Merge pull request #673 from prometheus/beorn7/fingerprint

Use FastFingerprint where appropriate.

Godeps/Godeps.json

@@ -29,23 +29,23 @@
 		},
 		{
 			"ImportPath": "github.com/prometheus/client_golang/extraction",
-			"Comment": "0.4.0-1-g692492e",
+			"Comment": "0.5.0",
-			"Rev": "692492e54b553a81013254cc1fba4b6dd76fad30"
+			"Rev": "b0bd7e1be33327b85cb4853e7011156e3cedd657"
 		},
 		{
 			"ImportPath": "github.com/prometheus/client_golang/model",
-			"Comment": "0.4.0-1-g692492e",
+			"Comment": "0.5.0",
-			"Rev": "692492e54b553a81013254cc1fba4b6dd76fad30"
+			"Rev": "b0bd7e1be33327b85cb4853e7011156e3cedd657"
 		},
 		{
 			"ImportPath": "github.com/prometheus/client_golang/prometheus",
-			"Comment": "0.4.0-1-g692492e",
+			"Comment": "0.5.0",
-			"Rev": "692492e54b553a81013254cc1fba4b6dd76fad30"
+			"Rev": "b0bd7e1be33327b85cb4853e7011156e3cedd657"
 		},
 		{
 			"ImportPath": "github.com/prometheus/client_golang/text",
-			"Comment": "0.4.0-1-g692492e",
+			"Comment": "0.5.0",
-			"Rev": "692492e54b553a81013254cc1fba4b6dd76fad30"
+			"Rev": "b0bd7e1be33327b85cb4853e7011156e3cedd657"
 		},
 		{
 			"ImportPath": "github.com/prometheus/client_model/go",

Godeps/_workspace/src/github.com/prometheus/client_golang/model/labelname.go

@@ -26,14 +26,30 @@ const (
 	// timeseries.
 	MetricNameLabel LabelName = "__name__"
 
+	// AddressLabel is the name of the label that holds the address of
+	// a scrape target.
+	AddressLabel LabelName = "__address__"
+
+	// MetricsPathLabel is the name of the label that holds the path on which to
+	// scrape a target.
+	MetricsPathLabel LabelName = "__metrics_path__"
+
 	// ReservedLabelPrefix is a prefix which is not legal in user-supplied
 	// label names.
 	ReservedLabelPrefix = "__"
 
+	// MetaLabelPrefix is a prefix for labels that provide meta information.
+	// Labels with this prefix are used for intermediate label processing and
+	// will not be attached to time series.
+	MetaLabelPrefix = "__meta_"
+
 	// JobLabel is the label name indicating the job from which a timeseries
 	// was scraped.
 	JobLabel LabelName = "job"
 
+	// InstanceLabel is the label name used for the instance label.
+	InstanceLabel LabelName = "instance"
+
 	// BucketLabel is used for the label that defines the upper bound of a
 	// bucket of a histogram ("le" -> "less or equal").
 	BucketLabel = "le"

Godeps/_workspace/src/github.com/prometheus/client_golang/model/metric.go

@@ -26,14 +26,68 @@ var separator = []byte{0}
 // a singleton and refers to one and only one stream of samples.
 type Metric map[LabelName]LabelValue
 
-// Equal compares the fingerprints of both metrics.
+// Equal compares the metrics.
 func (m Metric) Equal(o Metric) bool {
-	return m.Fingerprint().Equal(o.Fingerprint())
+	if len(m) != len(o) {
+		return false
+	}
+	for ln, lv := range m {
+		olv, ok := o[ln]
+		if !ok {
+			return false
+		}
+		if olv != lv {
+			return false
+		}
+	}
+	return true
 }
 
-// Before compares the fingerprints of both metrics.
+// Before compares the metrics, using the following criteria:
+//
+// If m has fewer labels than o, it is before o. If it has more, it is not.
+//
+// If the number of labels is the same, the superset of all label names is
+// sorted alphanumerically. The first differing label pair found in that order
+// determines the outcome: If the label does not exist at all in m, then m is
+// before o, and vice versa. Otherwise the label value is compared
+// alphanumerically.
+//
+// If m and o are equal, the method returns false.
 func (m Metric) Before(o Metric) bool {
-	return m.Fingerprint().Less(o.Fingerprint())
+	if len(m) < len(o) {
+		return true
+	}
+	if len(m) > len(o) {
+		return false
+	}
+
+	lns := make(LabelNames, 0, len(m)+len(o))
+	for ln := range m {
+		lns = append(lns, ln)
+	}
+	for ln := range o {
+		lns = append(lns, ln)
+	}
+	// It's probably not worth it to de-dup lns.
+	sort.Sort(lns)
+	for _, ln := range lns {
+		mlv, ok := m[ln]
+		if !ok {
+			return true
+		}
+		olv, ok := o[ln]
+		if !ok {
+			return false
+		}
+		if mlv < olv {
+			return true
+		}
+		if mlv > olv {
+			return false
+		}
+	}
+	return false
 }
 
 // String implements Stringer.
@@ -67,6 +121,12 @@ func (m Metric) Fingerprint() Fingerprint {
 	return metricToFingerprint(m)
 }
 
+// Fingerprint returns a Metric's Fingerprint calculated by a faster hashing
+// algorithm, which is, however, more susceptible to hash collisions.
+func (m Metric) FastFingerprint() Fingerprint {
+	return metricToFastFingerprint(m)
+}
+
 // Clone returns a copy of the Metric.
 func (m Metric) Clone() Metric {
 	clone := Metric{}

