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cancellable.go
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cancellable.go
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// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Package cancellable provides helper function to cancel http requests.
package cancellable
import (
"io"
"net/http"
"github.com/docker/engine-api/client/transport"
"golang.org/x/net/context"
)
func nop() {}
var (
testHookContextDoneBeforeHeaders = nop
testHookDoReturned = nop
testHookDidBodyClose = nop
)
// Do sends an HTTP request with the provided transport.Sender and returns an HTTP response.
// If the client is nil, http.DefaultClient is used.
// If the context is canceled or times out, ctx.Err() will be returned.
//
// FORK INFORMATION:
//
// This function deviates from the upstream version in golang.org/x/net/context/ctxhttp by
// taking a Sender interface rather than a *http.Client directly. That allow us to use
// this funcion with mocked clients and hijacked connections.
func Do(ctx context.Context, client transport.Sender, req *http.Request) (*http.Response, error) {
if client == nil {
client = http.DefaultClient
}
// Request cancelation changed in Go 1.5, see canceler.go and canceler_go14.go.
cancel := canceler(client, req)
type responseAndError struct {
resp *http.Response
err error
}
result := make(chan responseAndError, 1)
go func() {
resp, err := client.Do(req)
testHookDoReturned()
result <- responseAndError{resp, err}
}()
var resp *http.Response
select {
case <-ctx.Done():
testHookContextDoneBeforeHeaders()
cancel()
// Clean up after the goroutine calling client.Do:
go func() {
if r := <-result; r.resp != nil && r.resp.Body != nil {
testHookDidBodyClose()
r.resp.Body.Close()
}
}()
return nil, ctx.Err()
case r := <-result:
var err error
resp, err = r.resp, r.err
if err != nil {
return resp, err
}
}
c := make(chan struct{})
go func() {
select {
case <-ctx.Done():
cancel()
case <-c:
// The response's Body is closed.
}
}()
resp.Body = ¬ifyingReader{resp.Body, c}
return resp, nil
}
// notifyingReader is an io.ReadCloser that closes the notify channel after
// Close is called or a Read fails on the underlying ReadCloser.
type notifyingReader struct {
io.ReadCloser
notify chan<- struct{}
}
func (r *notifyingReader) Read(p []byte) (int, error) {
n, err := r.ReadCloser.Read(p)
if err != nil && r.notify != nil {
close(r.notify)
r.notify = nil
}
return n, err
}
func (r *notifyingReader) Close() error {
err := r.ReadCloser.Close()
if r.notify != nil {
close(r.notify)
r.notify = nil
}
return err
}