metrics: transition all metrics to using metricsgen generated constructors. (port of #8488) (#9178)

This pull request completes the change to the `metricsgen` metrics. It adds `go generate` directives to all of the files containing the `Metrics` structs.

Using the outputs of `metricsdiff` between these generated metrics and `main`, we can see that there is a minimal diff between the two sets of metrics when run locally. The diff here stems from removal of the word 'message' which was done in v0.36+ and is ultimately a better phrasing. This metric has not yet been released, so this phrasing is preferred.

```
./metricsdiff old new
Metric changes:
+++ tendermint_consensus_full_prevote_delay
+++ tendermint_consensus_quorum_prevote_delay
--- tendermint_consensus_full_prevote_message_delay
--- tendermint_consensus_quorum_prevote_message_delay
```

This change also adds parsing for a `metrics:` key in a field comment. If a comment line begins with `//metrics:` the rest of the line is interpreted to be the metric help text. Additionally, a bug where lists of labels were not properly quoted in the `metricsgen` rendered output was fixed.

In my view, docs and tests are not needed for this internal only change.

---
#### PR checklist

- [ ] Tests written/updated, or no tests needed
- [ ] `CHANGELOG_PENDING.md` updated, or no changelog entry needed
- [ ] Updated relevant documentation (`docs/`) and code comments, or no
      documentation updates needed

Ports #8488 to main

mempool/metrics.gen.go

@@ -0,0 +1,67 @@
+// Code generated by metricsgen. DO NOT EDIT.
+
+package mempool
+
+import (
+	"github.com/go-kit/kit/metrics/discard"
+	prometheus "github.com/go-kit/kit/metrics/prometheus"
+	stdprometheus "github.com/prometheus/client_golang/prometheus"
+)
+
+func PrometheusMetrics(namespace string, labelsAndValues ...string) *Metrics {
+	labels := []string{}
+	for i := 0; i < len(labelsAndValues); i += 2 {
+		labels = append(labels, labelsAndValues[i])
+	}
+	return &Metrics{
+		Size: prometheus.NewGaugeFrom(stdprometheus.GaugeOpts{
+			Namespace: namespace,
+			Subsystem: MetricsSubsystem,
+			Name:      "size",
+			Help:      "Number of uncommitted transactions in the mempool.",
+		}, labels).With(labelsAndValues...),
+		TxSizeBytes: prometheus.NewHistogramFrom(stdprometheus.HistogramOpts{
+			Namespace: namespace,
+			Subsystem: MetricsSubsystem,
+			Name:      "tx_size_bytes",
+			Help:      "Histogram of transaction sizes in bytes.",
+
+			Buckets: stdprometheus.ExponentialBuckets(1, 3, 7),
+		}, labels).With(labelsAndValues...),
+		FailedTxs: prometheus.NewCounterFrom(stdprometheus.CounterOpts{
+			Namespace: namespace,
+			Subsystem: MetricsSubsystem,
+			Name:      "failed_txs",
+			Help:      "Number of failed transactions.",
+		}, labels).With(labelsAndValues...),
+		RejectedTxs: prometheus.NewCounterFrom(stdprometheus.CounterOpts{
+			Namespace: namespace,
+			Subsystem: MetricsSubsystem,
+			Name:      "rejected_txs",
+			Help:      "Number of rejected transactions.",
+		}, labels).With(labelsAndValues...),
+		EvictedTxs: prometheus.NewCounterFrom(stdprometheus.CounterOpts{
+			Namespace: namespace,
+			Subsystem: MetricsSubsystem,
+			Name:      "evicted_txs",
+			Help:      "Number of evicted transactions.",
+		}, labels).With(labelsAndValues...),
+		RecheckTimes: prometheus.NewCounterFrom(stdprometheus.CounterOpts{
+			Namespace: namespace,
+			Subsystem: MetricsSubsystem,
+			Name:      "recheck_times",
+			Help:      "Number of times transactions are rechecked in the mempool.",
+		}, labels).With(labelsAndValues...),
+	}
+}
+
+func NopMetrics() *Metrics {
+	return &Metrics{
+		Size:         discard.NewGauge(),
+		TxSizeBytes:  discard.NewHistogram(),
+		FailedTxs:    discard.NewCounter(),
+		RejectedTxs:  discard.NewCounter(),
+		EvictedTxs:   discard.NewCounter(),
+		RecheckTimes: discard.NewCounter(),
+	}
+}

mempool/metrics.go

@@ -2,9 +2,6 @@ package mempool
 
 import (
 	"github.com/go-kit/kit/metrics"
-	"github.com/go-kit/kit/metrics/discard"
-	"github.com/go-kit/kit/metrics/prometheus"
-	stdprometheus "github.com/prometheus/client_golang/prometheus"
 )
 
 const (
@@ -13,14 +10,16 @@ const (
 	MetricsSubsystem = "mempool"
 )
 
