Module duration 

The wire format for durations.

Durations are exchanged as part of the x-sn-expiration header, for instance as ttl:7d 12h.

Emitted format

A duration is written as a space-separated list of <integer><unit> components, ordered from the largest unit to the smallest. Components that are zero are omitted, and a zero duration is written as 0s. Only four units are ever emitted:

Unit	Meaning
d	day, 24 hours
h	hour
m	minute
s	second

Day is deliberately the largest unit. Weeks, months, and years are never emitted, because they either have no fixed length (a calendar month) or invite a definition that differs between implementations (is a year 365 or 365.25 days?). Durations longer than a day therefore stay in days: 400 days is written as 400d, never as 1y 1m 5d.

Second is the smallest unit; any sub-second remainder is truncated.

Parsing

parse_duration accepts a superset of the emitted format, including units this crate never writes. That leniency exists to keep reading values that older versions persisted, and is not part of the wire format: do not rely on it, and do not reproduce it in clients.

Structs

FormattedDuration

A Duration that displays in the wire format.

ParseDurationError

The error returned when a string is not a valid duration in the wire format.

Functions

format_duration

Formats a duration in the wire format.

parse_duration

Parses a duration from the wire format.