Support for using statsd.Client as an otel.MeterProvider

go.mod

@@ -1,10 +1,25 @@
 module github.com/DataDog/datadog-go/v5
 
-go 1.13
+go 1.21
 
 require (
 	github.com/Microsoft/go-winio v0.5.0
 	github.com/golang/mock v1.6.0
-	github.com/stretchr/testify v1.8.1
+	github.com/stretchr/testify v1.8.4
+	go.opentelemetry.io/otel v1.24.0
+	go.opentelemetry.io/otel/metric v1.24.0
+	go.opentelemetry.io/otel/sdk v1.24.0
+	go.opentelemetry.io/otel/sdk/metric v1.24.0
 	golang.org/x/net v0.0.0-20210405180319-a5a99cb37ef4
 )
+
+require (
+	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/go-logr/logr v1.4.1 // indirect
+	github.com/go-logr/stdr v1.2.2 // indirect
+	github.com/pmezard/go-difflib v1.0.0 // indirect
+	github.com/stretchr/objx v0.5.0 // indirect
+	go.opentelemetry.io/otel/trace v1.24.0 // indirect
+	golang.org/x/sys v0.17.0 // indirect
+	gopkg.in/yaml.v3 v3.0.1 // indirect
+)

go.sum

@@ -3,8 +3,15 @@ github.com/Microsoft/go-winio v0.5.0/go.mod h1:JPGBdM1cNvN/6ISo+n8V5iA4v8pBzdOpz
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/go-logr/logr v1.2.2/go.mod h1:jdQByPbusPIv2/zmleS9BjJVeZ6kBagPoEUsqbVz/1A=
+github.com/go-logr/logr v1.4.1 h1:pKouT5E8xu9zeFC39JXRDukb6JFQPXM5p5I91188VAQ=
+github.com/go-logr/logr v1.4.1/go.mod h1:9T104GzyrTigFIr8wt5mBrctHMim0Nb2HLGrmQ40KvY=
+github.com/go-logr/stdr v1.2.2 h1:hSWxHoqTgW2S2qGc0LTAI563KZ5YKYRhT3MFKZMbjag=
+github.com/go-logr/stdr v1.2.2/go.mod h1:mMo/vtBO5dYbehREoey6XUKy/eSumjCCveDpRre4VKE=
 github.com/golang/mock v1.6.0 h1:ErTB+efbowRARo13NNdxyJji2egdxLGQhRaY+DUumQc=
 github.com/golang/mock v1.6.0/go.mod h1:p6yTPP+5HYm5mzsMV8JkE6ZKdX+/wYM6Hr+LicevLPs=
+github.com/google/go-cmp v0.6.0 h1:ofyhxvXcZhMsU5ulbFiLKl/XBFqE1GSq7atu8tAmTRI=
+github.com/google/go-cmp v0.6.0/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=
 github.com/pkg/errors v0.9.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
@@ -16,9 +23,19 @@ github.com/stretchr/objx v0.5.0/go.mod h1:Yh+to48EsGEfYuaHDzXPcE3xhTkx73EhmCGUpE
 github.com/stretchr/testify v1.2.2/go.mod h1:a8OnRcib4nhh0OaRAV+Yts87kKdq0PP7pXfy6kDkUVs=
 github.com/stretchr/testify v1.7.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
 github.com/stretchr/testify v1.8.0/go.mod h1:yNjHg4UonilssWZ8iaSj1OCr/vHnekPRkoO+kdMU+MU=
-github.com/stretchr/testify v1.8.1 h1:w7B6lhMri9wdJUVmEZPGGhZzrYTPvgJArz7wNPgYKsk=
-github.com/stretchr/testify v1.8.1/go.mod h1:w2LPCIKwWwSfY2zedu0+kehJoqGctiVI29o6fzry7u4=
+github.com/stretchr/testify v1.8.4 h1:CcVxjf3Q8PM0mHUKJCdn+eZZtm5yQwehR5yeSVQQcUk=
+github.com/stretchr/testify v1.8.4/go.mod h1:sz/lmYIOXD/1dqDmKjjqLyZ2RngseejIcXlSw2iwfAo=
 github.com/yuin/goldmark v1.3.5/go.mod h1:mwnBkeHKe2W/ZEtQ+71ViKU8L12m81fl3OWwC1Zlc8k=
+go.opentelemetry.io/otel v1.24.0 h1:0LAOdjNmQeSTzGBzduGe/rU4tZhMwL5rWgtp9Ku5Jfo=
+go.opentelemetry.io/otel v1.24.0/go.mod h1:W7b9Ozg4nkF5tWI5zsXkaKKDjdVjpD4oAt9Qi/MArHo=
+go.opentelemetry.io/otel/metric v1.24.0 h1:6EhoGWWK28x1fbpA4tYTOWBkPefTDQnb8WSGXlc88kI=
+go.opentelemetry.io/otel/metric v1.24.0/go.mod h1:VYhLe1rFfxuTXLgj4CBiyz+9WYBA8pNGJgDcSFRKBco=
+go.opentelemetry.io/otel/sdk v1.24.0 h1:YMPPDNymmQN3ZgczicBY3B6sf9n62Dlj9pWD3ucgoDw=
+go.opentelemetry.io/otel/sdk v1.24.0/go.mod h1:KVrIYw6tEubO9E96HQpcmpTKDVn9gdv35HoYiQWGDFg=
+go.opentelemetry.io/otel/sdk/metric v1.24.0 h1:yyMQrPzF+k88/DbH7o4FMAs80puqd+9osbiBrJrz/w8=
+go.opentelemetry.io/otel/sdk/metric v1.24.0/go.mod h1:I6Y5FjH6rvEnTTAYQz3Mmv2kl6Ek5IIrmwTLqMrrOE0=
+go.opentelemetry.io/otel/trace v1.24.0 h1:CsKnnL4dUAr/0llH9FKuc698G04IrpWV0MQA/Y1YELI=
+go.opentelemetry.io/otel/trace v1.24.0/go.mod h1:HPc3Xr/cOApsBI154IU0OI0HJexz+aw5uPdbs3UCjNU=
 golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
 golang.org/x/crypto v0.0.0-20191011191535-87dc89f01550/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=
 golang.org/x/mod v0.4.2/go.mod h1:s0Qsj1ACt9ePp/hMypM3fl4fZqREWJwdYDEqhRiZZUA=
@@ -34,8 +51,9 @@ golang.org/x/sys v0.0.0-20191026070338-33540a1f6037/go.mod h1:h1NjWce9XRLGQEsW7w
 golang.org/x/sys v0.0.0-20201119102817-f84b799fce68/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20210124154548-22da62e12c0c/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20210330210617-4fbd30eecc44/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
-golang.org/x/sys v0.0.0-20210510120138-977fb7262007 h1:gG67DSER+11cZvqIMb8S8bt0vZtiN6xWYARwirrOSfE=
 golang.org/x/sys v0.0.0-20210510120138-977fb7262007/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.17.0 h1:25cE3gD+tdBA7lp7QfhuV+rJiE9YXTcS3VG1SqssI/Y=
+golang.org/x/sys v0.17.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
 golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 golang.org/x/text v0.3.3/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=

