Struct AtomicSnowflakeGenerator

Source

pub struct AtomicSnowflakeGenerator<T, ID>where
    T: TimeSource<ID::Ty>,
    ID: Snowflake<Ty = u64>,
{ /* private fields */ }

Expand description

A lock-free Snowflake ID generator suitable for multi-threaded environments.

This generator stores the Snowflake state in an AtomicU64, allowing safe shared use across threads.

§Features

✅ Thread-safe
❌ Safely implement any Snowflake layout

§Caveats

This implementation uses an AtomicU64 internally, so it only supports ID layouts where the underlying type is u64. You cannot use layouts with larger or smaller representations (i.e., ID::Ty must be u64).

§Recommended When

You’re in a multi-threaded environment
You want the lowest possible latency under light-to-moderate contention

§See Also

Implementations§

Source §

impl<T, ID> AtomicSnowflakeGenerator<T, ID>
where T: TimeSource<u64>, ID: Snowflake<Ty = u64>,

Source

pub fn new(machine_id: ID::Ty, clock: T) -> Self

Creates a new AtomicSnowflakeGenerator initialized with the current time and a given machine ID.

This constructor sets the initial timestamp and sequence to zero, and uses the provided clock to fetch the current time during ID generation. It is the recommended way to create a new atomic generator for typical use cases.

§Parameters

machine_id: A unique identifier for the node or instance generating IDs. This value will be encoded into every generated ID.
clock: A TimeSource implementation (e.g., MonotonicClock) that determines how timestamps are generated.

§Returns

A new AtomicSnowflakeGenerator ready to produce unique, time-ordered IDs.

§Example

use ferroid::{AtomicSnowflakeGenerator, SnowflakeTwitterId, MonotonicClock};

let generator = AtomicSnowflakeGenerator::<_, SnowflakeTwitterId>::new(0, MonotonicClock::default());
let id = generator.next_id();

Source

pub fn from_components( timestamp: ID::Ty, machine_id: ID::Ty, sequence: ID::Ty, clock: T, ) -> Self

Creates a new ID generator from explicit component values.

This constructor is primarily useful for advanced use cases such as restoring state from persistent storage or controlling the starting point of the generator manually.

§Parameters

timestamp: The initial timestamp component (usually in milliseconds)
machine_id: The machine or worker identifier
sequence: The initial sequence number
clock: A TimeSource implementation used to fetch the current time

§Returns

A new generator instance preloaded with the given state.

§Note

In typical use cases, you should prefer Self::new to let the generator initialize itself from the current time.

Source

pub fn next_id(&self) -> IdGenStatus<ID>

Attempts to generate the next available ID.

Returns a new, time-ordered, unique ID if generation succeeds. If the generator is temporarily exhausted (e.g., the sequence is full and the clock has not advanced), it returns IdGenStatus::Pending.

§Panics

This method currently has no fallible code paths, but may panic if an internal error occurs in future implementations. For explicitly fallible behavior, use Self::try_next_id instead.

§Example

use ferroid::{AtomicSnowflakeGenerator, SnowflakeTwitterId, IdGenStatus, MonotonicClock, TimeSource};

// Create a clock and a generator with machine_id = 0
let clock = MonotonicClock::default();
let mut generator = AtomicSnowflakeGenerator::<_, SnowflakeTwitterId>::new(0, clock);

// Attempt to generate a new ID
match generator.next_id() {
    IdGenStatus::Ready { id } => {
        println!("ID: {}", id);
        assert_eq!(id.machine_id(), 0);
    }
    IdGenStatus::Pending { yield_until } => {
        // This should rarely happen on the first call, but if it does,
        // backoff or yield and try again.
        println!("Exhausted; wait until: {}", yield_until);
    }
}

Source

pub fn try_next_id(&self) -> Result<IdGenStatus<ID>>

A fallible version of Self::next_id that returns a Result.

This method attempts to generate the next ID based on the current time and internal state. If successful, it returns IdGenStatus::Ready with a newly generated ID. If the generator is temporarily exhausted, it returns IdGenStatus::Pending. If an internal failure occurs (e.g., a time source or lock error), it returns an error.

§Returns

Ok(IdGenStatus::Ready { id }): A new ID is available
Ok(IdGenStatus::Pending { yield_until }): Wait for time to advance
Err(e): A recoverable error occurred (e.g., time source failure)

§Example

use ferroid::{AtomicSnowflakeGenerator, SnowflakeTwitterId, IdGenStatus, MonotonicClock, TimeSource};

// Create a clock and a generator with machine_id = 0
let clock = MonotonicClock::default();
let mut generator = AtomicSnowflakeGenerator::<_, SnowflakeTwitterId>::new(0, clock);

// Attempt to generate a new ID
match generator.try_next_id() {
    Ok(IdGenStatus::Ready { id }) => {
        println!("ID: {}", id);
        assert_eq!(id.machine_id(), 0);
    }
    Ok(IdGenStatus::Pending { yield_until }) => {
        // This should rarely happen on the first call, but if it does,
        // backoff or yield and try again.
        println!("Exhausted; wait until: {}", yield_until);
    }
    Err(err) => eprintln!("Generator error: {}", err),
}