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caddyhttp: ResponseRecorder type for middlewares to buffer responses

Unfortunately, templates and markdown require buffering the full
response before it can be processed and written to the client
master
Matthew Holt 6 years ago
parent
commit
1c443beb9c
  1. 46
      modules/caddyhttp/markdown/markdown.go
  2. 73
      modules/caddyhttp/responsewriter.go
  3. 50
      modules/caddyhttp/templates/templates.go

46
modules/caddyhttp/markdown/markdown.go

@ -1,8 +1,10 @@
package markdown
import (
"bytes"
"net/http"
"strconv"
"sync"
"gopkg.in/russross/blackfriday.v2"
@ -22,31 +24,35 @@ type Markdown struct {
}
func (m Markdown) ServeHTTP(w http.ResponseWriter, r *http.Request, next caddyhttp.Handler) error {
mrw := &markdownResponseWriter{
ResponseWriterWrapper: &caddyhttp.ResponseWriterWrapper{ResponseWriter: w},
buf := bufPool.Get().(*bytes.Buffer)
buf.Reset()
defer bufPool.Put(buf)
rr := caddyhttp.NewResponseRecorder(w, buf)
err := next.ServeHTTP(rr, r)
if err != nil {
return err
}
return next.ServeHTTP(mrw, r)
}
type markdownResponseWriter struct {
*caddyhttp.ResponseWriterWrapper
statusCode int
wroteHeader bool
}
output := blackfriday.Run(buf.Bytes())
func (mrw *markdownResponseWriter) WriteHeader(code int) {
mrw.statusCode = code
w.Header().Set("Content-Length", strconv.Itoa(len(output)))
w.Header().Set("Content-Type", "text/html; charset=utf-8")
w.Header().Del("Accept-Ranges") // we don't know ranges for dynamically-created content
w.Header().Del("Etag") // don't know a way to quickly generate etag for dynamic content
w.Header().Del("Last-Modified") // useless for dynamic content since it's always changing
w.WriteHeader(rr.Status())
w.Write(output)
return nil
}
func (mrw *markdownResponseWriter) Write(d []byte) (int, error) {
output := blackfriday.Run(d)
if !mrw.wroteHeader {
mrw.Header().Set("Content-Length", strconv.Itoa(len(output)))
mrw.Header().Set("Content-Type", "text/html; charset=utf-8")
mrw.WriteHeader(mrw.statusCode)
mrw.wroteHeader = true
}
return mrw.ResponseWriter.Write(output)
var bufPool = sync.Pool{
New: func() interface{} {
return new(bytes.Buffer)
},
}
// Interface guard

73
modules/caddyhttp/responsewriter.go

@ -2,6 +2,7 @@ package caddyhttp
import (
"bufio"
"bytes"
"fmt"
"net"
"net/http"
@ -58,5 +59,75 @@ type HTTPInterfaces interface {
// ResponseWriter does not implement the required method.
var ErrNotImplemented = fmt.Errorf("method not implemented")
type responseRecorder struct {
*ResponseWriterWrapper
wroteHeader bool
statusCode int
buf *bytes.Buffer
}
// NewResponseRecorder returns a new ResponseRecorder that can be
// used instead of a real http.ResponseWriter. The recorder is useful
// for middlewares which need to buffer a responder's response and
// process it in its entirety before actually allowing the response to
// be written. Of course, this has a performance overhead, but
// sometimes there is no way to avoid buffering the whole response.
// Still, if at all practical, middlewares should strive to stream
// responses by wrapping Write and WriteHeader methods instead of
// buffering whole response bodies.
//
// Before calling this function in a middleware handler, make a
// new buffer or obtain one from a pool (use the sync.Pool) type.
// Using a pool is generally recommended for performance gains;
// do profiling to ensure this is the case. If using a pool, be
// sure to reset the buffer before using it.
//
// The returned recorder can be used in place of w when calling
// the next handler in the chain. When that handler returns, you
// can read the status code from the recorder's Status() method.
// The response body fills buf, and the headers are available in
// w.Header().
func NewResponseRecorder(w http.ResponseWriter, buf *bytes.Buffer) ResponseRecorder {
return &responseRecorder{
ResponseWriterWrapper: &ResponseWriterWrapper{ResponseWriter: w},
buf: buf,
}
}
func (rr *responseRecorder) WriteHeader(statusCode int) {
if rr.wroteHeader {
return
}
rr.statusCode = statusCode
rr.wroteHeader = true
}
func (rr *responseRecorder) Write(data []byte) (int, error) {
rr.WriteHeader(http.StatusOK)
return rr.buf.Write(data)
}
// Status returns the status code that was written, if any.
func (rr *responseRecorder) Status() int {
return rr.statusCode
}
// Buffer returns the body buffer that rr was created with.
// You should still have your original pointer, though.
func (rr *responseRecorder) Buffer() *bytes.Buffer {
return rr.buf
}
// ResponseRecorder is a http.ResponseWriter that records
// responses instead of writing them to the client.
type ResponseRecorder interface {
HTTPInterfaces
Status() int
Buffer() *bytes.Buffer
}
// Interface guards
var _ HTTPInterfaces = (*ResponseWriterWrapper)(nil)
var (
_ HTTPInterfaces = (*ResponseWriterWrapper)(nil)
_ ResponseRecorder = (*responseRecorder)(nil)
)

