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/*
* Copyright (C) 2015 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_LINEAR_ALLOC_H_
#define ART_RUNTIME_LINEAR_ALLOC_H_
#include "base/arena_allocator.h"
#include "base/casts.h"
#include "base/mutex.h"
namespace art {
class ArenaPool;
enum class LinearAllocKind : uint32_t {
kNoGCRoots = 0, // No GC-root kind should always be 0.
kGCRootArray,
kArtMethodArray,
kArtFieldArray,
kDexCacheArray,
kArtMethod
};
// Header for every allocation in LinearAlloc. The header provides the type
// and size information to the GC for invoking the right visitor.
class TrackingHeader final {
public:
static constexpr uint32_t kIs16Aligned = 1;
TrackingHeader(size_t size, LinearAllocKind kind, bool is_16_aligned = false)
: kind_(kind), size_(dchecked_integral_cast<uint32_t>(size)) {
// We need the last bit to store 16-byte alignment flag.
CHECK_EQ(size_ & kIs16Aligned, 0u);
if (is_16_aligned) {
size_ |= kIs16Aligned;
}
}
LinearAllocKind GetKind() const { return kind_; }
// Since we are linearly allocating and hop from one object to the next during
// visits, reading 'size_ == 0' indicates that there are no more objects to
// visit in the given page. But ASAN detects it as use-after-poison access.
ATTRIBUTE_NO_SANITIZE_ADDRESS size_t GetSize() const { return size_ & ~kIs16Aligned; }
bool Is16Aligned() const { return size_ & kIs16Aligned; }
private:
LinearAllocKind kind_;
uint32_t size_;
DISALLOW_IMPLICIT_CONSTRUCTORS(TrackingHeader);
};
std::ostream& operator<<(std::ostream& os, LinearAllocKind value);
class LinearAlloc {
public:
static constexpr size_t kAlignment = 8u;
static_assert(kAlignment >= ArenaAllocator::kAlignment);
static_assert(sizeof(TrackingHeader) == ArenaAllocator::kAlignment);
explicit LinearAlloc(ArenaPool* pool, bool track_allocs)
: lock_("linear alloc"), allocator_(pool), track_allocations_(track_allocs) {}
void* Alloc(Thread* self, size_t size, LinearAllocKind kind) REQUIRES(!lock_);
void* AllocAlign16(Thread* self, size_t size, LinearAllocKind kind) REQUIRES(!lock_);
// Realloc never frees the input pointer, it is the caller's job to do this if necessary.
void* Realloc(Thread* self, void* ptr, size_t old_size, size_t new_size, LinearAllocKind kind)
REQUIRES(!lock_);
// Allocate an array of structs of type T.
template<class T>
T* AllocArray(Thread* self, size_t elements, LinearAllocKind kind) REQUIRES(!lock_) {
return reinterpret_cast<T*>(Alloc(self, elements * sizeof(T), kind));
}
// Return the number of bytes used in the allocator.
size_t GetUsedMemory() const REQUIRES(!lock_);
ArenaPool* GetArenaPool() REQUIRES(!lock_);
// Force arena allocator to ask for a new arena on next allocation. This
// is to preserve private/shared clean pages across zygote fork.
void SetupForPostZygoteFork(Thread* self) REQUIRES(!lock_);
// Return true if the linear alloc contains an address.
bool Contains(void* ptr) const REQUIRES(!lock_);
// Unsafe version of 'Contains' only to be used when the allocator is going
// to be deleted.
bool ContainsUnsafe(void* ptr) const NO_THREAD_SAFETY_ANALYSIS {
return allocator_.Contains(ptr);
}
// Set the given object as the first object for all the pages where the
// page-beginning overlaps with the object.
void SetFirstObject(void* begin, size_t bytes) const REQUIRES(lock_);
private:
mutable Mutex lock_ DEFAULT_MUTEX_ACQUIRED_AFTER;
ArenaAllocator allocator_ GUARDED_BY(lock_);
const bool track_allocations_;
DISALLOW_IMPLICIT_CONSTRUCTORS(LinearAlloc);
};
} // namespace art
#endif // ART_RUNTIME_LINEAR_ALLOC_H_
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