Code optimization

vender/github.com/astaxie/beego/context/acceptencoder.go

@@ -0,0 +1,232 @@
+// 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"
+)
+
+var (
+	//Default size==20B same as nginx
+	defaultGzipMinLength = 20
+	//Content will only be compressed if content length is either unknown or greater than gzipMinLength.
+	gzipMinLength = defaultGzipMinLength
+	//The compression level used for deflate compression. (0-9).
+	gzipCompressLevel int
+	//List of HTTP methods to compress. If not set, only GET requests are compressed.
+	includedMethods map[string]bool
+	getMethodOnly   bool
+)
+
+// InitGzip init the gzipcompress
+func InitGzip(minLength, compressLevel int, methods []string) {
+	if minLength >= 0 {
+		gzipMinLength = minLength
+	}
+	gzipCompressLevel = compressLevel
+	if gzipCompressLevel < flate.NoCompression || gzipCompressLevel > flate.BestCompression {
+		gzipCompressLevel = flate.BestSpeed
+	}
+	getMethodOnly = (len(methods) == 0) || (len(methods) == 1 && strings.ToUpper(methods[0]) == "GET")
+	includedMethods = make(map[string]bool, len(methods))
+	for _, v := range methods {
+		includedMethods[strings.ToUpper(v)] = true
+	}
+}
+
+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
+	customCompressLevelPool *sync.Pool
+	bestCompressionPool     *sync.Pool
+}
+
+func (ac acceptEncoder) encode(wr io.Writer, level int) resetWriter {
+	if ac.customCompressLevelPool == nil || ac.bestCompressionPool == nil {
+		return nopResetWriter{wr}
+	}
+	var rwr resetWriter
+	switch level {
+	case flate.BestSpeed:
+		rwr = ac.customCompressLevelPool.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.customCompressLevelPool == nil || ac.bestCompressionPool == nil {
+		return
+	}
+	wr.Reset(nil)
+
+	//notice
+	//compressionLevel==BestCompression DOES NOT MATTER
+	//sync.Pool will not memory leak
+
+	switch level {
+	case gzipCompressLevel:
+		ac.customCompressLevelPool.Put(wr)
+	case flate.BestCompression:
+		ac.bestCompressionPool.Put(wr)
+	}
+}
+
+var (
+	noneCompressEncoder = acceptEncoder{"", nil, nil, nil}
+	gzipCompressEncoder = acceptEncoder{
+		name:                    "gzip",
+		levelEncode:             func(level int) resetWriter { wr, _ := gzip.NewWriterLevel(nil, level); return wr },
+		customCompressLevelPool: &sync.Pool{New: func() interface{} { wr, _ := gzip.NewWriterLevel(nil, gzipCompressLevel); return wr }},
+		bestCompressionPool:     &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{
+		name:                    "deflate",
+		levelEncode:             func(level int) resetWriter { wr, _ := zlib.NewWriterLevel(nil, level); return wr },
+		customCompressLevelPool: &sync.Pool{New: func() interface{} { wr, _ := zlib.NewWriterLevel(nil, gzipCompressLevel); return wr }},
+		bestCompressionPool:     &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) {
+	if encoding == "" || len(content) < gzipMinLength {
+		_, err := writer.Write(content)
+		return false, "", err
+	}
+	return writeLevel(encoding, writer, bytes.NewReader(content), gzipCompressLevel)
+}
+
+// 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 ""
+	}
+	if (getMethodOnly && r.Method == "GET") || includedMethods[r.Method] {
+		return parseEncoding(r)
+	}
+	return ""
+}
+
+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, ";")
+		var cf acceptEncoder
+		var ok bool
+		if cf, ok = encoderMap[vs[0]]; !ok {
+			continue
+		}
+		if len(vs) == 1 {
+			return cf.name
+		}
+		if len(vs) == 2 {
+			f, _ := strconv.ParseFloat(strings.Replace(vs[1], "q=", "", -1), 64)
+			if f == 0 {
+				continue
+			}
+			if f > lastQ.value {
+				lastQ = q{cf.name, f}
+			}
+		}
+	}
+	return lastQ.name
+}