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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 __LINKER_ALLOCATOR_H
#define __LINKER_ALLOCATOR_H
#include <stdlib.h>
#include <sys/cdefs.h>
#include <sys/mman.h>
#include <stddef.h>
#include <unistd.h>
#include <vector>
#include "private/bionic_prctl.h"
#include "private/libc_logging.h"
const uint32_t kSmallObjectMaxSizeLog2 = 10;
const uint32_t kSmallObjectMinSizeLog2 = 4;
const uint32_t kSmallObjectAllocatorsCount = kSmallObjectMaxSizeLog2 - kSmallObjectMinSizeLog2 + 1;
class LinkerSmallObjectAllocator;
// This structure is placed at the beginning of each addressable page
// and has all information we need to find the corresponding memory allocator.
struct page_info {
char signature[4];
uint32_t type;
union {
// we use allocated_size for large objects allocator
size_t allocated_size;
// and allocator_addr for small ones.
LinkerSmallObjectAllocator* allocator_addr;
};
};
struct small_object_page_record {
void* page_addr;
size_t free_blocks_cnt;
size_t allocated_blocks_cnt;
};
// for lower_bound...
bool operator<(const small_object_page_record& one, const small_object_page_record& two);
struct small_object_block_record {
small_object_block_record* next;
size_t free_blocks_cnt;
};
// This is implementation for std::vector allocator
template <typename T>
class linker_vector_allocator {
public:
typedef T value_type;
typedef T* pointer;
typedef const T* const_pointer;
typedef T& reference;
typedef const T& const_reference;
typedef size_t size_type;
typedef ptrdiff_t difference_type;
T* allocate(size_t n, const T* hint = nullptr) {
size_t size = n * sizeof(T);
void* ptr = mmap(const_cast<T*>(hint), size,
PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, 0, 0);
if (ptr == MAP_FAILED) {
// Spec says we need to throw std::bad_alloc here but because our
// code does not support exception handling anyways - we are going to abort.
__libc_fatal("mmap failed");
}
prctl(PR_SET_VMA, PR_SET_VMA_ANON_NAME, ptr, size, "linker_alloc_vector");
return reinterpret_cast<T*>(ptr);
}
void deallocate(T* ptr, size_t n) {
munmap(ptr, n * sizeof(T));
}
};
typedef
std::vector<small_object_page_record, linker_vector_allocator<small_object_page_record>>
linker_vector_t;
class LinkerSmallObjectAllocator {
public:
LinkerSmallObjectAllocator();
void init(uint32_t type, size_t block_size, const char* name);
void* alloc();
void free(void* ptr);
size_t get_block_size() const { return block_size_; }
private:
void alloc_page();
void free_page(linker_vector_t::iterator page_record);
linker_vector_t::iterator find_page_record(void* ptr);
void create_page_record(void* page_addr, size_t free_blocks_cnt);
uint32_t type_;
const char* name_;
size_t block_size_;
size_t free_pages_cnt_;
small_object_block_record* free_blocks_list_;
// sorted vector of page records
linker_vector_t page_records_;
};
class LinkerMemoryAllocator {
public:
LinkerMemoryAllocator();
void* alloc(size_t size);
// Note that this implementation of realloc never shrinks allocation
void* realloc(void* ptr, size_t size);
void free(void* ptr);
private:
void* alloc_mmap(size_t size);
page_info* get_page_info(void* ptr);
LinkerSmallObjectAllocator* get_small_object_allocator(uint32_t type);
LinkerSmallObjectAllocator allocators_[kSmallObjectAllocatorsCount];
};
#endif /* __LINKER_ALLOCATOR_H */
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