50
modules/caddyhttp/templates/templates.go

@ -37,35 +37,31 @@ func (t *Templates) ServeHTTP(w http.ResponseWriter, r *http.Request, next caddy
buf.Reset()
defer bufPool.Put(buf)
wb := &responseBuffer{
ResponseWriterWrapper: &caddyhttp.ResponseWriterWrapper{ResponseWriter: w},
buf: buf,
}
rr := caddyhttp.NewResponseRecorder(w, buf)
err := next.ServeHTTP(wb, r)
err := next.ServeHTTP(rr, r)
if err != nil {
return err
}
err = t.executeTemplate(wb, r)
err = t.executeTemplate(rr, r)
if err != nil {
return err
}
w.Header().Set("Content-Length", strconv.Itoa(wb.buf.Len()))
w.Header().Set("Content-Length", strconv.Itoa(buf.Len()))
w.Header().Del("Accept-Ranges") // we don't know ranges for dynamically-created content
w.Header().Del("Etag") // don't know a way to quickly generate etag for dynamic content
w.Header().Del("Last-Modified") // useless for dynamic content since it's always changing
w.WriteHeader(wb.statusCode)
io.Copy(w, wb.buf)
w.WriteHeader(rr.Status())
io.Copy(w, buf)
return nil
}
// executeTemplate executes the template contianed
// in wb.buf and replaces it with the results.
func (t *Templates) executeTemplate(wb *responseBuffer, r *http.Request) error {
// executeTemplate executes the template contained in wb.buf and replaces it with the results.
func (t *Templates) executeTemplate(rr caddyhttp.ResponseRecorder, r *http.Request) error {
var fs http.FileSystem
if t.FileRoot != "" {
fs = http.Dir(t.FileRoot)
@ -74,11 +70,11 @@ func (t *Templates) executeTemplate(wb *responseBuffer, r *http.Request) error {
ctx := &templateContext{
Root: fs,
Req: r,
RespHeader: tplWrappedHeader{wb.Header()},
RespHeader: tplWrappedHeader{rr.Header()},
config: t,
}
err := ctx.executeTemplateInBuffer(r.URL.Path, wb.buf)
err := ctx.executeTemplateInBuffer(r.URL.Path, rr.Buffer())
if err != nil {
return caddyhttp.Error(http.StatusInternalServerError, err)
}
@ -86,29 +82,8 @@ func (t *Templates) executeTemplate(wb *responseBuffer, r *http.Request) error {
return nil
}
// responseBuffer buffers the response so that it can be
// executed as a template.
type responseBuffer struct {
*caddyhttp.ResponseWriterWrapper
wroteHeader bool
statusCode int
buf *bytes.Buffer
}
func (rb *responseBuffer) WriteHeader(statusCode int) {
if rb.wroteHeader {
return
}
rb.statusCode = statusCode
rb.wroteHeader = true
}
func (rb *responseBuffer) Write(data []byte) (int, error) {
rb.WriteHeader(http.StatusOK)
return rb.buf.Write(data)
}
// virtualResponseWriter is used in virtualized HTTP requests.
// virtualResponseWriter is used in virtualized HTTP requests
// that templates may execute.
type virtualResponseWriter struct {
status int
header http.Header
@ -131,5 +106,4 @@ func (vrw *virtualResponseWriter) Write(data []byte) (int, error) {
var (
_ caddy.Validator = (*Templates)(nil)
_ caddyhttp.MiddlewareHandler = (*Templates)(nil)
_ caddyhttp.HTTPInterfaces = (*responseBuffer)(nil)
)

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