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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_SPACE_BUMP_POINTER_SPACE_H_
#define ART_RUNTIME_GC_SPACE_BUMP_POINTER_SPACE_H_
#include "root_visitor.h"
#include "space.h"
namespace art {
namespace gc {
namespace collector {
class MarkSweep;
} // namespace collector
namespace space {
// A bump pointer space is a space where objects may be allocated and garbage collected.
class BumpPointerSpace : public ContinuousMemMapAllocSpace {
public:
typedef void(*WalkCallback)(void *start, void *end, size_t num_bytes, void* callback_arg);
SpaceType GetType() const {
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);
// Allocate num_bytes, returns nullptr if the space is full.
virtual mirror::Object* Alloc(Thread* self, size_t num_bytes, size_t* bytes_allocated);
mirror::Object* AllocNonvirtual(size_t num_bytes);
mirror::Object* AllocNonvirtualWithoutAccounting(size_t num_bytes);
// Return the storage space required by obj.
virtual size_t AllocationSize(mirror::Object* obj) SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
// NOPS unless we support free lists.
virtual size_t Free(Thread*, mirror::Object*) {
return 0;
}
virtual size_t FreeList(Thread*, size_t, mirror::Object**) {
return 0;
}
size_t AllocationSizeNonvirtual(mirror::Object* obj)
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
return obj->SizeOf();
}
// 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::SpaceBitmap* GetLiveBitmap() const {
return nullptr;
}
accounting::SpaceBitmap* GetMarkBitmap() const {
return nullptr;
}
// Clear the memory and reset the pointer to the start of the space.
void Clear() 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_,
Locks::thread_list_lock_);
uint64_t GetBytesAllocated() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
uint64_t GetObjectsAllocated() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
bool IsEmpty() const;
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)
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
// Allocate a new TLAB, returns false if the allocation failed.
bool AllocNewTlab(Thread* self, size_t bytes);
virtual BumpPointerSpace* AsBumpPointerSpace() {
return this;
}
// Go through all of the blocks and visit the continuous objects.
void Walk(ObjectVisitorCallback callback, void* arg)
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
// Object alignment within the space.
static constexpr size_t kAlignment = 8;
protected:
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_);
mirror::Object* AllocWithoutGrowthLocked(size_t num_bytes, size_t* bytes_allocated)
EXCLUSIVE_LOCKS_REQUIRED(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 is also the block which starts at address 0.
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.
Mutex block_lock_ DEFAULT_MUTEX_ACQUIRED_AFTER;
// 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_);
private:
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,
continuous_block_must_be_kAlignment_aligned);
friend class collector::MarkSweep;
DISALLOW_COPY_AND_ASSIGN(BumpPointerSpace);
};
} // namespace space
} // namespace gc
} // namespace art
#endif // ART_RUNTIME_GC_SPACE_BUMP_POINTER_SPACE_H_
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