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handle.go
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handle.go
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package crawler
import (
"bytes"
"io"
"net/url"
"github.com/fanyang01/crawler/urlx"
"golang.org/x/net/html"
)
type handler struct {
workerConn
cw *Crawler
In <-chan *Response
Out chan *Response
ErrOut chan *Response
}
func (cw *Crawler) newRespHandler() *handler {
nworker := cw.opt.NWorker.Handler
this := &handler{
cw: cw,
Out: make(chan *Response, nworker),
}
cw.initWorker("handler", this, nworker)
return this
}
func (h *handler) cleanup() { close(h.Out) }
func (h *handler) work() {
for r := range h.In {
var (
err error
errOut chan *Response
out = h.Out
logger = h.logger.New("url", r.URL)
)
if err = h.handle(r); err == nil {
err = r.ctx.err
}
r.bodyCloser.Close()
if err != nil {
logger.Error("handle response", "err", err)
r.ctx.err = err
out, errOut = nil, h.ErrOut
}
select {
case out <- r:
case errOut <- r:
case <-h.quit:
return
}
}
}
func (h *handler) handle(r *Response) error {
depth := r.ctx.Depth()
ch := make(chan *url.URL, perPage)
go func() {
if h.cw.opt.FollowRedirect {
// Treat the new URL as one found under the original URL
original := r.URL.String()
if r.NewURL.String() != original {
newurl := *r.NewURL
ch <- &newurl
}
if refresh := r.Refresh.URL; refresh != nil &&
refresh.String() != original {
newurl := *refresh
ch <- &newurl
}
}
h.cw.ctrl.Handle(r, ch)
close(ch)
}()
return h.handleLink(r, ch, depth)
}
func (h *handler) handleLink(r *Response, ch <-chan *url.URL, depth int) error {
for u := range ch {
if err := h.cw.normalize(u); err != nil {
h.logger.Debug("normalize URL", "url", u, "err", err)
continue
}
if ok, err := h.filter(r, u, depth); err != nil {
return err
} else if ok {
r.links = append(r.links, u)
}
}
return nil
}
func (h *handler) filter(r *Response, u *url.URL, depth int) (bool, error) {
if !h.cw.ctrl.Accept(r, u) {
return false, nil
}
if ok, err := h.cw.store.Exist(u); err != nil {
return false, err
} else if ok {
return false, nil
}
// New link
if ok, err := h.cw.store.PutNX(&URL{
URL: *u,
Depth: depth + 1,
}); err != nil || !ok {
return false, err
}
return true, nil
}
func ExtractHref(base *url.URL, reader io.Reader, ch chan<- *url.URL) error {
z := html.NewTokenizer(reader)
f := func(z *html.Tokenizer, base *url.URL) *url.URL {
for {
key, val, more := z.TagAttr()
if bytes.Equal(key, []byte("href")) {
if u, err := urlx.ParseRef(base, string(val)); err == nil {
return u
}
break
}
if !more {
break
}
}
return nil
}
LOOP:
for {
tt := z.Next()
switch tt {
case html.ErrorToken:
if err := z.Err(); err != io.EOF {
return err
}
break LOOP
case html.StartTagToken:
tn, hasAttr := z.TagName()
if hasAttr && len(tn) == 1 && tn[0] == 'a' {
if u := f(z, base); u != nil {
ch <- u
}
}
case html.SelfClosingTagToken:
tn, hasAttr := z.TagName()
if hasAttr && len(tn) == 4 && bytes.Equal(tn, []byte("base")) {
if u := f(z, base); u != nil {
base = u
}
}
}
}
return nil
}