+//go:generate go run ../scripts/metricsgen -struct=Metrics
+
 // Metrics contains metrics exposed by this package.
 // see MetricsProvider for descriptions.
 type Metrics struct {
-	// Size of the mempool.
+	// Number of uncommitted transactions in the mempool.
 	Size metrics.Gauge
 
-	// Histogram of transaction sizes, in bytes.
-	TxSizeBytes metrics.Histogram
+	// Histogram of transaction sizes in bytes.
+	TxSizeBytes metrics.Histogram `metrics_buckettype:"exp" metrics_bucketsizes:"1,3,7"`
 
 	// Number of failed transactions.
 	FailedTxs metrics.Counter
@@ -29,80 +28,16 @@ type Metrics struct {
 	// transactions that passed CheckTx but failed to make it into the mempool
 	// due to resource limits, e.g. mempool is full and no lower priority
 	// transactions exist in the mempool.
+	//metrics:Number of rejected transactions.
 	RejectedTxs metrics.Counter
 
 	// EvictedTxs defines the number of evicted transactions. These are valid
 	// transactions that passed CheckTx and existed in the mempool but were later
 	// evicted to make room for higher priority valid transactions that passed
 	// CheckTx.
+	//metrics:Number of evicted transactions.
 	EvictedTxs metrics.Counter
 
 	// Number of times transactions are rechecked in the mempool.
 	RecheckTimes metrics.Counter
 }
-
-// PrometheusMetrics returns Metrics build using Prometheus client library.
-// Optionally, labels can be provided along with their values ("foo",
-// "fooValue").
-func PrometheusMetrics(namespace string, labelsAndValues ...string) *Metrics {
-	labels := []string{}
-	for i := 0; i < len(labelsAndValues); i += 2 {
-		labels = append(labels, labelsAndValues[i])
-	}
-	return &Metrics{
-		Size: prometheus.NewGaugeFrom(stdprometheus.GaugeOpts{
-			Namespace: namespace,
-			Subsystem: MetricsSubsystem,
-			Name:      "size",
-			Help:      "Size of the mempool (number of uncommitted transactions).",
-		}, labels).With(labelsAndValues...),
-
-		TxSizeBytes: prometheus.NewHistogramFrom(stdprometheus.HistogramOpts{
-			Namespace: namespace,
-			Subsystem: MetricsSubsystem,
-			Name:      "tx_size_bytes",
-			Help:      "Transaction sizes in bytes.",
-			Buckets:   stdprometheus.ExponentialBuckets(1, 3, 17),
-		}, labels).With(labelsAndValues...),
-
-		FailedTxs: prometheus.NewCounterFrom(stdprometheus.CounterOpts{
-			Namespace: namespace,
-			Subsystem: MetricsSubsystem,
-			Name:      "failed_txs",
-			Help:      "Number of failed transactions.",
-		}, labels).With(labelsAndValues...),
-
-		RejectedTxs: prometheus.NewCounterFrom(stdprometheus.CounterOpts{
-			Namespace: namespace,
-			Subsystem: MetricsSubsystem,
-			Name:      "rejected_txs",
-			Help:      "Number of rejected transactions.",
-		}, labels).With(labelsAndValues...),
-
-		EvictedTxs: prometheus.NewCounterFrom(stdprometheus.CounterOpts{
-			Namespace: namespace,
-			Subsystem: MetricsSubsystem,
-			Name:      "evicted_txs",
-			Help:      "Number of evicted transactions.",
-		}, labels).With(labelsAndValues...),
-
-		RecheckTimes: prometheus.NewCounterFrom(stdprometheus.CounterOpts{
-			Namespace: namespace,
-			Subsystem: MetricsSubsystem,
-			Name:      "recheck_times",
-			Help:      "Number of times transactions are rechecked in the mempool.",
-		}, labels).With(labelsAndValues...),
-	}
-}
-
-// NopMetrics returns no-op Metrics.
-func NopMetrics() *Metrics {
-	return &Metrics{
-		Size:         discard.NewGauge(),
-		TxSizeBytes:  discard.NewHistogram(),
-		FailedTxs:    discard.NewCounter(),
-		RejectedTxs:  discard.NewCounter(),
-		EvictedTxs:   discard.NewCounter(),
-		RecheckTimes: discard.NewCounter(),
-	}
-}