java/src/main/com/google/appengine/api/datastore/DatastoreServiceFactoryImpl.java

   1 // Copyright 2012 Google Inc. All rights reserved.
   2
   3 package com.google.appengine.api.datastore;
   4
   5 import com.google.appengine.api.datastore.DatastoreServiceConfig.ApiVersion;
   6 import com.google.common.base.Preconditions;
   7
   8 /**
   9  * Creates DatastoreService instances.
  10  *
  11  */
  12 final class DatastoreServiceFactoryImpl implements IDatastoreServiceFactory {
  13
  14   private static final String MIXED_SERVICES_MESSAGE =
  15       "Cannot create both Cloud and non-Cloud Datastore services.";
  16
  17   private static boolean constructedNonCloudService;
  18   private static boolean constructedCloudService;
  19
  20   @Override
  21   public DatastoreService getDatastoreService(DatastoreServiceConfig config) {
  22     return new DatastoreServiceImpl(getAsyncDatastoreService(config));
  23   }
  24
  25   @Override
  26   public AsyncDatastoreServiceInternal getAsyncDatastoreService(DatastoreServiceConfig config) {
  27     TransactionStack txnStack = new TransactionStackImpl();
  28     DatastoreV4Proxy datastoreProxy = config.getDatastoreV4Proxy();
  29
  30     ApiVersion apiVersion = config.getApiVersion();
  31
  32     synchronized (DatastoreServiceFactoryImpl.class) {
  33       if (apiVersion.isCloudService()) {
  34         if (constructedNonCloudService) {
  35           throw new IllegalArgumentException(MIXED_SERVICES_MESSAGE);
  36         }
  37         constructedCloudService = true;
  38       } else {
  39         if (constructedCloudService) {
  40           throw new IllegalArgumentException(MIXED_SERVICES_MESSAGE);
  41         }
  42         constructedNonCloudService = true;
  43       }
  44     }
  45
  46     switch (apiVersion) {
  47       case V3:
  48         Preconditions.checkState(datastoreProxy == null);
  49         return new AsyncDatastoreServiceImpl(config, config.constructApiConfig(), txnStack);
  50       case V4:
  51         Preconditions.checkState(datastoreProxy == null);
  52         return new AsyncDatastoreV4ServiceImpl(config,
  53             new AppEngineDatastoreV4Proxy(config.constructApiConfig()), txnStack);
  54       case CLOUD_DATASTORE:
  55         if (datastoreProxy == null) {
  56           datastoreProxy = CloudDatastoreProxy.create(config);
  57         }
  58         return new AsyncDatastoreV4ServiceImpl(config, datastoreProxy, txnStack);
  59       default:
  60         throw new IllegalArgumentException(
  61             "Can't instantiate service with API version: " + apiVersion);
  62     }
  63   }
  64
  65   static synchronized void resetConstructionStateForTest() {
  66     constructedNonCloudService = false;
  67     constructedCloudService = false;
  68   }
  69 }