Godeps/_workspace/src/github.com/prometheus/client_golang/model/metric_test.go

@@ -17,12 +17,14 @@ import "testing"
 
 func testMetric(t testing.TB) {
 	var scenarios = []struct {
-		input       Metric
+		input           Metric
-		fingerprint Fingerprint
+		fingerprint     Fingerprint
+		fastFingerprint Fingerprint
 	}{
 		{
-			input:       Metric{},
+			input:           Metric{},
-			fingerprint: 14695981039346656037,
+			fingerprint:     14695981039346656037,
+			fastFingerprint: 14695981039346656037,
 		},
 		{
 			input: Metric{
@@ -30,27 +32,31 @@ func testMetric(t testing.TB) {
 				"occupation":   "robot",
 				"manufacturer": "westinghouse",
 			},
-			fingerprint: 11310079640881077873,
+			fingerprint:     5911716720268894962,
+			fastFingerprint: 11310079640881077873,
 		},
 		{
 			input: Metric{
 				"x": "y",
 			},
-			fingerprint: 13948396922932177635,
+			fingerprint:     8241431561484471700,
+			fastFingerprint: 13948396922932177635,
 		},
 		{
 			input: Metric{
 				"a": "bb",
 				"b": "c",
 			},
-			fingerprint: 3198632812309449502,
+			fingerprint:     3016285359649981711,
+			fastFingerprint: 3198632812309449502,
 		},
 		{
 			input: Metric{
 				"a":  "b",
 				"bb": "c",
 			},
-			fingerprint: 5774953389407657638,
+			fingerprint:     7122421792099404749,
+			fastFingerprint: 5774953389407657638,
 		},
 	}
 
@@ -58,6 +64,9 @@ func testMetric(t testing.TB) {
 		if scenario.fingerprint != scenario.input.Fingerprint() {
 			t.Errorf("%d. expected %d, got %d", i, scenario.fingerprint, scenario.input.Fingerprint())
 		}
+		if scenario.fastFingerprint != scenario.input.FastFingerprint() {
+			t.Errorf("%d. expected %d, got %d", i, scenario.fastFingerprint, scenario.input.FastFingerprint())
+		}
 	}
 }
 

Godeps/_workspace/src/github.com/prometheus/client_golang/model/sample_test.go

@@ -21,42 +21,36 @@ import (
 func TestSamplesSort(t *testing.T) {
 	input := Samples{
 		&Sample{
-			// Fingerprint: 81f9c9ed24563f8f.
 			Metric: Metric{
 				MetricNameLabel: "A",
 			},
 			Timestamp: 1,
 		},
 		&Sample{
-			// Fingerprint: 81f9c9ed24563f8f.
 			Metric: Metric{
 				MetricNameLabel: "A",
 			},
 			Timestamp: 2,
 		},
 		&Sample{
-			// Fingerprint: 1bf6c9ed24543f8f.
 			Metric: Metric{
 				MetricNameLabel: "C",
 			},
 			Timestamp: 1,
 		},
 		&Sample{
-			// Fingerprint: 1bf6c9ed24543f8f.
 			Metric: Metric{
 				MetricNameLabel: "C",
 			},
 			Timestamp: 2,
 		},
 		&Sample{
-			// Fingerprint: 68f4c9ed24533f8f.
 			Metric: Metric{
 				MetricNameLabel: "B",
 			},
 			Timestamp: 1,
 		},
 		&Sample{
-			// Fingerprint: 68f4c9ed24533f8f.
 			Metric: Metric{
 				MetricNameLabel: "B",
 			},
@@ -66,47 +60,41 @@ func TestSamplesSort(t *testing.T) {
 
 	expected := Samples{
 		&Sample{
-			// Fingerprint: 1bf6c9ed24543f8f.
-			Metric: Metric{
-				MetricNameLabel: "C",
-			},
-			Timestamp: 1,
-		},
-		&Sample{
-			// Fingerprint: 1bf6c9ed24543f8f.
-			Metric: Metric{
-				MetricNameLabel: "C",
-			},
-			Timestamp: 2,
-		},
-		&Sample{
-			// Fingerprint: 68f4c9ed24533f8f.
-			Metric: Metric{
-				MetricNameLabel: "B",
-			},
-			Timestamp: 1,
-		},
-		&Sample{
-			// Fingerprint: 68f4c9ed24533f8f.
-			Metric: Metric{
-				MetricNameLabel: "B",
-			},
-			Timestamp: 2,
-		},
-		&Sample{
-			// Fingerprint: 81f9c9ed24563f8f.
 			Metric: Metric{
 				MetricNameLabel: "A",
 			},
 			Timestamp: 1,
 		},
 		&Sample{
-			// Fingerprint: 81f9c9ed24563f8f.
 			Metric: Metric{
 				MetricNameLabel: "A",
 			},
 			Timestamp: 2,
 		},
+		&Sample{
+			Metric: Metric{
+				MetricNameLabel: "B",
+			},
+			Timestamp: 1,
+		},
+		&Sample{
+			Metric: Metric{
+				MetricNameLabel: "B",
+			},
+			Timestamp: 2,
+		},
+		&Sample{
+			Metric: Metric{
+				MetricNameLabel: "C",
+			},
+			Timestamp: 1,
+		},
+		&Sample{
+			Metric: Metric{
+				MetricNameLabel: "C",
+			},
+			Timestamp: 2,
+		},
 	}
 
 	sort.Sort(input)

Godeps/_workspace/src/github.com/prometheus/client_golang/model/signature.go

@@ -17,6 +17,7 @@ import (
 	"bytes"
 	"hash"
 	"hash/fnv"
+	"sort"
 	"sync"
 )
 
@@ -46,30 +47,37 @@ func getHashAndBuf() *hashAndBuf {
 }
 
 func putHashAndBuf(hb *hashAndBuf) {
+	hb.h.Reset()
+	hb.b.Reset()
 	hashAndBufPool.Put(hb)
 }
 
-// LabelsToSignature returns a unique signature (i.e., fingerprint) for a given
+// LabelsToSignature returns a quasi-unique signature (i.e., fingerprint) for a
-// label set.
+// given label set. (Collisions are possible but unlikely if the number of label
+// sets the function is applied to is small.)
 func LabelsToSignature(labels map[string]string) uint64 {
 	if len(labels) == 0 {
 		return emptyLabelSignature
 	}
 
-	var result uint64
+	labelNames := make([]string, 0, len(labels))
+	for labelName := range labels {
+		labelNames = append(labelNames, labelName)
+	}
+	sort.Strings(labelNames)
+
 	hb := getHashAndBuf()
 	defer putHashAndBuf(hb)
 
-	for labelName, labelValue := range labels {
+	for _, labelName := range labelNames {
 		hb.b.WriteString(labelName)
 		hb.b.WriteByte(SeparatorByte)
-		hb.b.WriteString(labelValue)
+		hb.b.WriteString(labels[labelName])
+		hb.b.WriteByte(SeparatorByte)
 		hb.h.Write(hb.b.Bytes())
-		result ^= hb.h.Sum64()
-		hb.h.Reset()
 		hb.b.Reset()
 	}
-	return result
+	return hb.h.Sum64()
 }
 
