//分发task给Fetcher
func (this *Scheduler) DispatchTasks() {
//获取等待任务
tasks, err := this.FetchTasks()
if err != nil {
log.Errorln("[DispatchTasks] fetch tasks error: ", err)
return
}
if len(tasks) == 0 {
log.Warnln("[DispatchTasks] no wait tasks yet.")
return
}
//排序
sorter := lib.CrawlTaskSorter{Now: time.Now().Unix()}
sorter.Sort(tasks, nil)
//post到fetchers
picked := map[int32]bool{}
httpClient := lib.HttpClient{}
for _, fetcher := range this.fetchers {
taskPacks := []types.TaskPack{}
//挑选未分配的，且符合礼貌原则的任务
for _, task := range tasks {
_, ok := picked[task.Id]
if !ok && this.politeVisitor.IsPolite(task.Domain, fetcher) {
taskPacks = append(taskPacks, types.TaskPack{TaskId: task.Id, Domain: task.Domain, Urlpath: task.Urlpath})
picked[task.Id] = true
//缓存最后访问时间，实际有误差，但是实现简单
this.politeVisitor.SetLastVisitTime(task.Domain, fetcher, time.Now().Unix())
}
}
jsonBytes, err := json.Marshal(taskPacks)
if err != nil {
log.Errorln("make task packs error: ", err)
} else {
param := url.Values{}
param.Add("tasks", string(jsonBytes))
result, err := httpClient.Post("http://"+fetcher+this.fetcherApi["push_tasks"], param)
if err != nil {
log.Errorln("post task packs to fetcher:", fetcher, ", error:", err, " data:", string(jsonBytes))
} else {
jsonResult := types.JsonResult{}
err = json.Unmarshal(result, &jsonResult)
if err != nil {
log.Errorln("json unmarshal error:", err, " data:", string(result))
} else {
log.Infoln("get push tasks response: ", jsonResult)
}
}
}
}
}
