Update prometheus/client_golang vendoring (#1099)

This is mostly required to fix a bug with histograms on 32bit platforms.
(Which might or might not be used in node_exporter. Just in case...)

Signed-off-by: beorn7 <beorn@soundcloud.com>

vendor/github.com/prometheus/client_golang/prometheus/collector.go

@@ -40,7 +40,8 @@ type Collector interface {
 	// Collector may yield any Metric it sees fit in its Collect method.
 	//
 	// This method idempotently sends the same descriptors throughout the
-	// lifetime of the Collector.
+	// lifetime of the Collector. It may be called concurrently and
+	// therefore must be implemented in a concurrency safe way.
 	//
 	// If a Collector encounters an error while executing this method, it
 	// must send an invalid descriptor (created with NewInvalidDesc) to

vendor/github.com/prometheus/client_golang/prometheus/histogram.go

@@ -187,6 +187,7 @@ func newHistogram(desc *Desc, opts HistogramOpts, labelValues ...string) Histogr
 		desc:        desc,
 		upperBounds: opts.Buckets,
 		labelPairs:  makeLabelPairs(desc, labelValues),
+		counts:      [2]*histogramCounts{&histogramCounts{}, &histogramCounts{}},
 	}
 	for i, upperBound := range h.upperBounds {
 		if i < len(h.upperBounds)-1 {
@@ -223,6 +224,21 @@ type histogramCounts struct {
 }
 
 type histogram struct {
+	// countAndHotIdx is a complicated one. For lock-free yet atomic
+	// observations, we need to save the total count of observations again,
+	// combined with the index of the currently-hot counts struct, so that
+	// we can perform the operation on both values atomically. The least
+	// significant bit defines the hot counts struct. The remaining 63 bits
+	// represent the total count of observations. This happens under the
+	// assumption that the 63bit count will never overflow. Rationale: An
+	// observations takes about 30ns. Let's assume it could happen in
+	// 10ns. Overflowing the counter will then take at least (2^63)*10ns,
+	// which is about 3000 years.
+	//
+	// This has to be first in the struct for 64bit alignment. See
+	// http://golang.org/pkg/sync/atomic/#pkg-note-BUG
+	countAndHotIdx uint64
+
 	selfCollector
 	desc     *Desc
 	writeMtx sync.Mutex // Only used in the Write method.
@@ -230,23 +246,12 @@ type histogram struct {
 	upperBounds []float64
 
 	// Two counts, one is "hot" for lock-free observations, the other is
-	// "cold" for writing out a dto.Metric.
-	counts [2]histogramCounts
-
+	// "cold" for writing out a dto.Metric. It has to be an array of
+	// pointers to guarantee 64bit alignment of the histogramCounts, see
+	// http://golang.org/pkg/sync/atomic/#pkg-note-BUG.
+	counts [2]*histogramCounts
 	hotIdx int // Index of currently-hot counts. Only used within Write.
 
-	// This is a complicated one. For lock-free yet atomic observations, we
-	// need to save the total count of observations again, combined with the
-	// index of the currently-hot counts struct, so that we can perform the
-	// operation on both values atomically. The least significant bit
-	// defines the hot counts struct. The remaining 63 bits represent the
-	// total count of observations. This happens under the assumption that
-	// the 63bit count will never overflow. Rationale: An observations takes
-	// about 30ns. Let's assume it could happen in 10ns. Overflowing the
-	// counter will then take at least (2^63)*10ns, which is about 3000
-	// years.
-	countAndHotIdx uint64
-
 	labelPairs []*dto.LabelPair
 }
 
@@ -270,7 +275,7 @@ func (h *histogram) Observe(v float64) {
 	// 63 bits gets incremented by 1. At the same time, we get the new value
 	// back, which we can use to find the currently-hot counts.
 	n := atomic.AddUint64(&h.countAndHotIdx, 2)
-	hotCounts := &h.counts[n%2]
+	hotCounts := h.counts[n%2]
 
 	if i < len(h.upperBounds) {
 		atomic.AddUint64(&hotCounts.buckets[i], 1)
@@ -322,13 +327,13 @@ func (h *histogram) Write(out *dto.Metric) error {
 	if h.hotIdx == 0 {
 		count = atomic.AddUint64(&h.countAndHotIdx, 1) >> 1
 		h.hotIdx = 1
-		hotCounts = &h.counts[1]
-		coldCounts = &h.counts[0]
+		hotCounts = h.counts[1]
+		coldCounts = h.counts[0]
 	} else {
 		count = atomic.AddUint64(&h.countAndHotIdx, ^uint64(0)) >> 1 // Decrement.
 		h.hotIdx = 0
-		hotCounts = &h.counts[0]
-		coldCounts = &h.counts[1]
+		hotCounts = h.counts[0]
+		coldCounts = h.counts[1]
 	}
 
 	// Now we have to wait for the now-declared-cold counts to actually cool

vendor/github.com/prometheus/client_golang/prometheus/registry.go

@@ -107,9 +107,6 @@ type Registerer interface {
 	// Collector, and for providing a Collector that will not cause
 	// inconsistent metrics on collection. (This would lead to scrape
 	// errors.)
-	//
-	// It is in general not safe to register the same Collector multiple
-	// times concurrently.
 	Register(Collector) error
 	// MustRegister works like Register but registers any number of
 	// Collectors and panics upon the first registration that causes an
@@ -273,7 +270,12 @@ func (r *Registry) Register(c Collector) error {
 		close(descChan)
 	}()
 	r.mtx.Lock()
-	defer r.mtx.Unlock()
+	defer func() {
+		// Drain channel in case of premature return to not leak a goroutine.
+		for range descChan {
+		}
+		r.mtx.Unlock()
+	}()
 	// Conduct various tests...
 	for desc := range descChan {
 
