Moved to google.golang.org/genproto/googleapis/api/annotations

Fixes #52

vendor/github.com/go-kit/kit/metrics/README.md

@@ -0,0 +1,97 @@
+# package metrics
+
+`package metrics` provides a set of uniform interfaces for service instrumentation.
+It has
+ [counters](http://prometheus.io/docs/concepts/metric_types/#counter),
+ [gauges](http://prometheus.io/docs/concepts/metric_types/#gauge), and
+ [histograms](http://prometheus.io/docs/concepts/metric_types/#histogram),
+and provides adapters to popular metrics packages, like
+ [expvar](https://golang.org/pkg/expvar),
+ [StatsD](https://github.com/etsy/statsd), and
+ [Prometheus](https://prometheus.io).
+
+## Rationale
+
+Code instrumentation is absolutely essential to achieve
+ [observability](https://speakerdeck.com/mattheath/observability-in-micro-service-architectures)
+ into a distributed system.
+Metrics and instrumentation tools have coalesced around a few well-defined idioms.
+`package metrics` provides a common, minimal interface those idioms for service authors.
+
+## Usage
+
+A simple counter, exported via expvar.
+
+```go
+import (
+	"github.com/go-kit/kit/metrics"
+	"github.com/go-kit/kit/metrics/expvar"
+)
+
+func main() {
+	var myCount metrics.Counter
+	myCount = expvar.NewCounter("my_count")
+	myCount.Add(1)
+}
+```
+
+A histogram for request duration,
+ exported via a Prometheus summary with dynamically-computed quantiles.
+
+```go
+import (
+	"time"
+
+	stdprometheus "github.com/prometheus/client_golang/prometheus"
+
+	"github.com/go-kit/kit/metrics"
+	"github.com/go-kit/kit/metrics/prometheus"
+)
+
+func main() {
+	var dur metrics.Histogram = prometheus.NewSummaryFrom(stdprometheus.SummaryOpts{
+		Namespace: "myservice",
+		Subsystem: "api",
+		Name:     "request_duration_seconds",
+		Help:     "Total time spent serving requests.",
+	}, []string{})
+	// ...
+}
+
+func handleRequest(dur metrics.Histogram) {
+	defer func(begin time.Time) { dur.Observe(time.Since(begin).Seconds()) }(time.Now())
+	// handle request
+}
+```
+
+A gauge for the number of goroutines currently running, exported via StatsD.
+
+```go
+import (
+	"net"
+	"os"
+	"runtime"
+	"time"
+
+	"github.com/go-kit/kit/metrics"
+	"github.com/go-kit/kit/metrics/statsd"
+)
+
+func main() {
+	statsd := statsd.New("foo_svc.", log.NewNopLogger())
+	report := time.NewTicker(5 * time.Second)
+	defer report.Stop()
+	go statsd.SendLoop(report.C, "tcp", "statsd.internal:8125")
+	goroutines := statsd.NewGauge("goroutine_count")
+	go exportGoroutines(goroutines)
+	// ...
+}
+
+func exportGoroutines(g metrics.Gauge) {
+	for range time.Tick(time.Second) {
+		g.Set(float64(runtime.NumGoroutine()))
+	}
+}
+```
+
+For more information, see [the package documentation](https://godoc.org/github.com/go-kit/kit/metrics).