New encoding for OpenTSDB tag values (and metric names).

Change-Id: I0f4393f638c6e2bb2b2ce14e58e38b49ce456da8

storage/remote/opentsdb/client.go

@@ -5,11 +5,13 @@ import (
 	"encoding/json"
 	"fmt"
 	"io/ioutil"
+	"math"
 	"net/http"
 	"net/url"
 	"regexp"
 	"time"
 
+	"github.com/golang/glog"
 	clientmodel "github.com/prometheus/client_golang/model"
 
 	"github.com/prometheus/prometheus/utility"
@@ -41,26 +43,20 @@ func NewClient(url string, timeout time.Duration) *Client {
 // StoreSamplesRequest is used for building a JSON request for storing samples
 // via the OpenTSDB.
 type StoreSamplesRequest struct {
-	Metric    string                  `json:"metric"`
-	Timestamp int64                   `json:"timestamp"`
-	Value     clientmodel.SampleValue `json:"value"`
-	Tags      map[string]string       `json:"tags"`
-}
-
-// escapeTagValue escapes Prometheus label values to valid tag values for
-// OpenTSDB.
-func escapeTagValue(l clientmodel.LabelValue) string {
-	return illegalCharsRE.ReplaceAllString(string(l), "_")
+	Metric    TagValue            `json:"metric"`
+	Timestamp int64               `json:"timestamp"`
+	Value     float64             `json:"value"`
+	Tags      map[string]TagValue `json:"tags"`
 }
 
 // tagsFromMetric translates Prometheus metric into OpenTSDB tags.
-func tagsFromMetric(m clientmodel.Metric) map[string]string {
-	tags := make(map[string]string, len(m)-1)
+func tagsFromMetric(m clientmodel.Metric) map[string]TagValue {
+	tags := make(map[string]TagValue, len(m)-1)
 	for l, v := range m {
 		if l == clientmodel.MetricNameLabel {
 			continue
 		}
-		tags[string(l)] = escapeTagValue(v)
+		tags[string(l)] = TagValue(v)
 	}
 	return tags
 }
@@ -69,11 +65,16 @@ func tagsFromMetric(m clientmodel.Metric) map[string]string {
 func (c *Client) Store(samples clientmodel.Samples) error {
 	reqs := make([]StoreSamplesRequest, 0, len(samples))
 	for _, s := range samples {
-		metric := escapeTagValue(s.Metric[clientmodel.MetricNameLabel])
+		v := float64(s.Value)
+		if math.IsNaN(v) || math.IsInf(v, 0) {
+			glog.Warningf("cannot send value %d to OpenTSDB, skipping sample %#v", v, s)
+			continue
+		}
+		metric := TagValue(s.Metric[clientmodel.MetricNameLabel])
 		reqs = append(reqs, StoreSamplesRequest{
 			Metric:    metric,
 			Timestamp: s.Timestamp.Unix(),
-			Value:     s.Value,
+			Value:     v,
 			Tags:      tagsFromMetric(s.Metric),
 		})
 	}

storage/remote/opentsdb/client_test.go

@@ -14,28 +14,62 @@
 package opentsdb
 
 import (
+	"bytes"
+	"encoding/json"
+	"reflect"
 	"testing"
 
 	clientmodel "github.com/prometheus/client_golang/model"
 )
 
