Merge branch 'master' into event-tags

Author: danielgtaylor

CHANGELOG.md

@@ -6,9 +6,16 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 
 ## [Unreleased]
 
+- Add unreleased items here.
+
+## [1.2.0] - 2018-03-01
+
 - Update build to test with Go 1.9, drop support for 1.7 since `dep` now
   requires Go 1.8+. Go 1.7 users can still use this library but must manage
   their own dependencies.
+- Add `WithRate(rate float)` to the DataDog client to limit traffic sent to
+  the `dogstatsd` daemon. The set rate will be applied to all calls made
+  with the returned `Client`.
 - Automatically assign tags to events.
 
 ## [1.1.0] - 2017-08-01

metrics/datadog.go

@@ -10,6 +10,7 @@ import (
 // DataDogClient is a dogstatsd metrics client implementation.
 type DataDogClient struct {
 	client *statsd.Client
+	rate   float64
 	tagMap map[string]string
 }
 
@@ -29,6 +30,16 @@ func NewDataDogClient(address string, namespace string) *DataDogClient {
 
 	return &DataDogClient{
 		client: c,
+		rate:   1.0,
+	}
+}
+
+// WithRate clones this client with a new sample rate.
+func (c *DataDogClient) WithRate(rate float64) Client {
+	return &DataDogClient{
+		client: c.client,
+		rate:   rate,
+		tagMap: combine(c.tagMap, map[string]string{}),
 	}
 }
 
@@ -37,6 +48,7 @@ func NewDataDogClient(address string, namespace string) *DataDogClient {
 func (c *DataDogClient) WithTags(tags map[string]string) Client {
 	return &DataDogClient{
 		client: c.client,
+		rate:   c.rate,
 		tagMap: combine(c.tagMap, tags),
 	}
 }
@@ -47,7 +59,7 @@ func (c *DataDogClient) tagsList() []string {
 
 // Count adds some integer value to a metric.
 func (c *DataDogClient) Count(name string, value int64) {
-	c.client.Count(name, value, c.tagsList(), 1.0)
+	c.client.Count(name, value, c.tagsList(), c.rate)
 }
 
 // Incr adds one to a metric.
@@ -62,7 +74,7 @@ func (c *DataDogClient) Decr(name string) {
 
 // Gauge sets a numeric value.
 func (c *DataDogClient) Gauge(name string, value float64) {
-	c.client.Gauge(name, value, c.tagsList(), 1.0)
+	c.client.Gauge(name, value, c.tagsList(), c.rate)
 }
 
 // Event tracks an event that may be relevant to other metrics.
@@ -76,10 +88,10 @@ func (c *DataDogClient) Event(e *statsd.Event) {
 
 // Timing tracks a duration.
 func (c *DataDogClient) Timing(name string, value time.Duration) {
-	c.client.Timing(name, value, c.tagsList(), 1)
+	c.client.Timing(name, value, c.tagsList(), c.rate)
 }
 
 // Histogram sets a numeric value while tracking min/max/avg/p95/etc.
 func (c *DataDogClient) Histogram(name string, value float64) {
-	c.client.Histogram(name, value, c.tagsList(), 1.0)
+	c.client.Histogram(name, value, c.tagsList(), c.rate)
 }

metrics/datadog_test.go

@@ -9,6 +9,10 @@ import (
 	"github.com/istreamlabs/go-metrics/metrics"
 )
 
+type withRater interface {
+	WithRate(rate float64) metrics.Client
+}
+
 func ExampleDataDogClient() {
 	datadog := metrics.NewDataDogClient("127.0.0.1:8125", "myprefix")
 	datadog.WithTags(map[string]string{
@@ -36,6 +40,13 @@ func TestDataDogClient(t *testing.T) {
 	datadog.Gauge("memory", 1024)
 	datadog.Histogram("histo", 123)
 
+	if rater, ok := datadog.(withRater); ok {
+		ratedClient := rater.WithRate(0.5)
+		ratedClient.Incr("rated")
+	} else {
+		t.Fatalf("Expected DataDog client to support sample rate")
+	}
+
 	// Test that tag overrides work.
 	override := datadog.WithTags(map[string]string{
 		"tag1": "value1",