libtime::Tm::to_utc() is slow even if already utc

[steveklabnik]

Issue by seanmonstar
Friday Nov 07, 2014 at 01:29 GMT

For earlier discussion, see rust-lang/rust#18725

This issue was labelled with: in the Rust repository

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Tm.to_utc() calls out to the runtime fn rust_timegm twice, once to convert to a Timespec, and a second time to convert the timespec to a new Tm with offset of 0. If a Tm is already UTC, this should skip both those calls.

[zslayton]

Is this as simple as:

    /// Convert time to the UTC
    pub fn to_utc(&self) -> Tm {
        match self.tm_utcoff {
          0 => *self,
          _ => at_utc(self.to_timespec())
        }
    }

? If so, I'd be happy to put together a pull request!