From aa8d42077c3daa14f81a16f38781b2b8225528cb Mon Sep 17 00:00:00 2001
From: Markus Grüneis <gimpf@gimpf.org>
Date: Fri, 24 Oct 2014 15:18:31 +0200
Subject: hub: Implement basic forward support.

---
 src/hub/src/spreadspace.org/sfive/s5srvForward.go | 95 +++++++++++++++++------
 1 file changed, 70 insertions(+), 25 deletions(-)

diff --git a/src/hub/src/spreadspace.org/sfive/s5srvForward.go b/src/hub/src/spreadspace.org/sfive/s5srvForward.go
index 6ae0f99..475027a 100644
--- a/src/hub/src/spreadspace.org/sfive/s5srvForward.go
+++ b/src/hub/src/spreadspace.org/sfive/s5srvForward.go
@@ -3,53 +3,98 @@ package sfive
 import (
 	"bytes"
 	"encoding/json"
+	"io/ioutil"
 	"net/http"
+	"strconv"
 	"time"
 )
 
-func findMaxId(values []dataUpdateDb) int {
+func findMaxId(values []StatisticsData) int {
 	maxId := -1
 	for i := range values {
-		if values[i].Id > maxId {
-			maxId = values[i].Id
+		id := values[i].SourceHubDataUpdateId
+		if id != nil && *id > maxId {
+			maxId = *id
 		}
 	}
 	return maxId
 }
 
-func (self StatsSinkServer) handleForwarding(url string, client *http.Client) {
-	latestId := 0 // TODO retrieve latest known from server
-next:
-	// TODO forwarding
-	for {
-		time.Sleep(500)
+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)
+	}
 
-		updates, err := self.store.GetUpdatesAfter(latestId)
+	if len(body) == 0 {
+		latestId = -1
+	} else {
+		tid, err := strconv.ParseInt(string(body), 10, 32)
 		if err != nil {
-			s5l.Printf("fwd: failed reading updates: %v\n", err)
-			continue next
+			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.
+				}
 
-		for i := range updates {
-			data, err := json.Marshal(updates[i])
-			if err == nil {
-				s5l.Printf("fwd: encode failed: %v\n", err)
-				// TODO retry etc.
-				continue
+				_, 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.
+				}
 			}
 
-			_, err = client.Post(url, "application/json", bytes.NewBuffer(data))
-			if err == nil {
-				latestId = findMaxId(updates)
+			if len(updates) == 0 {
+				time.Sleep(1 * time.Second)
 			} else {
-				s5l.Printf("fwd: post failed: %v\n", err)
-				// TODO retry etc.
+				lastId = findMaxId(updates)
+				s5tl.Printf("fwd: new lastid: %d", lastId)
+				time.Sleep(100 * time.Millisecond)
 			}
 		}
 	}
 }
 
 func (self StatsSinkServer) RunForwarding(forwardBaseUrl string) {
-	forwardUrl := forwardBaseUrl + "/updates"
-	self.handleForwarding(forwardUrl, http.DefaultClient)
+	self.handleForwarding(forwardBaseUrl, http.DefaultClient)
 }
-- 
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