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- // Copyright 2017 The Prometheus Authors
- // Licensed under the Apache License, Version 2.0 (the "License");
- // you may not use this file except in compliance with the License.
- // You may obtain a copy of the License at
- //
- // http://www.apache.org/licenses/LICENSE-2.0
- //
- // Unless required by applicable law or agreed to in writing, software
- // distributed under the License is distributed on an "AS IS" BASIS,
- // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- // See the License for the specific language governing permissions and
- // limitations under the License.
-
- package promhttp
-
- import (
- "bufio"
- "io"
- "net"
- "net/http"
- )
-
- const (
- closeNotifier = 1 << iota
- flusher
- hijacker
- readerFrom
- pusher
- )
-
- type delegator interface {
- http.ResponseWriter
-
- Status() int
- Written() int64
- }
-
- type responseWriterDelegator struct {
- http.ResponseWriter
-
- status int
- written int64
- wroteHeader bool
- observeWriteHeader func(int)
- }
-
- func (r *responseWriterDelegator) Status() int {
- return r.status
- }
-
- func (r *responseWriterDelegator) Written() int64 {
- return r.written
- }
-
- func (r *responseWriterDelegator) WriteHeader(code int) {
- if r.observeWriteHeader != nil && !r.wroteHeader {
- // Only call observeWriteHeader for the 1st time. It's a bug if
- // WriteHeader is called more than once, but we want to protect
- // against it here. Note that we still delegate the WriteHeader
- // to the original ResponseWriter to not mask the bug from it.
- r.observeWriteHeader(code)
- }
- r.status = code
- r.wroteHeader = true
- r.ResponseWriter.WriteHeader(code)
- }
-
- func (r *responseWriterDelegator) Write(b []byte) (int, error) {
- // If applicable, call WriteHeader here so that observeWriteHeader is
- // handled appropriately.
- if !r.wroteHeader {
- r.WriteHeader(http.StatusOK)
- }
- n, err := r.ResponseWriter.Write(b)
- r.written += int64(n)
- return n, err
- }
-
- type closeNotifierDelegator struct{ *responseWriterDelegator }
- type flusherDelegator struct{ *responseWriterDelegator }
- type hijackerDelegator struct{ *responseWriterDelegator }
- type readerFromDelegator struct{ *responseWriterDelegator }
- type pusherDelegator struct{ *responseWriterDelegator }
-
- func (d closeNotifierDelegator) CloseNotify() <-chan bool {
- //nolint:staticcheck // Ignore SA1019. http.CloseNotifier is deprecated but we keep it here to not break existing users.
- return d.ResponseWriter.(http.CloseNotifier).CloseNotify()
- }
- func (d flusherDelegator) Flush() {
- // If applicable, call WriteHeader here so that observeWriteHeader is
- // handled appropriately.
- if !d.wroteHeader {
- d.WriteHeader(http.StatusOK)
- }
- d.ResponseWriter.(http.Flusher).Flush()
- }
- func (d hijackerDelegator) Hijack() (net.Conn, *bufio.ReadWriter, error) {
- return d.ResponseWriter.(http.Hijacker).Hijack()
- }
- func (d readerFromDelegator) ReadFrom(re io.Reader) (int64, error) {
- // If applicable, call WriteHeader here so that observeWriteHeader is
- // handled appropriately.
- if !d.wroteHeader {
- d.WriteHeader(http.StatusOK)
- }
- n, err := d.ResponseWriter.(io.ReaderFrom).ReadFrom(re)
- d.written += n
- return n, err
- }
- func (d pusherDelegator) Push(target string, opts *http.PushOptions) error {
- return d.ResponseWriter.(http.Pusher).Push(target, opts)
- }
-
- var pickDelegator = make([]func(*responseWriterDelegator) delegator, 32)
-
- func init() {
- // TODO(beorn7): Code generation would help here.
