4 releases
0.1.3 | Mar 21, 2021 |
---|---|
0.1.2 | May 30, 2020 |
0.1.1 | Dec 22, 2019 |
0.1.0 | Apr 23, 2019 |
#119 in Date and time
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Used in 4 crates
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tzfile
tzfile
is a chrono::TimeZone
implementation using the system tz database.
It can parse compiled (binary) time zone files inside /usr/share/zoneinfo
into
time zone objects for chrono
.
use chrono::{Utc, TimeZone};
use tzfile::Tz;
let tz = Tz::named("America/New_York")?;
let dt1 = Utc.ymd(2019, 3, 10).and_hms(6, 45, 0);
assert_eq!(dt1.with_timezone(&&tz).to_string(), "2019-03-10 01:45:00 EST");
let dt2 = Utc.ymd(2019, 3, 10).and_hms(7, 15, 0);
assert_eq!(dt2.with_timezone(&&tz).to_string(), "2019-03-10 03:15:00 EDT");
tzfile
vs chrono-tz
tzfile
loads the time zone information dynamically from the OS, while
chrono-tz
pins to a particular version of tz database and embeds the parsed
result statically in the resulting executable.
Users of tzfile
can get the same time zone configuration as the system, and
guarantees the same behavior with other non-Rust programs. However, some systems
do not provide a complete tz database (e.g. Windows), making the program not
portable across multiple platforms.
Performance
Conversion from UTC to local has comparable performance with chrono-tz
as both
uses the same data structure (sorted array). In the reverse direction (local to
UTC), tzfile
caches the conversion table, allowing to be faster than
chrono-tz
in all cases.
Time zone type | Asia/Tehran → UTC | UTC → Asia/Tehran |
---|---|---|
&tzfile::Tz |
107 ns | 33 ns |
tzfile::RcTz |
125 ns | 38 ns |
tzfile::ArcTz |
156 ns | 48 ns |
chrono_tz::Tz |
227 ns | 43 ns |
Note: parsing the tz file has an upfront cost of 16 µs.
Limitations
Due to how chrono
is designed, leap seconds are always ignored, even when
present in the tz file. Also, only Gregorian calendar is supported.
Currently the Tz::named()
and Tz::local()
convenient functions are available
on Unix only.
Parsing POSIX TZ rules is not yet supported, so the predicted time for the far future may be incorrect.
Dependencies
~1.5MB
~20K SLoC