pkg/util/log: plumb LogMetricRegistry into log package

This patch plumbs the LogMetricRegistry into the log package
as part of the initialization of the package where the
implementation lives.

With the log metrics plumbed into the log package and
made available in the server, we can now add them to the
metrics recorder used by the server, as well as begin using
metrics within the log package.

Release note: none

Author: abarganier

pkg/server/status/BUILD.bazel

@@ -65,6 +65,7 @@ go_library(
         "//pkg/util/humanizeutil",
         "//pkg/util/log",
         "//pkg/util/log/eventpb",
+        "//pkg/util/log/logmetrics",
         "//pkg/util/metric",
         "//pkg/util/syncutil",
         "//pkg/util/system",

pkg/server/status/recorder.go

@@ -45,6 +45,9 @@ import (
 	"github.com/cockroachdb/cockroach/pkg/util/hlc"
 	"github.com/cockroachdb/cockroach/pkg/util/humanizeutil"
 	"github.com/cockroachdb/cockroach/pkg/util/log"
+	// Import the logmetrics package to trigger its own init function, which inits and injects
+	// metrics functionality into pkg/util/log.
+	_ "github.com/cockroachdb/cockroach/pkg/util/log/logmetrics"
 	"github.com/cockroachdb/cockroach/pkg/util/metric"
 	"github.com/cockroachdb/cockroach/pkg/util/syncutil"
 	"github.com/cockroachdb/cockroach/pkg/util/system"

pkg/util/log/logmetrics/metrics.go

@@ -28,6 +28,18 @@ var (
 	}
 )
 
+// Inject our singleton LogMetricsRegistry into the logging
+// package. This ensures that the LogMetrics implementation within the
+// log package is always defined. This should only be called once from
+// a single init function.
+//
+// Since the primary user of the eventual metric.Registry's that come
+// from LogMetricsRegistry is the MetricsRecorder, we trigger this
+// init function via an import in pkg/util/log/logmetrics/metrics.go.
+func init() {
+	log.SetLogMetrics(logMetricsReg)
+}
+
 // logMetricsStruct is a struct used to contain all metrics
 // tracked by the LogMetricsRegistry. This container is necessary
 // to register all the metrics with the Registry internal to the