(feat) Add auto-discovery in k8s | Adarsh

vendor/golang.org/x/oauth2/google/appengine_gen1.go

@@ -0,0 +1,77 @@
+// Copyright 2018 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.
+
+// +build appengine
+
+// This file applies to App Engine first generation runtimes (<= Go 1.9).
+
+package google
+
+import (
+	"context"
+	"sort"
+	"strings"
+	"sync"
+
+	"golang.org/x/oauth2"
+	"google.golang.org/appengine"
+)
+
+func init() {
+	appengineTokenFunc = appengine.AccessToken
+	appengineAppIDFunc = appengine.AppID
+}
+
+// See comment on AppEngineTokenSource in appengine.go.
+func appEngineTokenSource(ctx context.Context, scope ...string) oauth2.TokenSource {
+	scopes := append([]string{}, scope...)
+	sort.Strings(scopes)
+	return &gaeTokenSource{
+		ctx:    ctx,
+		scopes: scopes,
+		key:    strings.Join(scopes, " "),
+	}
+}
+
+// aeTokens helps the fetched tokens to be reused until their expiration.
+var (
+	aeTokensMu sync.Mutex
+	aeTokens   = make(map[string]*tokenLock) // key is space-separated scopes
+)
+
+type tokenLock struct {
+	mu sync.Mutex // guards t; held while fetching or updating t
+	t  *oauth2.Token
+}
+
+type gaeTokenSource struct {
+	ctx    context.Context
+	scopes []string
+	key    string // to aeTokens map; space-separated scopes
+}
+
+func (ts *gaeTokenSource) Token() (*oauth2.Token, error) {
+	aeTokensMu.Lock()
+	tok, ok := aeTokens[ts.key]
+	if !ok {
+		tok = &tokenLock{}
+		aeTokens[ts.key] = tok
+	}
+	aeTokensMu.Unlock()
+
+	tok.mu.Lock()
+	defer tok.mu.Unlock()
+	if tok.t.Valid() {
+		return tok.t, nil
+	}
+	access, exp, err := appengineTokenFunc(ts.ctx, ts.scopes...)
+	if err != nil {
+		return nil, err
+	}
+	tok.t = &oauth2.Token{
+		AccessToken: access,
+		Expiry:      exp,
+	}
+	return tok.t, nil
+}