 // metricToFingerprint works exactly as LabelsToSignature but takes a Metric as
@@ -79,6 +87,34 @@ func metricToFingerprint(m Metric) Fingerprint {
 		return Fingerprint(emptyLabelSignature)
 	}
 
+	labelNames := make(LabelNames, 0, len(m))
+	for labelName := range m {
+		labelNames = append(labelNames, labelName)
+	}
+	sort.Sort(labelNames)
+
+	hb := getHashAndBuf()
+	defer putHashAndBuf(hb)
+
+	for _, labelName := range labelNames {
+		hb.b.WriteString(string(labelName))
+		hb.b.WriteByte(SeparatorByte)
+		hb.b.WriteString(string(m[labelName]))
+		hb.b.WriteByte(SeparatorByte)
+		hb.h.Write(hb.b.Bytes())
+		hb.b.Reset()
+	}
+	return Fingerprint(hb.h.Sum64())
+}
+
+// metricToFastFingerprint works similar to metricToFingerprint but uses a
+// faster and less allocation-heavy hash function, which is more susceptible to
+// create hash collisions. Therefore, collision detection should be applied.
+func metricToFastFingerprint(m Metric) Fingerprint {
+	if len(m) == 0 {
+		return Fingerprint(emptyLabelSignature)
+	}
+
 	var result uint64
 	hb := getHashAndBuf()
 	defer putHashAndBuf(hb)
@@ -97,13 +133,15 @@ func metricToFingerprint(m Metric) Fingerprint {
 
 // SignatureForLabels works like LabelsToSignature but takes a Metric as
 // parameter (rather than a label map) and only includes the labels with the
-// specified LabelNames into the signature calculation.
+// specified LabelNames into the signature calculation. The labels passed in
+// will be sorted by this function.
 func SignatureForLabels(m Metric, labels LabelNames) uint64 {
 	if len(m) == 0 || len(labels) == 0 {
 		return emptyLabelSignature
 	}
 
-	var result uint64
+	sort.Sort(labels)
+
 	hb := getHashAndBuf()
 	defer putHashAndBuf(hb)
 
@@ -111,12 +149,11 @@ func SignatureForLabels(m Metric, labels LabelNames) uint64 {
 		hb.b.WriteString(string(label))
 		hb.b.WriteByte(SeparatorByte)
 		hb.b.WriteString(string(m[label]))
+		hb.b.WriteByte(SeparatorByte)
 		hb.h.Write(hb.b.Bytes())
-		result ^= hb.h.Sum64()
-		hb.h.Reset()
 		hb.b.Reset()
 	}
-	return result
+	return hb.h.Sum64()
 }
 
 // SignatureWithoutLabels works like LabelsToSignature but takes a Metric as
@@ -127,24 +164,27 @@ func SignatureWithoutLabels(m Metric, labels map[LabelName]struct{}) uint64 {
 		return emptyLabelSignature
 	}
 
-	var result uint64
+	labelNames := make(LabelNames, 0, len(m))
+	for labelName := range m {
+		if _, exclude := labels[labelName]; !exclude {
+			labelNames = append(labelNames, labelName)
+		}
+	}
+	if len(labelNames) == 0 {
+		return emptyLabelSignature
+	}
+	sort.Sort(labelNames)
+
 	hb := getHashAndBuf()
 	defer putHashAndBuf(hb)
 
-	for labelName, labelValue := range m {
+	for _, labelName := range labelNames {
-		if _, exclude := labels[labelName]; exclude {
-			continue
-		}
 		hb.b.WriteString(string(labelName))
 		hb.b.WriteByte(SeparatorByte)
-		hb.b.WriteString(string(labelValue))
+		hb.b.WriteString(string(m[labelName]))
+		hb.b.WriteByte(SeparatorByte)
 		hb.h.Write(hb.b.Bytes())
-		result ^= hb.h.Sum64()
-		hb.h.Reset()
 		hb.b.Reset()
 	}
-	if result == 0 {
+	return hb.h.Sum64()
-		return emptyLabelSignature
-	}
-	return result
 }

Godeps/_workspace/src/github.com/prometheus/client_golang/model/signature_test.go

@@ -30,7 +30,7 @@ func TestLabelsToSignature(t *testing.T) {
 		},
 		{
 			in:  map[string]string{"name": "garland, briggs", "fear": "love is not enough"},
-			out: 12952432476264840823,
+			out: 5799056148416392346,
 		},
 	}
 
@@ -54,7 +54,7 @@ func TestMetricToFingerprint(t *testing.T) {
 		},
 		{
 			in:  Metric{"name": "garland, briggs", "fear": "love is not enough"},
-			out: 12952432476264840823,
+			out: 5799056148416392346,
 		},
 	}
 
@@ -67,6 +67,30 @@ func TestMetricToFingerprint(t *testing.T) {
 	}
 }
 
+func TestMetricToFastFingerprint(t *testing.T) {
+	var scenarios = []struct {
+		in  Metric
+		out Fingerprint
+	}{
+		{
+			in:  Metric{},
+			out: 14695981039346656037,
+		},
+		{
+			in:  Metric{"name": "garland, briggs", "fear": "love is not enough"},
+			out: 12952432476264840823,
+		},
+	}
+
+	for i, scenario := range scenarios {
+		actual := metricToFastFingerprint(scenario.in)
+
+		if actual != scenario.out {
+			t.Errorf("%d. expected %d, got %d", i, scenario.out, actual)
+		}
+	}
+}
+
 func TestSignatureForLabels(t *testing.T) {
 	var scenarios = []struct {
 		in     Metric
@@ -81,12 +105,12 @@ func TestSignatureForLabels(t *testing.T) {
 		{
 			in:     Metric{"name": "garland, briggs", "fear": "love is not enough"},
 			labels: LabelNames{"fear", "name"},
-			out:    12952432476264840823,
+			out:    5799056148416392346,
 		},
 		{
 			in:     Metric{"name": "garland, briggs", "fear": "love is not enough", "foo": "bar"},
 			labels: LabelNames{"fear", "name"},
-			out:    12952432476264840823,
+			out:    5799056148416392346,
 		},
 		{
 			in:     Metric{"name": "garland, briggs", "fear": "love is not enough"},
@@ -128,17 +152,17 @@ func TestSignatureWithoutLabels(t *testing.T) {
 		{
 			in:     Metric{"name": "garland, briggs", "fear": "love is not enough", "foo": "bar"},
 			labels: map[LabelName]struct{}{"foo": struct{}{}},
-			out:    12952432476264840823,
+			out:    5799056148416392346,
 		},
 		{
 			in:     Metric{"name": "garland, briggs", "fear": "love is not enough"},
 			labels: map[LabelName]struct{}{},
-			out:    12952432476264840823,
+			out:    5799056148416392346,
 		},
 		{
 			in:     Metric{"name": "garland, briggs", "fear": "love is not enough"},
 			labels: nil,
-			out:    12952432476264840823,
+			out:    5799056148416392346,
 		},
 	}
 
