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crawler.go
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crawler.go
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package main
import (
"log"
"os"
"path/filepath"
"time"
)
type fileStatus uint
const (
fileStatusDeleted fileStatus = iota
fileStatusAdded
fileStatusUpdated
fileStatusUnchanged
)
type fileMeta struct {
status fileStatus
info os.FileInfo
mfile mailFile
}
type crawler struct {
cache *caches
root string
files map[string]*fileMeta
interval time.Duration
wakeup chan struct{}
indexer *mailIndexer
}
func newCrawler(indexer *mailIndexer, cache *caches, root string) *crawler {
return &crawler{
cache: cache,
root: root,
files: make(map[string]*fileMeta),
wakeup: make(chan struct{}),
indexer: indexer,
}
}
func (c *crawler) markUpdated(file string, info os.FileInfo) {
c.files[file].status = fileStatusUpdated
c.files[file].info = info
}
func (c *crawler) markAdded(mfile mailFile, info os.FileInfo) {
file := mfile.filename()
msg, err := c.indexer.parse(file)
if msg == nil && err != nil {
log.Print(file, ": error parsing ", err)
return
}
// Non fatal errors
if err != nil {
log.Print(file, ": error parsing ", err)
}
if date, err := msg.Header.Date(); err == nil {
mfile.date = date
}
c.files[file] = &fileMeta{
status: fileStatusAdded,
info: info,
mfile: mfile,
}
// Index this entry
entries := c.indexer.cacheEntries(mfile, msg)
for i := range entries {
c.cache.addCh <- entries[i]
}
}
func (c *crawler) markUnchanged(file string) {
c.files[file].status = fileStatusUnchanged
}
func (c *crawler) markDeleted(file string) {
c.files[file].status = fileStatusDeleted
}
func (c *crawler) markAllDeleted() {
for key, entry := range c.files {
entry.status = fileStatusDeleted
c.files[key] = entry
}
}
func (c *crawler) markFile(mfile mailFile, finfo os.FileInfo) {
file := mfile.filename()
entry, found := c.files[file]
if !found {
c.markAdded(mfile, finfo)
return
}
if entry.info.Size() != finfo.Size() ||
entry.info.ModTime() != finfo.ModTime() {
c.markUpdated(file, finfo)
return
}
c.markUnchanged(file)
}
func (c *crawler) filesByStatus(status fileStatus) (mailFiles, []os.FileInfo) {
files := newMailFiles()
infos := make([]os.FileInfo, 0)
for _, entry := range c.files {
if entry.status == status {
files = append(files, entry.mfile)
infos = append(infos, entry.info)
}
}
return files, infos
}
func (c *crawler) remove(files mailFiles) {
for _, f := range files {
delete(c.files, f.filename())
}
}
func (c *crawler) walk() {
filepath.Walk(c.root, func(path string, f os.FileInfo, err error) error {
if err != nil || f.IsDir() {
return err
}
file, err := makeMailFile(path)
if err != nil {
log.Print(path, ": error parsing file ", err)
return nil
}
c.markFile(file, f)
return err
})
}
func (c *crawler) scan() {
// Initially, set all files as to be removed
c.markAllDeleted()
c.walk()
// Remove removed files
filesDel, _ := c.filesByStatus(fileStatusDeleted)
c.cache.removeCh <- filesDel
c.remove(filesDel)
// Remove and add again updated files
filesUp, infosUp := c.filesByStatus(fileStatusUpdated)
c.cache.removeCh <- filesUp
for i := 0; i < len(filesUp); i++ {
// XXX: Probably should only mark in markAdded,
// then select by status and add in a new function.
c.markAdded(filesUp[i], infosUp[i])
}
}
func (c *crawler) rescan() {
c.wakeup <- struct{}{}
}
func (c *crawler) run(events <-chan *event, errors <-chan error, tick <-chan time.Time) {
for {
select {
case e := <-events:
e.handle(c)
case err := <-errors:
log.Print(err)
case <-c.wakeup:
c.scan()
case <-tick:
c.scan()
}
}
}