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

   1 // Copyright 2018 The Go Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style
   3 // license that can be found in the LICENSE file.
   4
   5 // +build appengine
   6
   7 // This file applies to App Engine first generation runtimes (<= Go 1.9).
   8
   9 package google
  10
  11 import (
  12         "context"
  13         "sort"
  14         "strings"
  15         "sync"
  16
  17         "golang.org/x/oauth2"
  18         "google.golang.org/appengine"
  19 )
  20
  21 func init() {
  22         appengineTokenFunc = appengine.AccessToken
  23         appengineAppIDFunc = appengine.AppID
  24 }
  25
  26 // See comment on AppEngineTokenSource in appengine.go.
  27 func appEngineTokenSource(ctx context.Context, scope ...string) oauth2.TokenSource {
  28         scopes := append([]string{}, scope...)
  29         sort.Strings(scopes)
  30         return &gaeTokenSource{
  31                 ctx:    ctx,
  32                 scopes: scopes,
  33                 key:    strings.Join(scopes, " "),
  34         }
  35 }
  36
  37 // aeTokens helps the fetched tokens to be reused until their expiration.
  38 var (
  39         aeTokensMu sync.Mutex
  40         aeTokens   = make(map[string]*tokenLock) // key is space-separated scopes
  41 )
  42
  43 type tokenLock struct {
  44         mu sync.Mutex // guards t; held while fetching or updating t
  45         t  *oauth2.Token
  46 }
  47
  48 type gaeTokenSource struct {
  49         ctx    context.Context
  50         scopes []string
  51         key    string // to aeTokens map; space-separated scopes
  52 }
  53
  54 func (ts *gaeTokenSource) Token() (*oauth2.Token, error) {
  55         aeTokensMu.Lock()
  56         tok, ok := aeTokens[ts.key]
  57         if !ok {
  58                 tok = &tokenLock{}
  59                 aeTokens[ts.key] = tok
  60         }
  61         aeTokensMu.Unlock()
  62
  63         tok.mu.Lock()
  64         defer tok.mu.Unlock()
  65         if tok.t.Valid() {
  66                 return tok.t, nil
  67         }
  68         access, exp, err := appengineTokenFunc(ts.ctx, ts.scopes...)
  69         if err != nil {
  70                 return nil, err
  71         }
  72         tok.t = &oauth2.Token{
  73                 AccessToken: access,
  74                 Expiry:      exp,
  75         }
  76         return tok.t, nil
  77 }