@@ -164,15 +188,15 @@ func BenchmarkLabelToSignatureScalar(b *testing.B) {
 }
 
 func BenchmarkLabelToSignatureSingle(b *testing.B) {
-	benchmarkLabelToSignature(b, map[string]string{"first-label": "first-label-value"}, 5147259542624943964)
+	benchmarkLabelToSignature(b, map[string]string{"first-label": "first-label-value"}, 5146282821936882169)
 }
 
 func BenchmarkLabelToSignatureDouble(b *testing.B) {
-	benchmarkLabelToSignature(b, map[string]string{"first-label": "first-label-value", "second-label": "second-label-value"}, 18269973311206963528)
+	benchmarkLabelToSignature(b, map[string]string{"first-label": "first-label-value", "second-label": "second-label-value"}, 3195800080984914717)
 }
 
 func BenchmarkLabelToSignatureTriple(b *testing.B) {
-	benchmarkLabelToSignature(b, map[string]string{"first-label": "first-label-value", "second-label": "second-label-value", "third-label": "third-label-value"}, 15738406913934009676)
+	benchmarkLabelToSignature(b, map[string]string{"first-label": "first-label-value", "second-label": "second-label-value", "third-label": "third-label-value"}, 13843036195897128121)
 }
 
 func benchmarkMetricToFingerprint(b *testing.B, m Metric, e Fingerprint) {
@@ -188,15 +212,39 @@ func BenchmarkMetricToFingerprintScalar(b *testing.B) {
 }
 
 func BenchmarkMetricToFingerprintSingle(b *testing.B) {
-	benchmarkMetricToFingerprint(b, Metric{"first-label": "first-label-value"}, 5147259542624943964)
+	benchmarkMetricToFingerprint(b, Metric{"first-label": "first-label-value"}, 5146282821936882169)
 }
 
 func BenchmarkMetricToFingerprintDouble(b *testing.B) {
-	benchmarkMetricToFingerprint(b, Metric{"first-label": "first-label-value", "second-label": "second-label-value"}, 18269973311206963528)
+	benchmarkMetricToFingerprint(b, Metric{"first-label": "first-label-value", "second-label": "second-label-value"}, 3195800080984914717)
 }
 
 func BenchmarkMetricToFingerprintTriple(b *testing.B) {
-	benchmarkMetricToFingerprint(b, Metric{"first-label": "first-label-value", "second-label": "second-label-value", "third-label": "third-label-value"}, 15738406913934009676)
+	benchmarkMetricToFingerprint(b, Metric{"first-label": "first-label-value", "second-label": "second-label-value", "third-label": "third-label-value"}, 13843036195897128121)
+}
+
+func benchmarkMetricToFastFingerprint(b *testing.B, m Metric, e Fingerprint) {
+	for i := 0; i < b.N; i++ {
+		if a := metricToFastFingerprint(m); a != e {
+			b.Fatalf("expected signature of %d for %s, got %d", e, m, a)
+		}
+	}
+}
+
+func BenchmarkMetricToFastFingerprintScalar(b *testing.B) {
+	benchmarkMetricToFastFingerprint(b, nil, 14695981039346656037)
+}
+
+func BenchmarkMetricToFastFingerprintSingle(b *testing.B) {
+	benchmarkMetricToFastFingerprint(b, Metric{"first-label": "first-label-value"}, 5147259542624943964)
+}
+
+func BenchmarkMetricToFastFingerprintDouble(b *testing.B) {
+	benchmarkMetricToFastFingerprint(b, Metric{"first-label": "first-label-value", "second-label": "second-label-value"}, 18269973311206963528)
+}
+
+func BenchmarkMetricToFastFingerprintTriple(b *testing.B) {
+	benchmarkMetricToFastFingerprint(b, Metric{"first-label": "first-label-value", "second-label": "second-label-value", "third-label": "third-label-value"}, 15738406913934009676)
 }
 
 func TestEmptyLabelSignature(t *testing.T) {
@@ -218,7 +266,7 @@ func TestEmptyLabelSignature(t *testing.T) {
 	}
 }
 
-func benchmarkMetricToFingerprintConc(b *testing.B, m Metric, e Fingerprint, concLevel int) {
+func benchmarkMetricToFastFingerprintConc(b *testing.B, m Metric, e Fingerprint, concLevel int) {
 	var start, end sync.WaitGroup
 	start.Add(1)
 	end.Add(concLevel)
@@ -227,7 +275,7 @@ func benchmarkMetricToFingerprintConc(b *testing.B, m Metric, e Fingerprint, con
 		go func() {
 			start.Wait()
 			for j := b.N / concLevel; j >= 0; j-- {
-				if a := metricToFingerprint(m); a != e {
+				if a := metricToFastFingerprint(m); a != e {
 					b.Fatalf("expected signature of %d for %s, got %d", e, m, a)
 				}
 			}
@@ -239,18 +287,18 @@ func benchmarkMetricToFingerprintConc(b *testing.B, m Metric, e Fingerprint, con
 	end.Wait()
 }
 
