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blt-gp/include/blt/gp/stack.h

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#pragma once
/*
* Copyright (C) 2024 Brett Terpstra
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <https://www.gnu.org/licenses/>.
*/
#ifndef BLT_GP_STACK_H
#define BLT_GP_STACK_H
#include <blt/std/types.h>
#include <blt/std/assert.h>
#include <blt/std/logging.h>
#include <blt/std/allocator.h>
#include <blt/gp/fwdecl.h>
#include <utility>
#include <stdexcept>
#include <cstdlib>
#include <memory>
#include <type_traits>
#include <cstring>
#include <iostream>
namespace blt::gp
{
class huge_allocator
{
public:
constexpr static blt::size_t HUGE_PAGE_SIZE = BLT_2MB_SIZE;
static_assert(((HUGE_PAGE_SIZE & (HUGE_PAGE_SIZE - 1)) == 0) && "Must be a power of two!");
void* allocate(blt::size_t bytes)
{
std::scoped_lock lock(mutex);
if (bytes > HUGE_PAGE_SIZE)
throw std::runtime_error("Unable to allocate more than 2mb of space at a time!");
if (head == nullptr || head.load()->remaining_bytes() < bytes)
push_block();
auto ptr = head.load()->metadata.offset;
head.load()->metadata.offset += bytes;
head.load()->metadata.allocated_objects++;
return ptr;
}
void deallocate(void* ptr)
{
std::scoped_lock lock(mutex);
auto block = to_block(ptr);
block->metadata.allocated_objects--;
if (block->metadata.allocated_objects == 0)
delete_block(block);
}
private:
struct block
{
struct block_metadata_t
{
blt::ptrdiff_t allocated_objects = 0;
block* next = nullptr;
block* prev = nullptr;
blt::u8* offset = nullptr;
} metadata;
blt::u8 buffer[HUGE_PAGE_SIZE - sizeof(block_metadata_t)]{};
block()
{
metadata.offset = buffer;
}
void reset()
{
metadata.allocated_objects = 0;
metadata.offset = buffer;
metadata.next = nullptr;
metadata.prev = nullptr;
}
blt::size_t remaining_bytes()
{
static constexpr blt::size_t BLOCK_REMAINDER = HUGE_PAGE_SIZE - sizeof(block_metadata_t);
return BLOCK_REMAINDER - static_cast<blt::ptrdiff_t>(metadata.offset - buffer);
}
};
template<typename T>
static inline block* to_block(T* p)
{
return reinterpret_cast<block*>(reinterpret_cast<std::uintptr_t>(p) & static_cast<std::uintptr_t>(~(HUGE_PAGE_SIZE - 1)));
}
void delete_block(block* b)
{
if (b->metadata.prev != nullptr)
b->metadata.prev->metadata.next = b->metadata.next;
deallocated_blocks.push_back(b);
}
void push_block()
{
block* block;
if (deallocated_blocks.empty())
block = allocate_block();
else
{
block = deallocated_blocks.back();
deallocated_blocks.pop_back();
block->reset();
}
block->metadata.prev = head;
if (head != nullptr)
head.load()->metadata.next = block;
head = block;
}
static block* allocate_block()
{
auto* buffer = reinterpret_cast<block*>(std::aligned_alloc(HUGE_PAGE_SIZE, HUGE_PAGE_SIZE));
new(buffer) block{};
return buffer;
}
std::atomic<block*> head = nullptr;
std::mutex mutex;
std::vector<block*> deallocated_blocks;
};
huge_allocator& get_allocator();
class stack_allocator
{
constexpr static blt::size_t PAGE_SIZE = 0x1000;
constexpr static blt::size_t MAX_ALIGNMENT = 8;
template<typename T>
using NO_REF_T = std::remove_cv_t<std::remove_reference_t<T>>;
public:
struct size_data_t
{
blt::size_t total_size_bytes = 0;
blt::size_t total_used_bytes = 0;
blt::size_t total_remaining_bytes = 0;
blt::size_t total_no_meta_bytes = 0;
blt::size_t total_dealloc = 0;
blt::size_t total_dealloc_used = 0;
blt::size_t total_dealloc_remaining = 0;
blt::size_t total_dealloc_no_meta = 0;
blt::size_t blocks = 0;
friend std::ostream& operator<<(std::ostream& stream, const size_data_t& data)
{
stream << "[";
stream << data.total_used_bytes << "/";
stream << data.total_size_bytes << "(";
stream << (static_cast<double>(data.total_used_bytes) / static_cast<double>(data.total_size_bytes)) << "%), ";
stream << data.total_used_bytes << "/";
stream << data.total_no_meta_bytes << "(";
stream << (static_cast<double>(data.total_used_bytes) / static_cast<double>(data.total_no_meta_bytes)) << "%), (empty space: ";
stream << data.total_remaining_bytes << ") blocks: " << data.blocks << " || unallocated space: ";
stream << data.total_dealloc_used << "/";
stream << data.total_dealloc;
