archive-mail

 1package main
 2
 3import (
 4	"errors"
 5	"sync"
 6)
 7
 8type MailPair struct {
 9	old, new *Mail
10}
11
12type MailDatabase struct {
13	msgMtx *sync.Mutex
14
15	newMsgs []*Mail
16	modMsgs []*MailPair
17	oldMsgs map[string]*Mail
18}
19
20func NewMailDatabase() *MailDatabase {
21	db := new(MailDatabase)
22	db.msgMtx = new(sync.Mutex)
23	db.oldMsgs = make(map[string]*Mail)
24	return db
25}
26
27func (db *MailDatabase) AddOldMessage(mail *Mail) error {
28	csum, err := mail.Checksum()
29	if err != nil {
30		return err
31	}
32
33	db.msgMtx.Lock()
34	defer db.msgMtx.Unlock()
35
36	if _, ok := db.oldMsgs[csum]; ok {
37		return errors.New("hash collision")
38	}
39	db.oldMsgs[csum] = mail
40
41	return nil
42}
43
44func (db *MailDatabase) GetOldMessage(mail *Mail) (*Mail, error) {
45	csum, err := mail.Checksum()
46	if err != nil {
47		return nil, err
48	}
49
50	db.msgMtx.Lock()
51	defer db.msgMtx.Unlock()
52
53	mail, ok := db.oldMsgs[csum]
54	if !ok {
55		return nil, nil
56	}
57
58	return mail, nil
59}
60
61func (db *MailDatabase) AddNewMessage(old *Mail, new *Mail) {
62	db.msgMtx.Lock()
63	if old == nil {
64		db.newMsgs = append(db.newMsgs, new)
65	} else {
66		db.modMsgs = append(db.modMsgs, &MailPair{old, new})
67	}
68	db.msgMtx.Unlock()
69}