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December 19, 2015 21:29
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open/read vs open/mmap vs fopen/fread on golang
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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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