statsd/otel_cache.go

@@ -0,0 +1,80 @@
+package statsd
+
+import (
+	"sync"
+)
+
+// cache is a locking storage used to quickly return already computed values.
+//
+// The zero value of a cache is empty and ready to use.
+//
+// A cache must not be copied after first use.
+//
+// All methods of a cache are safe to call concurrently.
+type cache[K comparable, V any] struct {
+	sync.Mutex
+	data map[K]V
+}
+
+// Lookup returns the value stored in the cache with the associated key if it
+// exists. Otherwise, f is called and its returned value is set in the cache
+// for key and returned.
+//
+// Lookup is safe to call concurrently. It will hold the cache lock, so f
+// should not block excessively.
+func (c *cache[K, V]) Lookup(key K, f func() V) V {
+	c.Lock()
+	defer c.Unlock()
+
+	if c.data == nil {
+		val := f()
+		c.data = map[K]V{key: val}
+		return val
+	}
+	if v, ok := c.data[key]; ok {
+		return v
+	}
+	val := f()
+	c.data[key] = val
+	return val
+}
+
+// HasKey returns true if Lookup has previously been called with that key
+//
+// HasKey is safe to call concurrently.
+func (c *cache[K, V]) HasKey(key K) bool {
+	c.Lock()
+	defer c.Unlock()
+	_, ok := c.data[key]
+	return ok
+}
+
+// cacheWithErr is a locking storage used to quickly return already computed values and an error.
+//
+// The zero value of a cacheWithErr is empty and ready to use.
+//
+// A cacheWithErr must not be copied after first use.
+//
+// All methods of a cacheWithErr are safe to call concurrently.
+type cacheWithErr[K comparable, V any] struct {
+	cache[K, valAndErr[V]]
+}
+
+type valAndErr[V any] struct {
+	val V
+	err error
+}
+
+// Lookup returns the value stored in the cacheWithErr with the associated key
+// if it exists. Otherwise, f is called and its returned value is set in the
+// cacheWithErr for key and returned.
+//
+// Lookup is safe to call concurrently. It will hold the cacheWithErr lock, so f
+// should not block excessively.
+func (c *cacheWithErr[K, V]) Lookup(key K, f func() (V, error)) (V, error) {
+	combined := c.cache.Lookup(key, func() valAndErr[V] {
+		val, err := f()
+		return valAndErr[V]{val: val, err: err}
+	})
+	return combined.val, combined.err
+}

