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Idiomatic golang net/http gzip transparent compression, an updated version of https://gist.github.com/bryfry/09a650eb8aac0fb76c24
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package main | |
import ( | |
"net/http" | |
"compress/gzip" | |
"io/ioutil" | |
"strings" | |
"sync" | |
"io" | |
) | |
var gzPool = sync.Pool { | |
New: func() interface{} { | |
w := gzip.NewWriter(ioutil.Discard) | |
return w | |
}, | |
} | |
type gzipResponseWriter struct { | |
io.Writer | |
http.ResponseWriter | |
} | |
func (w *gzipResponseWriter) WriteHeader(status int) { | |
w.Header().Del("Content-Length") | |
w.ResponseWriter.WriteHeader(status) | |
} | |
func (w *gzipResponseWriter) Write(b []byte) (int, error) { | |
return w.Writer.Write(b) | |
} | |
func Gzip(next http.Handler) http.Handler { | |
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) { | |
if !strings.Contains(r.Header.Get("Accept-Encoding"), "gzip") { | |
next.ServeHTTP(w, r) | |
return | |
} | |
w.Header().Set("Content-Encoding", "gzip") | |
gz := gzPool.Get().(*gzip.Writer) | |
defer gzPool.Put(gz) | |
gz.Reset(w) | |
defer gz.Close() | |
next.ServeHTTP(&gzipResponseWriter{ResponseWriter: w, Writer: gz}, r) | |
}) | |
} |
Another issue - if applied to e.g. Prometheus HTTP handlers, it will lead to double-gzipping. To avoid it, strip Accept-Encoding
from the request before passing it down the handler chain.
r.Header.Del("Accept-Encoding") // prevent double-gzipping
next.ServeHTTP(&gzipResponseWriter{ResponseWriter: w, Writer: gz}, r)
})
}
See also github.com/NYTimes/gziphandler.
Created a package for this: https://github.com/TelephoneTan/GoHTTPGzipServer
this code doesn't work for me... instead of showing the content it transfers an empty file
I think the defer Close
line should be before the defer gzpool.Put
. To prevent any writes going to the writer before being put back on the pool.
I did a little benchmarking and I didn't see any improvement using sync pool. It was actually slower.
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First of all, thanks for a great solution. It really helped me out. However, I was running into a problem where the compressed response was being "ignored" because it breached the buffer-before-chunking threshold (
2KB
at the time of writing this) and it was being chunked. It meant my response jumped from 2 KB to 15 KB.To solve it, I updated the GZip handler to do the following instead of lines 45 & 46. I'm open to any feedback to make this better if this will cause too much GC headache.