sslobodr | d046be8 | 2019-01-16 10:02:22 -0500 | [diff] [blame] | 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 | handler, method string |
| 42 | status int |
| 43 | written int64 |
| 44 | wroteHeader bool |
| 45 | observeWriteHeader func(int) |
| 46 | } |
| 47 | |
| 48 | func (r *responseWriterDelegator) Status() int { |
| 49 | return r.status |
| 50 | } |
| 51 | |
| 52 | func (r *responseWriterDelegator) Written() int64 { |
| 53 | return r.written |
| 54 | } |
| 55 | |
| 56 | func (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 | |
| 65 | func (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 | |
| 74 | type closeNotifierDelegator struct{ *responseWriterDelegator } |
| 75 | type flusherDelegator struct{ *responseWriterDelegator } |
| 76 | type hijackerDelegator struct{ *responseWriterDelegator } |
| 77 | type readerFromDelegator struct{ *responseWriterDelegator } |
| 78 | |
| 79 | func (d closeNotifierDelegator) CloseNotify() <-chan bool { |
| 80 | return d.ResponseWriter.(http.CloseNotifier).CloseNotify() |
| 81 | } |
| 82 | func (d flusherDelegator) Flush() { |
| 83 | d.ResponseWriter.(http.Flusher).Flush() |
| 84 | } |
| 85 | func (d hijackerDelegator) Hijack() (net.Conn, *bufio.ReadWriter, error) { |
| 86 | return d.ResponseWriter.(http.Hijacker).Hijack() |
| 87 | } |
| 88 | func (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 | |
| 97 | var pickDelegator = make([]func(*responseWriterDelegator) delegator, 32) |
| 98 | |
| 99 | func 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 | } |