- pickDelegator[0] = func(d *responseWriterDelegator) delegator { // 0
- return d
- }
- pickDelegator[closeNotifier] = func(d *responseWriterDelegator) delegator { // 1
- return closeNotifierDelegator{d}
- }
- pickDelegator[flusher] = func(d *responseWriterDelegator) delegator { // 2
- return flusherDelegator{d}
- }
- pickDelegator[flusher+closeNotifier] = func(d *responseWriterDelegator) delegator { // 3
- return struct {
- *responseWriterDelegator
- http.Flusher
- http.CloseNotifier
- }{d, flusherDelegator{d}, closeNotifierDelegator{d}}
- }
- pickDelegator[hijacker] = func(d *responseWriterDelegator) delegator { // 4
- return hijackerDelegator{d}
- }
- pickDelegator[hijacker+closeNotifier] = func(d *responseWriterDelegator) delegator { // 5
- return struct {
- *responseWriterDelegator
- http.Hijacker
- http.CloseNotifier
- }{d, hijackerDelegator{d}, closeNotifierDelegator{d}}
- }
- pickDelegator[hijacker+flusher] = func(d *responseWriterDelegator) delegator { // 6
- return struct {
- *responseWriterDelegator
- http.Hijacker
- http.Flusher
- }{d, hijackerDelegator{d}, flusherDelegator{d}}
- }
- pickDelegator[hijacker+flusher+closeNotifier] = func(d *responseWriterDelegator) delegator { // 7
- return struct {
- *responseWriterDelegator
- http.Hijacker
- http.Flusher
- http.CloseNotifier
- }{d, hijackerDelegator{d}, flusherDelegator{d}, closeNotifierDelegator{d}}
- }
- pickDelegator[readerFrom] = func(d *responseWriterDelegator) delegator { // 8
- return readerFromDelegator{d}
- }
- pickDelegator[readerFrom+closeNotifier] = func(d *responseWriterDelegator) delegator { // 9
- return struct {
- *responseWriterDelegator
- io.ReaderFrom
- http.CloseNotifier
- }{d, readerFromDelegator{d}, closeNotifierDelegator{d}}
- }
- pickDelegator[readerFrom+flusher] = func(d *responseWriterDelegator) delegator { // 10
- return struct {
- *responseWriterDelegator
- io.ReaderFrom
- http.Flusher
- }{d, readerFromDelegator{d}, flusherDelegator{d}}
- }
- pickDelegator[readerFrom+flusher+closeNotifier] = func(d *responseWriterDelegator) delegator { // 11
- return struct {
- *responseWriterDelegator
- io.ReaderFrom
- http.Flusher
- http.CloseNotifier
- }{d, readerFromDelegator{d}, flusherDelegator{d}, closeNotifierDelegator{d}}
- }
- pickDelegator[readerFrom+hijacker] = func(d *responseWriterDelegator) delegator { // 12
- return struct {
- *responseWriterDelegator
- io.ReaderFrom
- http.Hijacker
- }{d, readerFromDelegator{d}, hijackerDelegator{d}}
- }
- pickDelegator[readerFrom+hijacker+closeNotifier] = func(d *responseWriterDelegator) delegator { // 13
- return struct {
- *responseWriterDelegator
- io.ReaderFrom
- http.Hijacker
- http.CloseNotifier
- }{d, readerFromDelegator{d}, hijackerDelegator{d}, closeNotifierDelegator{d}}
- }
- pickDelegator[readerFrom+hijacker+flusher] = func(d *responseWriterDelegator) delegator { // 14
- return struct {
- *responseWriterDelegator
- io.ReaderFrom
- http.Hijacker
- http.Flusher
- }{d, readerFromDelegator{d}, hijackerDelegator{d}, flusherDelegator{d}}
- }
- pickDelegator[readerFrom+hijacker+flusher+closeNotifier] = func(d *responseWriterDelegator) delegator { // 15
- return struct {
- *responseWriterDelegator
- io.ReaderFrom
- http.Hijacker
- http.Flusher
- http.CloseNotifier
- }{d, readerFromDelegator{d}, hijackerDelegator{d}, flusherDelegator{d}, closeNotifierDelegator{d}}
- }
- pickDelegator[pusher] = func(d *responseWriterDelegator) delegator { // 16
- return pusherDelegator{d}
- }
- pickDelegator[pusher+closeNotifier] = func(d *responseWriterDelegator) delegator { // 17
- return struct {
- *responseWriterDelegator
- http.Pusher
- http.CloseNotifier
- }{d, pusherDelegator{d}, closeNotifierDelegator{d}}
- }
- pickDelegator[pusher+flusher] = func(d *responseWriterDelegator) delegator { // 18
- return struct {
- *responseWriterDelegator
- http.Pusher
- http.Flusher
- }{d, pusherDelegator{d}, flusherDelegator{d}}
- }
- pickDelegator[pusher+flusher+closeNotifier] = func(d *responseWriterDelegator) delegator { // 19
- return struct {
- *responseWriterDelegator
- http.Pusher
- http.Flusher
- http.CloseNotifier
- }{d, pusherDelegator{d}, flusherDelegator{d}, closeNotifierDelegator{d}}
