Metrics rename (#346)

* metrics: inline all counter references

remove all calls to metrics.Counter
and instead inline using the prometheus/promauto package

* metrics: inject prometheus register dependency

that's used to give more control and therefore
create unique registers per tests
avoiding the "duplicate metrics collector registration attempted" panic
message
see prometheus/client_golang#716 (comment)

* metrics: inline gauge calls

* metrics: inline all gauge calls in debug reporter

couple things:
1 - semantics have changed, ie the metrics are initialized to 0
even if we can't ever generate metrics data

so think in a dashboard a 0 value vs simply nothing showing up

2 - some of the metrics generated were dynamic, for example,
based on files in a directory
that has been hardcoded

* metrics: inline timing calls and remove metrics pkg

* metrics: bring back type assertions

* metrics: create basic playground to compare metrics

* metrics: convert timing metrics to nanoseconds

* metrics: improve metrics-comparison docker-compose

* metrics: fixes /benchmark

* metrics: fix broken test

* dashboard: initial version created with jsonnet

* metrics: add pyroscope_ suffix

* metrics: make missing metrics greppable

* metrics: prepend pyroscope_ to missing metrics

* metrics: refactor storage and cache counters

* metrics: rename pyroscope_disk and pyroscope_cache_size

* metrics: rename _count suffix to _total

* metrics: timers are now histograms

* metrics: refactor cache writes/misses metrics

* metrics: rename a bunch of metrics

* metrics: add dashboard row for go metrics

* metrics: cleanup dashboard

* metrics: add help text to benchmark metrics

Author: eh-am

benchmark/main.go

@@ -72,10 +72,12 @@ func startClientThread(appName string, wg *sync.WaitGroup, appFixtures []*transp
 	reg := prometheus.NewRegistry()
 
 	uploadErrors := promauto.With(reg).NewCounter(prometheus.CounterOpts{
-		Name: "upload_errors",
+		Name: "pyroscope_upload_errors",
+		Help: "",
 	})
 	successfulUploads := promauto.With(reg).NewCounter(prometheus.CounterOpts{
-		Name: "successful_uploads",
+		Name: "pyroscope_successful_uploads",
+		Help: "",
 	})
 
 	for i := 0; i < requestsCount; i++ {
@@ -204,10 +206,12 @@ func main() {
 	logrus.Info("waiting for other services to load")
 
 	benchmark := promauto.NewGauge(prometheus.GaugeOpts{
-		Name: "benchmark",
+		Name: "pyroscope_benchmark",
+		Help: "",
 	})
 	runProgress := promauto.NewGauge(prometheus.GaugeOpts{
-		Name: "run_progress",
+		Name: "pyroscope_run_progress",
+		Help: "",
 	})
 
 	benchmark.Set(0)