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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_SRC_GC_SPACE_H_
#define ART_SRC_GC_SPACE_H_
#include <string>
#include "../mutex.h"
#include "UniquePtr.h"
#include "globals.h"
#include "image.h"
#include "macros.h"
#include "dlmalloc.h"
#include "mem_map.h"
namespace art {
#ifndef NDEBUG
static const bool kDebugSpaces = true;
#else
static const bool kDebugSpaces = false;
#endif
class DlMallocSpace;
class ImageSpace;
class LargeObjectSpace;
class Object;
class SpaceBitmap;
enum GcRetentionPolicy {
kGcRetentionPolicyNeverCollect,
kGcRetentionPolicyAlwaysCollect,
kGcRetentionPolicyFullCollect, // Collect only for full GC
};
std::ostream& operator<<(std::ostream& os, const GcRetentionPolicy& policy);
enum SpaceType {
kSpaceTypeImageSpace,
kSpaceTypeAllocSpace,
kSpaceTypeZygoteSpace,
kSpaceTypeLargeObjectSpace,
};
std::ostream& operator<<(std::ostream& os, const SpaceType& space_type);
// A space contains memory allocated for managed objects.
class Space {
public:
virtual bool CanAllocateInto() const = 0;
virtual bool IsCompactible() const = 0;
virtual bool Contains(const Object* obj) const = 0;
virtual SpaceType GetType() const = 0;
virtual GcRetentionPolicy GetGcRetentionPolicy() const = 0;
virtual std::string GetName() const = 0;
ImageSpace* AsImageSpace();
DlMallocSpace* AsAllocSpace();
DlMallocSpace* AsZygoteSpace();
LargeObjectSpace* AsLargeObjectSpace();
bool IsImageSpace() const {
return GetType() == kSpaceTypeImageSpace;
}
bool IsAllocSpace() const {
return GetType() == kSpaceTypeAllocSpace || GetType() == kSpaceTypeZygoteSpace;
}
bool IsZygoteSpace() const {
return GetType() == kSpaceTypeZygoteSpace;
}
bool IsLargeObjectSpace() const {
return GetType() == kSpaceTypeLargeObjectSpace;
}
virtual void Dump(std::ostream& /* os */) const { }
virtual ~Space() {}
protected:
Space() { }
private:
DISALLOW_COPY_AND_ASSIGN(Space);
};
// AllocSpace interface.
class AllocSpace {
public:
virtual bool CanAllocateInto() const {
return true;
}
// General statistics
virtual uint64_t GetNumBytesAllocated() const = 0;
virtual uint64_t GetNumObjectsAllocated() const = 0;
virtual uint64_t GetTotalBytesAllocated() const = 0;
virtual uint64_t GetTotalObjectsAllocated() const = 0;
// Allocate num_bytes without allowing growth.
virtual Object* Alloc(Thread* self, size_t num_bytes) = 0;
// Return the storage space required by obj.
virtual size_t AllocationSize(const Object* obj) = 0;
// Returns how many bytes were freed.
virtual size_t Free(Thread* self, Object* ptr) = 0;
// Returns how many bytes were freed.
virtual size_t FreeList(Thread* self, size_t num_ptrs, Object** ptrs) = 0;
protected:
AllocSpace() {}
virtual ~AllocSpace() {}
private:
DISALLOW_COPY_AND_ASSIGN(AllocSpace);
};
// Continuous spaces have bitmaps, and an address range.
class ContinuousSpace : public Space {
public:
// Address at which the space begins
byte* Begin() const {
return begin_;
}
// Address at which the space ends, which may vary as the space is filled.
byte* End() const {
return end_;
}
// Current size of space
size_t Size() const {
return End() - Begin();
}
virtual SpaceBitmap* GetLiveBitmap() const = 0;
virtual SpaceBitmap* GetMarkBitmap() const = 0;
// Is object within this space?
bool HasAddress(const Object* obj) const {
const byte* byte_ptr = reinterpret_cast<const byte*>(obj);
return Begin() <= byte_ptr && byte_ptr < End();
}
virtual bool Contains(const Object* obj) const {
return HasAddress(obj);
}
virtual ~ContinuousSpace() {}
virtual std::string GetName() const {
return name_;
}
virtual GcRetentionPolicy GetGcRetentionPolicy() const {
return gc_retention_policy_;
}
protected:
ContinuousSpace(const std::string& name, byte* begin, byte* end,
GcRetentionPolicy gc_retention_policy);
std::string name_;
GcRetentionPolicy gc_retention_policy_;
// The beginning of the storage for fast access.
