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 14package promhttp 15 16import ( 17 "bufio" 18 "io" 19 "net" 20 "net/http" 21) 22 23const ( 24 closeNotifier = 1 << iota 25 flusher 26 hijacker 27 readerFrom 28 pusher 29) 30 31type delegator interface { 32 http.ResponseWriter 33 34 Status() int 35 Written() int64 36} 37 38type responseWriterDelegator struct { 39 http.ResponseWriter 40 41 status int 42 written int64 43 wroteHeader bool 44 observeWriteHeader func(int) 45} 46 47func (r *responseWriterDelegator) Status() int { 48 return r.status 49} 50 51func (r *responseWriterDelegator) Written() int64 { 52 return r.written 53} 54 55func (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 64func (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 73type closeNotifierDelegator struct{ *responseWriterDelegator } 74type flusherDelegator struct{ *responseWriterDelegator } 75type hijackerDelegator struct{ *responseWriterDelegator } 76type readerFromDelegator struct{ *responseWriterDelegator } 77 78func (d closeNotifierDelegator) CloseNotify() <-chan bool { 79 return d.ResponseWriter.(http.CloseNotifier).CloseNotify() 80} 81func (d flusherDelegator) Flush() { 82 d.ResponseWriter.(http.Flusher).Flush() 83} 84func (d hijackerDelegator) Hijack() (net.Conn, *bufio.ReadWriter, error) { 85 return d.ResponseWriter.(http.Hijacker).Hijack() 86} 87func (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 96var pickDelegator = make([]func(*responseWriterDelegator) delegator, 32) 97 98func 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} 199