-func BenchmarkMetricToFingerprintTripleConc1(b *testing.B) {
+func BenchmarkMetricToFastFingerprintTripleConc1(b *testing.B) {
-	benchmarkMetricToFingerprintConc(b, Metric{"first-label": "first-label-value", "second-label": "second-label-value", "third-label": "third-label-value"}, 15738406913934009676, 1)
+	benchmarkMetricToFastFingerprintConc(b, Metric{"first-label": "first-label-value", "second-label": "second-label-value", "third-label": "third-label-value"}, 15738406913934009676, 1)
 }
 
-func BenchmarkMetricToFingerprintTripleConc2(b *testing.B) {
+func BenchmarkMetricToFastFingerprintTripleConc2(b *testing.B) {
-	benchmarkMetricToFingerprintConc(b, Metric{"first-label": "first-label-value", "second-label": "second-label-value", "third-label": "third-label-value"}, 15738406913934009676, 2)
+	benchmarkMetricToFastFingerprintConc(b, Metric{"first-label": "first-label-value", "second-label": "second-label-value", "third-label": "third-label-value"}, 15738406913934009676, 2)
 }
 
-func BenchmarkMetricToFingerprintTripleConc4(b *testing.B) {
+func BenchmarkMetricToFastFingerprintTripleConc4(b *testing.B) {
-	benchmarkMetricToFingerprintConc(b, Metric{"first-label": "first-label-value", "second-label": "second-label-value", "third-label": "third-label-value"}, 15738406913934009676, 4)
+	benchmarkMetricToFastFingerprintConc(b, Metric{"first-label": "first-label-value", "second-label": "second-label-value", "third-label": "third-label-value"}, 15738406913934009676, 4)
 }
 
-func BenchmarkMetricToFingerprintTripleConc8(b *testing.B) {
+func BenchmarkMetricToFastFingerprintTripleConc8(b *testing.B) {
-	benchmarkMetricToFingerprintConc(b, Metric{"first-label": "first-label-value", "second-label": "second-label-value", "third-label": "third-label-value"}, 15738406913934009676, 8)
+	benchmarkMetricToFastFingerprintConc(b, Metric{"first-label": "first-label-value", "second-label": "second-label-value", "third-label": "third-label-value"}, 15738406913934009676, 8)
 }

Godeps/_workspace/src/github.com/prometheus/client_golang/prometheus/counter.go

@@ -33,7 +33,7 @@ type Counter interface {
 
 	// Set is used to set the Counter to an arbitrary value. It is only used
 	// if you have to transfer a value from an external counter into this
-	// Prometheus metrics. Do not use it for regular handling of a
+	// Prometheus metric. Do not use it for regular handling of a
 	// Prometheus counter (as it can be used to break the contract of
 	// monotonically increasing values).
 	Set(float64)

Godeps/_workspace/src/github.com/prometheus/client_golang/prometheus/examples_test.go

@@ -455,6 +455,56 @@ func ExampleSummaryVec() {
 	// ]
 }
 
+func ExampleConstSummary() {
+	desc := prometheus.NewDesc(
+		"http_request_duration_seconds",
+		"A summary of the HTTP request durations.",
+		[]string{"code", "method"},
+		prometheus.Labels{"owner": "example"},
+	)
+
+	// Create a constant summary from values we got from a 3rd party telemetry system.
+	s := prometheus.MustNewConstSummary(
+		desc,
+		4711, 403.34,
+		map[float64]float64{0.5: 42.3, 0.9: 323.3},
+		"200", "get",
+	)
+
+	// Just for demonstration, let's check the state of the summary by
+	// (ab)using its Write method (which is usually only used by Prometheus
+	// internally).
+	metric := &dto.Metric{}
+	s.Write(metric)
+	fmt.Println(proto.MarshalTextString(metric))
+
+	// Output:
+	// label: <
+	//   name: "code"
+	//   value: "200"
+	// >
+	// label: <
+	//   name: "method"
+	//   value: "get"
+	// >
+	// label: <
+	//   name: "owner"
+	//   value: "example"
+	// >
+	// summary: <
+	//   sample_count: 4711
+	//   sample_sum: 403.34
+	//   quantile: <
+	//     quantile: 0.5
+	//     value: 42.3
+	//   >
+	//   quantile: <
+	//     quantile: 0.9
+	//     value: 323.3
+	//   >
+	// >
+}
+
 func ExampleHistogram() {
 	temps := prometheus.NewHistogram(prometheus.HistogramOpts{
 		Name:    "pond_temperature_celsius",
@@ -501,6 +551,64 @@ func ExampleHistogram() {
 	// >
 }
 
+func ExampleConstHistogram() {
+	desc := prometheus.NewDesc(
+		"http_request_duration_seconds",
+		"A histogram of the HTTP request durations.",
+		[]string{"code", "method"},
+		prometheus.Labels{"owner": "example"},
+	)
+
+	// Create a constant histogram from values we got from a 3rd party telemetry system.
+	h := prometheus.MustNewConstHistogram(
+		desc,
+		4711, 403.34,
+		map[float64]uint64{25: 121, 50: 2403, 100: 3221, 200: 4233},
+		"200", "get",
+	)
+
+	// Just for demonstration, let's check the state of the histogram by
+	// (ab)using its Write method (which is usually only used by Prometheus
+	// internally).
+	metric := &dto.Metric{}
+	h.Write(metric)
+	fmt.Println(proto.MarshalTextString(metric))
+
+	// Output:
+	// label: <
+	//   name: "code"
+	//   value: "200"
+	// >
+	// label: <
+	//   name: "method"
+	//   value: "get"
+	// >
+	// label: <
+	//   name: "owner"
+	//   value: "example"
+	// >
+	// histogram: <
+	//   sample_count: 4711
+	//   sample_sum: 403.34
+	//   bucket: <
+	//     cumulative_count: 121
+	//     upper_bound: 25
+	//   >
+	//   bucket: <
+	//     cumulative_count: 2403
+	//     upper_bound: 50
+	//   >
+	//   bucket: <
+	//     cumulative_count: 3221
+	//     upper_bound: 100
+	//   >
+	//   bucket: <
+	//     cumulative_count: 4233
+	//     upper_bound: 200
+	//   >
+	// >
+}
+
 func ExamplePushCollectors() {
 	hostname, _ := os.Hostname()
 	completionTime := prometheus.NewGauge(prometheus.GaugeOpts{

Godeps/_workspace/src/github.com/prometheus/client_golang/prometheus/go_collector.go

