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/*
* Copyright (C) 2013 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_SEMI_SPACE_H_
#define ART_RUNTIME_GC_COLLECTOR_SEMI_SPACE_H_
#include <memory>
#include "base/atomic.h"
#include "base/locks.h"
#include "base/macros.h"
#include "garbage_collector.h"
#include "gc/accounting/heap_bitmap.h"
#include "gc_root.h"
#include "immune_spaces.h"
#include "mirror/object_reference.h"
#include "offsets.h"
namespace art {
class Thread;
namespace mirror {
class Class;
class Object;
} // namespace mirror
namespace gc {
class Heap;
namespace accounting {
template <typename T> class AtomicStack;
typedef AtomicStack<mirror::Object> ObjectStack;
} // namespace accounting
namespace space {
class ContinuousMemMapAllocSpace;
class ContinuousSpace;
} // namespace space
namespace collector {
class SemiSpace : public GarbageCollector {
public:
// If true, use remembered sets in the generational mode.
static constexpr bool kUseRememberedSet = true;
explicit SemiSpace(Heap* heap, const std::string& name_prefix = "");
~SemiSpace() {}
void RunPhases() override NO_THREAD_SAFETY_ANALYSIS;
virtual void InitializePhase();
virtual void MarkingPhase() REQUIRES(Locks::mutator_lock_)
REQUIRES(!Locks::heap_bitmap_lock_);
virtual void ReclaimPhase() REQUIRES(Locks::mutator_lock_)
REQUIRES(!Locks::heap_bitmap_lock_);
virtual void FinishPhase() REQUIRES(Locks::mutator_lock_);
void MarkReachableObjects()
REQUIRES(Locks::mutator_lock_, Locks::heap_bitmap_lock_);
GcType GetGcType() const override {
return kGcTypePartial;
}
CollectorType GetCollectorType() const override {
return kCollectorTypeSS;
}
// Sets which space we will be copying objects to.
void SetToSpace(space::ContinuousMemMapAllocSpace* to_space);
// Set the space where we copy objects from.
void SetFromSpace(space::ContinuousMemMapAllocSpace* from_space);
// Set whether or not we swap the semi spaces in the heap. This needs to be done with mutators
// suspended.
void SetSwapSemiSpaces(bool swap_semi_spaces) {
swap_semi_spaces_ = swap_semi_spaces;
}
// Initializes internal structures.
void Init();
// Find the default mark bitmap.
void FindDefaultMarkBitmap();
// Updates obj_ptr if the object has moved. Takes either an ObjectReference or a HeapReference.
template<typename CompressedReferenceType>
void MarkObject(CompressedReferenceType* obj_ptr)
REQUIRES(Locks::heap_bitmap_lock_, Locks::mutator_lock_);
template<typename CompressedReferenceType>
void MarkObjectIfNotInToSpace(CompressedReferenceType* obj_ptr)
REQUIRES(Locks::heap_bitmap_lock_, Locks::mutator_lock_);
mirror::Object* MarkObject(mirror::Object* root) override
REQUIRES(Locks::heap_bitmap_lock_, Locks::mutator_lock_);
void MarkHeapReference(mirror::HeapReference<mirror::Object>* obj_ptr,
bool do_atomic_update) override
REQUIRES(Locks::heap_bitmap_lock_, Locks::mutator_lock_);
void ScanObject(mirror::Object* obj)
REQUIRES(Locks::heap_bitmap_lock_, Locks::mutator_lock_);
void VerifyNoFromSpaceReferences(mirror::Object* obj)
REQUIRES_SHARED(Locks::heap_bitmap_lock_, Locks::mutator_lock_);
// Marks the root set at the start of a garbage collection.
void MarkRoots()
REQUIRES(Locks::heap_bitmap_lock_, 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_)
REQUIRES(!Locks::heap_bitmap_lock_);
void UnBindBitmaps()
REQUIRES(Locks::heap_bitmap_lock_);
void ProcessReferences(Thread* self) REQUIRES(Locks::mutator_lock_)
REQUIRES(Locks::mutator_lock_);
// Sweeps unmarked objects to complete the garbage collection.
