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/
acceptencoder.go
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/
acceptencoder.go
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// Copyright 2015 beego Author. All Rights Reserved.
//
// 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 context
import (
"bytes"
"compress/flate"
"compress/gzip"
"compress/zlib"
"io"
"net/http"
"os"
"strconv"
"strings"
"sync"
)
type resetWriter interface {
io.Writer
Reset(w io.Writer)
}
type nopResetWriter struct {
io.Writer
}
func (n nopResetWriter) Reset(w io.Writer) {
//do nothing
}
type acceptEncoder struct {
name string
levelEncode func(int) resetWriter
bestSpeedPool *sync.Pool
bestCompressionPool *sync.Pool
}
func (ac acceptEncoder) encode(wr io.Writer, level int) resetWriter {
if ac.bestSpeedPool == nil || ac.bestCompressionPool == nil {
return nopResetWriter{wr}
}
var rwr resetWriter
switch level {
case flate.BestSpeed:
rwr = ac.bestSpeedPool.Get().(resetWriter)
case flate.BestCompression:
rwr = ac.bestCompressionPool.Get().(resetWriter)
default:
rwr = ac.levelEncode(level)
}
rwr.Reset(wr)
return rwr
}
func (ac acceptEncoder) put(wr resetWriter, level int) {
if ac.bestSpeedPool == nil || ac.bestCompressionPool == nil {
return
}
wr.Reset(nil)
switch level {
case flate.BestSpeed:
ac.bestSpeedPool.Put(wr)
case flate.BestCompression:
ac.bestCompressionPool.Put(wr)
}
}
var (
noneCompressEncoder = acceptEncoder{"", nil, nil, nil}
gzipCompressEncoder = acceptEncoder{"gzip",
func(level int) resetWriter { wr, _ := gzip.NewWriterLevel(nil, level); return wr },
&sync.Pool{
New: func() interface{} { wr, _ := gzip.NewWriterLevel(nil, flate.BestSpeed); return wr },
},
&sync.Pool{
New: func() interface{} { wr, _ := gzip.NewWriterLevel(nil, flate.BestCompression); return wr },
},
}
//according to the sec :http://tools.ietf.org/html/rfc2616#section-3.5 ,the deflate compress in http is zlib indeed
//deflate
//The "zlib" format defined in RFC 1950 [31] in combination with
//the "deflate" compression mechanism described in RFC 1951 [29].
deflateCompressEncoder = acceptEncoder{"deflate",
func(level int) resetWriter { wr, _ := zlib.NewWriterLevel(nil, level); return wr },
&sync.Pool{
New: func() interface{} { wr, _ := zlib.NewWriterLevel(nil, flate.BestSpeed); return wr },
},
&sync.Pool{
New: func() interface{} { wr, _ := zlib.NewWriterLevel(nil, flate.BestCompression); return wr },
},
}
)
var (
encoderMap = map[string]acceptEncoder{ // all the other compress methods will ignore
"gzip": gzipCompressEncoder,
"deflate": deflateCompressEncoder,
"*": gzipCompressEncoder, // * means any compress will accept,we prefer gzip
"identity": noneCompressEncoder, // identity means none-compress
}
)
// WriteFile reads from file and writes to writer by the specific encoding(gzip/deflate)
func WriteFile(encoding string, writer io.Writer, file *os.File) (bool, string, error) {
return writeLevel(encoding, writer, file, flate.BestCompression)
}
// WriteBody reads writes content to writer by the specific encoding(gzip/deflate)
func WriteBody(encoding string, writer io.Writer, content []byte) (bool, string, error) {
return writeLevel(encoding, writer, bytes.NewReader(content), flate.BestSpeed)
}
// writeLevel reads from reader,writes to writer by specific encoding and compress level
// the compress level is defined by deflate package
func writeLevel(encoding string, writer io.Writer, reader io.Reader, level int) (bool, string, error) {
var outputWriter resetWriter
var err error
var ce = noneCompressEncoder
if cf, ok := encoderMap[encoding]; ok {
ce = cf
}
encoding = ce.name
outputWriter = ce.encode(writer, level)
defer ce.put(outputWriter, level)
_, err = io.Copy(outputWriter, reader)
if err != nil {
return false, "", err
}
switch outputWriter.(type) {
case io.WriteCloser:
outputWriter.(io.WriteCloser).Close()
}
return encoding != "", encoding, nil
}
// ParseEncoding will extract the right encoding for response
// the Accept-Encoding's sec is here:
// http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.3
func ParseEncoding(r *http.Request) string {
if r == nil {
return ""
}
return parseEncoding(r)
}
type q struct {
name string
value float64
}
func parseEncoding(r *http.Request) string {
acceptEncoding := r.Header.Get("Accept-Encoding")
if acceptEncoding == "" {
return ""
}
var lastQ q
for _, v := range strings.Split(acceptEncoding, ",") {
v = strings.TrimSpace(v)
if v == "" {
continue
}
vs := strings.Split(v, ";")
if len(vs) == 1 {
lastQ = q{vs[0], 1}
break
}
if len(vs) == 2 {
f, _ := strconv.ParseFloat(strings.Replace(vs[1], "q=", "", -1), 64)
if f == 0 {
continue
}
if f > lastQ.value {
lastQ = q{vs[0], f}
}
}
}
if cf, ok := encoderMap[lastQ.name]; ok {
return cf.name
}
return ""
}