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>

4 files changed, 59 insertions, 40 deletions

diff --git a/vendor/github.com/prometheus/client_golang/prometheus/collector.go b/vendor/github.com/prometheus/client_golang/prometheus/collector.go
index 08491be..c0d70b2 100644
--- a/vendor/github.com/prometheus/client_golang/prometheus/collector.go
+++ b/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
diff --git a/vendor/github.com/prometheus/client_golang/prometheus/histogram.go b/vendor/github.com/prometheus/client_golang/prometheus/histogram.go
index 29dc8e3..4d7fa97 100644
--- a/vendor/github.com/prometheus/client_golang/prometheus/histogram.go
+++ b/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
diff --git a/vendor/github.com/prometheus/client_golang/prometheus/registry.go b/vendor/github.com/prometheus/client_golang/prometheus/registry.go
index 2c0b908..e422ef3 100644
--- a/vendor/github.com/prometheus/client_golang/prometheus/registry.go
+++ b/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 two or more labels with the same name: %s",
+                                name, dtoMetric, labelName,
+                        )
+                }
+                if !checkLabelName(labelName) {
                         return fmt.Errorf(
                                 "collected metric %q { %s} has a label with an invalid name: %s",
-                                metricFamily.GetName(), dtoMetric, labelPair.GetName(),
+                                name, dtoMetric, labelName,
                         )
                 }
-                if dtoMetric.Summary != nil && labelPair.GetName() == quantileLabel {
+                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{}{}
diff --git a/vendor/vendor.json b/vendor/vendor.json
index 320bda2..c05d99e 100644
--- a/vendor/vendor.json
+++ b/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=",