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_);
void SweepSystemWeaks()
REQUIRES_SHARED(Locks::heap_bitmap_lock_, Locks::mutator_lock_);
void VisitRoots(mirror::Object*** roots, size_t count, const RootInfo& info) override
REQUIRES(Locks::mutator_lock_, Locks::heap_bitmap_lock_);
void VisitRoots(mirror::CompressedReference<mirror::Object>** roots,
size_t count,
const RootInfo& info) override
REQUIRES(Locks::mutator_lock_, Locks::heap_bitmap_lock_);
virtual mirror::Object* MarkNonForwardedObject(mirror::Object* obj)
REQUIRES(Locks::heap_bitmap_lock_, Locks::mutator_lock_);
// 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 null if the object is not marked, otherwise returns the forwarding address (same as
// object for non movable things).
mirror::Object* IsMarked(mirror::Object* object) override
REQUIRES(Locks::mutator_lock_)
REQUIRES_SHARED(Locks::heap_bitmap_lock_);
bool IsNullOrMarkedHeapReference(mirror::HeapReference<mirror::Object>* object,
bool do_atomic_update) override
REQUIRES(Locks::mutator_lock_)
REQUIRES_SHARED(Locks::heap_bitmap_lock_);
// Marks or unmarks a large object based on whether or not set is true. If set is true, then we
// mark, otherwise we unmark.
bool MarkLargeObject(const mirror::Object* obj)
REQUIRES(Locks::heap_bitmap_lock_)
REQUIRES_SHARED(Locks::mutator_lock_);
// Expand mark stack to 2x its current size.
void ResizeMarkStack(size_t new_size) REQUIRES_SHARED(Locks::mutator_lock_);
// Returns true if we should sweep the space.
virtual bool ShouldSweepSpace(space::ContinuousSpace* space) const;
// Push an object onto the mark stack.
void MarkStackPush(mirror::Object* obj) REQUIRES_SHARED(Locks::mutator_lock_);
void UpdateAndMarkModUnion()
REQUIRES(Locks::heap_bitmap_lock_)
REQUIRES_SHARED(Locks::mutator_lock_);
// Recursively blackens objects on the mark stack.
void ProcessMarkStack() override
REQUIRES(Locks::mutator_lock_, Locks::heap_bitmap_lock_);
inline mirror::Object* GetForwardingAddressInFromSpace(mirror::Object* obj) const
REQUIRES_SHARED(Locks::mutator_lock_);
// Revoke all the thread-local buffers.
void RevokeAllThreadLocalBuffers() override;
// Current space, we check this space first to avoid searching for the appropriate space for an
// object.
accounting::ObjectStack* mark_stack_;
// Every object inside the immune spaces is assumed to be marked.
ImmuneSpaces immune_spaces_;
// Destination and source spaces (can be any type of ContinuousMemMapAllocSpace which either has
// a live bitmap or doesn't).
space::ContinuousMemMapAllocSpace* to_space_;
// Cached live bitmap as an optimization.
accounting::ContinuousSpaceBitmap* to_space_live_bitmap_;
space::ContinuousMemMapAllocSpace* from_space_;
// Cached mark bitmap as an optimization.
accounting::HeapBitmap* mark_bitmap_;
Thread* self_;
// The space which we copy to if the to_space_ is full.
space::ContinuousMemMapAllocSpace* fallback_space_;
// How many objects and bytes we moved, used so that we don't need to Get the size of the
// to_space_ when calculating how many objects and bytes we freed.
size_t bytes_moved_;
size_t objects_moved_;
// How many bytes we avoided dirtying.
size_t saved_bytes_;
// The name of the collector.
std::string collector_name_;
// Used for the generational mode. The default interval of the whole
// heap collection. If N, the whole heap collection occurs every N
// collections.
static constexpr int kDefaultWholeHeapCollectionInterval = 5;
// Whether or not we swap the semi spaces in the heap during the marking phase.
bool swap_semi_spaces_;
private:
class BitmapSetSlowPathVisitor;
class MarkObjectVisitor;
class VerifyNoFromSpaceReferencesVisitor;
DISALLOW_IMPLICIT_CONSTRUCTORS(SemiSpace);
};
} // namespace collector
} // namespace gc
} // namespace art
#endif // ART_RUNTIME_GC_COLLECTOR_SEMI_SPACE_H_