mirror of https://github.com/jlelse/GoBlog
Use custom compression middleware
parent
1f8c031e14
commit
6fc1e0dc03
@ -0,0 +1,293 @@
|
||||
package httpcompress
|
||||
|
||||
import (
|
||||
"bufio"
|
||||
"errors"
|
||||
"io"
|
||||
"io/ioutil"
|
||||
"net"
|
||||
"net/http"
|
||||
"strings"
|
||||
"sync"
|
||||
|
||||
"github.com/klauspost/compress/flate"
|
||||
"github.com/klauspost/compress/gzip"
|
||||
"github.com/thoas/go-funk"
|
||||
|
||||
"go.goblog.app/app/pkgs/contenttype"
|
||||
)
|
||||
|
||||
var defaultCompressibleContentTypes = []string{
|
||||
contenttype.AS,
|
||||
contenttype.ATOM,
|
||||
contenttype.CSS,
|
||||
contenttype.HTML,
|
||||
contenttype.JS,
|
||||
contenttype.JSON,
|
||||
contenttype.JSONFeed,
|
||||
contenttype.LDJSON,
|
||||
contenttype.RSS,
|
||||
contenttype.Text,
|
||||
contenttype.XML,
|
||||
"application/opensearchdescription+xml",
|
||||
"application/jrd+json",
|
||||
"application/xrd+xml",
|
||||
}
|
||||
|
||||
// Compress is a middleware that compresses response
|
||||
// body of a given content types to a data format based
|
||||
// on Accept-Encoding request header. It uses a given
|
||||
// compression level.
|
||||
//
|
||||
// Passing a compression level of 5 is sensible value
|
||||
func Compress(level int, types ...string) func(next http.Handler) http.Handler {
|
||||
return NewCompressor(level, types...).Handler
|
||||
}
|
||||
|
||||
// Compressor represents a set of encoding configurations.
|
||||
type Compressor struct {
|
||||
// The mapping of pooled encoders to pools.
|
||||
pooledEncoders map[string]*sync.Pool
|
||||
// The set of content types allowed to be compressed.
|
||||
allowedTypes map[string]interface{}
|
||||
// The list of encoders in order of decreasing precedence.
|
||||
encodingPrecedence []string
|
||||
// The compression level.
|
||||
level int
|
||||
}
|
||||
|
||||
// NewCompressor creates a new Compressor that will handle encoding responses.
|
||||
//
|
||||
// The level should be one of the ones defined in the flate package.
|
||||
// The types are the content types that are allowed to be compressed.
|
||||
func NewCompressor(level int, types ...string) *Compressor {
|
||||
// If types are provided, set those as the allowed types. If none are
|
||||
// provided, use the default list.
|
||||
allowedTypes := map[string]interface{}{}
|
||||
for _, t := range funk.ShortIf(len(types) > 0, types, defaultCompressibleContentTypes).([]string) {
|
||||
allowedTypes[t] = nil
|
||||
}
|
||||
|
||||
c := &Compressor{
|
||||
level: level,
|
||||
pooledEncoders: map[string]*sync.Pool{},
|
||||
allowedTypes: allowedTypes,
|
||||
}
|
||||
|
||||
c.SetEncoder("deflate", encoderDeflate)
|
||||
c.SetEncoder("gzip", encoderGzip)
|
||||
|
||||
return c
|
||||
}
|
||||
|
||||
// SetEncoder can be used to set the implementation of a compression algorithm.
