Struct Rfc3339Formatter 

pub(crate) struct Rfc3339Formatter {
    pub(crate) second: Option<i64>,
    pub(crate) prefix: String,
}

Formats timestamps exactly like chrono’s to_rfc3339, faster.

Archived rows arrive in time order, so the date and time up to the second changes only once per 100-2,000 rows. That part is built once per second with chrono; only the fractional part is written per row, digit by digit, following chrono’s to_rfc3339 rule: no fraction for whole seconds, otherwise 3, 6 or 9 digits for millisecond, microsecond or nanosecond precision.

Correctness does not depend on order: out-of-order timestamps only make the prefix rebuild more often.

Fields

second: Option<i64>

Unix second the cached prefix belongs to, or None before the first call.

prefix: String

YYYY-MM-DDTHH:MM:SS text for the cached second.

Implementations

impl Rfc3339Formatter

pub(crate) fn new() -> Self

Creates a formatter with an empty cache.

pub(crate) fn write(&mut self, out: &mut Vec<u8>, timestamp_unix_ns: i64)

Appends one timestamp to out, reusing the date and time prefix if the second is unchanged since the previous call.

Arguments

• out - Buffer the text is appended to.
• timestamp_unix_ns - Nanoseconds since the Unix epoch; any i64, including negative values.

Examples

1_790_000_000_008_000_000 -> "2026-09-21T14:13:20.008+00:00"
1_790_000_000_008_123_000 -> "2026-09-21T14:13:20.008123+00:00"
1_790_000_000_000_000_000 -> "2026-09-21T14:13:20+00:00"