go - Read log file from the end and get the offset of a particular string

Question

.e.g. 1. logfile

• Start
• Line1
• Line2
• Line3
• End

I am able to get the seek position of Line1 when I read the file from beginning.

func getSeekLocation() int64 {
    start := int64(0)
    input, err := os.Open(logFile)
    if err != nil {
        fmt.Println(err)
    }
    if _, err := input.Seek(start, io.SeekStart); err != nil {
        fmt.Println(err)
    }
    scanner := bufio.NewScanner(input)

    pos := start
    scanLines := func(data []byte, atEOF bool) (advance int, token []byte, 
    err error) {
        advance, token, err = bufio.ScanLines(data, atEOF)
        pos += int64(advance)
        return
    }
    scanner.Split(scanLines)
    for scanner.Scan() {
       if strings.Contains(scanner.Text(), "Line1") {
        break
       }
    }
    size, err := getFileSize()
    if err != nil {
        fmt.Println(err)
    }
    return size - pos
}

But this is not an efficient way to solve the problem because as the file size increases the time to get the location will also increase. I would like to get the location of the line from the EOF location which I think would be more efficient.

Answer 1

Waitting for answers