atomic allocator might not be possible

v1
Brett 2024-08-19 20:03:46 -04:00
parent 72211e3d7b
commit 78710a12cc
3 changed files with 85 additions and 85 deletions

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@ -1,6 +1,6 @@
cmake_minimum_required(VERSION 3.20)
include(cmake/color.cmake)
set(BLT_VERSION 0.18.38)
set(BLT_VERSION 0.18.39)
set(BLT_TEST_VERSION 0.0.1)
set(BLT_TARGET BLT)

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@ -36,89 +36,89 @@
namespace blt
{
template<typename Alloc = blt::aligned_huge_allocator>
class atomic_bump_allocator
{
private:
struct block
{
struct block_metadata_t
{
const blt::size_t size = 0;
std::atomic<blt::size_t> allocated_objects = 0;
std::atomic<block*> next = nullptr;
std::atomic<block*> prev = nullptr;
std::atomic<blt::u8*> offset = nullptr;
} metadata;
blt::u8 buffer[8]{};
explicit block(blt::size_t size)
{
metadata.size = size;
metadata.offset = buffer;
}
[[nodiscard]] blt::ptrdiff_t storage_size() const noexcept
{
return static_cast<blt::ptrdiff_t>(metadata.size - sizeof(typename block::block_metadata_t));
}
[[nodiscard]] blt::ptrdiff_t used_bytes_in_block() const noexcept
{
return static_cast<blt::ptrdiff_t>(metadata.offset - buffer);
}
[[nodiscard]] blt::ptrdiff_t remaining_bytes_in_block() const noexcept
{
return storage_size() - used_bytes_in_block();
}
};
public:
void* allocate(blt::size_t bytes)
{
auto head_ptr = head.load(std::memory_order_relaxed);
auto new_head = head_ptr;
do
{
if (head_ptr->remaining_bytes_in_block() < bytes)
{
}
} while (!head.compare_exchange_weak(head_ptr, new_head, std::memory_order_release, std::memory_order_acquire));
}
void deallocate(void* ptr)
{
auto blk = to_block(ptr);
--blk.metadata.allocated_objects;
if (blk.metadata.allocated_objects == 0)
{
if (blk->metadata.prev != nullptr)
blk->metadata.prev->metadata.next = blk->metadata.next;
if (blk->metadata.next != nullptr)
blk->metadata.next->metadata.prev = blk->metadata.prev;
alloc.deallocate(blk, blk.metadata.size);
}
}
private:
static inline block* to_block(void* p)
{
return reinterpret_cast<block*>(reinterpret_cast<std::uintptr_t>(p) & static_cast<std::uintptr_t>(~(BLT_2MB_SIZE - 1)));
}
inline block* allocate_block(blt::size_t bytes)
{
auto size = align_size_to(bytes, BLT_2MB_SIZE);
auto ptr = static_cast<block*>(alloc.allocate(size));
new(ptr) block{size};
return ptr;
}
std::atomic<block*> head = nullptr;
Alloc alloc;
};
// template<typename Alloc = blt::aligned_huge_allocator>
// class atomic_bump_allocator
// {
// private:
// struct block
// {
// struct block_metadata_t
// {
// const blt::size_t size = 0;
// std::atomic<blt::size_t> allocated_objects = 0;
// std::atomic<block*> next = nullptr;
// std::atomic<block*> prev = nullptr;
// std::atomic<blt::u8*> offset = nullptr;
// } metadata;
// blt::u8 buffer[8]{};
//
// explicit block(blt::size_t size)
// {
// metadata.size = size;
// metadata.offset = buffer;
// }
//
// [[nodiscard]] blt::ptrdiff_t storage_size() const noexcept
// {
// return static_cast<blt::ptrdiff_t>(metadata.size - sizeof(typename block::block_metadata_t));
// }
//
// [[nodiscard]] blt::ptrdiff_t used_bytes_in_block() const noexcept
// {
// return static_cast<blt::ptrdiff_t>(metadata.offset - buffer);
// }
//
// [[nodiscard]] blt::ptrdiff_t remaining_bytes_in_block() const noexcept
// {
// return storage_size() - used_bytes_in_block();
// }
// };
//
// public:
// void* allocate(blt::size_t bytes)
// {
// auto head_ptr = head.load(std::memory_order_relaxed);
// auto new_head = head_ptr;
// do
// {
// if (head_ptr->remaining_bytes_in_block() < bytes)
// {
//
// }
// } while (!head.compare_exchange_weak(head_ptr, new_head, std::memory_order_release, std::memory_order_acquire));
// }
//
// void deallocate(void* ptr)
// {
// auto blk = to_block(ptr);
// --blk.metadata.allocated_objects;
// if (blk.metadata.allocated_objects == 0)
// {
// if (blk->metadata.prev != nullptr)
// blk->metadata.prev->metadata.next = blk->metadata.next;
// if (blk->metadata.next != nullptr)
// blk->metadata.next->metadata.prev = blk->metadata.prev;
// alloc.deallocate(blk, blk.metadata.size);
// }
// }
//
// private:
// static inline block* to_block(void* p)
// {
// return reinterpret_cast<block*>(reinterpret_cast<std::uintptr_t>(p) & static_cast<std::uintptr_t>(~(BLT_2MB_SIZE - 1)));
// }
//
// inline block* allocate_block(blt::size_t bytes)
// {
// auto size = align_size_to(bytes, BLT_2MB_SIZE);
// auto ptr = static_cast<block*>(alloc.allocate(size));
// new(ptr) block{size};
// return ptr;
// }
//
// std::atomic<block*> head = nullptr;
// Alloc alloc;
// };
}

@ -1 +1 @@
Subproject commit 8a889d3699b3c09ade435641fb034427f3fd12b6
Subproject commit d88c5e15079047777b418132ece5879e7c9aaa2b