byte* begin_;
// Current end of the space.
byte* end_;
private:
DISALLOW_COPY_AND_ASSIGN(ContinuousSpace);
};
class DiscontinuousSpace : public virtual Space {
public:
// Is object within this space?
virtual bool Contains(const Object* obj) const = 0;
virtual std::string GetName() const {
return name_;
}
virtual GcRetentionPolicy GetGcRetentionPolicy() const {
return gc_retention_policy_;
}
protected:
DiscontinuousSpace(const std::string& name, GcRetentionPolicy gc_retention_policy);
private:
std::string name_;
GcRetentionPolicy gc_retention_policy_;
DISALLOW_COPY_AND_ASSIGN(DiscontinuousSpace);
};
std::ostream& operator<<(std::ostream& os, const Space& space);
class MemMapSpace : public ContinuousSpace {
public:
// Maximum which the mapped space can grow to.
virtual size_t Capacity() const {
return mem_map_->Size();
}
// Size of the space without a limit on its growth. By default this is just the Capacity, but
// for the allocation space we support starting with a small heap and then extending it.
virtual size_t NonGrowthLimitCapacity() const {
return Capacity();
}
protected:
MemMapSpace(const std::string& name, MemMap* mem_map, size_t initial_size,
GcRetentionPolicy gc_retention_policy);
MemMap* GetMemMap() {
return mem_map_.get();
}
const MemMap* GetMemMap() const {
return mem_map_.get();
}
private:
// Underlying storage of the space
UniquePtr<MemMap> mem_map_;
DISALLOW_COPY_AND_ASSIGN(MemMapSpace);
};
// An alloc space is a space where objects may be allocated and garbage collected.
class DlMallocSpace : public MemMapSpace, public AllocSpace {
public:
typedef void(*WalkCallback)(void *start, void *end, size_t num_bytes, void* callback_arg);
virtual bool CanAllocateInto() const {
return true;
}
virtual bool IsCompactible() const {
return false;
}
virtual SpaceType GetType() const {
return kSpaceTypeAllocSpace;
}
// Create a AllocSpace with the requested sizes. The requested
// base address is not guaranteed to be granted, if it is required,
// the caller should call Begin on the returned space to confirm
// the request was granted.
static DlMallocSpace* Create(const std::string& name, size_t initial_size, size_t growth_limit,
size_t capacity, byte* requested_begin);
// Allocate num_bytes without allowing the underlying mspace to grow.
virtual Object* AllocWithGrowth(Thread* self, size_t num_bytes);
// Allocate num_bytes allowing the underlying mspace to grow.
virtual Object* Alloc(Thread* self, size_t num_bytes);
// Return the storage space required by obj.
virtual size_t AllocationSize(const Object* obj);
virtual size_t Free(Thread* self, Object* ptr);
virtual size_t FreeList(Thread* self, size_t num_ptrs, Object** ptrs);
void* MoreCore(intptr_t increment);
void* GetMspace() const {
return mspace_;
}
// Hands unused pages back to the system.
void Trim();
// Perform a mspace_inspect_all which calls back for each allocation chunk. The chunk may not be
// in use, indicated by num_bytes equaling zero.
void Walk(WalkCallback callback, void* arg);
// Returns the number of bytes that the heap is allowed to obtain from the system via MoreCore.
size_t GetFootprintLimit();
// Set the maximum number of bytes that the heap is allowed to obtain from the system via
// MoreCore. Note this is used to stop the mspace growing beyond the limit to Capacity. When
// allocations fail we GC before increasing the footprint limit and allowing the mspace to grow.
void SetFootprintLimit(size_t limit);
// Removes the fork time growth limit on capacity, allowing the application to allocate up to the
// maximum reserved size of the heap.
void ClearGrowthLimit() {
growth_limit_ = NonGrowthLimitCapacity();
}
// Override capacity so that we only return the possibly limited capacity
virtual size_t Capacity() const {
return growth_limit_;
}
// The total amount of memory reserved for the alloc space
virtual size_t NonGrowthLimitCapacity() const {
return GetMemMap()->Size();
}
virtual SpaceBitmap* GetLiveBitmap() const {
return live_bitmap_.get();
}
virtual SpaceBitmap* GetMarkBitmap() const {
return mark_bitmap_.get();
}
virtual void Dump(std::ostream& os) const;
void SetGrowthLimit(size_t growth_limit);
// Swap the live and mark bitmaps of this space. This is used by the GC for concurrent sweeping.
virtual void SwapBitmaps();
// Turn ourself into a zygote space and return a new alloc space which has our unused memory.
