You could avoid allocations altogether by reusing the same byte array and passing it to the function.
To retain readability, use a buffer and fmt.Fprintf On Saturday, 11 November 2017 04:00:48 UTC+13, Vasiliy Tolstov wrote: > > Thanks, i know that optimization can lead obscurity, but for critical > paths i think that it useful =) > > 2017-11-10 8:41 GMT+03:00 peterGo <go.pe...@gmail.com <javascript:>>: > > Vasiliy, > > > > For portability, when you initialize cfg.WorkDir, clean it: cfg.WorkDir > = > > filepath.Clean(cfg.WorkDir) > > > > You can reduce the allocations from 5 to 1. However, optimization can > lead > > to obscurity. For example, > > > > $ go test oid_test.go -bench=. > > BenchmarkVasiliy-4 2000000 700 ns/op 88 B/op 5 allocs/op > > BenchmarkKrolaw-4 3000000 550 ns/op 80 B/op 4 allocs/op > > BenchmarkPeter-4 10000000 201 ns/op 48 B/op 1 allocs/op > > > > Playground: https://play.golang.org/p/DnGoM8PYd6 > > > > Peter > > > > > > On Thursday, November 9, 2017 at 3:58:03 PM UTC-5, Vasiliy Tolstov > wrote: > >> > >> Hi. I have server that read/write data to many files (each is about > >> 4-32Mb). To determine on which file i need to read/write i'm use this > >> function to os.OpenFile > >> > >> func oid2filepath(cfg *Config, oID uint64) string { > >> file_path := filepath.Join(cfg.WorkDir, fmt.Sprintf("%x", > >> oid2vid(oID)), fmt.Sprintf("%016x", oID)) > >> return file_path > >> } > >> > >> oid2vid function get uint32 and return uint32 with shift some bits > >> path looks like (for one of 4Mb chunk) > store/obj/7c2b25/007c2b2500000180 > >> > >> When i'm write 4Gb data i need to call this function 1024 times for > >> single big chunk of data. > >> Does it possible to write function that does not have additional > >> allocations? > >> And does it possible to write it in portable way (i mean path > separator). > >> > >> > >> -- > >> Vasiliy Tolstov, > >> e-mail: v.to...@selfip.ru > > > > -- > > You received this message because you are subscribed to the Google > Groups > > "golang-nuts" group. > > To unsubscribe from this group and stop receiving emails from it, send > an > > email to golang-nuts...@googlegroups.com <javascript:>. > > For more options, visit https://groups.google.com/d/optout. > > > > -- > Vasiliy Tolstov, > e-mail: v.to...@selfip.ru <javascript:> > -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to golang-nuts+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
