Struct SequenceNumberCounter 

pub struct SequenceNumberCounter(/* private fields */);

Thread-safe sequence number generator

Examples

let seqno = SequenceNumberCounter::default();
let visible_seqno = SequenceNumberCounter::default();

let tree = Config::new(path, seqno.clone(), visible_seqno.clone()).open()?;

// Do some inserts...
for k in [b"a", b"b", b"c"] {
    let batch_seqno = seqno.next();
    tree.insert(k, "abc", batch_seqno);
    visible_seqno.fetch_max(batch_seqno + 1);
}

// Create a batch
let batch_seqno = seqno.next();
tree.remove("a".as_bytes(), batch_seqno);
tree.remove("b".as_bytes(), batch_seqno);
tree.remove("c".as_bytes(), batch_seqno);
visible_seqno.fetch_max(batch_seqno + 1);

Implementations

impl SequenceNumberCounter

pub fn new(prev: SeqNo) -> Self

Creates a new counter, setting it to some previous value.

Panics

Panics if prev > MAX_SEQNO (reserved MSB range).

Note: prev == MAX_SEQNO is allowed but means the counter is exhausted — any subsequent call to next() will panic.

pub fn next(&self) -> SeqNo

Allocates and returns the next sequence number, atomically incrementing the internal counter.

The returned value is the counter’s value before the increment (i.e., pre-increment / fetch-then-add semantics).

Panics

Panics if the current value is already MAX_SEQNO (i.e., when advancing past it would enter the reserved MSB range).

pub fn get(&self) -> SeqNo

Returns the current internal counter value without incrementing.

This is the value that the next call to next() will return (and then advance past).

pub fn set(&self, value: SeqNo)

Sets the sequence number to the given value.

Panics

Panics if value > MAX_SEQNO (reserved MSB range).

pub fn fetch_max(&self, value: SeqNo)

Atomically updates the sequence number to the maximum of the current value and the provided value.

Trait Implementations

impl Clone for SequenceNumberCounter

fn clone(&self) -> SequenceNumberCounter

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for SequenceNumberCounter

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for SequenceNumberCounter

fn default() -> SequenceNumberCounter

Returns the “default value” for a type.

impl From<SequenceNumberCounter> for SharedSequenceNumberGenerator

fn from(counter: SequenceNumberCounter) -> Self

Converts to this type from the input type.

impl SequenceNumberGenerator for SequenceNumberCounter

fn next(&self) -> SeqNo

Gets the next sequence number, atomically incrementing the counter.

fn get(&self) -> SeqNo

Gets the current sequence number without incrementing.

fn set(&self, value: SeqNo)

Sets the sequence number to the given value.

fn fetch_max(&self, value: SeqNo)

Atomically updates the sequence number to the maximum of the current value and the given value.