-func TestTagsFromMetric(t *testing.T) {
-	input := clientmodel.Metric{
-		clientmodel.MetricNameLabel: "testmetric",
-		"test:label":                "test:value",
+var (
+	metric = clientmodel.Metric{
+		clientmodel.MetricNameLabel: "test:metric",
+		"testlabel":                 "test:value",
 		"many_chars":                "abc!ABC:012-3!45ö67~89./",
 	}
-	expected := map[string]string{
-		"test:label": "test_value",
-		"many_chars": "abc_ABC_012-3_45_67_89./",
+)
+
+func TestTagsFromMetric(t *testing.T) {
+	expected := map[string]TagValue{
+		"testlabel":  TagValue("test:value"),
+		"many_chars": TagValue("abc!ABC:012-3!45ö67~89./"),
 	}
-	actual := tagsFromMetric(input)
-	if len(actual) != len(expected) {
-		t.Fatalf("Expected %v, got %v", expected, actual)
-	}
-	for k, v := range expected {
-		if v != actual[k] {
-			t.Fatalf("Expected %s => %s, got %s => %s", k, v, k, actual[k])
-		}
+	actual := tagsFromMetric(metric)
+	if !reflect.DeepEqual(actual, expected) {
+		t.Errorf("Expected %#v, got %#v", expected, actual)
+	}
+}
+
+func TestMarshalStoreSamplesRequest(t *testing.T) {
+	request := StoreSamplesRequest{
+		Metric:    TagValue("test:metric"),
+		Timestamp: 4711,
+		Value:     3.1415,
+		Tags:      tagsFromMetric(metric),
+	}
+	expectedJSON := []byte(`{"metric":"test_.metric","timestamp":4711,"value":3.1415,"tags":{"many_chars":"abc_21ABC_.012-3_2145_C3_B667_7E89./","testlabel":"test_.value"}}`)
+
+	resultingJSON, err := json.Marshal(request)
+	if err != nil {
+		t.Fatalf("Marshal(request) resulted in err: %s", err)
+	}
+	if !bytes.Equal(resultingJSON, expectedJSON) {
+		t.Errorf(
+			"Marshal(request) => %q, want %q",
+			resultingJSON, expectedJSON,
+		)
+	}
+
+	var unmarshaledRequest StoreSamplesRequest
+	err = json.Unmarshal(expectedJSON, &unmarshaledRequest)
+	if err != nil {
+		t.Fatalf("Unarshal(expectedJSON, &unmarshaledRequest) resulted in err: %s", err)
+	}
+	if !reflect.DeepEqual(unmarshaledRequest, request) {
+		t.Errorf(
+			"Unarshal(expectedJSON, &unmarshaledRequest) => %#v, want %#v",
+			unmarshaledRequest, request,
+		)
 	}
 }

storage/remote/opentsdb/tagvalue.go

@@ -0,0 +1,144 @@
+package opentsdb
+
+import (
+	"bytes"
+	"fmt"
+
+	clientmodel "github.com/prometheus/client_golang/model"
+)
+
+// TagValue is a clientmodel.LabelValue that implements json.Marshaler and
+// json.Unmarshaler. These implementations avoid characters illegal in
+// OpenTSDB. See the MarshalJSON for details. TagValue is used for the values of
+// OpenTSDB tags as well as for OpenTSDB metric names.
+type TagValue clientmodel.LabelValue
+
+// MarshalJSON marshals this TagValue into JSON that only contains runes allowed
+// in OpenTSDB. It implements json.Marshaler. The runes allowed in OpenTSDB are
+// all single-byte. This function encodes the arbitrary byte sequence found in
+// this TagValue in the following way:
+//
+// - The string that underlies TagValue is scanned byte by byte.
+//
+// - If a byte represents a legal OpenTSDB rune with the exception of '_', that
+// byte is directly copied to the resulting JSON byte slice.
+//
+// - If '_' is encountered, it is replaced by '__'.
+//
+// - If ':' is encountered, it is replaced by '_.'.
+//
+// - All other bytes are replaced by '_' followed by two bytes containing the
+// uppercase ASCII representation of their hexadecimal value.
+//
+// This encoding allows to save arbitrary Go strings in OpenTSDB. That's
+// required because Prometheus label values can contain anything, and even
+// Prometheus metric names may (and often do) contain ':' (which is disallowed
+// in OpenTSDB strings). The encoding uses '_' as an escape character and
+// renders a ':' more or less recognizable as '_.'
+//
+// Examples:
+//
+// "foo-bar-42" -> "foo-bar-42"
+//
+// "foo_bar_42" -> "foo__bar__42"
+//
+// "http://example.org:8080" -> "http_.//example.org_.8080"
+//
+// "Björn's email: bjoern@soundcloud.com" ->
+// "Bj_C3_B6rn_27s_20email_._20bjoern_40soundcloud.com"
+//
+// "日" -> "_E6_97_A5"
+func (tv TagValue) MarshalJSON() ([]byte, error) {
+	length := len(tv)
+	// Need at least two more bytes than in tv.
+	result := bytes.NewBuffer(make([]byte, 1, length+2))
+	result.WriteByte('"')
+	for i := 0; i < length; i++ {
+		b := tv[i]
+		switch {
+		case (b >= '-' && b <= '9') || // '-', '.', '/', 0-9
+			(b >= 'A' && b <= 'Z') ||
+			(b >= 'a' && b <= 'z'):
+			result.WriteByte(b)
+		case b == '_':
+			result.WriteString("__")
+		case b == ':':
+			result.WriteString("_.")
+		default:
+			result.WriteString(fmt.Sprintf("_%X", b))
+		}
+	}
+	result.WriteByte('"')
+	return result.Bytes(), nil
+}
+
+// UnmarshalJSON unmarshals JSON strings coming from OpenTSDB into Go strings
+// by applying the inverse of what is described for the MarshalJSON method.
+func (tv *TagValue) UnmarshalJSON(json []byte) error {
+	escapeLevel := 0 // How many bytes after '_'.
+	var parsedByte byte
+
+	// Might need fewer bytes, but let's avoid realloc.
+	result := bytes.NewBuffer(make([]byte, 0, len(json)-2))
+
+	for i, b := range json {
+		if i == 0 {
+			if b != '"' {
+				return fmt.Errorf("expected '\"', got %q", b)
+			}
+			continue
+		}
+		if i == len(json)-1 {
+			if b != '"' {
+				return fmt.Errorf("expected '\"', got %q", b)
+			}
+			break
+		}
+		switch escapeLevel {
+		case 0:
+			if b == '_' {
+				escapeLevel = 1
+				continue
+			}
+			result.WriteByte(b)
+		case 1:
+			switch {
+			case b == '_':
+				result.WriteByte('_')
+				escapeLevel = 0
+			case b == '.':
+				result.WriteByte(':')
+				escapeLevel = 0
+			case b >= '0' && b <= '9':
+				parsedByte = (b - 48) << 4
+				escapeLevel = 2
+			case b >= 'A' && b <= 'F': // A-F
+				parsedByte = (b - 55) << 4
+				escapeLevel = 2
+			default:
+				return fmt.Errorf(
+					"illegal escape sequence at byte %d (%c)",
+					i, b,
+				)
+			}
+		case 2:
+			switch {
+			case b >= '0' && b <= '9':
+				parsedByte += b - 48
+			case b >= 'A' && b <= 'F': // A-F
+				parsedByte += b - 55
+			default:
+				return fmt.Errorf(
+					"illegal escape sequence at byte %d (%c)",
+					i, b,
+				)
+			}
+			result.WriteByte(parsedByte)
+			escapeLevel = 0
+		default:
+			panic("unexpected escape level")
+		}
+	}
+	*tv = TagValue(result.String())
+	return nil
+}

