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path: root/src/hub/src/spreadspace.org/sfive/s5srvForward.go
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package sfive

import (
	"bytes"
	"encoding/json"
	"io/ioutil"
	"net/http"
	"strconv"
	"time"
)

func findMaxId(values []StatisticsData) int {
	maxId := -1
	for i := range values {
		id := values[i].SourceHubDataUpdateId
		if id != nil && *id > maxId {
			maxId = *id
		}
	}
	return maxId
}

func (self StatsSinkServer) getLastUpdate(baseurl string, client *http.Client) (latestId int, storeId string) {
	storeId, err := self.store.GetStoreId()
	if err != nil {
		s5l.Panicf("fwd: failed to get own hubid: %v\n", err)
	}

	resp, err := client.Get(baseurl + "/lastupdate/" + storeId)
	if err != nil {
		s5l.Panicf("fwd: failed to query for lastupdate: %v\n", err)
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusOK {
		s5l.Panicf("fwd: server failed to fulfill query for lastupdate: %v\n", resp.StatusCode)
	}

	body, err := ioutil.ReadAll(resp.Body)
	if err != nil {
		s5l.Panicf("fwd: failed to read lastupdate response: %v\n", err)
	}

	if len(body) == 0 {
		latestId = -1
	} else {
		tid, err := strconv.ParseInt(string(body), 10, 32)
		if err != nil {
			s5l.Panicf("fwd: invalid lastupdate response: %v\n", err)
		}
		latestId = int(tid)
	}

	return
}

func (self StatsSinkServer) handleForwarding(baseurl string, client *http.Client) {
	url := baseurl + "/updates"
tryResync:
	for {
		lastId, _ := self.getLastUpdate(baseurl, client)

	nextBatch:
		for {
			updates, err := self.store.GetUpdatesAfter(lastId)
			if err != nil {
				s5l.Printf("fwd: failed reading updates: %v\n", err)
				time.Sleep(500 * time.Millisecond)
				continue nextBatch
			}

			for i := range updates {
				data, err := json.Marshal(updates[i])
				if err != nil {
					s5l.Panicf("fwd: encode failed: %v\n", err)
					// TODO retry etc.
				}

				_, err = client.Post(url, "application/json", bytes.NewBuffer(data))
				if err != nil {
					s5l.Printf("fwd: post failed: %v\n", err)
					continue tryResync
					// TODO retry etc.
				}
			}

			if len(updates) == 0 {
				time.Sleep(1 * time.Second)
			} else {
				lastId = findMaxId(updates)
				s5tl.Printf("fwd: new lastid: %d", lastId)
				time.Sleep(100 * time.Millisecond)
			}
		}
	}
}

func (self StatsSinkServer) RunForwarding(forwardBaseUrl string) {
	self.handleForwarding(forwardBaseUrl, http.DefaultClient)
}