if (static_cast<double>(data.total_dealloc) > 0)
stream << "(" << (static_cast<double>(data.total_dealloc_used) / static_cast<double>(data.total_dealloc)) << "%)";
stream << ", ";
stream << data.total_dealloc_used << "/";
stream << data.total_dealloc_no_meta;
if (data.total_dealloc_no_meta > 0)
stream << "(" << (static_cast<double>(data.total_dealloc_used) / static_cast<double>(data.total_dealloc_no_meta)) << "%)";
stream << ", (empty space: " << data.total_dealloc_remaining << ")]";
return stream;
}
};
/**
* Pushes an instance of an object on to the stack
* @tparam T type to push
* @param value universal reference to the object to push
*/
template<typename T>
void push(T&& value)
{
using NO_REF_T = std::remove_cv_t<std::remove_reference_t<T>>;
static_assert(std::is_trivially_copyable_v<NO_REF_T> && "Type must be bitwise copyable!");
static_assert(alignof(NO_REF_T) <= MAX_ALIGNMENT && "Type must not be greater than the max alignment!");
auto ptr = allocate_bytes<NO_REF_T>();
head->metadata.offset = static_cast<blt::u8*>(ptr) + aligned_size<NO_REF_T>();
new(ptr) NO_REF_T(std::forward<T>(value));
}
template<typename T>
T pop()
{
using NO_REF_T = std::remove_cv_t<std::remove_reference_t<T>>;
static_assert(std::is_trivially_copyable_v<NO_REF_T> && "Type must be bitwise copyable!");
constexpr static auto TYPE_SIZE = aligned_size<NO_REF_T>();
while (head->used_bytes_in_block() == 0 && move_back());
if (empty())
throw std::runtime_error("Silly boi the stack is empty!");
if (head->used_bytes_in_block() < static_cast<blt::ptrdiff_t>(aligned_size<NO_REF_T>()))
throw std::runtime_error((std::string("Mismatched Types! Not enough space left in block! Bytes: ") += std::to_string(
head->used_bytes_in_block()) += " Size: " + std::to_string(sizeof(NO_REF_T))).c_str());
// make copy
NO_REF_T t = *reinterpret_cast<NO_REF_T*>(head->metadata.offset - TYPE_SIZE);
// call destructor
reinterpret_cast<NO_REF_T*>(head->metadata.offset - TYPE_SIZE)->~NO_REF_T();
// move offset back
head->metadata.offset -= TYPE_SIZE;
return t;
}
template<typename T>
T& from(blt::size_t bytes)
{
using NO_REF_T = std::remove_cv_t<std::remove_reference_t<T>>;
constexpr static auto TYPE_SIZE = aligned_size<NO_REF_T>();
auto remaining_bytes = static_cast<blt::ptrdiff_t>(bytes + TYPE_SIZE);
block* blk = head;
while (remaining_bytes > 0)
{
if (blk == nullptr)
throw std::runtime_error("Requested size is beyond the scope of this stack!");
auto bytes_available = blk->used_bytes_in_block() - remaining_bytes;
if (bytes_available < 0)
{
remaining_bytes -= blk->used_bytes_in_block();
blk = head->metadata.prev;
} else
break;
}
if (blk == nullptr)
throw std::runtime_error("Some nonsense is going on. This function already smells");
if (blk->used_bytes_in_block() < static_cast<blt::ptrdiff_t>(TYPE_SIZE))
throw std::runtime_error((std::string("Mismatched Types! Not enough space left in block! Bytes: ") += std::to_string(
blk->used_bytes_in_block()) += " Size: " + std::to_string(sizeof(NO_REF_T))).c_str());
return *reinterpret_cast<NO_REF_T*>(blk->metadata.offset - remaining_bytes);
}
void pop_bytes(blt::ptrdiff_t bytes)
{
#if BLT_DEBUG_LEVEL >= 3
blt::size_t counter = 0;
#endif
while (bytes > 0)
{
#if BLT_DEBUG_LEVEL > 0
if (head == nullptr)
{
BLT_WARN("Head is nullptr, unable to pop bytes!");
BLT_WARN("This error is normally caused by an invalid tree!");
#if BLT_DEBUG_LEVEL >= 3
BLT_WARN("Made it to %ld iterations", counter);
#endif
return;
}
#if BLT_DEBUG_LEVEL >= 3
counter++;
#endif
#endif
auto diff = head->used_bytes_in_block() - bytes;
// if there is not enough room left to pop completely off the block, then move to the next previous block
// and pop from it, update the amount of bytes to reflect the amount removed from the current block
if (diff <= 0)
{
bytes -= head->used_bytes_in_block();
if (diff == 0)
break;
move_back();
} else
{
// otherwise update the offset pointer
head->metadata.offset -= bytes;
break;
}
}
}
/**
* Warning this function should be used to transfer types, not arrays of types! It will produce an error if you attempt to pass more
* than one type # of bytes at a time~!
