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package imap
import (
"bufio"
"bytes"
"encoding/gob"
"errors"
"fmt"
"strings"
"time"
"git.sr.ht/~rjarry/aerc/lib/log"
"git.sr.ht/~rjarry/aerc/lib/parse"
"git.sr.ht/~rjarry/aerc/lib/xdg"
"git.sr.ht/~rjarry/aerc/models"
"git.sr.ht/~rjarry/aerc/worker/types"
"github.com/emersion/go-message"
"github.com/emersion/go-message/mail"
"github.com/emersion/go-message/textproto"
"github.com/syndtr/goleveldb/leveldb"
)
type CachedHeader struct {
BodyStructure models.BodyStructure
Envelope models.Envelope
InternalDate time.Time
Uid models.UID
Size uint32
Header []byte
Created time.Time
}
var (
// cacheTag should be updated when changing the cache
// structure; this will ensure that the user's cache is cleared and
// reloaded when the underlying cache structure changes
cacheTag = []byte("0003")
cacheTagKey = []byte("cache.tag")
)
// initCacheDb opens (or creates) the database for the cache. One database is
// created per account
func (w *IMAPWorker) initCacheDb(acct string) {
switch {
case len(w.config.headersExclude) > 0:
headerTag := strings.Join(w.config.headersExclude, "")
cacheTag = append(cacheTag, headerTag...)
case len(w.config.headers) > 0:
headerTag := strings.Join(w.config.headers, "")
cacheTag = append(cacheTag, headerTag...)
}
p := xdg.CachePath("aerc", acct)
db, err := leveldb.OpenFile(p, nil)
if err != nil {
w.cache = nil
w.worker.Errorf("failed opening cache db: %v", err)
return
}
w.cache = db
w.worker.Debugf("cache db opened: %s", p)
tag, err := w.cache.Get(cacheTagKey, nil)
clearCache := errors.Is(err, leveldb.ErrNotFound) ||
!bytes.Equal(tag, cacheTag)
switch {
case clearCache:
w.worker.Infof("current cache tag is '%s' but found '%s'",
cacheTag, tag)
w.worker.Warnf("tag mismatch: clear cache")
w.clearCache()
if err = w.cache.Put(cacheTagKey, cacheTag, nil); err != nil {
w.worker.Errorf("could not set the current cache tag")
}
case err != nil:
w.worker.Errorf("could not get the cache tag from db")
default:
if w.config.cacheMaxAge.Hours() > 0 {
go w.cleanCache(p)
}
}
}
func (w *IMAPWorker) cacheHeader(mi *models.MessageInfo) {
key := w.headerKey(mi.Uid)
w.worker.Debugf("caching header for message %s", key)
hdr := bytes.NewBuffer(nil)
err := textproto.WriteHeader(hdr, mi.RFC822Headers.Header.Header)
if err != nil {
w.worker.Errorf("cannot write header %s: %v", key, err)
return
}
h := &CachedHeader{
BodyStructure: *mi.BodyStructure,
Envelope: *mi.Envelope,
InternalDate: mi.InternalDate,
Uid: mi.Uid,
Size: mi.Size,
Header: hdr.Bytes(),
Created: time.Now(),
}
data := bytes.NewBuffer(nil)
enc := gob.NewEncoder(data)
err = enc.Encode(h)
if err != nil {
w.worker.Errorf("cannot encode message %s: %v", key, err)
return
}
err = w.cache.Put(key, data.Bytes(), nil)
if err != nil {
w.worker.Errorf("cannot write header for message %s: %v", key, err)
return
}
}
func (w *IMAPWorker) getCachedHeaders(msg *types.FetchMessageHeaders) []models.UID {
w.worker.Tracef("Retrieving headers from cache: %v", msg.Uids)
var need []models.UID
for _, uid := range msg.Uids {
key := w.headerKey(uid)
data, err := w.cache.Get(key, nil)
if err != nil {
need = append(need, uid)
continue
}
ch := &CachedHeader{}
dec := gob.NewDecoder(bytes.NewReader(data))
err = dec.Decode(ch)
if err != nil {
w.worker.Errorf("cannot decode cached header %s: %v", key, err)
need = append(need, uid)
continue
}
hr := bytes.NewReader(ch.Header)
textprotoHeader, err := textproto.ReadHeader(bufio.NewReader(hr))
if err != nil {
w.worker.Errorf("cannot read cached header %s: %v", key, err)
need = append(need, uid)
continue
}
hdr := &mail.Header{Header: message.Header{Header: textprotoHeader}}
mi := &models.MessageInfo{
BodyStructure: &ch.BodyStructure,
Envelope: &ch.Envelope,
Flags: models.SeenFlag, // Always return a SEEN flag
Uid: ch.Uid,
RFC822Headers: hdr,
Refs: parse.MsgIDList(hdr, "references"),
Size: ch.Size,
}
w.worker.PostMessage(&types.MessageInfo{
Message: types.RespondTo(msg),
Info: mi,
NeedsFlags: true,
}, nil)
}
return need
}
func (w *IMAPWorker) headerKey(uid models.UID) []byte {
key := fmt.Sprintf("header.%s.%d.%s",
w.selected.Name, w.selected.UidValidity, uid)
return []byte(key)
}
// cleanCache removes stale entries from the selected mailbox cachedb
func (w *IMAPWorker) cleanCache(path string) {
defer log.PanicHandler()
start := time.Now()
var scanned, removed int
iter := w.cache.NewIterator(nil, nil)
for iter.Next() {
if bytes.Equal(iter.Key(), cacheTagKey) {
continue
}
data := iter.Value()
ch := &CachedHeader{}
dec := gob.NewDecoder(bytes.NewReader(data))
err := dec.Decode(ch)
if err != nil {
w.worker.Errorf("cannot clean database %d: %v",
w.selected.UidValidity, err)
continue
}
exp := ch.Created.Add(w.config.cacheMaxAge)
if exp.Before(time.Now()) {
err = w.cache.Delete(iter.Key(), nil)
if err != nil {
w.worker.Errorf("cannot clean database %d: %v",
w.selected.UidValidity, err)
continue
}
removed++
}
scanned++
}
iter.Release()
elapsed := time.Since(start)
w.worker.Debugf("%s: removed %d/%d expired entries in %s",
path, removed, scanned, elapsed)
}
// clearCache clears the entire cache
func (w *IMAPWorker) clearCache() {
iter := w.cache.NewIterator(nil, nil)
for iter.Next() {
if err := w.cache.Delete(iter.Key(), nil); err != nil {
w.worker.Errorf("error clearing cache: %v", err)
}
}
iter.Release()
}
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