@@ -2,10 +2,13 @@ package prometheus
 
 import (
 	"runtime"
+	"runtime/debug"
+	"time"
 )
 
 type goCollector struct {
 	goroutines Gauge
+	gcDesc     *Desc
 }
 
 // NewGoCollector returns a collector which exports metrics about the current
@@ -16,16 +19,32 @@ func NewGoCollector() *goCollector {
 			Name: "process_goroutines",
 			Help: "Number of goroutines that currently exist.",
 		}),
+		gcDesc: NewDesc(
+			"go_gc_duration_seconds",
+			"A summary of the GC invocation durations.",
+			nil, nil),
 	}
 }
 
 // Describe returns all descriptions of the collector.
 func (c *goCollector) Describe(ch chan<- *Desc) {
 	ch <- c.goroutines.Desc()
+	ch <- c.gcDesc
 }
 
 // Collect returns the current state of all metrics of the collector.
 func (c *goCollector) Collect(ch chan<- Metric) {
 	c.goroutines.Set(float64(runtime.NumGoroutine()))
 	ch <- c.goroutines
+
+	var stats debug.GCStats
+	stats.PauseQuantiles = make([]time.Duration, 5)
+	debug.ReadGCStats(&stats)
+
+	quantiles := make(map[float64]float64)
+	for idx, pq := range stats.PauseQuantiles[1:] {
+		quantiles[float64(idx+1)/float64(len(stats.PauseQuantiles)-1)] = pq.Seconds()
+	}
+	quantiles[0.0] = stats.PauseQuantiles[0].Seconds()
+	ch <- MustNewConstSummary(c.gcDesc, uint64(stats.NumGC), float64(stats.PauseTotal.Seconds()), quantiles)
 }

Godeps/_workspace/src/github.com/prometheus/client_golang/prometheus/go_collector_test.go

@@ -1,7 +1,7 @@
 package prometheus
 
 import (
-	"reflect"
+	"runtime"
 	"testing"
 	"time"
 
@@ -35,6 +35,9 @@ func TestGoCollector(t *testing.T) {
 			case Gauge:
 				pb := &dto.Metric{}
 				m.Write(pb)
+				if pb.GetGauge() == nil {
+					continue
+				}
 
 				if old == -1 {
 					old = int(pb.GetGauge().GetValue())
@@ -48,8 +51,66 @@ func TestGoCollector(t *testing.T) {
 				}
 
 				return
-			default:
+			}
-				t.Errorf("want type Gauge, got %s", reflect.TypeOf(metric))
+		case <-time.After(1 * time.Second):
+			t.Fatalf("expected collect timed out")
+		}
+	}
+}
+
+func TestGCCollector(t *testing.T) {
+	var (
+		c        = NewGoCollector()
+		ch       = make(chan Metric)
+		waitc    = make(chan struct{})
+		closec   = make(chan struct{})
+		oldGC    uint64
+		oldPause float64
+	)
+	defer close(closec)
+
+	go func() {
+		c.Collect(ch)
+		// force GC
+		runtime.GC()
+		<-waitc
+		c.Collect(ch)
+	}()
+
+	first := true
+	for {
+		select {
+		case metric := <-ch:
+			switch m := metric.(type) {
+			case *constSummary, *value:
+				pb := &dto.Metric{}
+				m.Write(pb)
+				if pb.GetSummary() == nil {
+					continue
+				}
+
+				if len(pb.GetSummary().Quantile) != 5 {
+					t.Errorf("expected 4 buckets, got %d", len(pb.GetSummary().Quantile))
+				}
+				for idx, want := range []float64{0.0, 0.25, 0.5, 0.75, 1.0} {
+					if *pb.GetSummary().Quantile[idx].Quantile != want {
+						t.Errorf("bucket #%d is off, got %f, want %f", idx, *pb.GetSummary().Quantile[idx].Quantile, want)
+					}
+				}
+				if first {
+					first = false
+					oldGC = *pb.GetSummary().SampleCount
+					oldPause = *pb.GetSummary().SampleSum
+					close(waitc)
+					continue
+				}
+				if diff := *pb.GetSummary().SampleCount - oldGC; diff != 1 {
+					t.Errorf("want 1 new garbage collection run, got %d", diff)
+				}
+				if diff := *pb.GetSummary().SampleSum - oldPause; diff <= 0 {
+					t.Errorf("want moar pause, got %f", diff)
+				}
+				return
 			}
 		case <-time.After(1 * time.Second):
 			t.Fatalf("expected collect timed out")

Godeps/_workspace/src/github.com/prometheus/client_golang/prometheus/histogram.go

@@ -342,3 +342,102 @@ func (m *HistogramVec) WithLabelValues(lvs ...string) Histogram {
 func (m *HistogramVec) With(labels Labels) Histogram {
 	return m.MetricVec.With(labels).(Histogram)
 }
+
+type constHistogram struct {
+	desc       *Desc
+	count      uint64
+	sum        float64
+	buckets    map[float64]uint64
+	labelPairs []*dto.LabelPair
+}
+
+func (h *constHistogram) Desc() *Desc {
+	return h.desc
+}
+
+func (h *constHistogram) Write(out *dto.Metric) error {
+	his := &dto.Histogram{}
+	buckets := make([]*dto.Bucket, 0, len(h.buckets))
+
+	his.SampleCount = proto.Uint64(h.count)
+	his.SampleSum = proto.Float64(h.sum)
+
+	for upperBound, count := range h.buckets {
+		buckets = append(buckets, &dto.Bucket{
+			CumulativeCount: proto.Uint64(count),
+			UpperBound:      proto.Float64(upperBound),
+		})
+	}
+
+	if len(buckets) > 0 {
+		sort.Sort(buckSort(buckets))
+	}
+	his.Bucket = buckets
+
+	out.Histogram = his
+	out.Label = h.labelPairs
+
+	return nil
+}
+
+// NewConstHistogram returns a metric representing a Prometheus histogram with
+// fixed values for the count, sum, and bucket counts. As those parameters
+// cannot be changed, the returned value does not implement the Histogram
+// interface (but only the Metric interface). Users of this package will not
+// have much use for it in regular operations. However, when implementing custom
+// Collectors, it is useful as a throw-away metric that is generated on the fly
+// to send it to Prometheus in the Collect method.
+//
+// buckets is a map of upper bounds to cumulative counts, excluding the +Inf
+// bucket.
+//
+// NewConstHistogram returns an error if the length of labelValues is not
+// consistent with the variable labels in Desc.
+func NewConstHistogram(
+	desc *Desc,
+	count uint64,
+	sum float64,
+	buckets map[float64]uint64,
+	labelValues ...string,
+) (Metric, error) {
+	if len(desc.variableLabels) != len(labelValues) {
+		return nil, errInconsistentCardinality
+	}
+	return &constHistogram{
+		desc:       desc,
+		count:      count,
+		sum:        sum,
+		buckets:    buckets,
+		labelPairs: makeLabelPairs(desc, labelValues),
+	}, nil
+}
+
+// MustNewConstHistogram is a version of NewConstHistogram that panics where
+// NewConstMetric would have returned an error.
+func MustNewConstHistogram(
+	desc *Desc,
+	count uint64,
+	sum float64,
+	buckets map[float64]uint64,
+	labelValues ...string,
+) Metric {
+	m, err := NewConstHistogram(desc, count, sum, buckets, labelValues...)
+	if err != nil {
+		panic(err)
+	}
+	return m
+}
+
+type buckSort []*dto.Bucket
+
+func (s buckSort) Len() int {
+	return len(s)
+}
+
+func (s buckSort) Swap(i, j int) {
+	s[i], s[j] = s[j], s[i]
+}
+
+func (s buckSort) Less(i, j int) bool {
+	return s[i].GetUpperBound() < s[j].GetUpperBound()
+}

