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tailscale/tstime
Brad Fitzpatrick febdac0499 tstime: write Parse3339 parse that doesn't use time.Parse
It doesn't allocate and it's half the time of time.Parse (which
allocates), and 2/3rds the time of time.ParseInLocation (which
doesn't).

Go with a UTC time:

BenchmarkGoParse3339/Z-8                 2200995               534 ns/op               0 B/op          0 allocs/op
BenchmarkGoParse3339/Z-8                 2254816               554 ns/op               0 B/op          0 allocs/op
BenchmarkGoParse3339/Z-8                 2159504               522 ns/op               0 B/op          0 allocs/op

Go allocates with a "-08:00" suffix instead of ending in "Z":

BenchmarkGoParse3339/TZ-8                1276491               884 ns/op             144 B/op          3 allocs/op
BenchmarkGoParse3339/TZ-8                1355858               942 ns/op             144 B/op          3 allocs/op
BenchmarkGoParse3339/TZ-8                1385484               911 ns/op             144 B/op          3 allocs/op

Go doesn't allocate if you use time.ParseInLocation, but then you need
to parse the string to find the location anyway, so might as well go
all the way (below).

BenchmarkGoParse3339InLocation-8         1912254               597 ns/op               0 B/op          0 allocs/op
BenchmarkGoParse3339InLocation-8         1980043               612 ns/op               0 B/op          0 allocs/op
BenchmarkGoParse3339InLocation-8         1891366               612 ns/op               0 B/op          0 allocs/op

Parsing RFC3339 ourselves, UTC:

BenchmarkParse3339/Z-8                   3889220               307 ns/op               0 B/op          0 allocs/op
BenchmarkParse3339/Z-8                   3718500               309 ns/op               0 B/op          0 allocs/op
BenchmarkParse3339/Z-8                   3621231               303 ns/op               0 B/op          0 allocs/op

Parsing RFC3339 ourselves, with timezone (w/ *time.Location fetched
from sync.Map)

BenchmarkParse3339/TZ-8                  3019612               418 ns/op               0 B/op          0 allocs/op
BenchmarkParse3339/TZ-8                  2921618               401 ns/op               0 B/op          0 allocs/op
BenchmarkParse3339/TZ-8                  3031671               408 ns/op               0 B/op          0 allocs/op

Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
5 years ago
..
tstime.go tstime: write Parse3339 parse that doesn't use time.Parse 5 years ago
tstime_test.go tstime: write Parse3339 parse that doesn't use time.Parse 5 years ago