sparkid

Fast, monotonic, time-sortable, 22-char Base58 unique ID generator. Only dependency is rand.

1ocmpHE1bFnygEBAPTzMK4
1ocmpHE1bFnygFv4Wp4dL2
1ocmpHE1bFnygGoUXUL7Xo

Install

cargo add sparkid

Usage

use sparkid::SparkId;

let id = SparkId::new();
// => "1ocmpHE1bFnygEBAPTzMK4"

println!("{id}");              // Display, no heap allocation
let s: &str = &id;             // Deref to &str, zero-cost
let owned: String = id.into(); // Into<String> when needed

Properties

How it works

Each ID is composed of two parts:

[8-char timestamp][14-char suffix]

• Timestamp (8 chars): Current time in milliseconds, Base58-encoded. IDs generated in a later millisecond always sort after earlier ones.
• Suffix (14 chars): Seeded from a cryptographically secure PRNG (rejection-sampled, no modulo bias) at the start of each millisecond, then monotonically incremented for each subsequent ID within that millisecond. This guarantees strict ordering even when multiple IDs share a timestamp.

SparkId type

SparkId is a stack-allocated, Copy type — no heap allocation on creation. It implements Deref<Target = str>, Display, Ord, Hash, and Into<String>, so it works anywhere a string is expected.

use sparkid::SparkId;

let a = SparkId::new();
let b = SparkId::new();
assert!(b > a);                      // Ord — monotonically increasing
println!("{a}");                      // Display — no allocation
let set: std::collections::HashSet<SparkId> = [a, b].into(); // Hash

Ordering guarantees

IDs from a single IdGenerator instance (or a single thread using SparkId::new()) are strictly monotonically increasing — every ID is lexicographically greater than the one before it.

Across threads, IDs are unique but not ordered relative to each other. Each thread gets its own generator via thread_local!, so there is no cross-thread coordination.

If you need process-wide monotonic ordering across threads, wrap a single IdGenerator in a Mutex:

use std::sync::{LazyLock, Mutex};
use sparkid::IdGenerator;

static GEN: LazyLock<Mutex<IdGenerator>> =
    LazyLock::new(|| Mutex::new(IdGenerator::new()));

fn generate_id_monotonic() -> sparkid::SparkId {
    GEN.lock().unwrap().next_id()
}

Advanced usage

For manual control, use the IdGenerator struct directly:

use sparkid::IdGenerator;

let mut gen = IdGenerator::new();
let id = gen.next_id();

IdGenerator also implements Iterator<Item = SparkId>:

let mut gen = sparkid::IdGenerator::new();
let ids: Vec<sparkid::SparkId> = gen.take(100).collect();

Performance

~27 million IDs/sec with SparkId::new() (~37 ns/call, zero-allocation):

cargo bench

License

MIT