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new arena implementation using std::align()

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This commit is contained in:
Florian Lüke 2025-01-05 20:19:54 +01:00
parent 1765cf676e
commit 85e68c9abb
1 changed files with 21 additions and 13 deletions
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34
src/internal/mana_arena.h
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@ -13,6 +13,11 @@
namespace mesytec::mnode::mana
{
template <typename T> inline bool is_aligned(const T *ptr, size_t alignment = alignof(T))
{
return (((uintptr_t)ptr) % alignment) == 0;
}
class Arena
{
public:
@ -26,16 +31,11 @@ class Arena
Arena(Arena &&other) = default;
Arena &operator=(Arena &&other) = default;
// pushes at least the required amount of memory onto the arena.
// 'required' is rounded up to the nearest multiple of 'default_align_to' to make
// subsequent allocations aligned.
// Pushes at least the required amount of memory onto the arena. The memory is aligned to
// 'default_align_to' and zeroed
u8 *push_size(size_t required)
{
size_t padded = round_up(required, default_align_to);
size_t pad_waste = padded - required;
required = padded;
if (!segment_ || segment_->free() < required)
if (!segment_)
{
if (segment_count() < max_segments())
{
@ -52,12 +52,20 @@ class Arena
assert(segment_ && segment_->free() >= required);
auto result = segment_->cur();
std::memset(result, 0, required);
segment_->used += required;
++allocations_;
void *ptr = segment_->cur();
size_t space = segment_->free();
if (!std::align(default_align_to, required, ptr, space))
throw std::bad_alloc();
assert(is_aligned(ptr, default_align_to));
size_t pad_waste = segment_->free() - space;
segment_->used += required + pad_waste;
pad_waste_ += pad_waste;
return result;
++allocations_;
std::memset(ptr, 0, required);
return reinterpret_cast<u8 *>(ptr);
}
template <typename T> T *push_t(size_t count = 1)