- }
- pickDelegator[pusher+hijacker] = func(d *responseWriterDelegator) delegator { // 20
- return struct {
- *responseWriterDelegator
- http.Pusher
- http.Hijacker
- }{d, pusherDelegator{d}, hijackerDelegator{d}}
- }
- pickDelegator[pusher+hijacker+closeNotifier] = func(d *responseWriterDelegator) delegator { // 21
- return struct {
- *responseWriterDelegator
- http.Pusher
- http.Hijacker
- http.CloseNotifier
- }{d, pusherDelegator{d}, hijackerDelegator{d}, closeNotifierDelegator{d}}
- }
- pickDelegator[pusher+hijacker+flusher] = func(d *responseWriterDelegator) delegator { // 22
- return struct {
- *responseWriterDelegator
- http.Pusher
- http.Hijacker
- http.Flusher
- }{d, pusherDelegator{d}, hijackerDelegator{d}, flusherDelegator{d}}
- }
- pickDelegator[pusher+hijacker+flusher+closeNotifier] = func(d *responseWriterDelegator) delegator { //23
- return struct {
- *responseWriterDelegator
- http.Pusher
- http.Hijacker
- http.Flusher
- http.CloseNotifier
- }{d, pusherDelegator{d}, hijackerDelegator{d}, flusherDelegator{d}, closeNotifierDelegator{d}}
- }
- pickDelegator[pusher+readerFrom] = func(d *responseWriterDelegator) delegator { // 24
- return struct {
- *responseWriterDelegator
- http.Pusher
- io.ReaderFrom
- }{d, pusherDelegator{d}, readerFromDelegator{d}}
- }
- pickDelegator[pusher+readerFrom+closeNotifier] = func(d *responseWriterDelegator) delegator { // 25
- return struct {
- *responseWriterDelegator
- http.Pusher
- io.ReaderFrom
- http.CloseNotifier
- }{d, pusherDelegator{d}, readerFromDelegator{d}, closeNotifierDelegator{d}}
- }
- pickDelegator[pusher+readerFrom+flusher] = func(d *responseWriterDelegator) delegator { // 26
- return struct {
- *responseWriterDelegator
- http.Pusher
- io.ReaderFrom
- http.Flusher
- }{d, pusherDelegator{d}, readerFromDelegator{d}, flusherDelegator{d}}
- }
- pickDelegator[pusher+readerFrom+flusher+closeNotifier] = func(d *responseWriterDelegator) delegator { // 27
- return struct {
- *responseWriterDelegator
- http.Pusher
- io.ReaderFrom
- http.Flusher
- http.CloseNotifier
- }{d, pusherDelegator{d}, readerFromDelegator{d}, flusherDelegator{d}, closeNotifierDelegator{d}}
- }
- pickDelegator[pusher+readerFrom+hijacker] = func(d *responseWriterDelegator) delegator { // 28
- return struct {
- *responseWriterDelegator
- http.Pusher
- io.ReaderFrom
- http.Hijacker
- }{d, pusherDelegator{d}, readerFromDelegator{d}, hijackerDelegator{d}}
- }
- pickDelegator[pusher+readerFrom+hijacker+closeNotifier] = func(d *responseWriterDelegator) delegator { // 29
- return struct {
- *responseWriterDelegator
- http.Pusher
- io.ReaderFrom
- http.Hijacker
- http.CloseNotifier
- }{d, pusherDelegator{d}, readerFromDelegator{d}, hijackerDelegator{d}, closeNotifierDelegator{d}}
- }
- pickDelegator[pusher+readerFrom+hijacker+flusher] = func(d *responseWriterDelegator) delegator { // 30
- return struct {
- *responseWriterDelegator
- http.Pusher
- io.ReaderFrom
- http.Hijacker
- http.Flusher
- }{d, pusherDelegator{d}, readerFromDelegator{d}, hijackerDelegator{d}, flusherDelegator{d}}
- }
- pickDelegator[pusher+readerFrom+hijacker+flusher+closeNotifier] = func(d *responseWriterDelegator) delegator { // 31
- return struct {
- *responseWriterDelegator
- http.Pusher
- io.ReaderFrom
- http.Hijacker
- http.Flusher
- http.CloseNotifier
- }{d, pusherDelegator{d}, readerFromDelegator{d}, hijackerDelegator{d}, flusherDelegator{d}, closeNotifierDelegator{d}}
- }
- }
-
- func newDelegator(w http.ResponseWriter, observeWriteHeaderFunc func(int)) delegator {
- d := &responseWriterDelegator{
- ResponseWriter: w,
- observeWriteHeader: observeWriteHeaderFunc,
- }
-
- id := 0
- //nolint:staticcheck // Ignore SA1019. http.CloseNotifier is deprecated but we keep it here to not break existing users.
- if _, ok := w.(http.CloseNotifier); ok {
- id += closeNotifier
- }
- if _, ok := w.(http.Flusher); ok {
- id += flusher
- }
- if _, ok := w.(http.Hijacker); ok {
- id += hijacker
- }
- if _, ok := w.(io.ReaderFrom); ok {
- id += readerFrom
- }
- if _, ok := w.(http.Pusher); ok {
- id += pusher
- }
-
- return pickDelegator[id](d)
- }
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