Golang Context.Step方法代碼示例

func GetFeed(c mpg.Context, w http.ResponseWriter, r *http.Request) {
	gn := goon.FromContext(c)
	f := Feed{Url: r.FormValue("f")}
	var stars []string
	wg := sync.WaitGroup{}
	fk := gn.Key(&f)
	q := datastore.NewQuery(gn.Kind(&Story{})).Ancestor(fk).KeysOnly()
	q = q.Order("-" + IDX_COL)
	if cur := r.FormValue("c"); cur != "" {
		if dc, err := datastore.DecodeCursor(cur); err == nil {
			q = q.Start(dc)
		}
	} else {
		// grab the stars list on the first run
		wg.Add(1)
		go c.Step("stars", func(c mpg.Context) {
			gn := goon.FromContext(c)
			usk := starKey(c, f.Url, "")
			q := datastore.NewQuery(gn.Kind(&UserStar{})).Ancestor(gn.Key(usk).Parent()).KeysOnly()
			keys, _ := gn.GetAll(q, nil)
			stars = make([]string, len(keys))
			for i, key := range keys {
				stars[i] = starID(key)
			}
			wg.Done()
		})
	}
	iter := gn.Run(q)
	var stories []*Story
	for i := 0; i < 20; i++ {
		if k, err := iter.Next(nil); err == nil {
			stories = append(stories, &Story{
				Id:     k.StringID(),
				Parent: k.Parent(),
			})
		} else if err == datastore.Done {
			break
		} else {
			serveError(w, err)
			return
		}
	}
	cursor := ""
	if ic, err := iter.Cursor(); err == nil {
		cursor = ic.String()
	}
	gn.GetMulti(&stories)
	wg.Wait()
	b, _ := json.Marshal(struct {
		Cursor  string
		Stories []*Story
		Stars   []string `json:",omitempty"`
	}{
		Cursor:  cursor,
		Stories: stories,
		Stars:   stars,
	})
	w.Write(b)
}

func ListFeeds(c mpg.Context, w http.ResponseWriter, r *http.Request) {
	cu := user.Current(c)
	gn := goon.FromContext(c)
	u := &User{Id: cu.ID}
	ud := &UserData{Id: "data", Parent: gn.Key(u)}
	if err := gn.GetMulti([]interface{}{u, ud}); err != nil && !goon.NotFound(err, 1) {
		serveError(w, err)
		return
	}
	l := &Log{
		Parent: ud.Parent,
		Id:     time.Now().UnixNano(),
		Text:   "list feeds",
	}
	l.Text += fmt.Sprintf(", len opml %v", len(ud.Opml))
	putU := false
	putUD := false
	fixRead := false
	if time.Since(u.Read) > oldDuration {
		u.Read = time.Now().Add(-oldDuration)
		putU = true
		fixRead = true
		l.Text += ", u.Read"
	}
	trialRemaining := 0
	if STRIPE_KEY != "" && ud.Opml != nil && u.Account == AFree && u.Until.Before(time.Now()) {
		if u.Created.IsZero() {
			u.Created = time.Now()
			putU = true
		} else if time.Since(u.Created) > accountFreeDuration {
			b, _ := json.Marshal(struct {
				ErrorSubscription bool
			}{
				true,
			})
			w.Write(b)
			return
		}
		trialRemaining = int((accountFreeDuration-time.Since(u.Created))/time.Hour/24) + 1
	}
	read := make(Read)
	var uf Opml
	c.Step("unmarshal user data", func(c mpg.Context) {
		gob.NewDecoder(bytes.NewReader(ud.Read)).Decode(&read)
		json.Unmarshal(ud.Opml, &uf)
	})
	var feeds []*Feed
	opmlMap := make(map[string]*OpmlOutline)
	var merr error
	c.Step("fetch feeds", func(c mpg.Context) {
		gn := goon.FromContext(appengine.Timeout(c, time.Minute))
		for _, outline := range uf.Outline {
			if outline.XmlUrl == "" {
				for _, so := range outline.Outline {
					feeds = append(feeds, &Feed{Url: so.XmlUrl})
					opmlMap[so.XmlUrl] = so
				}
			} else {
				feeds = append(feeds, &Feed{Url: outline.XmlUrl})
				opmlMap[outline.XmlUrl] = outline
			}
		}
		merr = gn.GetMulti(feeds)
	})
	lock := sync.Mutex{}
	fl := make(map[string][]*Story)
	q := datastore.NewQuery(gn.Kind(&Story{})).
		Filter(IDX_COL+" >=", u.Read).
		KeysOnly().
		Order("-" + IDX_COL).
		Limit(250)
	updatedLinks := false
	now := time.Now()
	numStories := 0
	var stars []string

	c.Step(fmt.Sprintf("feed unreads: %v", u.Read), func(c mpg.Context) {
		queue := make(chan *Feed)
		tc := make(chan *taskqueue.Task)
		done := make(chan bool)
		wg := sync.WaitGroup{}
		feedProc := func() {
			for f := range queue {
				c.Step(f.Title, func(c mpg.Context) {
					defer wg.Done()
					var stories []*Story
					gn := goon.FromContext(appengine.Timeout(c, time.Minute))

					if !f.Date.Before(u.Read) {
						fk := gn.Key(f)
						sq := q.Ancestor(fk)
						keys, _ := gn.GetAll(sq, nil)
						stories = make([]*Story, len(keys))
						for j, key := range keys {
							stories[j] = &Story{
								Id:     key.StringID(),
								Parent: fk,
							}
						}
						gn.GetMulti(stories)
//.........這裏部分代碼省略.........