//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)
}
}
}
}
}
func (this *Fetcher) fetchPage(pageStore PageStore) {
defer this.wg.Done()
httpClient := lib.HttpClient{}
loop:
for {
select {
case taskPack := <-this.taskQueue:
destUrl := taskPack.Domain + taskPack.Urlpath
html, err := httpClient.Get(destUrl)
log.Debugln("goto fetch ", destUrl)
done := 0
if err == nil {
//report success to scheduler, make a log, save html
html, err = httpClient.IconvHtml(html, "utf-8")
done = 1
log.Infoln("fetch '" + destUrl + "' done.")
err = pageStore.Save(taskPack.Domain, taskPack.Urlpath, string(html))
if err != nil {
log.Errorln("fetcher save ", taskPack.Domain, taskPack.Urlpath, " error:", err)
}
} else {
//report fail to scheduler
log.Errorln("fetch '"+destUrl+"' failed!", err)
}
//向scheduler报告任务完成情况
reportUrl := fmt.Sprintf("http://%s%s?task_id=%d&done=%d", this.scheduler_addr, this.scheduler_api["report"], taskPack.TaskId, done)
res, err := httpClient.Get(reportUrl)
if err != nil {
log.Errorln("report ", reportUrl, " failed!")
} else {
result := types.JsonResult{}
err = json.Unmarshal(res, &result)
if err != nil || result.Err != 0 {
log.Errorln("report ", reportUrl, ", get error response: ", string(res))
}
}
case <-this.quitChan:
//this.quitChan should be closed somewhere
log.Infoln("quit fetch page...")
break loop
}
}
}