storage/remote/opentsdb/tagvalue_test.go

@@ -0,0 +1,51 @@
+package opentsdb
+
+import (
+	"bytes"
+	"encoding/json"
+	"testing"
+)
+
+var stringtests = []struct {
+	tv   TagValue
+	json []byte
+}{
+	{TagValue("foo-bar-42"), []byte(`"foo-bar-42"`)},
+	{TagValue("foo_bar_42"), []byte(`"foo__bar__42"`)},
+	{TagValue("http://example.org:8080"), []byte(`"http_.//example.org_.8080"`)},
+	{TagValue("Björn's email: bjoern@soundcloud.com"), []byte(`"Bj_C3_B6rn_27s_20email_._20bjoern_40soundcloud.com"`)},
+	{TagValue("日"), []byte(`"_E6_97_A5"`)},
+}
+
+func TestTagValueMarshaling(t *testing.T) {
+	for i, tt := range stringtests {
+		json, err := json.Marshal(tt.tv)
+		if err != nil {
+			t.Errorf("%d. Marshal(%q) returned err: %s", i, tt.tv, err)
+		} else {
+			if !bytes.Equal(json, tt.json) {
+				t.Errorf(
+					"%d. Marshal(%q) => %q, want %q",
+					i, tt.tv, json, tt.json,
+				)
+			}
+		}
+	}
+}
+
+func TestTagValueUnMarshaling(t *testing.T) {
+	for i, tt := range stringtests {
+		var tv TagValue
+		err := json.Unmarshal(tt.json, &tv)
+		if err != nil {
+			t.Errorf("%d. Unmarshal(%q, &str) returned err: %s", i, tt.json, err)
+		} else {
+			if tv != tt.tv {
+				t.Errorf(
+					"%d. Unmarshal(%q, &str) => str==%q, want %q",
+					i, tt.json, tv, tt.tv,
+				)
+			}
+		}
+	}
+}