Update vendor

vendor/github.com/mattermost/logr/v2/metrics.go

@@ -0,0 +1,140 @@
+package logr
+
+import "time"
+
+const (
+	DefMetricsUpdateFreqMillis = 15000 // 15 seconds
+)
+
+// Counter is a simple metrics sink that can only increment a value.
+// Implementations are external to Logr and provided via `MetricsCollector`.
+type Counter interface {
+	// Inc increments the counter by 1. Use Add to increment it by arbitrary non-negative values.
+	Inc()
+	// Add adds the given value to the counter. It panics if the value is < 0.
+	Add(float64)
+}
+
+// Gauge is a simple metrics sink that can receive values and increase or decrease.
+// Implementations are external to Logr and provided via `MetricsCollector`.
+type Gauge interface {
+	// Set sets the Gauge to an arbitrary value.
+	Set(float64)
+	// Add adds the given value to the Gauge. (The value can be negative, resulting in a decrease of the Gauge.)
+	Add(float64)
+	// Sub subtracts the given value from the Gauge. (The value can be negative, resulting in an increase of the Gauge.)
+	Sub(float64)
+}
+
+// MetricsCollector provides a way for users of this Logr package to have metrics pushed
+// in an efficient way to any backend, e.g. Prometheus.
+// For each target added to Logr, the supplied MetricsCollector will provide a Gauge
+// and Counters that will be called frequently as logging occurs.
+type MetricsCollector interface {
+	// QueueSizeGauge returns a Gauge that will be updated by the named target.
+	QueueSizeGauge(target string) (Gauge, error)
+	// LoggedCounter returns a Counter that will be incremented by the named target.
+	LoggedCounter(target string) (Counter, error)
+	// ErrorCounter returns a Counter that will be incremented by the named target.
+	ErrorCounter(target string) (Counter, error)
+	// DroppedCounter returns a Counter that will be incremented by the named target.
+	DroppedCounter(target string) (Counter, error)
+	// BlockedCounter returns a Counter that will be incremented by the named target.
+	BlockedCounter(target string) (Counter, error)
+}
+
+// TargetWithMetrics is a target that provides metrics.
+type TargetWithMetrics interface {
+	EnableMetrics(collector MetricsCollector, updateFreqMillis int64) error
+}
+
+type metrics struct {
+	collector        MetricsCollector
+	updateFreqMillis int64
+	queueSizeGauge   Gauge
+	loggedCounter    Counter
+	errorCounter     Counter
+	done             chan struct{}
+}
+
+// initMetrics initializes metrics collection.
+func (lgr *Logr) initMetrics(collector MetricsCollector, updatefreq int64) {
+	lgr.stopMetricsUpdater()
+
+	if collector == nil {
+		lgr.metricsMux.Lock()
+		lgr.metrics = nil
+		lgr.metricsMux.Unlock()
+		return
+	}
+
+	metrics := &metrics{
+		collector:        collector,
+		updateFreqMillis: updatefreq,
+		done:             make(chan struct{}),
+	}
+	metrics.queueSizeGauge, _ = collector.QueueSizeGauge("_logr")
+	metrics.loggedCounter, _ = collector.LoggedCounter("_logr")
+	metrics.errorCounter, _ = collector.ErrorCounter("_logr")
+
+	lgr.metricsMux.Lock()
+	lgr.metrics = metrics
+	lgr.metricsMux.Unlock()
+
+	go lgr.startMetricsUpdater()
+}
+
+func (lgr *Logr) setQueueSizeGauge(val float64) {
+	lgr.metricsMux.RLock()
+	defer lgr.metricsMux.RUnlock()
+
+	if lgr.metrics != nil {
+		lgr.metrics.queueSizeGauge.Set(val)
+	}
+}
+
+func (lgr *Logr) incLoggedCounter() {
+	lgr.metricsMux.RLock()
+	defer lgr.metricsMux.RUnlock()
+
+	if lgr.metrics != nil {
+		lgr.metrics.loggedCounter.Inc()
+	}
+}
+
+func (lgr *Logr) incErrorCounter() {
+	lgr.metricsMux.RLock()
+	defer lgr.metricsMux.RUnlock()
+
+	if lgr.metrics != nil {
+		lgr.metrics.errorCounter.Inc()
+	}
+}
+
+// startMetricsUpdater updates the metrics for any polled values every `metricsUpdateFreqSecs` seconds until
+// logr is closed.
+func (lgr *Logr) startMetricsUpdater() {
+	for {
+		lgr.metricsMux.RLock()
+		metrics := lgr.metrics
+		c := metrics.done
+		lgr.metricsMux.RUnlock()
+
+		select {
+		case <-c:
+			return
+		case <-time.After(time.Duration(metrics.updateFreqMillis) * time.Millisecond):
+			lgr.setQueueSizeGauge(float64(len(lgr.in)))
+		}
+	}
+}
+
+func (lgr *Logr) stopMetricsUpdater() {
+	lgr.metricsMux.Lock()
+	defer lgr.metricsMux.Unlock()
+
+	if lgr.metrics != nil && lgr.metrics.done != nil {
+		close(lgr.metrics.done)
+		lgr.metrics.done = nil
+	}
+}