Module tier2 

Available on crate feature tier2 only.

Tier 2 — Process-unique seeds

Fast pseudo-random values derived from process ID, high-resolution time, and a monotonic atomic counter, then run through several rounds of a strong scalar mixer. Good for:

• Tempdir / temp-file names
• Request and trace IDs
• Log correlation IDs
• Any application-level “good-enough” uniqueness

Not cryptographic. An attacker who can observe outputs can often reconstruct internal state and predict subsequent values. Use tier3 for security-sensitive randomness.

Uniqueness guarantees

• Within a single process: every unique_u64 call returns a distinct value (guaranteed by a never-resetting atomic counter, modulo wrap at 2^64 calls — about 584 years at 1 GHz).
• Across processes on the same host: PID + nanosecond timestamp make collisions vanishingly unlikely.
• Across hosts: this tier makes no claims. Use tier3 when you need values unique across machines.

Thread safety

All functions in this module are thread-safe and lock-free. The shared atomic counter ensures uniqueness even under concurrent access from any number of threads.

Performance

Target <100ns per call. Cost is dominated by a SystemTime::now() reading; the mixing itself is a handful of multiplies and rotates.

Functions

random_alpha

Generate a random ASCII alphabetic string (A-Z, a-z) of exactly len characters.

random_alphanumeric

Generate a random ASCII alphanumeric string (A-Z, a-z, 0-9) of exactly len characters.

random_hex_string

Generate a random lowercase hex string (0-9, a-f) of exactly len characters.

random_numeric

Generate a random ASCII numeric string (0-9) of exactly len characters. Leading zeros may appear.

random_string

Generate a random string of exactly len characters drawn from charset (uniformly).

range_i8

Generate a uniformly-distributed i8 in the half-open range [range.start, range.end).

range_i16

Generate a uniformly-distributed i16 in the half-open range [range.start, range.end).

range_i32

Generate a uniformly-distributed i32 in the half-open range [range.start, range.end).

range_i64

Generate a uniformly-distributed i64 in the half-open range [range.start, range.end).

range_i128

Generate a uniformly-distributed i128 in the half-open range [range.start, range.end).

range_inclusive_i8

Generate a uniformly-distributed i8 in the closed range [range.start(), range.end()]. The full-width i8::MIN..=i8::MAX is supported.

range_inclusive_i16

Generate a uniformly-distributed i16 in the closed range [range.start(), range.end()]. The full-width i16::MIN..=i16::MAX is supported.

range_inclusive_i32

Generate a uniformly-distributed i32 in the closed range [range.start(), range.end()].

range_inclusive_i64

Generate a uniformly-distributed i64 in the closed range [range.start(), range.end()].

range_inclusive_i128

Generate a uniformly-distributed i128 in the closed range [range.start(), range.end()]. The full-width i128::MIN..=i128::MAX is supported.

range_inclusive_isize

Generate a uniformly-distributed isize in the closed range [range.start(), range.end()]. The full-width isize::MIN..=isize::MAX is supported.

range_inclusive_u8

Generate a uniformly-distributed u8 in the closed range [range.start(), range.end()]. The full-width 0..=u8::MAX is supported.

range_inclusive_u16

Generate a uniformly-distributed u16 in the closed range [range.start(), range.end()]. The full-width 0..=u16::MAX is supported.

range_inclusive_u32

Generate a uniformly-distributed u32 in the closed range [range.start(), range.end()].

range_inclusive_u64

Generate a uniformly-distributed u64 in the closed range [range.start(), range.end()].

range_inclusive_u128

Generate a uniformly-distributed u128 in the closed range [range.start(), range.end()]. The full-width 0..=u128::MAX is supported.

range_inclusive_usize

Generate a uniformly-distributed usize in the closed range [range.start(), range.end()]. The full-width 0..=usize::MAX is supported.

range_isize

Generate a uniformly-distributed isize in the half-open range [range.start, range.end).

range_u8

Generate a uniformly-distributed u8 in the half-open range [range.start, range.end).

range_u16

Generate a uniformly-distributed u16 in the half-open range [range.start, range.end).

range_u32

Generate a uniformly-distributed u32 in the half-open range [range.start, range.end).

range_u64

Generate a uniformly-distributed u64 in the half-open range [range.start, range.end).

range_u128

Generate a uniformly-distributed u128 in the half-open range [range.start, range.end).

range_usize

Generate a uniformly-distributed usize in the half-open range [range.start, range.end).

unique_base32

Produce a process-unique base32 (Crockford alphabet) string of exactly len characters. Equivalent to unique_name; provided for symmetry with unique_hex.

unique_hex

Produce a process-unique lowercase hex string of exactly len characters.

unique_name

Produce a process-unique base32 (Crockford alphabet) name of exactly len characters.

unique_u64

Produce a process-unique u64.