Update vendor (#1265)

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

@@ -0,0 +1,117 @@
+package logr
+
+import (
+	"errors"
+
+	"github.com/wiggin77/merror"
+)
+
+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
+}
+
+func (logr *Logr) getMetricsCollector() MetricsCollector {
+	logr.mux.RLock()
+	defer logr.mux.RUnlock()
+	return logr.metrics
+}
+
+// SetMetricsCollector enables metrics collection by supplying a MetricsCollector.
+// The MetricsCollector provides counters and gauges that are updated by log targets.
+func (logr *Logr) SetMetricsCollector(collector MetricsCollector) error {
+	if collector == nil {
+		return errors.New("collector cannot be nil")
+	}
+
+	logr.mux.Lock()
+	logr.metrics = collector
+	logr.queueSizeGauge, _ = collector.QueueSizeGauge("_logr")
+	logr.loggedCounter, _ = collector.LoggedCounter("_logr")
+	logr.errorCounter, _ = collector.ErrorCounter("_logr")
+	logr.mux.Unlock()
+
+	logr.metricsInitOnce.Do(func() {
+		logr.metricsDone = make(chan struct{})
+		go logr.startMetricsUpdater()
+	})
+
+	merr := merror.New()
+
+	logr.tmux.RLock()
+	defer logr.tmux.RUnlock()
+	for _, target := range logr.targets {
+		if tm, ok := target.(TargetWithMetrics); ok {
+			if err := tm.EnableMetrics(collector, logr.MetricsUpdateFreqMillis); err != nil {
+				merr.Append(err)
+			}
+		}
+
+	}
+	return merr.ErrorOrNil()
+}
+
+func (logr *Logr) setQueueSizeGauge(val float64) {
+	logr.mux.RLock()
+	defer logr.mux.RUnlock()
+	if logr.queueSizeGauge != nil {
+		logr.queueSizeGauge.Set(val)
+	}
+}
+
+func (logr *Logr) incLoggedCounter() {
+	logr.mux.RLock()
+	defer logr.mux.RUnlock()
+	if logr.loggedCounter != nil {
+		logr.loggedCounter.Inc()
+	}
+}
+
+func (logr *Logr) incErrorCounter() {
+	logr.mux.RLock()
+	defer logr.mux.RUnlock()
+	if logr.errorCounter != nil {
+		logr.errorCounter.Inc()
+	}
+}