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 handler, method string 42 status int 43 written int64 44 wroteHeader bool 45 observeWriteHeader func(int) 46} 47 48func (r *responseWriterDelegator) Status() int { 49 return r.status 50} 51 52func (r *responseWriterDelegator) Written() int64 { 53 return r.written 54} 55 56func (r *responseWriterDelegator) WriteHeader(code int) { 57 r.status = code 58 r.wroteHeader = true 59 r.ResponseWriter.WriteHeader(code) 60 if r.observeWriteHeader != nil { 61 r.observeWriteHeader(code) 62 } 63} 64 65func (r *responseWriterDelegator) Write(b []byte) (int, error) { 66 if !r.wroteHeader { 67 r.WriteHeader(http.StatusOK) 68 } 69 n, err := r.ResponseWriter.Write(b) 70 r.written += int64(n) 71 return n, err 72} 73 74type closeNotifierDelegator struct{ *responseWriterDelegator } 75type flusherDelegator struct{ *responseWriterDelegator } 76type hijackerDelegator struct{ *responseWriterDelegator } 77type readerFromDelegator struct{ *responseWriterDelegator } 78 79func (d closeNotifierDelegator) CloseNotify() <-chan bool { 80 return d.ResponseWriter.(http.CloseNotifier).CloseNotify() 81} 82func (d flusherDelegator) Flush() { 83 d.ResponseWriter.(http.Flusher).Flush() 84} 85func (d hijackerDelegator) Hijack() (net.Conn, *bufio.ReadWriter, error) { 86 return d.ResponseWriter.(http.Hijacker).Hijack() 87} 88func (d readerFromDelegator) ReadFrom(re io.Reader) (int64, error) { 89 if !d.wroteHeader { 90 d.WriteHeader(http.StatusOK) 91 } 92 n, err := d.ResponseWriter.(io.ReaderFrom).ReadFrom(re) 93 d.written += n 94 return n, err 95} 96 97var pickDelegator = make([]func(*responseWriterDelegator) delegator, 32) 98 99func init() { 100 // TODO(beorn7): Code generation would help here. 101 pickDelegator[0] = func(d *responseWriterDelegator) delegator { // 0 102 return d 103 } 104 pickDelegator[closeNotifier] = func(d *responseWriterDelegator) delegator { // 1 105 return closeNotifierDelegator{d} 106 } 107 pickDelegator[flusher] = func(d *responseWriterDelegator) delegator { // 2 108 return flusherDelegator{d} 109 } 110 pickDelegator[flusher+closeNotifier] = func(d *responseWriterDelegator) delegator { // 3 111 return struct { 112 *responseWriterDelegator 113 http.Flusher 114 http.CloseNotifier 115 }{d, flusherDelegator{d}, closeNotifierDelegator{d}} 116 } 117 pickDelegator[hijacker] = func(d *responseWriterDelegator) delegator { // 4 118 return hijackerDelegator{d} 119 } 120 pickDelegator[hijacker+closeNotifier] = func(d *responseWriterDelegator) delegator { // 5 121 return struct { 122 *responseWriterDelegator 123 http.Hijacker 124 http.CloseNotifier 125 }{d, hijackerDelegator{d}, closeNotifierDelegator{d}} 126 } 127 pickDelegator[hijacker+flusher] = func(d *responseWriterDelegator) delegator { // 6 128 return struct { 129 *responseWriterDelegator 130 http.Hijacker 131 http.Flusher 132 }{d, hijackerDelegator{d}, flusherDelegator{d}} 133 } 134 pickDelegator[hijacker+flusher+closeNotifier] = func(d *responseWriterDelegator) delegator { // 7 135 return struct { 136 *responseWriterDelegator 137 http.Hijacker 138 http.Flusher 139 http.CloseNotifier 140 }{d, hijackerDelegator{d}, flusherDelegator{d}, closeNotifierDelegator{d}} 141 } 142 pickDelegator[readerFrom] = func(d *responseWriterDelegator) delegator { // 8 143 return readerFromDelegator{d} 144 } 145 pickDelegator[readerFrom+closeNotifier] = func(d *responseWriterDelegator) delegator { // 9 146 return struct { 147 *responseWriterDelegator 148 io.ReaderFrom 149 http.CloseNotifier 150 }{d, readerFromDelegator{d}, closeNotifierDelegator{d}} 151 } 152 pickDelegator[readerFrom+flusher] = func(d *responseWriterDelegator) delegator { // 10 153 return struct { 154 *responseWriterDelegator 155 io.ReaderFrom 156 http.Flusher 157 }{d, readerFromDelegator{d}, flusherDelegator{d}} 158 } 159 pickDelegator[readerFrom+flusher+closeNotifier] = func(d *responseWriterDelegator) delegator { // 11 160 return struct { 161 *responseWriterDelegator 162 io.ReaderFrom 163 http.Flusher 164 http.CloseNotifier 165 }{d, readerFromDelegator{d}, flusherDelegator{d}, closeNotifierDelegator{d}} 166 } 167 pickDelegator[readerFrom+hijacker] = func(d *responseWriterDelegator) delegator { // 12 168 return struct { 169 *responseWriterDelegator 170 io.ReaderFrom 171 http.Hijacker 172 }{d, readerFromDelegator{d}, hijackerDelegator{d}} 173 } 174 pickDelegator[readerFrom+hijacker+closeNotifier] = func(d *responseWriterDelegator) delegator { // 13 175 return struct { 176 *responseWriterDelegator 177 io.ReaderFrom 178 http.Hijacker 179 http.CloseNotifier 180 }{d, readerFromDelegator{d}, hijackerDelegator{d}, closeNotifierDelegator{d}} 181 } 182 pickDelegator[readerFrom+hijacker+flusher] = func(d *responseWriterDelegator) delegator { // 14 183 return struct { 184 *responseWriterDelegator 185 io.ReaderFrom 186 http.Hijacker 187 http.Flusher 188 }{d, readerFromDelegator{d}, hijackerDelegator{d}, flusherDelegator{d}} 189 } 190 pickDelegator[readerFrom+hijacker+flusher+closeNotifier] = func(d *responseWriterDelegator) delegator { // 15 191 return struct { 192 *responseWriterDelegator 193 io.ReaderFrom 194 http.Hijacker 195 http.Flusher 196 http.CloseNotifier 197 }{d, readerFromDelegator{d}, hijackerDelegator{d}, flusherDelegator{d}, closeNotifierDelegator{d}} 198 } 199} 200