Support Google App Engine with recent context changes (google#582)

* Support Google App Engine with recent context changes

Fixes google#578.

Author: gmlewis

README.md

@@ -201,6 +201,17 @@ straightforward.
 [contributing]: CONTRIBUTING.md
 
 
+## Google App Engine ##
+
+Go on App Engine Classic (which as of this writing uses Go 1.6) can not use
+the `"context"` import and still relies on `"golang.org/x/net/context"`.
+As a result, if you wish to continue to use `go-github` on App Engine Classic,
+you will need to rewrite all the `"context"` imports using the following command:
+
+    `gofmt -w -r '"context" -> "golang.org/x/net/context"' *.go`
+
+See `with_appengine.go` for more details.
+
 ## License ##
 
 This library is distributed under the BSD-style license found in the [LICENSE](./LICENSE)

github/doc.go

@@ -157,5 +157,16 @@ github.Response struct.
 		opt.ListOptions.Page = resp.NextPage
 	}
 
+Google App Engine
+
+Go on App Engine Classic (which as of this writing uses Go 1.6) can not use
+the "context" import and still relies on "golang.org/x/net/context".
+As a result, if you wish to continue to use "go-github" on App Engine Classic,
+you will need to rewrite all the "context" imports using the following command:
+
+    gofmt -w -r '"context" -> "golang.org/x/net/context"' *.go
+
+See "with_appengine.go" for more details.
+
 */
 package github

github/github.go

@@ -390,7 +390,7 @@ func parseRate(r *http.Response) Rate {
 // The provided ctx must be non-nil. If it is canceled or times out,
 // ctx.Err() will be returned.
 func (c *Client) Do(ctx context.Context, req *http.Request, v interface{}) (*Response, error) {
-	req = req.WithContext(ctx)
+	ctx, req = withContext(ctx, req)
 
 	rateLimitCategory := category(req.URL.Path)
 

github/repos_contents.go

@@ -248,10 +248,11 @@ func (s *RepositoriesService) GetArchiveLink(ctx context.Context, owner, repo st
 	}
 	var resp *http.Response
 	// Use http.DefaultTransport if no custom Transport is configured
+	ctx, req = withContext(ctx, req)
 	if s.client.client.Transport == nil {
-		resp, err = http.DefaultTransport.RoundTrip(req.WithContext(ctx))
+		resp, err = http.DefaultTransport.RoundTrip(req)
 	} else {
-		resp, err = s.client.client.Transport.RoundTrip(req.WithContext(ctx))
+		resp, err = s.client.client.Transport.RoundTrip(req)
 	}
 	if err != nil {
 		return nil, nil, err

github/repos_releases.go

@@ -244,7 +244,8 @@ func (s *RepositoriesService) DownloadReleaseAsset(ctx context.Context, owner, r
 	}
 	defer func() { s.client.client.CheckRedirect = saveRedirect }()
 
-	resp, err := s.client.client.Do(req.WithContext(ctx))
+	ctx, req = withContext(ctx, req)
+	resp, err := s.client.client.Do(req)
 	if err != nil {
 		if !strings.Contains(err.Error(), "disable redirect") {
 			return nil, "", err

github/with_appengine.go

@@ -0,0 +1,26 @@
+// Copyright 2017 The go-github AUTHORS. All rights reserved.
+//
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build appengine
+
+// This file provides glue for making github work on App Engine.
+// In order to get the entire github package to compile with
+// Go 1.6, you will need to rewrite all the import "context" lines.
+// Fortunately, this is easy with "gofmt":
+//
+//     gofmt -w -r '"context" -> "golang.org/x/net/context"' *.go
+
+package github
+
+import (
+	"context"
+	"net/http"
+
+	"google.golang.org/appengine"
+)
+
+func withContext(ctx context.Context, req *http.Request) (context.Context, *http.Request) {
+	return appengine.WithContext(ctx, req), req
+}

github/without_appengine.go

@@ -0,0 +1,19 @@
+// Copyright 2017 The go-github AUTHORS. All rights reserved.
+//
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build !appengine
+
+// This file provides glue for making github work without App Engine.
+
+package github
+
+import (
+	"context"
+	"net/http"
+)
+
+func withContext(ctx context.Context, req *http.Request) (context.Context, *http.Request) {
+	return ctx, req.WithContext(ctx)
+}