc_barrier_;
}
// Schedules an unmarked object for reference processing.
void DelayReferenceReferent(ObjPtr<mirror::Class> klass, ObjPtr<mirror::Reference> reference)
override REQUIRES_SHARED(Locks::heap_bitmap_lock_, Locks::mutator_lock_);
protected:
// Returns object if the object is marked in the heap bitmap, otherwise null.
mirror::Object* IsMarked(mirror::Object* object) override
REQUIRES_SHARED(Locks::heap_bitmap_lock_, Locks::mutator_lock_);
void MarkObjectNonNull(mirror::Object* obj,
mirror::Object* holder = nullptr,
MemberOffset offset = MemberOffset(0))
REQUIRES(Locks::heap_bitmap_lock_)
REQUIRES(!mark_stack_lock_)
REQUIRES_SHARED(Locks::mutator_lock_);
// Marks an object atomically, safe to use from multiple threads.
void MarkObjectNonNullParallel(mirror::Object* obj)
REQUIRES(!mark_stack_lock_)
REQUIRES_SHARED(Locks::mutator_lock_);
// Returns true if we need to add obj to a mark stack.
bool MarkObjectParallel(mirror::Object* obj) NO_THREAD_SAFETY_ANALYSIS;
// Verify the roots of the heap and print out information related to any invalid roots.
// Called in MarkObject, so may we may not hold the mutator lock.
void VerifySuspendedThreadRoots(std::ostream& os)
REQUIRES_SHARED(Locks::mutator_lock_);
// Expand mark stack to 2x its current size.
void ExpandMarkStack()
REQUIRES(mark_stack_lock_)
REQUIRES_SHARED(Locks::mutator_lock_);
void ResizeMarkStack(size_t new_size)
REQUIRES(mark_stack_lock_)
REQUIRES_SHARED(Locks::mutator_lock_);
// Returns how many threads we should use for the current GC phase based on if we are paused,
// whether or not we care about pauses.
size_t GetThreadCount(bool paused) const;
// Push a single reference on a mark stack.
void PushOnMarkStack(mirror::Object* obj)
REQUIRES(!mark_stack_lock_)
REQUIRES_SHARED(Locks::mutator_lock_);
// Blackens objects grayed during a garbage collection.
void ScanGrayObjects(bool paused, uint8_t minimum_age)
REQUIRES(Locks::heap_bitmap_lock_)
REQUIRES(!mark_stack_lock_)
REQUIRES_SHARED(Locks::mutator_lock_);
void ProcessMarkStack() override
REQUIRES(Locks::heap_bitmap_lock_)
REQUIRES(!mark_stack_lock_)
REQUIRES_SHARED(Locks::mutator_lock_) {
ProcessMarkStack(false);
}
// Recursively blackens objects on the mark stack.
void ProcessMarkStack(bool paused)
REQUIRES(Locks::heap_bitmap_lock_)
REQUIRES(!mark_stack_lock_)
REQUIRES_SHARED(Locks::mutator_lock_);
void ProcessMarkStackParallel(size_t thread_count)
REQUIRES(Locks::heap_bitmap_lock_)
REQUIRES(!mark_stack_lock_)
REQUIRES_SHARED(Locks::mutator_lock_);
// Used to Get around thread safety annotations. The call is from MarkingPhase and is guarded by
// IsExclusiveHeld.
void RevokeAllThreadLocalAllocationStacks(Thread* self) NO_THREAD_SAFETY_ANALYSIS;
// Revoke all the thread-local buffers.
void RevokeAllThreadLocalBuffers() override;
// Whether or not we count how many of each type of object were scanned.
static constexpr bool kCountScannedTypes = false;
// Current space, we check this space first to avoid searching for the appropriate space for an
// object.
accounting::ContinuousSpaceBitmap* current_space_bitmap_;
// Cache the heap's mark bitmap to prevent having to do 2 loads during slow path marking.
accounting::HeapBitmap* mark_bitmap_;
accounting::ObjectStack* mark_stack_;
// Every object inside the immune spaces is assumed to be marked. Immune spaces that aren't in the
// immune region are handled by the normal marking logic.
ImmuneSpaces immune_spaces_;
// Parallel finger.
AtomicInteger atomic_finger_;
AtomicInteger no_reference_class_count_;
AtomicInteger normal_count_;
// Number of classes scanned, if kCountScannedTypes.
AtomicInteger class_count_;
// Number of object arrays scanned, if kCountScannedTypes.
AtomicInteger object_array_count_;
// Number of non-class/arrays scanned, if kCountScannedTypes.
AtomicInteger other_count_;
// Number of java.lang.ref.Reference instances.
AtomicInteger reference_count_;
AtomicInteger large_object_test_;
AtomicInteger large_object_mark_;
AtomicInteger overhead_time_;
AtomicInteger work_chunks_created_;
AtomicInteger work_chunks_deleted_;
AtomicInteger mark_null_count_;
AtomicInteger mark_immune_count_;
AtomicInteger mark_fastpath_count_;
AtomicInteger mark_slowpath_count_;
std::unique_ptr<Barrier> gc_barrier_;
Mutex mark_stack_lock_ ACQUIRED_AFTER(Locks::classlinker_classes_lock_);
const bool is_concurrent_;
// Verification.
size_t live_stack_freeze_size_;
// Sweep array free buffer, used to sweep the spaces based on an array more
// efficiently, by recording dead objects to be freed in batches (see
// MarkSweep::SweepArray).
MemMap sweep_array_free_buffer_mem_map_;
private:
class CardScanTask;
class CheckpointMarkThreadRoots;
class DelayReferenceReferentVisitor;
template<bool kUseFinger> class MarkStackTask;
class MarkObjectSlowPath;
class RecursiveMarkTask;
class ScanObjectParallelVisitor;
class ScanObjectVisitor;
class VerifyRootMarkedVisitor;
class VerifyRootVisitor;
class VerifySystemWeakVisitor;
DISALLOW_IMPLICIT_CONSTRUCTORS(MarkSweep);
};
} // namespace collector
} // namespace gc
} // namespace art
#endif // ART_RUNTIME_GC_COLLECTOR_MARK_SWEEP_H_