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xo-arena: annex AllocInfo.*pp from xo-alloc2

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Roland Conybeare 2026-01-06 00:14:13 -05:00
commit e2cf88eb10
3 changed files with 1 additions and 143 deletions
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97
include/xo/alloc2/AllocInfo.hpp
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/** @file AllocInfo.hpp
*
* @author Roland Conybeare, Dec 2025
**/
#pragma once
#include "AllocHeaderConfig.hpp"
#include <utility>
namespace xo {
namespace mm {
/** @class AllocInfo
* @brief bookkeeping information for an allocation
*
* AllocInfo instances are 1:1 with sum of calls to
* {@ref AAllocator::alloc, @ref AAllocator::alloc_super}
*
**/
struct AllocInfo {
/** @defgroup mm-allocinfo-traits **/
///@{
using size_type = AllocHeader::size_type;
using byte = std::byte;
using span_type = std::pair<const byte *, const byte *>;
///@}
/** @defgroup mm-allocinfo-ctors **/
///@{
AllocInfo(const AllocHeaderConfig * p_cfg,
const byte * p_guard_lo,
const AllocHeader * p_hdr,
const byte * p_guard_hi) : p_config_{p_cfg},
p_guard_lo_{p_guard_lo},
p_header_{p_hdr},
p_guard_hi_{p_guard_hi} {}
/** error when alloc-header not configured **/
static AllocInfo error_not_configured(const AllocHeaderConfig * p_cfg) {
return AllocInfo(p_cfg, nullptr, nullptr, nullptr);
}
/** error on deref empty iterator **/
static AllocInfo error_invalid_iterator(const AllocHeaderConfig * p_cfg) {
return AllocInfo(p_cfg, nullptr, nullptr, nullptr);
}
///@}
/** @defgroup mm-allocinfo-methods **/
///@{
AllocHeader header() const noexcept { return *p_header_; }
/** true for non-sentinel AllocInfo instance **/
bool is_valid() const noexcept { return ((p_config_ != nullptr)
&& (p_header_ != nullptr)); }
/** true iff sentinel tseq, flagging a forwarding pointer **/
bool is_forwarding_tseq() const noexcept {
return p_config_->is_forwarding_tseq(*p_header_);
}
/** Guard bytes preceding allocation-header **/
span_type guard_lo() const noexcept;
/** Type sequence number in garbage collector **/
std::uint32_t tseq() const noexcept { return p_config_->tseq(*p_header_); }
/** Allocation age in garbage collector **/
std::uint32_t age() const noexcept { return p_config_->age (*p_header_); }
/** Allocation size (including allocator-supplied padding, excluding alloc header) **/
size_type size() const noexcept { return p_config_->size(*p_header_); }
/** Payload for this allocation. This is the memory available to application **/
span_type payload() const noexcept;
/** Guard bytes immediately following allocation **/
span_type guard_hi() const noexcept;
/** Number of guard bytes **/
size_type guard_z() const noexcept { return p_config_->guard_z_; }
/** Value (fixed test pattern) of guard byte **/
char guard_byte() const noexcept { return p_config_->guard_byte_; }
///@}
/** @defgroup mm-allocinfo-instance-vars **/
///@{
const AllocHeaderConfig * p_config_ = nullptr;
const byte * p_guard_lo_ = nullptr;
const AllocHeader * p_header_ = nullptr;
const byte * p_guard_hi_ = nullptr;
///@}
};
} /*namespace mm*/
} /*namespace xo*/
/* end AllocInfo.hpp */