Class RelativePointerData

Class Documentation

class RelativePointerData

This are the data for a relative pointer. To be able so safely be used in the shared memory and prevent torn writes/reads, the class must not be larger than 64 bits and trivially copy-able.

Public Types

using id_t = uint16_t
using offset_t = uint64_t

Public Functions

constexpr RelativePointerData() noexcept = default

Default constructed RelativePointerData which is logically equal to a nullptr.

constexpr RelativePointerData(id_t id, offset_t offset) noexcept

constructs a RelativePointerData from a given offset and segment id

Parameters:

  • id – [in] is the unique id of the segment

  • offset – [in] is the offset within the segment

id_t id() const noexcept

Getter for the id which identifies the segment.

Returns:

the id which identifies the segment

offset_t offset() const noexcept

Getter for the offset within the segment.

Returns:

the offset

void reset() noexcept

Resets the pointer to a logically nullptr.

bool isLogicalNullptr() const noexcept

Checks if the pointer is logically a nullptr.

Returns:

true if logically a nullptr otherwise false

Public Static Attributes

static constexpr id_t ID_RANGE = {std::numeric_limits<id_t>::max()}

Note

the maximum number of available ids

static constexpr id_t NULL_POINTER_ID = {ID_RANGE}

Note

this represents the id of a logically nullptr

static constexpr id_t MAX_VALID_ID = {ID_RANGE - 1U}

Note

the maximum number of valid ids

static constexpr offset_t OFFSET_RANGE = {(1ULL << 48U) - 1U}

id_t is 16 bit and the offset consumes the remaining 48 bits -> offset range is 2^48 - 1

static constexpr offset_t NULL_POINTER_OFFSET = {OFFSET_RANGE}

Note

this represents the offset of a logically nullptr;

static constexpr offset_t MAX_VALID_OFFSET = {OFFSET_RANGE - 1U}

Note

the maximum offset which can be represented

static constexpr offset_t LOGICAL_NULLPTR = {NULL_POINTER_OFFSET << 16 | NULL_POINTER_ID}

Note

internal representation of a nullptr