Fix miscellaneous prod bugs.

impl/prod/info.go

 // Copyright 2015 The Chromium 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 prod
 
 import (
         "time"
 
         "github.com/luci/gae/service/info"
         "golang.org/x/net/context"
         "google.golang.org/appengine"
+        "google.golang.org/appengine/datastore"
 )
 
 type key int
 
-var namespaceCopyKey key
+var probeCacheKey key
 
 // useGI adds a gae.GlobalInfo implementation to context, accessible
 // by gae.GetGI(c)
 func useGI(c context.Context) context.Context {
-        // TODO(iannucci): make a better way to get the initial namespace?
-        c = context.WithValue(c, namespaceCopyKey, "")
+        probeCache := getProbeCache(c)
+        if probeCache == nil {
+                c = withProbeCache(c, probe(c))
+        }
+
         return info.SetFactory(c, func(ci context.Context) info.Interface {
                 return giImpl{ci}
         })
 }
 
 type giImpl struct{ context.Context }
 
 func (g giImpl) AccessToken(scopes ...string) (token string, expiry time.Time, err error) {
         return appengine.AccessToken(g, scopes...)
 }
 func (g giImpl) AppID() string {
         return appengine.AppID(g)
 }
+func (g giImpl) FullyQualifiedAppID() string {
+        return getProbeCache(g).fqaid
+}
 func (g giImpl) GetNamespace() string {
-        return g.Value(namespaceCopyKey).(string)
+        return getProbeCache(g).namespace
 }
 func (g giImpl) Datacenter() string {
         return appengine.Datacenter(g)
 }
 func (g giImpl) DefaultVersionHostname() string {
         return appengine.DefaultVersionHostname(g)
 }
 func (g giImpl) InstanceID() string {
         return appengine.InstanceID()
 }
@@ skipping 10 matching lines @@
         return appengine.ModuleHostname(g, module, version, instance)
 }
 func (g giImpl) ModuleName() (name string) {
         return appengine.ModuleName(g)
 }
 func (g giImpl) Namespace(namespace string) (context.Context, error) {
         c, err := appengine.Namespace(g, namespace)
         if err != nil {
                 return c, err
         }
-        return context.WithValue(c, namespaceCopyKey, namespace), nil
+        pc := *getProbeCache(g)
+        pc.namespace = namespace
+        return withProbeCache(c, &pc), nil
 }
 func (g giImpl) PublicCertificates() ([]info.Certificate, error) {
         certs, err := appengine.PublicCertificates(g)
         if err != nil {
                 return nil, err
         }
         ret := make([]info.Certificate, len(certs))
         for i, c := range certs {
                 ret[i] = info.Certificate(c)
         }
         return ret, nil
 }
 func (g giImpl) RequestID() string {
         return appengine.RequestID(g)
 }
 func (g giImpl) ServerSoftware() string {
         return appengine.ServerSoftware()
 }
 func (g giImpl) ServiceAccount() (string, error) {
         return appengine.ServiceAccount(g)
 }
 func (g giImpl) SignBytes(bytes []byte) (keyName string, signature []byte, err error) {
         return appengine.SignBytes(g, bytes)
 }
 func (g giImpl) VersionID() string {
         return appengine.VersionID(g)
 }
+
+type infoProbeCache struct {
+        namespace string
+        fqaid     string
+}
+
+func probe(c context.Context) *infoProbeCache {
+        probeKey := datastore.NewKey(c, "Kind", "id", 0, nil)
+        return &infoProbeCache{
+                namespace: probeKey.Namespace(),
+                fqaid:     probeKey.AppID(),
+        }
+}
+
+func getProbeCache(c context.Context) *infoProbeCache {
+        if pc, ok := c.Value(probeCacheKey).(*infoProbeCache); ok {
+                return pc
+        }
+        return nil
+}
+
+func withProbeCache(c context.Context, pc *infoProbeCache) context.Context {
+        return context.WithValue(c, probeCacheKey, pc)
+}