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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
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* See the License for the specific language governing permissions and
* limitations under the License.
#include "gc/allocator/dlmalloc.h"
#include "space.h"
namespace art {
namespace gc {
namespace collector {
class MarkSweep;
} // namespace collector
namespace space {
// An alloc space is a space where objects may be allocated and garbage collected.
class DlMallocSpace : public MemMapSpace, public AllocSpace {
typedef void(*WalkCallback)(void *start, void *end, size_t num_bytes, void* callback_arg);
SpaceType GetType() const {
if (GetGcRetentionPolicy() == kGcRetentionPolicyFullCollect) {
return kSpaceTypeZygoteSpace;
} else {
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 mirror::Object* AllocWithGrowth(Thread* self, size_t num_bytes,
size_t* bytes_allocated) LOCKS_EXCLUDED(lock_);
// Allocate num_bytes allowing the underlying mspace to grow.
virtual mirror::Object* Alloc(Thread* self, size_t num_bytes, size_t* bytes_allocated);
// Return the storage space required by obj.
virtual size_t AllocationSize(const mirror::Object* obj);
virtual size_t Free(Thread* self, mirror::Object* ptr);
virtual size_t FreeList(Thread* self, size_t num_ptrs, mirror::Object** ptrs);
mirror::Object* AllocNonvirtual(Thread* self, size_t num_bytes, size_t* bytes_allocated);
size_t AllocationSizeNonvirtual(const mirror::Object* obj) {
return mspace_usable_size(const_cast<void*>(reinterpret_cast<const void*>(obj))) +
void* MoreCore(intptr_t increment);
void* GetMspace() const {
return mspace_;
// Hands unused pages back to the system.
size_t 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) LOCKS_EXCLUDED(lock_);
// Returns the number of bytes that the space has currently obtained from the system. This is
// greater or equal to the amount of live data in the space.
size_t GetFootprint();
// 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
size_t Capacity() const {
return growth_limit_;
// The total amount of memory reserved for the alloc space.
size_t NonGrowthLimitCapacity() const {
return GetMemMap()->Size();
accounting::SpaceBitmap* GetLiveBitmap() const {
return live_bitmap_.get();
accounting::SpaceBitmap* GetMarkBitmap() const {
return mark_bitmap_.get();
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.
void SwapBitmaps();
// Turn ourself into a zygote space and return a new alloc space which has our unused memory.
DlMallocSpace* CreateZygoteSpace(const char* alloc_space_name);
uint64_t GetBytesAllocated() const {
return num_bytes_allocated_;
uint64_t GetObjectsAllocated() const {
return num_objects_allocated_;
uint64_t GetTotalBytesAllocated() const {
return total_bytes_allocated_;
uint64_t GetTotalObjectsAllocated() const {
return total_objects_allocated_;
DlMallocSpace(const std::string& name, MemMap* mem_map, void* mspace, byte* begin, byte* end,
size_t growth_limit);
size_t InternalAllocationSize(const mirror::Object* obj);
mirror::Object* AllocWithoutGrowthLocked(size_t num_bytes, size_t* bytes_allocated)
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);
UniquePtr<accounting::SpaceBitmap> live_bitmap_;
UniquePtr<accounting::SpaceBitmap> mark_bitmap_;
UniquePtr<accounting::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_;
// The boundary tag overhead.
static const size_t kChunkOverhead = kWordSize;
// Used to ensure mutual exclusion when the allocation spaces data structures are being modified.
// 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 collector::MarkSweep;
} // namespace space
} // namespace gc
} // namespace art