cmd/bpa-operator/vendor/github.com/prometheus/client_golang/prometheus/promhttp/delegator.go

   1 // Copyright 2017 The Prometheus Authors
   2 // Licensed under the Apache License, Version 2.0 (the "License");
   3 // you may not use this file except in compliance with the License.
   4 // You may obtain a copy of the License at
   5 //
   6 // http://www.apache.org/licenses/LICENSE-2.0
   7 //
   8 // Unless required by applicable law or agreed to in writing, software
   9 // distributed under the License is distributed on an "AS IS" BASIS,
  10 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  11 // See the License for the specific language governing permissions and
  12 // limitations under the License.
  13
  14 package promhttp
  15
  16 import (
  17         "bufio"
  18         "io"
  19         "net"
  20         "net/http"
  21 )
  22
  23 const (
  24         closeNotifier = 1 << iota
  25         flusher
  26         hijacker
  27         readerFrom
  28         pusher
  29 )
  30
  31 type delegator interface {
  32         http.ResponseWriter
  33
  34         Status() int
  35         Written() int64
  36 }
  37
  38 type responseWriterDelegator struct {
  39         http.ResponseWriter
  40
  41         status             int
  42         written            int64
  43         wroteHeader        bool
  44         observeWriteHeader func(int)
  45 }
  46
  47 func (r *responseWriterDelegator) Status() int {
  48         return r.status
  49 }
  50
  51 func (r *responseWriterDelegator) Written() int64 {
  52         return r.written
  53 }
  54
  55 func (r *responseWriterDelegator) WriteHeader(code int) {
  56         r.status = code
  57         r.wroteHeader = true
  58         r.ResponseWriter.WriteHeader(code)
  59         if r.observeWriteHeader != nil {
  60                 r.observeWriteHeader(code)
  61         }
  62 }
  63
  64 func (r *responseWriterDelegator) Write(b []byte) (int, error) {
  65         if !r.wroteHeader {
  66                 r.WriteHeader(http.StatusOK)
  67         }
  68         n, err := r.ResponseWriter.Write(b)
  69         r.written += int64(n)
  70         return n, err
  71 }
  72
  73 type closeNotifierDelegator struct{ *responseWriterDelegator }
  74 type flusherDelegator struct{ *responseWriterDelegator }
  75 type hijackerDelegator struct{ *responseWriterDelegator }
  76 type readerFromDelegator struct{ *responseWriterDelegator }
  77
  78 func (d closeNotifierDelegator) CloseNotify() <-chan bool {
  79         return d.ResponseWriter.(http.CloseNotifier).CloseNotify()
  80 }
  81 func (d flusherDelegator) Flush() {
  82         d.ResponseWriter.(http.Flusher).Flush()
  83 }
  84 func (d hijackerDelegator) Hijack() (net.Conn, *bufio.ReadWriter, error) {
  85         return d.ResponseWriter.(http.Hijacker).Hijack()
  86 }
  87 func (d readerFromDelegator) ReadFrom(re io.Reader) (int64, error) {
  88         if !d.wroteHeader {
  89                 d.WriteHeader(http.StatusOK)
  90         }
  91         n, err := d.ResponseWriter.(io.ReaderFrom).ReadFrom(re)
  92         d.written += n
  93         return n, err
  94 }
  95
  96 var pickDelegator = make([]func(*responseWriterDelegator) delegator, 32)
  97
  98 func init() {
  99         // TODO(beorn7): Code generation would help here.