Godeps/_workspace/src/github.com/prometheus/client_golang/prometheus/summary.go

@@ -448,3 +448,89 @@ func (m *SummaryVec) WithLabelValues(lvs ...string) Summary {
 func (m *SummaryVec) With(labels Labels) Summary {
 	return m.MetricVec.With(labels).(Summary)
 }
+
+type constSummary struct {
+	desc       *Desc
+	count      uint64
+	sum        float64
+	quantiles  map[float64]float64
+	labelPairs []*dto.LabelPair
+}
+
+func (s *constSummary) Desc() *Desc {
+	return s.desc
+}
+
+func (s *constSummary) Write(out *dto.Metric) error {
+	sum := &dto.Summary{}
+	qs := make([]*dto.Quantile, 0, len(s.quantiles))
+
+	sum.SampleCount = proto.Uint64(s.count)
+	sum.SampleSum = proto.Float64(s.sum)
+
+	for rank, q := range s.quantiles {
+		qs = append(qs, &dto.Quantile{
+			Quantile: proto.Float64(rank),
+			Value:    proto.Float64(q),
+		})
+	}
+
+	if len(qs) > 0 {
+		sort.Sort(quantSort(qs))
+	}
+	sum.Quantile = qs
+
+	out.Summary = sum
+	out.Label = s.labelPairs
+
+	return nil
+}
+
+// NewConstSummary returns a metric representing a Prometheus summary with fixed
+// values for the count, sum, and quantiles. As those parameters cannot be
+// changed, the returned value does not implement the Summary interface (but
+// only the Metric interface). Users of this package will not have much use for
+// it in regular operations. However, when implementing custom Collectors, it is
+// useful as a throw-away metric that is generated on the fly to send it to
+// Prometheus in the Collect method.
+//
+// quantiles maps ranks to quantile values. For example, a median latency of
+// 0.23s and a 99th percentile latency of 0.56s would be expressed as:
+//     map[float64]float64{0.5: 0.23, 0.99: 0.56}
+//
+// NewConstSummary returns an error if the length of labelValues is not
+// consistent with the variable labels in Desc.
+func NewConstSummary(
+	desc *Desc,
+	count uint64,
+	sum float64,
+	quantiles map[float64]float64,
+	labelValues ...string,
+) (Metric, error) {
+	if len(desc.variableLabels) != len(labelValues) {
+		return nil, errInconsistentCardinality
+	}
+	return &constSummary{
+		desc:       desc,
+		count:      count,
+		sum:        sum,
+		quantiles:  quantiles,
+		labelPairs: makeLabelPairs(desc, labelValues),
+	}, nil
+}
+
+// MustNewConstSummary is a version of NewConstSummary that panics where
+// NewConstMetric would have returned an error.
+func MustNewConstSummary(
+	desc *Desc,
+	count uint64,
+	sum float64,
+	quantiles map[float64]float64,
+	labelValues ...string,
+) Metric {
+	m, err := NewConstSummary(desc, count, sum, quantiles, labelValues...)
+	if err != nil {
+		panic(err)
+	}
+	return m
+}

storage/local/persistence_test.go

@@ -50,9 +50,9 @@ func newTestPersistence(t *testing.T, encoding chunkEncoding) (*persistence, tes
 
 func buildTestChunks(encoding chunkEncoding) map[clientmodel.Fingerprint][]chunk {
 	fps := clientmodel.Fingerprints{
-		m1.Fingerprint(),
+		m1.FastFingerprint(),
-		m2.Fingerprint(),
+		m2.FastFingerprint(),
-		m3.Fingerprint(),
+		m3.FastFingerprint(),
 	}
 	fpToChunks := map[clientmodel.Fingerprint][]chunk{}
 
@@ -375,11 +375,11 @@ func testCheckpointAndLoadSeriesMapAndHeads(t *testing.T, encoding chunkEncoding
 	s5.persistWatermark = 3
 	chunkCountS4 := len(s4.chunkDescs)
 	chunkCountS5 := len(s5.chunkDescs)
-	sm.put(m1.Fingerprint(), s1)
+	sm.put(m1.FastFingerprint(), s1)
-	sm.put(m2.Fingerprint(), s2)
+	sm.put(m2.FastFingerprint(), s2)
-	sm.put(m3.Fingerprint(), s3)
+	sm.put(m3.FastFingerprint(), s3)
-	sm.put(m4.Fingerprint(), s4)
+	sm.put(m4.FastFingerprint(), s4)
-	sm.put(m5.Fingerprint(), s5)
+	sm.put(m5.FastFingerprint(), s5)
 
