1 package main
2
3 import (
4 "crypto/md5"
5 "fmt"
6 "io"
7
8 "github.com/peterbourgon/diskv"
9 )
10
11 const transformBlockSize = 2
12
13 func blockTransform(s string) []string {
14 var (
15 sliceSize = len(s) / transformBlockSize
16 pathSlice = make([]string, sliceSize)
17 )
18 for i := 0; i < sliceSize; i++ {
19 from, to := i*transformBlockSize, (i*transformBlockSize)+transformBlockSize
20 pathSlice[i] = s[from:to]
21 }
22 return pathSlice
23 }
24
25 func main() {
26 d := diskv.New(diskv.Options{
27 BasePath: "data",
28 Transform: blockTransform,
29 CacheSizeMax: 1024 * 1024,
30 })
31
32 for _, valueStr := range []string{
33 "I am the very model of a modern Major-General",
34 "I've information vegetable, animal, and mineral",
35 "I know the kings of England, and I quote the fights historical",
36 "From Marathon to Waterloo, in order categorical",
37 "I'm very well acquainted, too, with matters mathematical",
38 "I understand equations, both the simple and quadratical",
39 "About binomial theorem I'm teeming with a lot o' news",
40 "With many cheerful facts about the square of the hypotenuse",
41 } {
42 d.Write(md5sum(valueStr), []byte(valueStr))
43 }
44
45 var keyCount int
46 for key := range d.Keys(nil) {
47 val, err := d.Read(key)
48 if err != nil {
49 panic(fmt.Sprintf("key %s had no value", key))
50 }
51 fmt.Printf("%s: %s\n", key, val)
52 keyCount++
53 }
54 fmt.Printf("%d total keys\n", keyCount)
55
56
57 }
58
59 func md5sum(s string) string {
60 h := md5.New()
61 io.WriteString(h, s)
62 return fmt.Sprintf("%x", h.Sum(nil))
63 }
64
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