* @param to stack to push to
* @param bytes number of bytes to transfer out.
*/
void transfer_bytes(stack_allocator& to, blt::size_t bytes)
{
while (head->used_bytes_in_block() == 0 && move_back());
if (empty())
throw std::runtime_error("This stack is empty!");
auto type_size = aligned_size(bytes);
if (head->used_bytes_in_block() < static_cast<blt::ptrdiff_t>(type_size))
BLT_ABORT(("This stack doesn't contain enough data for this type! " + std::to_string(head->used_bytes_in_block()) + " / " +
std::to_string(bytes) + " This is an invalid runtime state!").c_str());
auto ptr = to.allocate_bytes(type_size);
to.head->metadata.offset = static_cast<blt::u8*>(ptr) + type_size;
std::memcpy(ptr, head->metadata.offset - type_size, type_size);
head->metadata.offset -= type_size;
}
template<typename... Args>
void call_destructors()
{
blt::size_t offset = 0;
((from<NO_REF_T<Args >>(offset).~NO_REF_T<Args>(), offset += stack_allocator::aligned_size<NO_REF_T<Args>>
()), ...);
}
[[nodiscard]] bool empty() const
{
if (head == nullptr)
return true;
if (head->metadata.prev != nullptr)
return false;
return head->used_bytes_in_block() == 0;
}
[[nodiscard]] blt::ptrdiff_t bytes_in_head() const
{
if (head == nullptr)
return 0;
return head->used_bytes_in_block();
}
/**
* Warning this function is slow!
* @return the size of the stack allocator in bytes
*/
[[nodiscard]] size_data_t size()
{
size_data_t size_data;
auto* prev = head;
while (prev != nullptr)
{
size_data.total_size_bytes += prev->metadata.size;
size_data.total_no_meta_bytes += prev->storage_size();
size_data.total_remaining_bytes += prev->remaining_bytes_in_block();
size_data.total_used_bytes += prev->used_bytes_in_block();
size_data.blocks++;
prev = prev->metadata.prev;
}
if (head != nullptr)
{
auto next = head->metadata.next;
while (next != nullptr)
{
size_data.total_dealloc += next->metadata.size;
size_data.total_dealloc_no_meta += next->storage_size();
size_data.total_dealloc_remaining += next->remaining_bytes_in_block();
size_data.total_dealloc_used += next->used_bytes_in_block();
size_data.blocks++;
next = next->metadata.next;
}
}
return size_data;
}
stack_allocator() = default;
// TODO: cleanup this allocator!
