api/metrics.go

   1 package api
   2
   3 import (
   4         "net/http"
   5         "sync"
   6         "time"
   7
   8         "github.com/vapor/metrics"
   9 )
  10
  11 var (
  12         latencyMu sync.Mutex
  13         latencies = map[string]*metrics.RotatingLatency{}
  14 )
  15
  16 // latency returns a rotating latency histogram for the given request.
  17 func latency(tab *http.ServeMux, req *http.Request) *metrics.RotatingLatency {
  18         latencyMu.Lock()
  19         defer latencyMu.Unlock()
  20         if l := latencies[req.URL.Path]; l != nil {
  21                 return l
  22         }
  23         // Create a histogram only if the path is legit.
  24         if _, pat := tab.Handler(req); pat == req.URL.Path {
  25                 d := 100 * time.Millisecond
  26                 l := metrics.NewRotatingLatency(5, d)
  27                 latencies[req.URL.Path] = l
  28                 metrics.PublishLatency(req.URL.Path, l)
  29                 return l
  30         }
  31         return nil
  32 }