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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
* 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 "object_callbacks.h"
#include "space.h"
namespace art {
namespace gc {
namespace collector {
class MarkSweep;
} // namespace collector
namespace space {
// A bump pointer space allocates by incrementing a pointer, it doesn't provide a free
// implementation as its intended to be evacuated.
class BumpPointerSpace FINAL : public ContinuousMemMapAllocSpace {
typedef void(*WalkCallback)(void *start, void *end, size_t num_bytes, void* callback_arg);
SpaceType GetType() const OVERRIDE {
return kSpaceTypeBumpPointerSpace;
// Create a bump pointer space 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 BumpPointerSpace* Create(const std::string& name, size_t capacity, byte* requested_begin);
static BumpPointerSpace* CreateFromMemMap(const std::string& name, MemMap* mem_map);
// Allocate num_bytes, returns nullptr if the space is full.
mirror::Object* Alloc(Thread* self, size_t num_bytes, size_t* bytes_allocated,
size_t* usable_size) OVERRIDE;
// Thread-unsafe allocation for when mutators are suspended, used by the semispace collector.
mirror::Object* AllocThreadUnsafe(Thread* self, size_t num_bytes, size_t* bytes_allocated,
size_t* usable_size)
mirror::Object* AllocNonvirtual(size_t num_bytes);
mirror::Object* AllocNonvirtualWithoutAccounting(size_t num_bytes);
// Return the storage space required by obj.
size_t AllocationSize(mirror::Object* obj, size_t* usable_size) OVERRIDE
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
return AllocationSizeNonvirtual(obj, usable_size);
// NOPS unless we support free lists.
size_t Free(Thread*, mirror::Object*) OVERRIDE {
return 0;
size_t FreeList(Thread*, size_t, mirror::Object**) OVERRIDE {
return 0;
size_t AllocationSizeNonvirtual(mirror::Object* obj, size_t* usable_size)
// 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_end_ = Limit();
// Override capacity so that we only return the possibly limited capacity
size_t Capacity() const {
return growth_end_ - begin_;
// The total amount of memory reserved for the space.
size_t NonGrowthLimitCapacity() const {
return GetMemMap()->Size();
accounting::ContinuousSpaceBitmap* GetLiveBitmap() const OVERRIDE {
return nullptr;
accounting::ContinuousSpaceBitmap* GetMarkBitmap() const OVERRIDE {
return nullptr;
// Reset the space to empty.
void Clear() OVERRIDE LOCKS_EXCLUDED(block_lock_);
void Dump(std::ostream& os) const;
void RevokeThreadLocalBuffers(Thread* thread) LOCKS_EXCLUDED(block_lock_);
void RevokeAllThreadLocalBuffers() LOCKS_EXCLUDED(Locks::runtime_shutdown_lock_,
void AssertThreadLocalBuffersAreRevoked(Thread* thread) LOCKS_EXCLUDED(block_lock_);
void AssertAllThreadLocalBuffersAreRevoked() LOCKS_EXCLUDED(Locks::runtime_shutdown_lock_,
uint64_t GetBytesAllocated() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
uint64_t GetObjectsAllocated() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
bool IsEmpty() const {
return Begin() == End();
bool CanMoveObjects() const OVERRIDE {
return true;
bool Contains(const mirror::Object* obj) const {
const byte* byte_obj = reinterpret_cast<const byte*>(obj);
return byte_obj >= Begin() && byte_obj < End();
// TODO: Change this? Mainly used for compacting to a particular region of memory.
BumpPointerSpace(const std::string& name, byte* begin, byte* limit);
// Return the object which comes after obj, while ensuring alignment.
static mirror::Object* GetNextObject(mirror::Object* obj)
// Allocate a new TLAB, returns false if the allocation failed.
bool AllocNewTlab(Thread* self, size_t bytes);
BumpPointerSpace* AsBumpPointerSpace() OVERRIDE {
return this;
// Go through all of the blocks and visit the continuous objects.
void Walk(ObjectCallback* callback, void* arg)
accounting::ContinuousSpaceBitmap::SweepCallback* GetSweepCallback() OVERRIDE;
// Record objects / bytes freed.
void RecordFree(int32_t objects, int32_t bytes) {
void LogFragmentationAllocFailure(std::ostream& os, size_t failed_alloc_bytes) OVERRIDE
// Object alignment within the space.
static constexpr size_t kAlignment = 8;
BumpPointerSpace(const std::string& name, MemMap* mem_map);
// Allocate a raw block of bytes.
byte* AllocBlock(size_t bytes) EXCLUSIVE_LOCKS_REQUIRED(block_lock_);
void RevokeThreadLocalBuffersLocked(Thread* thread) EXCLUSIVE_LOCKS_REQUIRED(block_lock_);
// The main block is an unbounded block where objects go when there are no other blocks. This
// enables us to maintain tightly packed objects when you are not using thread local buffers for
// allocation. The main block starts at the space Begin().
void UpdateMainBlock() EXCLUSIVE_LOCKS_REQUIRED(block_lock_);
byte* growth_end_;
AtomicInteger objects_allocated_; // Accumulated from revoked thread local regions.
AtomicInteger bytes_allocated_; // Accumulated from revoked thread local regions.
// The objects at the start of the space are stored in the main block. The main block doesn't
// have a header, this lets us walk empty spaces which are mprotected.
size_t main_block_size_ GUARDED_BY(block_lock_);
// The number of blocks in the space, if it is 0 then the space has one long continuous block
// which doesn't have an updated header.
size_t num_blocks_ GUARDED_BY(block_lock_);
struct BlockHeader {
size_t size_; // Size of the block in bytes, does not include the header.
size_t unused_; // Ensures alignment of kAlignment.
COMPILE_ASSERT(sizeof(BlockHeader) % kAlignment == 0,
friend class collector::MarkSweep;
} // namespace space
} // namespace gc
} // namespace art