statsd/otel_config.go

@@ -0,0 +1,72 @@
+package statsd
+
+import (
+	"log/slog"
+	"time"
+
+	"go.opentelemetry.io/otel/sdk/resource"
+)
+
+type Config struct {
+	client                     *Client
+	logger                     *slog.Logger
+	res                        *resource.Resource
+	observerCollectionInterval time.Duration
+	observerCollectionTimeout  time.Duration
+}
+
+// OTELOption applies a configuration option to the MeterProvider.
+type OTELOption func(Config) Config
+
+const (
+	defaultObserverCollectionInterval = time.Second * 10
+	defaultObserverCollectionTimeout  = time.Second * 2
+)
+
+func newConfig(options ...OTELOption) Config {
+	cfg := Config{
+		observerCollectionInterval: defaultObserverCollectionInterval,
+		observerCollectionTimeout:  defaultObserverCollectionTimeout,
+	}
+
+	for _, option := range options {
+		cfg = option(cfg)
+	}
+
+	return cfg
+}
+
+func WithClient(client *Client) OTELOption {
+	return func(cfg Config) Config {
+		cfg.client = client
+		return cfg
+	}
+}
+
+func WithObserverCollectionInterval(interval time.Duration) OTELOption {
+	return func(cfg Config) Config {
+		cfg.observerCollectionInterval = interval
+		return cfg
+	}
+}
+
+func WithObserverCollectionTimeout(timeout time.Duration) OTELOption {
+	return func(cfg Config) Config {
+		cfg.observerCollectionTimeout = timeout
+		return cfg
+	}
+}
+
+func WithLogger(logger *slog.Logger) OTELOption {
+	return func(cfg Config) Config {
+		cfg.logger = logger
+		return cfg
+	}
+}
+
+func WithResource(res *resource.Resource) OTELOption {
+	return func(cfg Config) Config {
+		cfg.res = res
+		return cfg
+	}
+}

statsd/otel_error.go

@@ -0,0 +1,13 @@
+package statsd
+
+import (
+	"fmt"
+
+	sdkmetric "go.opentelemetry.io/otel/sdk/metric"
+)
+
+func warnRepeatedObservableCallbacks(handler ErrorHandler, id sdkmetric.Instrument) {
+	handler(fmt.Errorf("Repeated observable instrument creation with callbacks. Ignoring new callbacks. Use meter.RegisterCallback and Registration.Unregister to manage callbacks. Instrument{Name: %q, Description: %q, Kind: %q, Unit: %q}",
+		id.Name, id.Description, "InstrumentKind"+id.Kind.String(), id.Unit,
+	))
+}

statsd/otel_format_tags.go

@@ -0,0 +1,23 @@
+package statsd
+
+import (
+	"fmt"
+
+	"go.opentelemetry.io/otel/attribute"
+)
+
+// TODO: Optimize this by hoisting the top level resource attributes.
+func attrsToTags(resAttrs attribute.Set, optAttrs []attribute.KeyValue) []string {
+	attrs := make([]string, 0, resAttrs.Len()+len(optAttrs))
+	for _, keyValue := range resAttrs.ToSlice() {
+		attrs = append(attrs, keyValueAttrToTag(keyValue))
+	}
+	for _, keyValue := range optAttrs {
+		attrs = append(attrs, keyValueAttrToTag(keyValue))
+	}
+	return attrs
+}
+
+func keyValueAttrToTag(keyValue attribute.KeyValue) string {
+	return fmt.Sprintf("%s:%v", keyValue.Key, keyValue.Value.AsInterface())
+}