Vendor main dependencies.

vendor/github.com/go-kit/kit/metrics/doc.go

@@ -0,0 +1,60 @@
+// Package metrics provides a framework for application instrumentation. All
+// metrics are safe for concurrent use. Considerable design influence has been
+// taken from https://github.com/codahale/metrics and https://prometheus.io.
+//
+// This package contains the common interfaces. Your code should take these
+// interfaces as parameters. Implementations are provided for different
+// instrumentation systems in the various subdirectories.
+//
+// Usage
+//
+// Metrics are dependencies and should be passed to the components that need
+// them in the same way you'd construct and pass a database handle, or reference
+// to another component. So, create metrics in your func main, using whichever
+// concrete implementation is appropriate for your organization.
+//
+//    latency := prometheus.NewSummaryFrom(stdprometheus.SummaryOpts{
+//        Namespace: "myteam",
+//        Subsystem: "foosvc",
+//        Name:      "request_latency_seconds",
+//        Help:      "Incoming request latency in seconds."
+//    }, []string{"method", "status_code"})
+//
+// Write your components to take the metrics they will use as parameters to
+// their constructors. Use the interface types, not the concrete types. That is,
+//
+//    // NewAPI takes metrics.Histogram, not *prometheus.Summary
+//    func NewAPI(s Store, logger log.Logger, latency metrics.Histogram) *API {
+//        // ...
+//    }
+//
+//    func (a *API) ServeFoo(w http.ResponseWriter, r *http.Request) {
+//        begin := time.Now()
+//        // ...
+//        a.latency.Observe(time.Since(begin).Seconds())
+//    }
+//
+// Finally, pass the metrics as dependencies when building your object graph.
+// This should happen in func main, not in the global scope.
+//
+//    api := NewAPI(store, logger, latency)
+//    http.ListenAndServe("/", api)
+//
+// Implementation details
+//
+// Each telemetry system has different semantics for label values, push vs.
+// pull, support for histograms, etc. These properties influence the design of
+// their respective packages. This table attempts to summarize the key points of
+// distinction.
+//
+//    SYSTEM      DIM  COUNTERS               GAUGES                 HISTOGRAMS
+//    dogstatsd   n    batch, push-aggregate  batch, push-aggregate  native, batch, push-each
+//    statsd      1    batch, push-aggregate  batch, push-aggregate  native, batch, push-each
+//    graphite    1    batch, push-aggregate  batch, push-aggregate  synthetic, batch, push-aggregate
+//    expvar      1    atomic                 atomic                 synthetic, batch, in-place expose
+//    influx      n    custom                 custom                 custom
+//    prometheus  n    native                 native                 native
+//    circonus    1    native                 native                 native
+//    pcp         1    native                 native                 native
+//
+package metrics