From afb82609350433eda9415e8203a29b140f9d4294 Mon Sep 17 00:00:00 2001
From: Marcin Wielgus <mwielgus@google.com>
Date: Fri, 11 Dec 2015 17:47:36 +0100
Subject: [PATCH] Better connection handling for InfluxDB:

---
 sinks/external.go        | 11 +++++++-
 sinks/influxdb/driver.go | 57 ++++++++++++++++++++++++++++++++--------
 2 files changed, 56 insertions(+), 12 deletions(-)

diff --git a/sinks/external.go b/sinks/external.go
index 9d0205021a..131c0c442a 100644
--- a/sinks/external.go
+++ b/sinks/external.go
@@ -146,7 +146,16 @@ func (esm *externalSinkManager) store() error {
 	var errors []string
 	for i := 0; i < errorsLen; i++ {
 		if err := <-errorsChan; err != nil {
-			errors = append(errors, fmt.Sprintf("%v ", err))
+			strError := fmt.Sprintf("%v ", err)
+			found := false
+			for _, otherError := range errors {
+				if otherError == strError {
+					found = true
+				}
+			}
+			if !found {
+				errors = append(errors, strError)
+			}
 		}
 	}
 	if len(errors) > 0 {
diff --git a/sinks/influxdb/driver.go b/sinks/influxdb/driver.go
index dbf9834461..8fcbb1a3e6 100644
--- a/sinks/influxdb/driver.go
+++ b/sinks/influxdb/driver.go
@@ -70,6 +70,9 @@ var (
 )
 
 func (sink *influxdbSink) Register(metrics []sink_api.MetricDescriptor) error {
+	sink.Lock()
+	defer sink.Unlock()
+
 	if err := sink.createDatabase(); err != nil {
 		glog.Error(err)
 	}
@@ -109,6 +112,9 @@ func (sink *influxdbSink) metricToPoint(timeseries *sink_api.Timeseries) influxd
 
 // Stores events into the backend.
 func (sink *influxdbSink) StoreEvents(events []kube_api.Event) error {
+	sink.Lock()
+	defer sink.Unlock()
+
 	if err := sink.createDatabase(); err != nil {
 		return err
 	}
@@ -126,7 +132,10 @@ func (sink *influxdbSink) StoreEvents(events []kube_api.Event) error {
 	}
 	if _, err = sink.client.Write(bp); err != nil {
 		if strings.Contains(err.Error(), dbNotFoundError) {
-			sink.dbExists = false
+			sink.resetConnection()
+		} else if _, _, err := sink.client.Ping(); err != nil {
+			glog.Errorf("InfluxDB ping failed: %v", err)
+			sink.resetConnection()
 		}
 		glog.Errorf("failed to write events to influxDB - %s", err)
 		sink.recordWriteFailure()
@@ -136,6 +145,12 @@ func (sink *influxdbSink) StoreEvents(events []kube_api.Event) error {
 	return nil
 }
 
+func (sink *influxdbSink) resetConnection() {
+	glog.Infof("Influxdb connection reset")
+	sink.dbExists = false
+	sink.client = nil
+}
+
 func (sink *influxdbSink) eventsToPoints(events []kube_api.Event) ([]influxdb.Point, error) {
 	if events == nil || len(events) <= 0 {
 		return nil, nil
@@ -168,6 +183,9 @@ func (sink *influxdbSink) eventsToPoints(events []kube_api.Event) ([]influxdb.Po
 }
 
 func (sink *influxdbSink) StoreTimeseries(timeseries []sink_api.Timeseries) error {
+	sink.Lock()
+	defer sink.Unlock()
+
 	var err error
 	if err = sink.createDatabase(); err != nil {
 		return err
@@ -184,10 +202,14 @@ func (sink *influxdbSink) StoreTimeseries(timeseries []sink_api.Timeseries) erro
 	// TODO: Record the average time taken to flush data.
 	if _, err = sink.client.Write(bp); err != nil {
 		if strings.Contains(err.Error(), dbNotFoundError) {
-			sink.dbExists = false
+			sink.resetConnection()
 		}
 		glog.Errorf("failed to write stats to influxDB - %v", err)
 		sink.recordWriteFailure()
+		if _, _, err := sink.client.Ping(); err != nil {
+			glog.Errorf("InfluxDB ping failed: %v", err)
+			sink.resetConnection()
+		}
 		return err
 	}
 	glog.V(4).Info("flushed stats to influxDB")
@@ -204,18 +226,17 @@ func getEventValue(event *kube_api.Event) (string, error) {
 }
 
 func (sink *influxdbSink) recordWriteFailure() {
-	sink.Lock()
-	defer sink.Unlock()
 	sink.writeFailures++
 }
 
 func (sink *influxdbSink) getState() string {
-	sink.RLock()
-	defer sink.RUnlock()
 	return fmt.Sprintf("\tNumber of write failures: %d\n", sink.writeFailures)
 }
 
 func (sink *influxdbSink) DebugInfo() string {
+	sink.RLock()
+	defer sink.RUnlock()
+
 	desc := "Sink Type: InfluxDB\n"
 	desc += fmt.Sprintf("\tclient: Host %q, Database %q\n", sink.c.host, sink.c.dbName)
 	desc += sink.getState()
@@ -228,8 +249,14 @@ func (sink *influxdbSink) Name() string {
 }
 
 func (sink *influxdbSink) createDatabase() error {
-	sink.Lock()
-	defer sink.Unlock()
+	if sink.client == nil {
+		client, err := newClient(sink.c)
+		if err != nil {
+			return err
+		}
+		sink.client = client
+	}
+
 	if sink.dbExists {
 		return nil
 	}
@@ -246,8 +273,7 @@ func (sink *influxdbSink) createDatabase() error {
 	return nil
 }
 
-// Returns a thread-compatible implementation of influxdb interactions.
-func new(c config) (sink_api.ExternalSink, error) {
+func newClient(c config) (influxdbClient, error) {
 	url := &url.URL{
 		Scheme: "http",
 		Host:   c.host,
@@ -270,8 +296,17 @@ func new(c config) (sink_api.ExternalSink, error) {
 	if _, _, err := client.Ping(); err != nil {
 		return nil, fmt.Errorf("failed to ping InfluxDB server at %q - %v", c.host, err)
 	}
+	return client, nil
+}
+
+// Returns a thread-compatible implementation of influxdb interactions.
+func new(c config) (sink_api.ExternalSink, error) {
+	client, err := newClient(c)
+	if err != nil {
+		fmt.Errorf("issues while creating an InfluxDB sink: %v, will retry on use", err)
+	}
 	return &influxdbSink{
-		client: client,
+		client: client, // can be nil
 		c:      c,
 	}, nil
 }