 100         pickDelegator[0] = func(d *responseWriterDelegator) delegator { // 0
 101                 return d
 102         }
 103         pickDelegator[closeNotifier] = func(d *responseWriterDelegator) delegator { // 1
 104                 return closeNotifierDelegator{d}
 105         }
 106         pickDelegator[flusher] = func(d *responseWriterDelegator) delegator { // 2
 107                 return flusherDelegator{d}
 108         }
 109         pickDelegator[flusher+closeNotifier] = func(d *responseWriterDelegator) delegator { // 3
 110                 return struct {
 111                         *responseWriterDelegator
 112                         http.Flusher
 113                         http.CloseNotifier
 114                 }{d, flusherDelegator{d}, closeNotifierDelegator{d}}
 115         }
 116         pickDelegator[hijacker] = func(d *responseWriterDelegator) delegator { // 4
 117                 return hijackerDelegator{d}
 118         }
 119         pickDelegator[hijacker+closeNotifier] = func(d *responseWriterDelegator) delegator { // 5
 120                 return struct {
 121                         *responseWriterDelegator
 122                         http.Hijacker
 123                         http.CloseNotifier
 124                 }{d, hijackerDelegator{d}, closeNotifierDelegator{d}}
 125         }
 126         pickDelegator[hijacker+flusher] = func(d *responseWriterDelegator) delegator { // 6
 127                 return struct {
 128                         *responseWriterDelegator
 129                         http.Hijacker
 130                         http.Flusher
 131                 }{d, hijackerDelegator{d}, flusherDelegator{d}}
 132         }
 133         pickDelegator[hijacker+flusher+closeNotifier] = func(d *responseWriterDelegator) delegator { // 7
 134                 return struct {
 135                         *responseWriterDelegator
 136                         http.Hijacker
 137                         http.Flusher
 138                         http.CloseNotifier
 139                 }{d, hijackerDelegator{d}, flusherDelegator{d}, closeNotifierDelegator{d}}
 140         }
 141         pickDelegator[readerFrom] = func(d *responseWriterDelegator) delegator { // 8
 142                 return readerFromDelegator{d}
 143         }
 144         pickDelegator[readerFrom+closeNotifier] = func(d *responseWriterDelegator) delegator { // 9
 145                 return struct {
 146                         *responseWriterDelegator
 147                         io.ReaderFrom
 148                         http.CloseNotifier
 149                 }{d, readerFromDelegator{d}, closeNotifierDelegator{d}}
 150         }
 151         pickDelegator[readerFrom+flusher] = func(d *responseWriterDelegator) delegator { // 10
 152                 return struct {
 153                         *responseWriterDelegator
 154                         io.ReaderFrom
 155                         http.Flusher
 156                 }{d, readerFromDelegator{d}, flusherDelegator{d}}
 157         }
 158         pickDelegator[readerFrom+flusher+closeNotifier] = func(d *responseWriterDelegator) delegator { // 11
 159                 return struct {
 160                         *responseWriterDelegator
 161                         io.ReaderFrom
 162                         http.Flusher
 163                         http.CloseNotifier
 164                 }{d, readerFromDelegator{d}, flusherDelegator{d}, closeNotifierDelegator{d}}
 165         }
 166         pickDelegator[readerFrom+hijacker] = func(d *responseWriterDelegator) delegator { // 12
 167                 return struct {
 168                         *responseWriterDelegator
 169                         io.ReaderFrom
 170                         http.Hijacker
 171                 }{d, readerFromDelegator{d}, hijackerDelegator{d}}
 172         }
 173         pickDelegator[readerFrom+hijacker+closeNotifier] = func(d *responseWriterDelegator) delegator { // 13
 174                 return struct {
 175                         *responseWriterDelegator
 176                         io.ReaderFrom
 177                         http.Hijacker
 178                         http.CloseNotifier
 179                 }{d, readerFromDelegator{d}, hijackerDelegator{d}, closeNotifierDelegator{d}}
 180         }
 181         pickDelegator[readerFrom+hijacker+flusher] = func(d *responseWriterDelegator) delegator { // 14
 182                 return struct {
 183                         *responseWriterDelegator
 184                         io.ReaderFrom
 185                         http.Hijacker
 186                         http.Flusher
 187                 }{d, readerFromDelegator{d}, hijackerDelegator{d}, flusherDelegator{d}}
 188         }
 189         pickDelegator[readerFrom+hijacker+flusher+closeNotifier] = func(d *responseWriterDelegator) delegator { // 15
 190                 return struct {
 191                         *responseWriterDelegator
 192                         io.ReaderFrom
 193                         http.Hijacker
 194                         http.Flusher
 195                         http.CloseNotifier
 196                 }{d, readerFromDelegator{d}, hijackerDelegator{d}, flusherDelegator{d}, closeNotifierDelegator{d}}
 197         }
 198 }