@@ -785,6 +787,8 @@ func checkMetricConsistency(
 	dtoMetric *dto.Metric,
 	metricHashes map[uint64]struct{},
 ) error {
+	name := metricFamily.GetName()
+
 	// Type consistency with metric family.
 	if metricFamily.GetType() == dto.MetricType_GAUGE && dtoMetric.Gauge == nil ||
 		metricFamily.GetType() == dto.MetricType_COUNTER && dtoMetric.Counter == nil ||
@@ -793,33 +797,42 @@ func checkMetricConsistency(
 		metricFamily.GetType() == dto.MetricType_UNTYPED && dtoMetric.Untyped == nil {
 		return fmt.Errorf(
 			"collected metric %q { %s} is not a %s",
-			metricFamily.GetName(), dtoMetric, metricFamily.GetType(),
+			name, dtoMetric, metricFamily.GetType(),
 		)
 	}
 
+	previousLabelName := ""
 	for _, labelPair := range dtoMetric.GetLabel() {
-		if !checkLabelName(labelPair.GetName()) {
+		labelName := labelPair.GetName()
+		if labelName == previousLabelName {
 			return fmt.Errorf(
-				"collected metric %q { %s} has a label with an invalid name: %s",
-				metricFamily.GetName(), dtoMetric, labelPair.GetName(),
+				"collected metric %q { %s} has two or more labels with the same name: %s",
+				name, dtoMetric, labelName,
 			)
 		}
-		if dtoMetric.Summary != nil && labelPair.GetName() == quantileLabel {
+		if !checkLabelName(labelName) {
+			return fmt.Errorf(
+				"collected metric %q { %s} has a label with an invalid name: %s",
+				name, dtoMetric, labelName,
+			)
+		}
+		if dtoMetric.Summary != nil && labelName == quantileLabel {
 			return fmt.Errorf(
 				"collected metric %q { %s} must not have an explicit %q label",
-				metricFamily.GetName(), dtoMetric, quantileLabel,
+				name, dtoMetric, quantileLabel,
 			)
 		}
 		if !utf8.ValidString(labelPair.GetValue()) {
 			return fmt.Errorf(
 				"collected metric %q { %s} has a label named %q whose value is not utf8: %#v",
-				metricFamily.GetName(), dtoMetric, labelPair.GetName(), labelPair.GetValue())
+				name, dtoMetric, labelName, labelPair.GetValue())
 		}
+		previousLabelName = labelName
 	}
 
 	// Is the metric unique (i.e. no other metric with the same name and the same labels)?
 	h := hashNew()
-	h = hashAdd(h, metricFamily.GetName())
+	h = hashAdd(h, name)
 	h = hashAddByte(h, separatorByte)
 	// Make sure label pairs are sorted. We depend on it for the consistency
 	// check.
@@ -833,7 +846,7 @@ func checkMetricConsistency(
 	if _, exists := metricHashes[h]; exists {
 		return fmt.Errorf(
 			"collected metric %q { %s} was collected before with the same name and label values",
-			metricFamily.GetName(), dtoMetric,
+			name, dtoMetric,
 		)
 	}
 	metricHashes[h] = struct{}{}

vendor/vendor.json

@@ -115,22 +115,22 @@
 			"revisionTime": "2017-09-01T18:29:50Z"
 		},
 		{
-			"checksumSHA1": "lLvg5TpUtFbkyAoh+aI5T/nnpWw=",
+			"checksumSHA1": "frS661rlSEZWE9CezHhnFioQK/I=",
 			"path": "github.com/prometheus/client_golang/prometheus",
-			"revision": "e637cec7d9c8990247098639ebc6d43dd34ddd49",
-			"revisionTime": "2018-09-17T10:21:22Z"
+			"revision": "0a8115f42e037a6e327f9a269a26ff6603fb8472",
+			"revisionTime": "2018-10-01T17:40:01Z"
 		},
 		{
 			"checksumSHA1": "UBqhkyjCz47+S19MVTigxJ2VjVQ=",
 			"path": "github.com/prometheus/client_golang/prometheus/internal",
-			"revision": "e637cec7d9c8990247098639ebc6d43dd34ddd49",
-			"revisionTime": "2018-09-17T10:21:22Z"
+			"revision": "0a8115f42e037a6e327f9a269a26ff6603fb8472",
+			"revisionTime": "2018-10-01T17:40:01Z"
 		},
 		{
 			"checksumSHA1": "d5BiEvD8MrgpWQ6PQJUvawJsMak=",
 			"path": "github.com/prometheus/client_golang/prometheus/promhttp",
-			"revision": "e637cec7d9c8990247098639ebc6d43dd34ddd49",
-			"revisionTime": "2018-09-17T10:21:22Z"
+			"revision": "0a8115f42e037a6e327f9a269a26ff6603fb8472",
+			"revisionTime": "2018-10-01T17:40:01Z"
 		},
 		{
 			"checksumSHA1": "DvwvOlPNAgRntBzt3b3OSRMS2N4=",