code review 12180043: go.tools: add dashboard

dashboard/app/build/key.go

Index: dashboard/app/build/key.go 
=================================================================== 
new file mode 100644 
--- /dev/null 
+++ b/dashboard/app/build/key.go 
@@ -0,0 +1,64 @@ 
+// 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. 
+ 
+// +build appengine 
+ 
+package build 
+ 
+import ( 
+	"sync" 
+ 
+	"appengine" 
+	"appengine/datastore" 
+) 
+ 
+var theKey struct { 
+	sync.RWMutex 
+	BuilderKey 
+} 
+ 
+type BuilderKey struct { 
+	Secret string 
+} 
+ 
+func (k *BuilderKey) Key(c appengine.Context) *datastore.Key { 
+	return datastore.NewKey(c, "BuilderKey", "root", 0, nil) 
+} 
+ 
+func secretKey(c appengine.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 
+}