Struct Context

pub struct Context { /* private fields */ }

A thread-safe, wrapping counter that produces 14-bit values.

This type works by:

1. Atomically incrementing the counter value for each timestamp.
2. Wrapping the counter back to zero if it overflows its 14-bit storage.

This type should be used when constructing versions 1 and 6 UUIDs.

This type should not be used when constructing version 7 UUIDs. When used to construct a version 7 UUID, the 14-bit counter will be padded with random data. Counter overflows are more likely with a 14-bit counter than they are with a 42-bit counter when working at millisecond precision. This type doesn’t attempt to adjust the timestamp on overflow.

Implementations

impl Context

pub const fn new(count: u16) -> Self

Construct a new context that’s initialized with the given value.

The starting value should be a random number, so that UUIDs from different systems with the same timestamps are less likely to collide. When the rng feature is enabled, prefer the Context::new_random method.

pub fn new_random() -> Self

Construct a new context that’s initialized with a random value.

Trait Implementations

impl ClockSequence for Context

type Output = u16

The type of sequence returned by this counter.

fn generate_sequence(&self, _seconds: u64, _nanos: u32) -> Self::Output

Get the next value in the sequence to feed into a timestamp.

fn usable_bits(&self) -> usize

The number of usable bits from the least significant bit in the result of ClockSequence::generate_sequence or ClockSequence::generate_timestamp_sequence.

fn generate_timestamp_sequence( &self, seconds: u64, subsec_nanos: u32, ) -> (Self::Output, u64, u32)

Get the next value in the sequence, potentially also adjusting the timestamp.

impl Debug for Context

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

Formats the value using the given formatter.