Skip to content

Class gme::signal::LockFreeQueue

template <typename T, std::size_t N>

ClassList > gme > signal > LockFreeQueue

Fixed-capacity SPSC ring buffer with drop-oldest-on-full. More...

  • #include <LockFreeQueue.h>

Public Functions

Type Name
LockFreeQueue () noexcept
Construct an empty queue.
LockFreeQueue (const LockFreeQueue &) = delete
bool empty () noexcept const
Advisory empty check.
LockFreeQueue & operator= (const LockFreeQueue &) = delete
bool pop (T & out) noexcept
Pop an item from the queue.
bool push (T && item) noexcept
Push an item into the queue.
std::size_t size () noexcept const
Advisory current occupancy.

Public Static Functions

Type Name
constexpr std::size_t capacity () noexcept
Compile-time capacity.

Detailed Description

See file-level documentation for the full contract.

Public Functions Documentation

function LockFreeQueue [1/2]

Construct an empty queue. 

gme::signal::LockFreeQueue::LockFreeQueue () noexcept

Zero heap allocation; the std::array<T, N> storage is embedded. head_ and tail_ are initialised to 0.

function LockFreeQueue [2/2]

gme::signal::LockFreeQueue::LockFreeQueue (
    const LockFreeQueue &
) = delete

function empty

Advisory empty check. 

bool gme::signal::LockFreeQueue::empty () noexcept const

Returns:

true if head_ == tail_ at the moment of call. Advisory only.

function operator=

LockFreeQueue & gme::signal::LockFreeQueue::operator= (
    const LockFreeQueue &
) = delete

function pop

Pop an item from the queue. 

bool gme::signal::LockFreeQueue::pop (
    T & out
) noexcept

Consumer-only. Not reentrant with other pop calls (the serialisation between the MTC-tick and fallback-drain sites is the owner's responsibility — see Decision 4 in research.md).

Parameters:

  • out [out] Populated with the popped item on success. Untouched on failure.

Returns:

true if an item was popped into out. false if the queue was empty.

Exception:

  • None.

** **

FadeCommand cmd;
while (q.pop(cmd)) registry.apply(cmd);

function push

Push an item into the queue. 

bool gme::signal::LockFreeQueue::push (
    T && item
) noexcept

Producer-only. Not reentrant with other push calls.

If the queue is currently full (occupancy N - 1), the oldest entry is dropped: tail_ is advanced by one slot via a compare-exchange loop, then the new item is stored.

Parameters:

  • item Item to enqueue; moved into the buffer slot.

Returns:

true if the queue had free space. false if the oldest entry was dropped to make room — caller SHOULD log a warning (FR-008).

Exception:

  • None.

** **

if (!q.push(std::move(cmd))) log_warning("queue overflow");

function size

Advisory current occupancy. 

std::size_t gme::signal::LockFreeQueue::size () noexcept const

Returns:

Approximate number of unread items. May be transiently inconsistent under concurrent push/pop. Do not use for flow control.

Public Static Functions Documentation

function capacity

Compile-time capacity. 

static inline constexpr std::size_t gme::signal::LockFreeQueue::capacity () noexcept

Returns:

The template parameter N. The usable capacity is N - 1 (one slot reserved to distinguish empty from full).

The documentation for this class was generated from the following file src/signal/LockFreeQueue.h