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open/read vs open/mmap vs fopen/fread on golang
package main
import (
"fmt"
"log"
"os"
"syscall"
)
func main() {
if len(os.Args) < 2 {
return
}
path := os.Args[1]
f, err := os.Open(path)
if err != nil {
log.Fatal(err)
}
fi, err := f.Stat()
if err != nil {
log.Fatal(err)
}
mem, err := syscall.Mmap(int(f.Fd()), 0, int(fi.Size()),
syscall.PROT_READ, syscall.MAP_SHARED)
if err != nil {
log.Fatal(err)
}
cnt := 0
for _, b := range mem {
if b == 0x00 {
cnt++
}
}
err = syscall.Munmap(mem)
if err != nil {
log.Fatal(err)
}
f.Close()
fmt.Printf("%s: size=%d cnt=%d\n", path, fi.Size(), cnt);
}
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