gzip.go

// Copyright 2020 H2O.ai, Inc.
//
// 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 wave

import (
	"compress/gzip"
	"io"
	"io/ioutil"
	"net/http"
	"sync"
)

type gzipResponseWriter struct {
	io.Writer
	http.ResponseWriter
}

var gzPool = sync.Pool{
	New: func() interface{} {
		return gzip.NewWriter(ioutil.Discard)
	},
}

func (w *gzipResponseWriter) Write(b []byte) (int, error) {
	return w.Writer.Write(b)
}

func serveGzipped(h http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.Header().Set("Content-Encoding", "gzip")

		gz := gzPool.Get().(*gzip.Writer)
		defer gzPool.Put(gz)

		gz.Reset(w)
		defer gz.Close()

		h.ServeHTTP(&gzipResponseWriter{ResponseWriter: w, Writer: gz}, r)
	})
}