/*
Create a http.HandlerFunc that is tied to r Registry such that requests
against it generate a representation of the housed metrics.
*/
func (registry *Registry) YieldExporter() http.HandlerFunc {
return func(w http.ResponseWriter, r *http.Request) {
var instrumentable metrics.InstrumentableCall = func() {
requestCount.Increment(nil)
url := r.URL
if strings.HasSuffix(url.Path, jsonSuffix) {
header := w.Header()
header.Set(ProtocolVersionHeader, APIVersion)
header.Set(contentTypeHeader, jsonContentType)
writer := decorateWriter(r, w)
// TODO(matt): Migrate to ioutil.NopCloser.
if closer, ok := writer.(io.Closer); ok {
defer closer.Close()
}
registry.dumpToWriter(writer)
} else {
w.WriteHeader(http.StatusNotFound)
}
}
metrics.InstrumentCall(instrumentable, requestLatencyAccumulator)
}
}
func (t *target) Scrape(earliest time.Time, results chan format.Result) (err error) {
defer func() {
futureState := t.state
switch err {
case nil:
futureState = ALIVE
default:
futureState = UNREACHABLE
}
t.scheduler.Reschedule(earliest, futureState)
t.state = futureState
}()
done := make(chan bool)
request := func() {
defer func() {
done <- true
}()
var resp *http.Response // Don't shadow "err" from the enclosing function.
resp, err = http.Get(t.Address())
if err != nil {
return
}
defer resp.Body.Close()
processor, err := format.DefaultRegistry.ProcessorForRequestHeader(resp.Header)
if err != nil {
return
}
// XXX: This is a wart; we need to handle this more gracefully down the
// road, especially once we have service discovery support.
baseLabels := model.LabelSet{instance: model.LabelValue(t.Address())}
for baseLabel, baseValue := range t.baseLabels {
baseLabels[baseLabel] = baseValue
}
err = processor.Process(resp.Body, baseLabels, results)
if err != nil {
return
}
}
accumulator := func(d time.Duration) {
ms := float64(d) / float64(time.Millisecond)
labels := map[string]string{address: t.Address(), outcome: success}
if err != nil {
labels[outcome] = failure
}
targetOperationLatencies.Add(labels, ms)
targetOperations.Increment(labels)
}
go metrics.InstrumentCall(request, accumulator)
select {
case <-done:
break
case <-time.After(t.Deadline):
err = fmt.Errorf("Target %s exceeded %s deadline.", t, t.Deadline)
}
return
}