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net/http: add a Request.Cancel channel.
This allows for "race free" cancellation, in the sense discussed in issue #11013: in contrast to Transport.CancelRequest, the cancellation will not be lost if the user cancels before the request is put into the transport's internal map. Fixes #11013. Change-Id: I0b5e7181231bdd65d900e343f764b4d1d7c422cd Reviewed-on: https://go-review.googlesource.com/11601 Run-TryBot: David Symonds <dsymonds@golang.org> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
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@ -224,6 +224,13 @@ type Request struct {
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// otherwise it leaves the field nil.
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// This field is ignored by the HTTP client.
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TLS *tls.ConnectionState
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// Cancel is an optional channel whose closure indicates that the client
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// request should be regarded as canceled. Not all implementations of
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// RoundTripper may support Cancel.
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//
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// For server requests, this field is not applicable.
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Cancel <-chan struct{}
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}
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// ProtoAtLeast reports whether the HTTP protocol used
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@ -274,8 +274,8 @@ func (t *Transport) CloseIdleConnections() {
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}
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}
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// CancelRequest cancels an in-flight request by closing its
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// connection.
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// CancelRequest cancels an in-flight request by closing its connection.
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// CancelRequest should only be called after RoundTrip has returned.
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func (t *Transport) CancelRequest(req *Request) {
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t.reqMu.Lock()
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cancel := t.reqCanceler[req]
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@ -563,6 +563,9 @@ func (t *Transport) getConn(req *Request, cm connectMethod) (*persistConn, error
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// when it finishes:
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handlePendingDial()
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return pc, nil
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case <-req.Cancel:
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handlePendingDial()
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return nil, errors.New("net/http: request canceled while waiting for connection")
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case <-cancelc:
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handlePendingDial()
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return nil, errors.New("net/http: request canceled while waiting for connection")
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@ -971,6 +974,8 @@ func (pc *persistConn) readLoop() {
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// response body to be fully consumed before peek on
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// the underlying bufio reader.
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select {
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case <-rc.req.Cancel:
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pc.t.CancelRequest(rc.req)
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case bodyEOF := <-waitForBodyRead:
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pc.t.setReqCanceler(rc.req, nil) // before pc might return to idle pool
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alive = alive &&
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@ -1153,6 +1158,7 @@ func (pc *persistConn) roundTrip(req *transportRequest) (resp *Response, err err
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var re responseAndError
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var respHeaderTimer <-chan time.Time
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cancelChan := req.Request.Cancel
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WaitResponse:
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for {
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select {
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@ -1193,6 +1199,9 @@ WaitResponse:
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break WaitResponse
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case re = <-resc:
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break WaitResponse
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case <-cancelChan:
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pc.t.CancelRequest(req.Request)
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cancelChan = nil
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}
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}
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@ -1466,6 +1466,93 @@ Get = Get http://something.no-network.tld/: net/http: request canceled while wai
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}
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}
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func TestCancelRequestWithChannel(t *testing.T) {
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defer afterTest(t)
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if testing.Short() {
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t.Skip("skipping test in -short mode")
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}
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unblockc := make(chan bool)
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ts := httptest.NewServer(HandlerFunc(func(w ResponseWriter, r *Request) {
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fmt.Fprintf(w, "Hello")
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w.(Flusher).Flush() // send headers and some body
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<-unblockc
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}))
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defer ts.Close()
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defer close(unblockc)
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tr := &Transport{}
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defer tr.CloseIdleConnections()
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c := &Client{Transport: tr}
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req, _ := NewRequest("GET", ts.URL, nil)
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ch := make(chan struct{})
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req.Cancel = ch
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res, err := c.Do(req)
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if err != nil {
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t.Fatal(err)
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}
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go func() {
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time.Sleep(1 * time.Second)
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close(ch)
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}()
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t0 := time.Now()
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body, err := ioutil.ReadAll(res.Body)
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d := time.Since(t0)
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if err != ExportErrRequestCanceled {
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t.Errorf("Body.Read error = %v; want errRequestCanceled", err)
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}
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if string(body) != "Hello" {
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t.Errorf("Body = %q; want Hello", body)
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}
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if d < 500*time.Millisecond {
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t.Errorf("expected ~1 second delay; got %v", d)
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}
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// Verify no outstanding requests after readLoop/writeLoop
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// goroutines shut down.
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for tries := 5; tries > 0; tries-- {
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n := tr.NumPendingRequestsForTesting()
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if n == 0 {
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break
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}
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time.Sleep(100 * time.Millisecond)
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if tries == 1 {
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t.Errorf("pending requests = %d; want 0", n)
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}
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}
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}
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func TestCancelRequestWithChannelBeforeDo(t *testing.T) {
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defer afterTest(t)
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unblockc := make(chan bool)
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ts := httptest.NewServer(HandlerFunc(func(w ResponseWriter, r *Request) {
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<-unblockc
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}))
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defer ts.Close()
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defer close(unblockc)
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// Don't interfere with the next test on plan9.
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// Cf. http://golang.org/issues/11476
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if runtime.GOOS == "plan9" {
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defer time.Sleep(500 * time.Millisecond)
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}
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tr := &Transport{}
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defer tr.CloseIdleConnections()
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c := &Client{Transport: tr}
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req, _ := NewRequest("GET", ts.URL, nil)
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ch := make(chan struct{})
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req.Cancel = ch
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close(ch)
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_, err := c.Do(req)
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if err == nil || !strings.Contains(err.Error(), "canceled") {
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t.Errorf("Do error = %v; want cancelation", err)
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}
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}
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// golang.org/issue/3672 -- Client can't close HTTP stream
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// Calling Close on a Response.Body used to just read until EOF.
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// Now it actually closes the TCP connection.
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