Struct SubscriberPosition 

pub struct SubscriberPosition { /* private fields */ }

MMF-backed monotonically-increasing consumer position counter.

Implementations

impl SubscriberPosition

pub fn create(path: impl AsRef<Path>, initial: u64) -> Result<Self, Error>

Create a new position counter at path initialised to initial.

pub fn open(path: impl AsRef<Path>) -> Result<Self, Error>

Open an existing position counter at path for read/write. Used by a subscriber restart path.

pub fn get(&self) -> u64

Current position (Acquire load).

pub fn advance(&self, by: u64) -> u64

Advance the position by by. Returns the NEW position. Atomic; safe for one subscriber to call concurrently with another holder reading via get.

pub fn set(&self, new: u64)

Set the position to new unconditionally. Used by restart paths that want to reset rather than advance.

pub fn compare_and_set(&self, expected: u64, new: u64) -> Result<u64, u64>

Compare-and-set semantics. Returns Ok(new) if the previous value matched expected; Err(actual) otherwise.

pub fn counter_handle(&self) -> Arc<SharedAtomicU64>

Clone the underlying Arc<SharedAtomicU64> so a second in-process holder can read the same counter cheaply.