buildlet: make exec fail with a remote error if no headers after 5 seconds
The reverse buildlets' RoundTrip are hanging, which is its own problem,
but this calling code should be robust and time out anyway.
Change-Id: Id9e3e1d9feb6ffa58cc0995d0623bd90845bb9d6
Reviewed-on: https://go-review.googlesource.com/10847
Reviewed-by: Andrew Gerrand <adg@golang.org>
diff --git a/buildlet/buildletclient.go b/buildlet/buildletclient.go
index a840744..53b3445 100644
--- a/buildlet/buildletclient.go
+++ b/buildlet/buildletclient.go
@@ -114,6 +114,37 @@
return c.httpClient.Do(req)
}
+var errHeaderTimeout = errors.New("timeout waiting for headers")
+
+// doHeaderTimeout calls c.do(req) and returns its results, or
+// errHeaderTimeout if max elapses first.
+func (c *Client) doHeaderTimeout(req *http.Request, max time.Duration) (res *http.Response, err error) {
+ type resErr struct {
+ res *http.Response
+ err error
+ }
+ resErrc := make(chan resErr, 1)
+ go func() {
+ res, err := c.do(req)
+ resErrc <- resErr{res, err}
+ }()
+
+ timer := time.NewTimer(max)
+ defer timer.Stop()
+
+ select {
+ case re := <-resErrc:
+ return re.res, re.err
+ case <-timer.C:
+ go func() {
+ if re := <-resErrc; re.res != nil {
+ res.Body.Close()
+ }
+ }()
+ return nil, errHeaderTimeout
+ }
+}
+
// doOK sends the request and expects a 200 OK response.
func (c *Client) doOK(req *http.Request) error {
res, err := c.do(req)
@@ -264,7 +295,14 @@
return nil, err
}
req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
- res, err := c.do(req)
+
+ // The first thing the buildlet's exec handler does is flush the headers, so
+ // 5 seconds should be plenty of time, regardless of where on the planet
+ // (Atlanta, Paris, etc) the reverse buildlet is:
+ res, err := c.doHeaderTimeout(req, 5*time.Second)
+ if err == errHeaderTimeout {
+ return nil, errors.New("buildlet: timeout waiting for exec header response")
+ }
if err != nil {
return nil, err
}