|
||||
//
|
||||
// The encoding should be a standardised identifier. See:
|
||||
// https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Accept-Encoding
|
||||
func (c *Compressor) SetEncoder(encoding string, fn EncoderFunc) {
|
||||
encoding = strings.ToLower(encoding)
|
||||
if encoding == "" {
|
||||
panic("the encoding can not be empty")
|
||||
}
|
||||
if fn == nil {
|
||||
panic("attempted to set a nil encoder function")
|
||||
}
|
||||
|
||||
// Deleted already registered encoder
|
||||
delete(c.pooledEncoders, encoding)
|
||||
|
||||
c.pooledEncoders[encoding] = &sync.Pool{
|
||||
New: func() interface{} {
|
||||
return fn(ioutil.Discard, c.level)
|
||||
},
|
||||
}
|
||||
|
||||
for i, v := range c.encodingPrecedence {
|
||||
if v == encoding {
|
||||
c.encodingPrecedence = append(c.encodingPrecedence[:i], c.encodingPrecedence[i+1:]...)
|
||||
break
|
||||
}
|
||||
}
|
||||
|
||||
c.encodingPrecedence = append([]string{encoding}, c.encodingPrecedence...)
|
||||
}
|
||||
|
||||
// Handler returns a new middleware that will compress the response based on the
|
||||
// current Compressor.
|
||||
func (c *Compressor) Handler(next http.Handler) http.Handler {
|
||||
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
|
||||
cw := &compressResponseWriter{
|
||||
compressor: c,
|
||||
ResponseWriter: w,
|
||||
request: r,
|
||||
}
|
||||
next.ServeHTTP(cw, r)
|
||||
cw.Close()
|
||||
})
|
||||
}
|
||||
|
||||
func matchAcceptEncoding(accepted []string, encoding string) bool {
|
||||
return funk.ContainsString(accepted, encoding)
|
||||
}
|
||||
|
||||
// An EncoderFunc is a function that wraps the provided io.Writer with a
|
||||
// streaming compression algorithm and returns it.
|
||||
//
|
||||
// In case of failure, the function should return nil.
|
||||
type EncoderFunc func(w io.Writer, level int) compressWriter
|
||||
|
||||
// Interface for types that allow resetting io.Writers.
|
||||
type compressWriter interface {
|
||||
io.Writer
|
||||
Reset(w io.Writer)
|
||||
Flush() error
|
||||
}
|
||||
|
||||
type compressResponseWriter struct {
|
||||
http.ResponseWriter // The response writer to delegate to.
|
||||
encoder compressWriter // The encoder to use (if any).
|
||||
cleanup func() // Cleanup function to reset and repool encoder.
|
||||
compressor *Compressor // Holds the compressor configuration.
|
||||
request *http.Request // The request that is being handled.
|
||||
wroteHeader bool // Whether the header has been written.
|
||||
closed bool // Whether the connection has been closed.
|
||||
}
|
||||
|
||||
func (cw *compressResponseWriter) isCompressable() bool {
|
||||
// Parse the first part of the Content-Type response header.
|
||||
contentType := cw.Header().Get("Content-Type")
|
||||
if idx := strings.Index(contentType, ";"); idx >= 0 {
|
||||
contentType = contentType[0:idx]
|
||||
}
|
||||
|
||||
// Is the content type compressable?
|
||||
_, ok := cw.compressor.allowedTypes[contentType]
|
||||
return ok
|
||||
}
|
||||
|
||||
func (cw *compressResponseWriter) writer() io.Writer {
|
||||
if cw.encoder != nil {
|
||||
return cw.encoder
|
||||
}
|
||||
return cw.ResponseWriter
|
||||
}
|
||||
|
||||
// selectEncoder returns the encoder, the name of the encoder, and a closer function.
|
||||
func (cw *compressResponseWriter) selectEncoder() (compressWriter, string, func()) {
|
||||
// Parse the names of all accepted algorithms from the header.
