vendor/go.opencensus.io/plugin/ochttp/client_stats.go

   1 // Copyright 2018, OpenCensus Authors
   2 //
   3 // Licensed under the Apache License, Version 2.0 (the "License");
   4 // you may not use this file except in compliance with the License.
   5 // You may obtain a copy of the License at
   6 //
   7 //     http://www.apache.org/licenses/LICENSE-2.0
   8 //
   9 // Unless required by applicable law or agreed to in writing, software
  10 // distributed under the License is distributed on an "AS IS" BASIS,
  11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  12 // See the License for the specific language governing permissions and
  13 // limitations under the License.
  14
  15 package ochttp
  16
  17 import (
  18         "context"
  19         "io"
  20         "net/http"
  21         "strconv"
  22         "sync"
  23         "time"
  24
  25         "go.opencensus.io/stats"
  26         "go.opencensus.io/tag"
  27 )
  28
  29 // statsTransport is an http.RoundTripper that collects stats for the outgoing requests.
  30 type statsTransport struct {
  31         base http.RoundTripper
  32 }
  33
  34 // RoundTrip implements http.RoundTripper, delegating to Base and recording stats for the request.
  35 func (t statsTransport) RoundTrip(req *http.Request) (*http.Response, error) {
  36         ctx, _ := tag.New(req.Context(),
  37                 tag.Upsert(KeyClientHost, req.URL.Host),
  38                 tag.Upsert(Host, req.URL.Host),
  39                 tag.Upsert(KeyClientPath, req.URL.Path),
  40                 tag.Upsert(Path, req.URL.Path),
  41                 tag.Upsert(KeyClientMethod, req.Method),
  42                 tag.Upsert(Method, req.Method))
  43         req = req.WithContext(ctx)
  44         track := &tracker{
  45                 start: time.Now(),
  46                 ctx:   ctx,
  47         }
  48         if req.Body == nil {
  49                 // TODO: Handle cases where ContentLength is not set.
  50                 track.reqSize = -1
  51         } else if req.ContentLength > 0 {
  52                 track.reqSize = req.ContentLength
  53         }
  54         stats.Record(ctx, ClientRequestCount.M(1))
  55
  56         // Perform request.
  57         resp, err := t.base.RoundTrip(req)
  58
  59         if err != nil {
  60                 track.statusCode = http.StatusInternalServerError
  61                 track.end()
  62         } else {
  63                 track.statusCode = resp.StatusCode
  64                 if resp.Body == nil {
  65                         track.end()
  66                 } else {
  67                         track.body = resp.Body
  68                         resp.Body = track
  69                 }
  70         }
  71         return resp, err
  72 }
  73
  74 // CancelRequest cancels an in-flight request by closing its connection.
  75 func (t statsTransport) CancelRequest(req *http.Request) {
  76         type canceler interface {
  77                 CancelRequest(*http.Request)
  78         }
  79         if cr, ok := t.base.(canceler); ok {
  80                 cr.CancelRequest(req)
  81         }
  82 }
  83
  84 type tracker struct {
  85         ctx        context.Context
  86         respSize   int64
  87         reqSize    int64
  88         start      time.Time
  89         body       io.ReadCloser
  90         statusCode int
  91         endOnce    sync.Once
  92 }
  93
  94 var _ io.ReadCloser = (*tracker)(nil)
  95
  96 func (t *tracker) end() {
  97         t.endOnce.Do(func() {
  98                 latencyMs := float64(time.Since(t.start)) / float64(time.Millisecond)
  99                 m := []stats.Measurement{
 100                         ClientSentBytes.M(t.reqSize),
 101                         ClientReceivedBytes.M(t.respSize),
 102                         ClientRoundtripLatency.M(latencyMs),
 103                         ClientLatency.M(latencyMs),
 104                         ClientResponseBytes.M(t.respSize),
 105                 }
 106                 if t.reqSize >= 0 {
 107                         m = append(m, ClientRequestBytes.M(t.reqSize))
 108                 }
 109
 110                 stats.RecordWithTags(t.ctx, []tag.Mutator{
 111                         tag.Upsert(StatusCode, strconv.Itoa(t.statusCode)),
 112                         tag.Upsert(KeyClientStatus, strconv.Itoa(t.statusCode)),
 113                 }, m...)
 114         })
 115 }
 116
 117 func (t *tracker) Read(b []byte) (int, error) {
 118         n, err := t.body.Read(b)
 119         switch err {
 120         case nil:
 121                 t.respSize += int64(n)
 122                 return n, nil
 123         case io.EOF:
 124                 t.end()
 125         }
 126         return n, err
 127 }
 128
 129 func (t *tracker) Close() error {
 130         // Invoking endSpan on Close will help catch the cases
 131         // in which a read returned a non-nil error, we set the
 132         // span status but didn't end the span.
 133         t.end()
 134         return t.body.Close()
 135 }