Serge Bazanski | cc25bdf | 2018-10-25 14:02:58 +0200 | [diff] [blame] | 1 | package client |
| 2 | |
| 3 | import ( |
| 4 | "io" |
| 5 | "io/ioutil" |
| 6 | "net/http" |
| 7 | "sync/atomic" |
| 8 | ) |
| 9 | |
| 10 | // KeepAliveTransport drains the remaining body from a response |
| 11 | // so that go will reuse the TCP connections. |
| 12 | // This is not enabled by default because there are servers where |
| 13 | // the response never gets closed and that would make the code hang forever. |
| 14 | // So instead it's provided as a http client middleware that can be used to override |
| 15 | // any request. |
| 16 | func KeepAliveTransport(rt http.RoundTripper) http.RoundTripper { |
| 17 | return &keepAliveTransport{wrapped: rt} |
| 18 | } |
| 19 | |
| 20 | type keepAliveTransport struct { |
| 21 | wrapped http.RoundTripper |
| 22 | } |
| 23 | |
| 24 | func (k *keepAliveTransport) RoundTrip(r *http.Request) (*http.Response, error) { |
| 25 | resp, err := k.wrapped.RoundTrip(r) |
| 26 | if err != nil { |
| 27 | return resp, err |
| 28 | } |
| 29 | resp.Body = &drainingReadCloser{rdr: resp.Body} |
| 30 | return resp, nil |
| 31 | } |
| 32 | |
| 33 | type drainingReadCloser struct { |
| 34 | rdr io.ReadCloser |
| 35 | seenEOF uint32 |
| 36 | } |
| 37 | |
| 38 | func (d *drainingReadCloser) Read(p []byte) (n int, err error) { |
| 39 | n, err = d.rdr.Read(p) |
| 40 | if err == io.EOF || n == 0 { |
| 41 | atomic.StoreUint32(&d.seenEOF, 1) |
| 42 | } |
| 43 | return |
| 44 | } |
| 45 | |
| 46 | func (d *drainingReadCloser) Close() error { |
| 47 | // drain buffer |
| 48 | if atomic.LoadUint32(&d.seenEOF) != 1 { |
| 49 | //#nosec |
| 50 | io.Copy(ioutil.Discard, d.rdr) |
| 51 | } |
| 52 | return d.rdr.Close() |
| 53 | } |