Bump Prometheus client_golang vendoring (thanos-io#523)

* Bump Prometheus client_golang vendoring

Use the version recommended by the upstream maintainer until there is an
official release. There are a number of issues with the very old 0.8.0
verision.

Specifically for client_golang, master is considered stable enough to
rely on. Experiments are kept in branches.

[0]: prometheus/node_exporter#1076

* Fix ProcessCollectorOpts.

* Fix 0 counter initializer.

* Fixup objstore metrics.

Author: SuperQ

Gopkg.lock

@@ -30,7 +30,7 @@ ignored = ["github.com/improbable-eng/thanos/benchmark/*"]
 
 [[constraint]]
   name = "github.com/prometheus/client_golang"
-  version = "0.8.0"
+  revision = "e637cec7d9c8990247098639ebc6d43dd34ddd49"
 
 [[constraint]]
   branch = "master"

Gopkg.toml

@@ -104,7 +104,7 @@ func main() {
 	metrics.MustRegister(
 		version.NewCollector("thanos"),
 		prometheus.NewGoCollector(),
-		prometheus.NewProcessCollector(os.Getpid(), ""),
+		prometheus.NewProcessCollector(prometheus.ProcessCollectorOpts{}),
 	)
 
 	prometheus.DefaultRegisterer = metrics

cmd/thanos/main.go

@@ -231,8 +231,12 @@ func (b *metricBucket) Get(ctx context.Context, name string) (io.ReadCloser, err
 		b.opsFailures.WithLabelValues(op).Inc()
 		return nil, err
 	}
-	rc = newTimingReadCloser(rc,
-		b.opsDuration.WithLabelValues(op), b.opsFailures.WithLabelValues(op))
+	rc = newTimingReadCloser(
+		rc,
+		op,
+		b.opsDuration,
+		b.opsFailures,
+	)
 
 	return rc, nil
 }
@@ -246,8 +250,12 @@ func (b *metricBucket) GetRange(ctx context.Context, name string, off, length in
 		b.opsFailures.WithLabelValues(op).Inc()
 		return nil, err
 	}
-	rc = newTimingReadCloser(rc,
-		b.opsDuration.WithLabelValues(op), b.opsFailures.WithLabelValues(op))
+	rc = newTimingReadCloser(
+		rc,
+		op,
+		b.opsDuration,
+		b.opsFailures,
+	)
 
 	return rc, nil
 }
@@ -310,25 +318,30 @@ type timingReadCloser struct {
 
 	ok       bool
 	start    time.Time
-	duration prometheus.Histogram
-	failed   prometheus.Counter
+	op       string
+	duration *prometheus.HistogramVec
+	failed   *prometheus.CounterVec
 }
 
-func newTimingReadCloser(rc io.ReadCloser, dur prometheus.Histogram, failed prometheus.Counter) *timingReadCloser {
+func newTimingReadCloser(rc io.ReadCloser, op string, dur *prometheus.HistogramVec, failed *prometheus.CounterVec) *timingReadCloser {
+	// Initialize the metrics with 0.
+	dur.WithLabelValues(op)
+	failed.WithLabelValues(op)
 	return &timingReadCloser{
 		ReadCloser: rc,
 		ok:         true,
 		start:      time.Now(),
+		op:         op,
 		duration:   dur,
 		failed:     failed,
 	}
 }
 
 func (rc *timingReadCloser) Close() error {
 	err := rc.ReadCloser.Close()
-	rc.duration.Observe(time.Since(rc.start).Seconds())
+	rc.duration.WithLabelValues(rc.op).Observe(time.Since(rc.start).Seconds())
 	if rc.ok && err != nil {
-		rc.failed.Inc()
+		rc.failed.WithLabelValues(rc.op).Inc()
 		rc.ok = false
 	}
 	return err
@@ -337,7 +350,7 @@ func (rc *timingReadCloser) Close() error {
 func (rc *timingReadCloser) Read(b []byte) (n int, err error) {
 	n, err = rc.ReadCloser.Read(b)
 	if rc.ok && err != nil && err != io.EOF {
-		rc.failed.Inc()
+		rc.failed.WithLabelValues(rc.op).Inc()
 		rc.ok = false
 	}
 	return n, err

pkg/objstore/objstore.go

@@ -82,8 +82,8 @@ func newIndexCache(reg prometheus.Registerer, maxBytes uint64) (*indexCache, err
 	}, []string{"item_type"})
 
 	// Initialize eviction metric with 0.
-	evicted.WithLabelValues(cacheTypePostings).Set(0)
-	evicted.WithLabelValues(cacheTypeSeries).Set(0)
+	evicted.WithLabelValues(cacheTypePostings)
+	evicted.WithLabelValues(cacheTypeSeries)
 
 	// Initialize LRU cache with a high size limit since we will manage evictions ourselves
 	// based on stored size.