func (pc *persistConn) readLoop() {
// eofc is used to block http.Handler goroutines reading from Response.Body
// at EOF until this goroutines has (potentially) added the connection
// back to the idle pool.
eofc := make(chan struct{})
defer close(eofc) // unblock reader on errors
// Read this once, before loop starts. (to avoid races in tests)
testHookMu.Lock()
testHookReadLoopBeforeNextRead := testHookReadLoopBeforeNextRead
testHookMu.Unlock()
alive := true
for alive {
pb, err := pc.br.Peek(1)
pc.lk.Lock()
if pc.numExpectedResponses == 0 {
if !pc.closed {
pc.closeLocked()
if len(pb) > 0 {
log.Printf("Unsolicited response received on idle HTTP channel starting with %q; err=%v",
string(pb), err)
}
}
pc.lk.Unlock()
return
}
pc.lk.Unlock()
rc := <-pc.reqch
var resp *http.Response
if err == nil {
resp, err = http.ReadResponse(pc.br, rc.req)
if err == nil && resp.StatusCode == 100 {
// Skip any 100-continue for now.
// TODO(bradfitz): if rc.req had "Expect: 100-continue",
// actually block the request body write and signal the
// writeLoop now to begin sending it. (Issue 2184) For now we
// eat it, since we're never expecting one.
resp, err = http.ReadResponse(pc.br, rc.req)
}
}
if resp != nil {
resp.TLS = pc.tlsState
}
hasBody := resp != nil && rc.req.Method != "HEAD" && resp.ContentLength != 0
if err != nil {
pc.close()
} else {
resp.Body = &bodyEOFSignal{body: resp.Body}
}
if err != nil || resp.Close || rc.req.Close || resp.StatusCode <= 199 {
// Don't do keep-alive on error if either party requested a close
// or we get an unexpected informational (1xx) response.
// StatusCode 100 is already handled above.
alive = false
}
var waitForBodyRead chan bool // channel is nil when there's no body
if hasBody {
waitForBodyRead = make(chan bool, 2)
resp.Body.(*bodyEOFSignal).earlyCloseFn = func() error {
waitForBodyRead <- false
return nil
}
resp.Body.(*bodyEOFSignal).fn = func(err error) error {
isEOF := err == io.EOF
waitForBodyRead <- isEOF
if isEOF {
<-eofc // see comment at top
} else if err != nil && pc.isCanceled() {
return errRequestCanceled
}
return err
}
}
pc.lk.Lock()
pc.numExpectedResponses--
pc.lk.Unlock()
// The connection might be going away when we put the
// idleConn below. When that happens, we close the response channel to signal
// to roundTrip that the connection is gone. roundTrip waits for
// both closing and a response in a select, so it might choose
// the close channel, rather than the response.
// We send the response first so that roundTrip can check
// if there is a pending one with a non-blocking select
// on the response channel before erroring out.
rc.ch <- responseAndError{resp, err}
if hasBody {
// To avoid a race, wait for the just-returned
// response body to be fully consumed before peek on
// the underlying bufio reader.
select {
case bodyEOF := <-waitForBodyRead:
pc.t.setReqCanceler(rc.req, nil) // before pc might return to idle pool
alive = alive &&
bodyEOF &&
!pc.sawEOF &&
pc.wroteRequest() &&
pc.t.putIdleConn(pc)
if bodyEOF {
eofc <- struct{}{}
}
case <-pc.closech:
alive = false
}
} else {
pc.t.setReqCanceler(rc.req, nil) // before pc might return to idle pool
alive = alive &&
!pc.sawEOF &&
pc.wroteRequest() &&
pc.t.putIdleConn(pc)
}
if hook := testHookReadLoopBeforeNextRead; hook != nil {
hook()
}
}
pc.close()
}