Optimise display methods

[zhuxiujia]

impl for #16 I think the time is also important to the performance of the Format string, such as crates the httpdate, It directly affects HTTP Web framework performance

• bench code impl

  
  #[bench]
  fn bench_format_date(bench: &mut Bencher) {
  let date = Date{
      year: 2022,
      month: 7,
      day: 10
  };
  bench.iter(|| {
      date.to_string();
  })
  }

[bench]

fn bench_format_time(bench: &mut Bencher) { let time = Time{ hour: 10, minute: 11, second: 12, microsecond: 11 }; bench.iter(|| { time.to_string(); }) }

[bench]

fn bench_format_date_time(bench: &mut Bencher) { let date = DateTime{ date: Date { year: 2022, month: 7, day: 10 }, time: Time { hour: 0, minute: 0, second: 0, microsecond: 0 }, offset: Some(60) }; bench.iter(|| { date.to_string(); }) }

* befor  change

test bench_format_date ... bench: 149 ns/iter (+/- 3) test bench_format_time ... bench: 231 ns/iter (+/- 4) test bench_format_date_time ... bench: 283 ns/iter (+/- 3) //offset None test bench_format_date_time ... bench: 326 ns/iter (+/- 6) //offset Some(60)

* after change

test bench_format_date ... bench: 51 ns/iter (+/- 0) test bench_format_time ... bench: 53 ns/iter (+/- 3) test bench_format_date_time ... bench: 50 ns/iter (+/- 0) //offset None test bench_format_date_time ... bench: 115 ns/iter (+/- 0) //offset Some(60)

The DateTime format will affect about 50ns due to offset, because it is divided twice of  Memory allocation

f.write_str(std::str::from_utf8(&buf[..]).unwrap())?;

so.If I can fix the DateTime  format string length to Fixed length, then this performance can be improved to 50ns/iter

[codecov[bot]]

Codecov Report

Merging #17 (273f795) into main (d697efc) will not change coverage. The diff coverage is 100.00%.

@@            Coverage Diff            @@
##              main       #17   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            5         5           
  Lines          617       666   +49     
=========================================
+ Hits           617       666   +49     

Impacted Files	Coverage Δ
src/date.rs	100.00% <100.00%> (ø)
src/datetime.rs	100.00% <100.00%> (ø)
src/lib.rs	100.00% <100.00%> (ø)
src/time.rs	100.00% <100.00%> (ø)

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[samuelcolvin]

thanks so much 🙏 🚀 .