Add withAppEngineService() to package:appengine

lib/src/appengine_internal.dart

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library appengine.internal;
 
 import 'dart:async';
 import 'dart:io';
 
 import 'package:gcloud/service_scope.dart' as ss;
@@ skipping 79 matching lines @@
         return new Future.value();
       }
     } else {
       return auth.clientViaMetadataServer().then((client) {
         _authClient = client;
         return new storage.Storage(client, context.applicationID);
       });
     }
   }
 
-  var context = getDockerContext();
-  var rpcService = initializeRPC();
+  if (_contextRegistry != null) {
+    return new Future.value(_contextRegistry);
+  } else {
+    var context = getDockerContext();
+    var rpcService = initializeRPC();
 
-  return getStorage(context).then((storage) {
-    return new ContextRegistry(rpcService, storage, context);
-  });
+    return getStorage(context).then((storage) {
+      _contextRegistry = new ContextRegistry(rpcService, storage, context);
+      return _contextRegistry;
+    });
+  }
 }
 
 void initializeContext(Services services) {
   db.registerDbService(services.db);
   datastore.registerDatastoreService(services.db.datastore);
   storage.registerStorageService(services.storage);
   logging.registerLoggingService(services.logging);
   modules.registerModulesService(services.modules);
   memcache.registerMemcacheService(services.memcache);
 
   if (_authClient != null) {
     gcloud_http.registerAuthClientService(_authClient);
 
     // This will automatically close the authenticated HTTP client when the
     // HTTP server shuts down.
     ss.registerScopeExitCallback(() => _authClient.close());
   }
 }
 
 void initializeRequestSpecificServices(Services services) {
   logging.registerLoggingService(services.logging);
   users.registerUserService(services.users);
 }
 
+Future withAppEngineServices(Future callback()) {
+  return initializeAppEngine().then((ContextRegistry contextRegistry) {
+    return ss.fork(() {
+      var backgroundServices = _contextRegistry.newBackgroundServices();
+      initializeContext(backgroundServices);
+      return callback();
+    });
+  });
+}
+
 Future runAppEngine(void handler(request, context), void onError(e, s)) {
   return initializeAppEngine().then((ContextRegistry contextRegistry) {

[wibling, 2014/12/03 11:11:03]

Why call initializeAppEngine here? 

Isn't it enough to call withAppEngineServices() which then sets up the
_contextRegistry by calling initializeAppEngine?

[kustermann, 2014/12/03 11:14:42]

Sure. Forgot to remove that wrapper.

Done

-    _contextRegistry = contextRegistry;
-    var appengineServer = new AppEngineHttpServer(_contextRegistry);
-    var backgroundServices = _contextRegistry.newBackgroundServices();
-
-    ss.fork(() {
-      initializeContext(backgroundServices);
+    return withAppEngineServices(() {
+      var appengineServer = new AppEngineHttpServer(_contextRegistry);
       appengineServer.run((request, context) {
         ss.fork(() {
           initializeRequestSpecificServices(context.services);
           handler(request, context);
           return request.response.done;
         }, onError: (error, stack) {
           var context = _contextRegistry.lookup(request);
           if (context != null) {
             try {
               context.services.logging.error(
@@ skipping 15 matching lines @@
           } on StateError catch (_) {}
             request.response.close().catchError((closeError, closeErrorStack) {
               onError('Forcefully closing response, due to error in request '
                       'handler zone, resulted in an error: $closeError',
                       closeErrorStack);
           });
         });
       });
       return appengineServer.done;
     });
-
-    return new Future.value();
   });
 }