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|
package metrics
import (
"bytes"
"fmt"
"log"
"net"
"net/url"
"strings"
"time"
)
const (
// statsdMaxLen is the maximum size of a packet
// to send to statsd
statsdMaxLen = 1400
)
// StatsdSink provides a MetricSink that can be used
// with a statsite or statsd metrics server. It uses
// only UDP packets, while StatsiteSink uses TCP.
type StatsdSink struct {
addr string
metricQueue chan string
}
// NewStatsdSinkFromURL creates an StatsdSink from a URL. It is used
// (and tested) from NewMetricSinkFromURL.
func NewStatsdSinkFromURL(u *url.URL) (MetricSink, error) {
return NewStatsdSink(u.Host)
}
// NewStatsdSink is used to create a new StatsdSink
func NewStatsdSink(addr string) (*StatsdSink, error) {
s := &StatsdSink{
addr: addr,
metricQueue: make(chan string, 4096),
}
go s.flushMetrics()
return s, nil
}
// Close is used to stop flushing to statsd
func (s *StatsdSink) Shutdown() {
close(s.metricQueue)
}
func (s *StatsdSink) SetGauge(key []string, val float32) {
flatKey := s.flattenKey(key)
s.pushMetric(fmt.Sprintf("%s:%f|g\n", flatKey, val))
}
func (s *StatsdSink) SetGaugeWithLabels(key []string, val float32, labels []Label) {
flatKey := s.flattenKeyLabels(key, labels)
s.pushMetric(fmt.Sprintf("%s:%f|g\n", flatKey, val))
}
func (s *StatsdSink) EmitKey(key []string, val float32) {
flatKey := s.flattenKey(key)
s.pushMetric(fmt.Sprintf("%s:%f|kv\n", flatKey, val))
}
func (s *StatsdSink) IncrCounter(key []string, val float32) {
flatKey := s.flattenKey(key)
s.pushMetric(fmt.Sprintf("%s:%f|c\n", flatKey, val))
}
func (s *StatsdSink) IncrCounterWithLabels(key []string, val float32, labels []Label) {
flatKey := s.flattenKeyLabels(key, labels)
s.pushMetric(fmt.Sprintf("%s:%f|c\n", flatKey, val))
}
func (s *StatsdSink) AddSample(key []string, val float32) {
flatKey := s.flattenKey(key)
s.pushMetric(fmt.Sprintf("%s:%f|ms\n", flatKey, val))
}
func (s *StatsdSink) AddSampleWithLabels(key []string, val float32, labels []Label) {
flatKey := s.flattenKeyLabels(key, labels)
s.pushMetric(fmt.Sprintf("%s:%f|ms\n", flatKey, val))
}
// Flattens the key for formatting, removes spaces
func (s *StatsdSink) flattenKey(parts []string) string {
joined := strings.Join(parts, ".")
return strings.Map(func(r rune) rune {
switch r {
case ':':
fallthrough
case ' ':
return '_'
default:
return r
}
}, joined)
}
// Flattens the key along with labels for formatting, removes spaces
func (s *StatsdSink) flattenKeyLabels(parts []string, labels []Label) string {
for _, label := range labels {
parts = append(parts, label.Value)
}
return s.flattenKey(parts)
}
// Does a non-blocking push to the metrics queue
func (s *StatsdSink) pushMetric(m string) {
select {
case s.metricQueue <- m:
default:
}
}
// Flushes metrics
func (s *StatsdSink) flushMetrics() {
var sock net.Conn
var err error
var wait <-chan time.Time
ticker := time.NewTicker(flushInterval)
defer ticker.Stop()
CONNECT:
// Create a buffer
buf := bytes.NewBuffer(nil)
// Attempt to connect
sock, err = net.Dial("udp", s.addr)
if err != nil {
log.Printf("[ERR] Error connecting to statsd! Err: %s", err)
goto WAIT
}
for {
select {
case metric, ok := <-s.metricQueue:
// Get a metric from the queue
if !ok {
goto QUIT
}
// Check if this would overflow the packet size
if len(metric)+buf.Len() > statsdMaxLen {
_, err := sock.Write(buf.Bytes())
buf.Reset()
if err != nil {
log.Printf("[ERR] Error writing to statsd! Err: %s", err)
goto WAIT
}
}
// Append to the buffer
buf.WriteString(metric)
case <-ticker.C:
if buf.Len() == 0 {
continue
}
_, err := sock.Write(buf.Bytes())
buf.Reset()
if err != nil {
log.Printf("[ERR] Error flushing to statsd! Err: %s", err)
goto WAIT
}
}
}
WAIT:
// Wait for a while
wait = time.After(time.Duration(5) * time.Second)
for {
select {
// Dequeue the messages to avoid backlog
case _, ok := <-s.metricQueue:
if !ok {
goto QUIT
}
case <-wait:
goto CONNECT
}
}
QUIT:
s.metricQueue = nil
}
|