// if you keep track of type size information you can memcpy between stack allocators as you already only allow trivially copyable types
stack_allocator(const stack_allocator& copy)
{
if (copy.empty())
return;
head = nullptr;
block* list_itr = nullptr;
// start at the beginning of the list
block* current = copy.head;
while (current != nullptr)
{
list_itr = current;
current = current->metadata.prev;
}
// copy all the blocks
while (list_itr != nullptr)
{
push_block(list_itr->metadata.size);
std::memcpy(head->buffer, list_itr->buffer, list_itr->storage_size());
head->metadata.size = list_itr->metadata.size;
head->metadata.offset = head->buffer + list_itr->used_bytes_in_block();
list_itr = list_itr->metadata.next;
}
}
stack_allocator& operator=(const stack_allocator& copy) = delete;
stack_allocator(stack_allocator&& move) noexcept
{
head = move.head;
move.head = nullptr;
}
stack_allocator& operator=(stack_allocator&& move) noexcept
{
move.head = std::exchange(head, move.head);
return *this;
}
~stack_allocator()
{
if (head != nullptr)
{
auto blk = head->metadata.next;
while (blk != nullptr)
{
auto ptr = blk;
blk = blk->metadata.next;
std::free(ptr);
}
}
free_chain(head);
}
template<typename T>
static inline constexpr blt::size_t aligned_size() noexcept
{
return aligned_size(sizeof(NO_REF_T<T>));
}
static inline constexpr blt::size_t aligned_size(blt::size_t size) noexcept
{
return (size + (MAX_ALIGNMENT - 1)) & ~(MAX_ALIGNMENT - 1);
}
private:
struct block
{
struct block_metadata_t
{
blt::size_t size = 0;
block* next = nullptr;
block* prev = nullptr;
blt::u8* offset = nullptr;
} metadata;
blt::u8 buffer[8]{};
explicit block(blt::size_t size)
{
#if BLT_DEBUG_LEVEL > 0
if (size < PAGE_SIZE)
{
BLT_WARN("Hey this block is too small, who allocated it?");
std::abort();
}
#endif
metadata.size = size;
metadata.offset = buffer;
}
void reset()
{
metadata.offset = buffer;
}
[[nodiscard]] blt::ptrdiff_t storage_size() const
{
return static_cast<blt::ptrdiff_t>(metadata.size - sizeof(typename block::block_metadata_t));
}
[[nodiscard]] blt::ptrdiff_t used_bytes_in_block() const
{
return static_cast<blt::ptrdiff_t>(metadata.offset - buffer);
}
[[nodiscard]] blt::ptrdiff_t remaining_bytes_in_block() const
{
return storage_size() - used_bytes_in_block();
}
};
template<typename T>
void* allocate_bytes()
{
return allocate_bytes(sizeof(NO_REF_T<T>));
}
void* allocate_bytes(blt::size_t size)
{
auto ptr = get_aligned_pointer(size);
if (ptr == nullptr)
{
while (head != nullptr && head->metadata.next != nullptr)
{
head = head->metadata.next;
if (head != nullptr)
head->reset();
if (head->remaining_bytes_in_block() >= static_cast<blt::ptrdiff_t>(size))
break;
}
if (head == nullptr || head->remaining_bytes_in_block() < static_cast<blt::ptrdiff_t>(size))
push_block(aligned_size(size) + sizeof(typename block::block_metadata_t));
}
ptr = get_aligned_pointer(size);
if (ptr == nullptr)
throw std::bad_alloc();
return ptr;
}
void* get_aligned_pointer(blt::size_t bytes)
{
if (head == nullptr)
return nullptr;
blt::size_t remaining_bytes = head->remaining_bytes_in_block();
auto* pointer = static_cast<void*>(head->metadata.offset);
return std::align(MAX_ALIGNMENT, bytes, pointer, remaining_bytes);
}
void push_block(blt::size_t size)
{
auto blk = allocate_block(size);
if (head == nullptr)
{
head = blk;
return;
}
head->metadata.next = blk;
blk->metadata.prev = head;
head = blk;
}
static size_t to_nearest_page_size(blt::size_t bytes)
{
constexpr static blt::size_t MASK = ~(PAGE_SIZE - 1);
return (bytes & MASK) + PAGE_SIZE;
}
static block* allocate_block(blt::size_t bytes)
{
auto size = to_nearest_page_size(bytes);
auto* data = std::aligned_alloc(PAGE_SIZE, size);
//auto* data = get_allocator().allocate(size);
new(data) block{size};
return reinterpret_cast<block*>(data);
}
static void free_chain(block* current)
{
while (current != nullptr)
{
block* ptr = current;
current = current->metadata.prev;
std::free(ptr);
//get_allocator().deallocate(ptr);
}
}
inline bool move_back()
{
auto old = head;
head = head->metadata.prev;
if (head == nullptr)
{
head = old;
return false;
}
return true;
//free_chain(old);
// required to prevent silly memory :3
// if (head != nullptr)
// head->metadata.next = nullptr;
// std::free(old);
}
private:
block* head = nullptr;
};
}
#endif //BLT_GP_STACK_H
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