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ton/tdutils/td/utils/StackAllocator.h
2019-09-07 14:33:36 +04:00

96 lines
2.3 KiB
C++

/*
This file is part of TON Blockchain Library.
TON Blockchain Library is free software: you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation, either version 2 of the License, or
(at your option) any later version.
TON Blockchain Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with TON Blockchain Library. If not, see <http://www.gnu.org/licenses/>.
Copyright 2017-2019 Telegram Systems LLP
*/
#pragma once
#include "td/utils/common.h"
#include "td/utils/MovableValue.h"
#include "td/utils/Slice.h"
#include <array>
#include <cstdlib>
#include <memory>
namespace td {
class StackAllocator {
class Deleter {
public:
void operator()(char *ptr) {
free_ptr(ptr);
}
};
// TODO: alloc memory with mmap and unload unused pages
// memory still can be corrupted, but it is better than explicit free function
// TODO: use pointer that can't be even copied
using PtrImpl = std::unique_ptr<char, Deleter>;
class Ptr {
public:
Ptr(char *ptr, size_t size) : ptr_(ptr), size_(size) {
}
MutableSlice as_slice() const {
return MutableSlice(ptr_.get(), size_.get());
}
private:
PtrImpl ptr_;
MovableValue<size_t> size_;
};
static void free_ptr(char *ptr) {
impl().free_ptr(ptr);
}
struct Impl {
static const size_t MEM_SIZE = 1024 * 1024;
std::array<char, MEM_SIZE> mem;
size_t pos{0};
char *alloc(size_t size) {
if (size == 0) {
size = 1;
}
char *res = mem.data() + pos;
size = (size + 7) & -8;
pos += size;
if (pos > MEM_SIZE) {
std::abort(); // memory is over
}
return res;
}
void free_ptr(char *ptr) {
size_t new_pos = ptr - mem.data();
if (new_pos >= pos) {
std::abort(); // shouldn't happen
}
pos = new_pos;
}
};
static Impl &impl();
public:
static Ptr alloc(size_t size) {
return Ptr(impl().alloc(size), size);
}
};
} // namespace td