DlMallocSpace* CreateZygoteSpace();
void SetGcRetentionPolicy(GcRetentionPolicy gc_retention_policy) {
gc_retention_policy_ = gc_retention_policy;
}
virtual uint64_t GetNumBytesAllocated() const {
return num_bytes_allocated_;
}
virtual uint64_t GetNumObjectsAllocated() const {
return num_objects_allocated_;
}
virtual uint64_t GetTotalBytesAllocated() const {
return total_bytes_allocated_;
}
virtual uint64_t GetTotalObjectsAllocated() const {
return total_objects_allocated_;
}
private:
Object* AllocWithoutGrowthLocked(size_t num_bytes) EXCLUSIVE_LOCKS_REQUIRED(lock_);
UniquePtr<SpaceBitmap> live_bitmap_;
UniquePtr<SpaceBitmap> mark_bitmap_;
UniquePtr<SpaceBitmap> temp_bitmap_;
// Approximate number of bytes which have been allocated into the space.
size_t num_bytes_allocated_;
size_t num_objects_allocated_;
size_t total_bytes_allocated_;
size_t total_objects_allocated_;
static size_t bitmap_index_;
DlMallocSpace(const std::string& name, MemMap* mem_map, void* mspace, byte* begin, byte* end,
size_t growth_limit);
bool Init(size_t initial_size, size_t maximum_size, size_t growth_size, byte* requested_base);
static void* CreateMallocSpace(void* base, size_t morecore_start, size_t initial_size);
// The boundary tag overhead.
static const size_t kChunkOverhead = kWordSize;
// Used to ensure mutual exclusion when the allocation spaces data structures are being modified.
Mutex lock_;
// Underlying malloc space
void* const mspace_;
// The capacity of the alloc space until such time that ClearGrowthLimit is called.
// The underlying mem_map_ controls the maximum size we allow the heap to grow to. The growth
// limit is a value <= to the mem_map_ capacity used for ergonomic reasons because of the zygote.
// Prior to forking the zygote the heap will have a maximally sized mem_map_ but the growth_limit_
// will be set to a lower value. The growth_limit_ is used as the capacity of the alloc_space_,
// however, capacity normally can't vary. In the case of the growth_limit_ it can be cleared
// one time by a call to ClearGrowthLimit.
size_t growth_limit_;
friend class MarkSweep;
DISALLOW_COPY_AND_ASSIGN(DlMallocSpace);
};
// An image space is a space backed with a memory mapped image
class ImageSpace : public MemMapSpace {
public:
virtual bool CanAllocateInto() const {
return false;
}
virtual bool IsCompactible() const {
return false;
}
virtual SpaceType GetType() const {
return kSpaceTypeImageSpace;
}
// create a Space from an image file. cannot be used for future allocation or collected.
static ImageSpace* Create(const std::string& image)
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
const ImageHeader& GetImageHeader() const {
return *reinterpret_cast<ImageHeader*>(Begin());
}
const std::string GetImageFilename() const {
return GetName();
}
// Mark the objects defined in this space in the given live bitmap
void RecordImageAllocations(SpaceBitmap* live_bitmap) const
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
virtual SpaceBitmap* GetLiveBitmap() const {
return live_bitmap_.get();
}
virtual SpaceBitmap* GetMarkBitmap() const {
// ImageSpaces have the same bitmap for both live and marked. This helps reduce the number of
// special cases to test against.
return live_bitmap_.get();
}
virtual void Dump(std::ostream& os) const;
private:
friend class Space;
UniquePtr<SpaceBitmap> live_bitmap_;
static size_t bitmap_index_;
ImageSpace(const std::string& name, MemMap* mem_map);
DISALLOW_COPY_AND_ASSIGN(ImageSpace);
};
// Callback for dlmalloc_inspect_all or mspace_inspect_all that will madvise(2) unused
// pages back to the kernel.
void MspaceMadviseCallback(void* start, void* end, size_t used_bytes, void* /*arg*/);
} // namespace art
#endif // ART_SRC_GC_SPACE_H_