Improved http sink (#78)

* automatic flush in NatsSink

* tweak default options of HttpSink

* shorter cirt. section and retries for HttpSink

* fix error handling

* Remove file added by mistake.

* Use http instead of ftp to download likwid

* Fix serial number in rocmCollector

Co-authored-by: Thomas Roehl <thomas.roehl@fau.de>

sinks/httpSink.go

@@ -19,9 +19,9 @@ type HttpSinkConfig struct {
 	URL             string `json:"url,omitempty"`
 	JWT             string `json:"jwt,omitempty"`
 	Timeout         string `json:"timeout,omitempty"`
-	MaxIdleConns    int    `json:"max_idle_connections,omitempty"`
 	IdleConnTimeout string `json:"idle_connection_timeout,omitempty"`
 	FlushDelay      string `json:"flush_delay,omitempty"`
+	MaxRetries      int    `json:"max_retries,omitempty"`
 }
 
 type HttpSink struct {
@@ -32,58 +32,56 @@ type HttpSink struct {
 	buffer          *bytes.Buffer
 	flushTimer      *time.Timer
 	config          HttpSinkConfig
-	maxIdleConns    int
 	idleConnTimeout time.Duration
 	timeout         time.Duration
 	flushDelay      time.Duration
 }
 
 func (s *HttpSink) Write(m lp.CCMetric) error {
-	if s.buffer.Len() == 0 && s.flushDelay != 0 {
-		// This is the first write since the last flush, start the flushTimer!
-		if s.flushTimer != nil && s.flushTimer.Stop() {
-			cclog.ComponentDebug(s.name, "unexpected: the flushTimer was already running?")
-		}
-
-		// Run a batched flush for all lines that have arrived in the last second
-		s.flushTimer = time.AfterFunc(s.flushDelay, func() {
-			if err := s.Flush(); err != nil {
-				cclog.ComponentError(s.name, "flush failed:", err.Error())
-			}
-		})
-	}
-
 	p := m.ToPoint(s.meta_as_tags)
-
 	s.lock.Lock()
+	firstWriteOfBatch := s.buffer.Len() == 0
 	_, err := s.encoder.Encode(p)
-	s.lock.Unlock() // defer does not work here as Flush() takes the lock as well
-
+	s.lock.Unlock()
 	if err != nil {
 		cclog.ComponentError(s.name, "encoding failed:", err.Error())
 		return err
 	}
 
-	// Flush synchronously if "flush_delay" is zero
 	if s.flushDelay == 0 {
 		return s.Flush()
 	}
 
-	return err
+	if firstWriteOfBatch {
+		if s.flushTimer == nil {
+			s.flushTimer = time.AfterFunc(s.flushDelay, func() {
+				if err := s.Flush(); err != nil {
+					cclog.ComponentError(s.name, "flush failed:", err.Error())
+				}
+			})
+		} else {
+			s.flushTimer.Reset(s.flushDelay)
+		}
+	}
+
+	return nil
 }
 
 func (s *HttpSink) Flush() error {
-	// buffer is read by client.Do, prevent concurrent modifications
+	// Own lock for as short as possible: the time it takes to copy the buffer.
 	s.lock.Lock()
-	defer s.lock.Unlock()
-
-	// Do not flush empty buffer
-	if s.buffer.Len() == 0 {
+	buf := make([]byte, s.buffer.Len())
+	copy(buf, s.buffer.Bytes())
+	s.buffer.Reset()
+	s.lock.Unlock()
+	if len(buf) == 0 {
 		return nil
 	}
 
+	var res *http.Response
+	for i := 0; i < s.config.MaxRetries; i++ {
 		// Create new request to send buffer
-	req, err := http.NewRequest(http.MethodPost, s.config.URL, s.buffer)
+		req, err := http.NewRequest(http.MethodPost, s.config.URL, bytes.NewReader(buf))
 		if err != nil {
 			cclog.ComponentError(s.name, "failed to create request:", err.Error())
 			return err
@@ -94,21 +92,25 @@ func (s *HttpSink) Flush() error {
 			req.Header.Set("Authorization", fmt.Sprintf("Bearer %s", s.config.JWT))
 		}
 
-	// Send
-	res, err := s.client.Do(req)
-
-	// Clear buffer
-	s.buffer.Reset()
-
-	// Handle transport/tcp errors
+		// Do request
+		res, err = s.client.Do(req)
 		if err != nil {
 			cclog.ComponentError(s.name, "transport/tcp error:", err.Error())
-		return err
+			// Wait between retries
+			time.Sleep(time.Duration(i+1) * (time.Second / 2))
+			continue
+		}
+
+		break
+	}
+
+	if res == nil {
+		return errors.New("flush failed due to repeated errors")
 	}
 
 	// Handle application errors
 	if res.StatusCode != http.StatusOK {
-		err = errors.New(res.Status)
+		err := errors.New(res.Status)
 		cclog.ComponentError(s.name, "application error:", err.Error())
 		return err
 	}
@@ -128,10 +130,10 @@ func NewHttpSink(name string, config json.RawMessage) (Sink, error) {
 	s := new(HttpSink)
 	// Set default values
 	s.name = fmt.Sprintf("HttpSink(%s)", name)
-	s.config.MaxIdleConns = 10
-	s.config.IdleConnTimeout = "5s"
+	s.config.IdleConnTimeout = "120s" // should be larger than the measurement interval.
 	s.config.Timeout = "5s"
-	s.config.FlushDelay = "1s"
+	s.config.FlushDelay = "5s"
+	s.config.MaxRetries = 3
 