 	if err := p.checkpointSeriesMapAndHeads(sm, fpLocker); err != nil {
 		t.Fatal(err)
@@ -392,7 +392,7 @@ func testCheckpointAndLoadSeriesMapAndHeads(t *testing.T, encoding chunkEncoding
 	if loadedSM.length() != 4 {
 		t.Errorf("want 4 series in map, got %d", loadedSM.length())
 	}
-	if loadedS1, ok := loadedSM.get(m1.Fingerprint()); ok {
+	if loadedS1, ok := loadedSM.get(m1.FastFingerprint()); ok {
 		if !reflect.DeepEqual(loadedS1.metric, m1) {
 			t.Errorf("want metric %v, got %v", m1, loadedS1.metric)
 		}
@@ -408,7 +408,7 @@ func testCheckpointAndLoadSeriesMapAndHeads(t *testing.T, encoding chunkEncoding
 	} else {
 		t.Errorf("couldn't find %v in loaded map", m1)
 	}
-	if loadedS3, ok := loadedSM.get(m3.Fingerprint()); ok {
+	if loadedS3, ok := loadedSM.get(m3.FastFingerprint()); ok {
 		if !reflect.DeepEqual(loadedS3.metric, m3) {
 			t.Errorf("want metric %v, got %v", m3, loadedS3.metric)
 		}
@@ -424,7 +424,7 @@ func testCheckpointAndLoadSeriesMapAndHeads(t *testing.T, encoding chunkEncoding
 	} else {
 		t.Errorf("couldn't find %v in loaded map", m3)
 	}
-	if loadedS4, ok := loadedSM.get(m4.Fingerprint()); ok {
+	if loadedS4, ok := loadedSM.get(m4.FastFingerprint()); ok {
 		if !reflect.DeepEqual(loadedS4.metric, m4) {
 			t.Errorf("want metric %v, got %v", m4, loadedS4.metric)
 		}
@@ -449,7 +449,7 @@ func testCheckpointAndLoadSeriesMapAndHeads(t *testing.T, encoding chunkEncoding
 	} else {
 		t.Errorf("couldn't find %v in loaded map", m4)
 	}
-	if loadedS5, ok := loadedSM.get(m5.Fingerprint()); ok {
+	if loadedS5, ok := loadedSM.get(m5.FastFingerprint()); ok {
 		if !reflect.DeepEqual(loadedS5.metric, m5) {
 			t.Errorf("want metric %v, got %v", m5, loadedS5.metric)
 		}

storage/local/series.go

@@ -318,7 +318,7 @@ func (s *memorySeries) preloadChunks(indexes []int, mss *memorySeriesStorage) ([
 		if s.chunkDescsOffset == -1 {
 			panic("requested loading chunks from persistence in a situation where we must not have persisted data for chunk descriptors in memory")
 		}
-		fp := s.metric.Fingerprint()
+		fp := s.metric.FastFingerprint() // TODO(beorn): Handle collisions.
 		chunks, err := mss.loadChunks(fp, loadIndexes, s.chunkDescsOffset)
 		if err != nil {
 			// Unpin the chunks since we won't return them as pinned chunks now.

storage/local/storage.go

@@ -382,7 +382,7 @@ func (s *memorySeriesStorage) Append(sample *clientmodel.Sample) {
 		}
 		glog.Warning("Sample ingestion resumed.")
 	}
-	fp := sample.Metric.Fingerprint()
+	fp := sample.Metric.FastFingerprint() // TODO(beorn): Handle collisions.
 	s.fpLocker.Lock(fp)
 	series := s.getOrCreateSeries(fp, sample.Metric)
 	completedChunksCount := series.add(&metric.SamplePair{

storage/local/storage_test.go

@@ -46,7 +46,7 @@ func TestGetFingerprintsForLabelMatchers(t *testing.T) {
 			Timestamp: clientmodel.Timestamp(i),
 			Value:     clientmodel.SampleValue(i),
 		}
-		fingerprints[i] = metric.Fingerprint()
+		fingerprints[i] = metric.FastFingerprint()
 	}
 	for _, s := range samples {
 		storage.Append(s)
@@ -172,7 +172,7 @@ func TestLoop(t *testing.T) {
 		storage.Append(s)
 	}
 	storage.WaitForIndexing()
-	series, _ := storage.(*memorySeriesStorage).fpToSeries.get(clientmodel.Metric{}.Fingerprint())
+	series, _ := storage.(*memorySeriesStorage).fpToSeries.get(clientmodel.Metric{}.FastFingerprint())
 	cdsBefore := len(series.chunkDescs)
 	time.Sleep(fpMaxWaitDuration + time.Second) // TODO(beorn7): Ugh, need to wait for maintenance to kick in.
 	cdsAfter := len(series.chunkDescs)
@@ -251,7 +251,7 @@ func testGetValueAtTime(t *testing.T, encoding chunkEncoding) {
 	}
 	s.WaitForIndexing()
 
-	fp := clientmodel.Metric{}.Fingerprint()
+	fp := clientmodel.Metric{}.FastFingerprint()
 
 	it := s.NewIterator(fp)
 
@@ -344,7 +344,7 @@ func testGetRangeValues(t *testing.T, encoding chunkEncoding) {
 	}
 	s.WaitForIndexing()
 
-	fp := clientmodel.Metric{}.Fingerprint()
+	fp := clientmodel.Metric{}.FastFingerprint()
 
 	it := s.NewIterator(fp)
 
@@ -498,7 +498,7 @@ func testEvictAndPurgeSeries(t *testing.T, encoding chunkEncoding) {
 	}
 	s.WaitForIndexing()
 
-	fp := clientmodel.Metric{}.Fingerprint()
+	fp := clientmodel.Metric{}.FastFingerprint()
 
 	// Drop ~half of the chunks.
 	ms.maintainMemorySeries(fp, 1000)
@@ -896,7 +896,7 @@ func verifyStorage(t testing.TB, s Storage, samples clientmodel.Samples, maxAge
 			// retention period, we can verify here that no results
 			// are returned.
 		}
-		fp := sample.Metric.Fingerprint()
+		fp := sample.Metric.FastFingerprint()
 		p := s.NewPreloader()
 		p.PreloadRange(fp, sample.Timestamp, sample.Timestamp, time.Hour)
 		found := s.NewIterator(fp).GetValueAtTime(sample.Timestamp)