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

Fixes #52

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

@@ -0,0 +1,96 @@
+// Package metrics provides a framework for application instrumentation. It's
+// primarily designed to help you get started with good and robust
+// instrumentation, and to help you migrate from a less-capable system like
+// Graphite to a more-capable system like Prometheus. If your organization has
+// already standardized on an instrumentation system like Prometheus, and has no
+// plans to change, it may make sense to use that system's instrumentation
+// library directly.
+//
+// This package provides three core metric abstractions (Counter, Gauge, and
+// Histogram) and implementations for almost all common instrumentation
+// backends. Each metric has an observation method (Add, Set, or Observe,
+// respectively) used to record values, and a With method to "scope" the
+// observation by various parameters. For example, you might have a Histogram to
+// record request durations, parameterized by the method that's being called.
+//
+//    var requestDuration metrics.Histogram
+//    // ...
+//    requestDuration.With("method", "MyMethod").Observe(time.Since(begin))
+//
+// This allows a single high-level metrics object (requestDuration) to work with
+// many code paths somewhat dynamically. The concept of With is fully supported
+// in some backends like Prometheus, and not supported in other backends like
+// Graphite. So, With may be a no-op, depending on the concrete implementation
+// you choose. Please check the implementation to know for sure. For
+// implementations that don't provide With, it's necessary to fully parameterize
+// each metric in the metric name, e.g.
+//
+//    // Statsd
+//    c := statsd.NewCounter("request_duration_MyMethod_200")
+//    c.Add(1)
+//
+//    // Prometheus
+//    c := prometheus.NewCounter(stdprometheus.CounterOpts{
+//        Name: "request_duration",
+//        ...
+//    }, []string{"method", "status_code"})
+//    c.With("method", "MyMethod", "status_code", strconv.Itoa(code)).Add(1)
+//
+// 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. Metrics should *not* be created in the global scope.
+// Instead, instantiate 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)
+//
+// Note that metrics are "write-only" interfaces.
+//
+// Implementation details
+//
+// All metrics are safe for concurrent use. Considerable design influence has
+// been taken from https://github.com/codahale/metrics and
+// https://prometheus.io.
+//
+// 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
+//    pcp         1    native                 native                 native
+//
+package metrics