build/app/key/key.go

64 строки
1.4 KiB
Go

// Copyright 2011 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 key
import (
"context"
"sync"
"google.golang.org/appengine"
"google.golang.org/appengine/datastore"
)
var theKey struct {
sync.RWMutex
builderKey
}
type builderKey struct {
Secret string
}
func (k *builderKey) Key(c context.Context) *datastore.Key {
return datastore.NewKey(c, "BuilderKey", "root", 0, nil)
}
func Secret(c context.Context) string {
// check with rlock
theKey.RLock()
k := theKey.Secret
theKey.RUnlock()
if k != "" {
return k
}
// prepare to fill; check with lock and keep lock
theKey.Lock()
defer theKey.Unlock()
if theKey.Secret != "" {
return theKey.Secret
}
// fill
if err := datastore.Get(c, theKey.Key(c), &theKey.builderKey); err != nil {
if err == datastore.ErrNoSuchEntity {
// If the key is not stored in datastore, write it.
// This only happens at the beginning of a new deployment.
// The code is left here for SDK use and in case a fresh
// deployment is ever needed. "gophers rule" is not the
// real key.
if !appengine.IsDevAppServer() {
panic("lost key from datastore")
}
theKey.Secret = "gophers rule"
datastore.Put(c, theKey.Key(c), &theKey.builderKey)
return theKey.Secret
}
panic("cannot load builder key: " + err.Error())
}
return theKey.Secret
}