// NewSnappyResponseWriter returns a `http.ResponseWriter` wrapper which can encode
// the output with Snappy if requested by the client.
// If snappy isn't enabled, it will act like a regular `http.ResponseWriter`
// `Close` must be call so the `*snappy.Writer` instance can be put back in the `sync.Pool`
func NewSnappyResponseWriter(rw http.ResponseWriter, r *http.Request) *snappyResponseWriter {
var s *snappy.Writer
// Set the necessary `Vary` header
rw.Header().Set("Vary", "Accept-Encoding")
// Disable caching of responses.
rw.Header().Set("Cache-control", "no-cache")
var writer io.Writer
switch r.Header.Get("Accept-Encoding") {
case "snappy":
rw.Header().Set("Content-Encoding", "snappy")
// Try to get a snappy.Writer from the pool
if is := snappyWriterPool.Get(); is != nil {
s = is.(*snappy.Writer)
s.Reset(rw)
} else {
// Creates a new one if the pool is empty
s = snappy.NewWriter(rw)
}
writer = s
default:
// No `Accept-Encoding` header (or unsupported)
// Default to plain-text
writer = rw
}
return &snappyResponseWriter{
snappyWriter: s,
rw: rw,
w: writer,
}
}
