douren5490 2018-07-17 13:26
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读取Mmap的有效方法

I am using syscall to read a byte array out of mmap:

file, e := os.Open(path)
if e != nil {...}
defer file.Close()

fi, e := file.Stat()
if e != nil {...}
data, e := syscall.Mmap(int(file.Fd()), 0, int(fi.Size()), syscall.PROT_READ, syscall.MAP_SHARED)
if e != nil {...}

data is the binary array I need.

I am using || as a delimiter, so I can get slices by using bytes.Split:

slices := bytes.Split(data, []byte("||"))
for _, s := range slices {
    str := string(s[:])
    fmt.Println(str)
}

This works fine, and I also stored the total number of messages (its type is uint32 which takes 8 bytes) at the beginning of the mmap.

When a new message is written in, I can get the total number of messages by reading the first 8 bytes.

Assuming I have the number of messages as n, I still need to do the following to read the new message:

slices := bytes.Split(data, []byte("||"))
s := slices[n - 1]
str := string(s[:])
fmt.Println(str)

Is there a more efficient way to do this?

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