|
||||
accepted := strings.Split(strings.ToLower(cw.request.Header.Get("Accept-Encoding")), ",")
|
||||
|
||||
// Find supported encoder by accepted list by precedence
|
||||
for _, name := range cw.compressor.encodingPrecedence {
|
||||
if matchAcceptEncoding(accepted, name) {
|
||||
if pool, ok := cw.compressor.pooledEncoders[name]; ok {
|
||||
encoder := pool.Get().(compressWriter)
|
||||
cleanup := func() {
|
||||
encoder.Reset(nil)
|
||||
pool.Put(encoder)
|
||||
}
|
||||
encoder.Reset(cw.ResponseWriter)
|
||||
return encoder, name, cleanup
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
// No encoder found to match the accepted encoding
|
||||
return nil, "", nil
|
||||
}
|
||||
|
||||
func (cw *compressResponseWriter) doCleanup() {
|
||||
if cw.encoder != nil {
|
||||
cw.encoder = nil
|
||||
cw.cleanup()
|
||||
cw.cleanup = nil
|
||||
}
|
||||
}
|
||||
|
||||
func (cw *compressResponseWriter) WriteHeader(code int) {
|
||||
defer cw.ResponseWriter.WriteHeader(code)
|
||||
|
||||
if cw.wroteHeader {
|
||||
return
|
||||
}
|
||||
|
||||
cw.wroteHeader = true
|
||||
|
||||
if cw.Header().Get("Content-Encoding") != "" {
|
||||
// Data has already been compressed.
|
||||
return
|
||||
}
|
||||
|
||||
if !cw.isCompressable() {
|
||||
// Data is not compressable.
|
||||
return
|
||||
}
|
||||
|
||||
var encoding string
|
||||
cw.encoder, encoding, cw.cleanup = cw.selectEncoder()
|
||||
if encoding != "" {
|
||||
cw.Header().Set("Content-Encoding", encoding)
|
||||
cw.Header().Add("Vary", "Accept-Encoding")
|
||||
|
||||
// The content-length after compression is unknown
|
||||
cw.Header().Del("Content-Length")
|
||||
}
|
||||
}
|
||||
|
||||
func (cw *compressResponseWriter) Write(p []byte) (int, error) {
|
||||
if !cw.wroteHeader {
|
||||
cw.WriteHeader(http.StatusOK)
|
||||
}
|
||||
return cw.writer().Write(p)
|
||||
}
|
||||
|
||||
func (cw *compressResponseWriter) Flush() {
|
||||
if cw.encoder != nil {
|
||||
cw.encoder.Flush()
|
||||
}
|
||||
if f, ok := cw.ResponseWriter.(http.Flusher); ok {
|
||||
f.Flush()
|
||||
}
|
||||
}
|
||||
|
||||
func (cw *compressResponseWriter) Hijack() (net.Conn, *bufio.ReadWriter, error) {
|
||||
if hj, ok := cw.writer().(http.Hijacker); ok {
|
||||
return hj.Hijack()
|
||||
}
|
||||
return nil, nil, errors.New("http.Hijacker is unavailable on the writer")
|
||||
}
|
||||
|
||||
func (cw *compressResponseWriter) Push(target string, opts *http.PushOptions) error {
|
||||
if ps, ok := cw.writer().(http.Pusher); ok {
|
||||
return ps.Push(target, opts)
|
||||
}
|
||||
return errors.New("http.Pusher is unavailable on the writer")
|
||||
}
|
||||
|
||||
func (cw *compressResponseWriter) Close() error {
|
||||
if cw.closed {
|
||||
return nil
|
||||
}
|
||||
cw.closed = true
|
||||
defer cw.doCleanup()
|
||||
if c, ok := cw.writer().(io.WriteCloser); ok {
|
||||
return c.Close()
|
||||
}
|
||||
return errors.New("io.WriteCloser is unavailable on the writer")
|
||||
}
|
||||
|
||||
func encoderGzip(w io.Writer, level int) compressWriter {
|
||||
gw, err := gzip.NewWriterLevel(w, level)
|
||||
if err != nil {
|
||||
return nil
|
||||
}
|
||||
return gw
|
||||
}
|
||||
|
||||
func encoderDeflate(w io.Writer, level int) compressWriter {
|
||||
dw, err := flate.NewWriter(w, level)
|
||||
if err != nil {
|
||||
return nil
|
||||
}
|
||||
return dw
|
||||
}
|
||||
Loading…
Reference in New Issue