 	// Read config
 	if len(config) > 0 {
@@ -143,9 +145,6 @@ func NewHttpSink(name string, config json.RawMessage) (Sink, error) {
 	if len(s.config.URL) == 0 {
 		return nil, errors.New("`url` config option is required for HTTP sink")
 	}
-	if s.config.MaxIdleConns > 0 {
-		s.maxIdleConns = s.config.MaxIdleConns
-	}
 	if len(s.config.IdleConnTimeout) > 0 {
 		t, err := time.ParseDuration(s.config.IdleConnTimeout)
 		if err == nil {
@@ -170,7 +169,7 @@ func NewHttpSink(name string, config json.RawMessage) (Sink, error) {
 		s.meta_as_tags[k] = true
 	}
 	tr := &http.Transport{
-		MaxIdleConns:    s.maxIdleConns,
+		MaxIdleConns:    1, // We will only ever talk to one host.
 		IdleConnTimeout: s.idleConnTimeout,
 	}
 	s.client = &http.Client{Transport: tr, Timeout: s.timeout}

sinks/natsSink.go

@@ -5,6 +5,7 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
+	"sync"
 	"time"
 
 	cclog "github.com/ClusterCockpit/cc-metric-collector/internal/ccLogger"
@@ -17,9 +18,10 @@ type NatsSinkConfig struct {
 	defaultSinkConfig
 	Host       string `json:"host,omitempty"`
 	Port       string `json:"port,omitempty"`
-	Database string `json:"database,omitempty"`
+	Subject    string `json:"subject,omitempty"`
 	User       string `json:"user,omitempty"`
 	Password   string `json:"password,omitempty"`
+	FlushDelay string `json:"flush_delay,omitempty"`
 }
 
 type NatsSink struct {
@@ -28,6 +30,10 @@ type NatsSink struct {
 	encoder *influx.Encoder
 	buffer  *bytes.Buffer
 	config  NatsSinkConfig
+
+	lock       sync.Mutex
+	flushDelay time.Duration
+	flushTimer *time.Timer
 }
 
 func (s *NatsSink) connect() error {
@@ -54,37 +60,53 @@ func (s *NatsSink) connect() error {
 }
 
 func (s *NatsSink) Write(m lp.CCMetric) error {
-	if s.client != nil {
+	s.lock.Lock()
 	_, err := s.encoder.Encode(m.ToPoint(s.meta_as_tags))
+	s.lock.Unlock()
 	if err != nil {
 		cclog.ComponentError(s.name, "Write:", err.Error())
 		return err
 	}
+
+	if s.flushDelay == 0 {
+		s.Flush()
+	} else if s.flushTimer == nil {
+		s.flushTimer = time.AfterFunc(s.flushDelay, func() {
+			s.Flush()
+		})
+	} else {
+		s.flushTimer.Reset(s.flushDelay)
 	}
+
 	return nil
 }
 
 func (s *NatsSink) Flush() error {
-	if s.client != nil {
-		if err := s.client.Publish(s.config.Database, s.buffer.Bytes()); err != nil {
+	s.lock.Lock()
+	buf := append([]byte{}, s.buffer.Bytes()...) // copy bytes
+	s.buffer.Reset()
+	s.lock.Unlock()
+
+	if len(buf) == 0 {
+		return nil
+	}
+
+	if err := s.client.Publish(s.config.Subject, buf); err != nil {
 		cclog.ComponentError(s.name, "Flush:", err.Error())
 		return err
 	}
-		s.buffer.Reset()
-	}
 	return nil
 }
 
 func (s *NatsSink) Close() {
-	if s.client != nil {
 	cclog.ComponentDebug(s.name, "Close")
 	s.client.Close()
-	}
 }
 
 func NewNatsSink(name string, config json.RawMessage) (Sink, error) {
 	s := new(NatsSink)
 	s.name = fmt.Sprintf("NatsSink(%s)", name)
+	s.flushDelay = 10 * time.Second
 	if len(config) > 0 {
 		err := json.Unmarshal(config, &s.config)
 		if err != nil {
@@ -94,7 +116,7 @@ func NewNatsSink(name string, config json.RawMessage) (Sink, error) {
 	}
 	if len(s.config.Host) == 0 ||
 		len(s.config.Port) == 0 ||
-		len(s.config.Database) == 0 {
+		len(s.config.Subject) == 0 {
 		return nil, errors.New("not all configuration variables set required by NatsSink")
 	}
 	// Create lookup map to use meta infos as tags in the output metric
@@ -112,5 +134,15 @@ func NewNatsSink(name string, config json.RawMessage) (Sink, error) {
 	if err := s.connect(); err != nil {
 		return nil, fmt.Errorf("unable to connect: %v", err)
 	}
+
+	s.flushTimer = nil
+	if len(s.config.FlushDelay) != 0 {
+		var err error
+		s.flushDelay, err = time.ParseDuration(s.config.FlushDelay)
+		if err != nil {
+			return nil, err
+		}
+	}
+
 	return s, nil
 }