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|
package gziphandler
import (
"compress/gzip"
"io/ioutil"
"net/http"
"strings"
"sync"
)
type respWriter struct {
http.ResponseWriter
w *gzip.Writer
}
func (w *respWriter) Write(d []byte) (int, error) {
return w.w.Write(d)
}
func (w *respWriter) Close() error {
return w.w.Close()
}
type handler struct {
next http.Handler
pool sync.Pool
}
func acceptsGzip(r *http.Request) bool {
ae := r.Header.Get("Accept-Encoding")
for _, e := range strings.Split(ae, ",") {
vals := strings.Split(e, ";")
if len(vals) < 1 {
continue
}
if strings.TrimSpace(vals[0]) == "gzip" {
return true
}
}
return false
}
func (h *handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
if !acceptsGzip(r) {
h.next.ServeHTTP(w, r)
return
}
w.Header().Set("Content-Encoding", "gzip")
gw := h.pool.Get().(*gzip.Writer)
gw.Reset(w)
rw := &respWriter{
ResponseWriter: w,
w: gw,
}
h.next.ServeHTTP(rw, r)
gw.Close()
h.pool.Put(gw)
}
// Handler returns an http.Handler that compresses the response data written
// by an existing handler h, using the compress/gzip.Writer with default
// compression level.
func Handler(h http.Handler) http.Handler {
return &handler{
next: h,
pool: sync.Pool{
New: func() interface{} {
return gzip.NewWriter(ioutil.Discard)
},
},
}
}
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