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compress.go
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compress.go
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package middleware
import (
"bufio"
"compress/gzip"
"io"
"net"
"net/http"
"strings"
"sync"
"github.com/webx-top/echo"
"github.com/webx-top/echo/engine"
)
type (
// GzipConfig defines the config for Gzip middleware.
GzipConfig struct {
// Skipper defines a function to skip middleware.
Skipper echo.Skipper `json:"-"`
// Gzip compression level.
// Optional. Default value -1.
Level int `json:"level"`
}
gzipWriter struct {
io.Writer
engine.Response
}
)
const (
gzipScheme = "gzip"
)
var (
// DefaultGzipConfig is the default Gzip middleware config.
DefaultGzipConfig = &GzipConfig{
Skipper: echo.DefaultSkipper,
Level: -1,
}
)
func (w *gzipWriter) WriteHeader(code int) {
if code == http.StatusNoContent {
w.Header().Del(echo.HeaderContentEncoding)
}
w.Header().Del(echo.HeaderContentLength)
w.WriteHeader(code)
}
func (w *gzipWriter) Write(b []byte) (int, error) {
if len(w.Header().Get(echo.HeaderContentType)) == 0 {
w.Header().Set(echo.HeaderContentType, http.DetectContentType(b))
}
return w.Writer.Write(b)
}
func (w *gzipWriter) Flush() {
w.Writer.(*gzip.Writer).Flush()
if flusher, ok := w.Response.(http.Flusher); ok {
flusher.Flush()
return
}
if flusher, ok := w.StdResponseWriter().(http.Flusher); ok {
flusher.Flush()
}
}
func (w *gzipWriter) Hijack() (net.Conn, *bufio.ReadWriter, error) {
if hijacker, ok := w.Response.(http.Hijacker); ok {
return hijacker.Hijack()
}
return w.StdResponseWriter().(http.Hijacker).Hijack()
}
func (w *gzipWriter) CloseNotify() <-chan bool {
if closeNotifiler, ok := w.Response.(http.CloseNotifier); ok {
return closeNotifiler.CloseNotify()
}
return w.StdResponseWriter().(http.CloseNotifier).CloseNotify()
}
func (w *gzipWriter) Push(target string, opts *http.PushOptions) error {
if p, ok := w.Response.(http.Pusher); ok {
return p.Push(target, opts)
}
return http.ErrNotSupported
}
// Gzip returns a middleware which compresses HTTP response using gzip compression
// scheme.
func Gzip(config ...*GzipConfig) echo.MiddlewareFunc {
if len(config) < 1 || config[0] == nil {
return GzipWithConfig(DefaultGzipConfig)
}
return GzipWithConfig(config[0])
}
// GzipWithConfig return Gzip middleware with config.
// See: `Gzip()`.
func GzipWithConfig(config *GzipConfig) echo.MiddlewareFunc {
// Defaults
if config.Skipper == nil {
config.Skipper = DefaultGzipConfig.Skipper
}
if config.Level == 0 {
config.Level = DefaultGzipConfig.Level
}
pool := gzipCompressPool(config)
return func(h echo.Handler) echo.Handler {
return echo.HandlerFunc(func(c echo.Context) error {
if config.Skipper(c) {
return h.Handle(c)
}
resp := c.Response()
resp.Header().Add(echo.HeaderVary, echo.HeaderAcceptEncoding)
if strings.Contains(c.Request().Header().Get(echo.HeaderAcceptEncoding), gzipScheme) {
resp.Header().Add(echo.HeaderContentEncoding, gzipScheme)
i := pool.Get()
w, ok := i.(*gzip.Writer)
if !ok {
return echo.NewHTTPError(http.StatusInternalServerError, i.(error).Error()).SetRaw(i.(error))
}
rw := resp.Writer()
w.Reset(rw)
defer func() {
if resp.Size() == 0 {
if resp.Header().Get(echo.HeaderContentEncoding) == gzipScheme {
resp.Header().Del(echo.HeaderContentEncoding)
}
// We have to reset response to it's pristine state when
// nothing is written to body or error is returned.
// See issue #424, #407.
resp.SetWriter(rw)
w.Reset(io.Discard)
}
w.Close()
pool.Put(w)
}()
resp.SetWriter(&gzipWriter{Writer: w, Response: resp})
}
return h.Handle(c)
})
}
}
func gzipCompressPool(config *GzipConfig) sync.Pool {
return sync.Pool{
New: func() interface{} {
w, err := gzip.NewWriterLevel(io.Discard, config.Level)
if err != nil {
return err
}
return w
},
}
}