java/src/main/com/google/appengine/api/datastore/InternalTransactionV3.java

   1 // Copyright 2008 Google Inc. All Rights Reserved.
   2 package com.google.appengine.api.datastore;
   3
   4 import com.google.appengine.api.utils.FutureWrapper;
   5 import com.google.apphosting.api.ApiBasePb;
   6 import com.google.apphosting.api.ApiProxy;
   7 import com.google.apphosting.api.ApiProxy.ApiConfig;
   8 import com.google.apphosting.datastore.DatastoreV3Pb;
   9 import com.google.apphosting.datastore.DatastoreV3Pb.CommitResponse;
  10 import com.google.apphosting.datastore.DatastoreV3Pb.DatastoreService_3.Method;
  11 import com.google.io.protocol.ProtocolMessage;
  12
  13 import java.util.concurrent.Future;
  14
  15 /**
  16  * Implementation of the V3-specific logic to handle a {@link Transaction}.
  17  *
  18  * All calls are routed through the {@link ApiProxy}.
  19  */
  20 class InternalTransactionV3 implements TransactionImpl.InternalTransaction {
  21
  22   private final ApiConfig apiConfig;
  23   private final String app;
  24   /**
  25    * The {@link Future} associated with the BeginTransaction RPC we sent to the
  26    * datastore server.
  27    */
  28   private final Future<DatastoreV3Pb.Transaction> beginTxnFuture;
  29
  30   InternalTransactionV3(ApiConfig apiConfig, String app,
  31       Future<DatastoreV3Pb.Transaction> beginTxnFuture) {
  32     this.apiConfig = apiConfig;
  33     this.app = app;
  34     this.beginTxnFuture = beginTxnFuture;
  35   }
  36
  37   /**
  38    * Provides the unique identifier for the txn.
  39    * Blocks on the future since the handle comes back from the datastore
  40    * server.
  41    */
  42   private long getHandle() {
  43     return FutureHelper.quietGet(beginTxnFuture).getHandle();
  44   }
  45
  46   <T extends ProtocolMessage<T>> Future<Void> makeAsyncCall(
  47       Method method, ProtocolMessage<?> request, T response) {
  48     Future<T> resultProto = DatastoreApiHelper.makeAsyncCall(apiConfig, method, request, response);
  49     return new FutureWrapper<T, Void>(resultProto) {
  50       @Override
  51       protected Void wrap(T ignore) throws Exception {
  52         return null;
  53       }
  54
  55       @Override
  56       protected Throwable convertException(Throwable cause) {
  57         return cause;
  58       }
  59     };
  60   }
  61
  62   private <T extends ProtocolMessage<T>> Future<Void> makeAsyncTxnCall(Method method, T response) {
  63     DatastoreV3Pb.Transaction txn = new DatastoreV3Pb.Transaction();
  64     txn.setApp(app);
  65     txn.setHandle(getHandle());
  66     return makeAsyncCall(method, txn, response);
  67   }
  68
  69   @Override
  70   public Future<Void> doCommitAsync() {
  71     return makeAsyncTxnCall(Method.Commit, new CommitResponse());
  72   }
  73
  74   @Override
  75   public Future<Void> doRollbackAsync() {
  76     return makeAsyncTxnCall(Method.Rollback, new ApiBasePb.VoidProto());
  77   }
  78
  79   @Override
  80   public String getId() {
  81     return Long.toString(getHandle());
  82   }
  83
  84   @Override
  85   public boolean equals(Object o) {
  86     if (this == o) {
  87       return true;
  88     }
  89     if (o == null || getClass() != o.getClass()) {
  90       return false;
  91     }
  92
  93     InternalTransactionV3 that = (InternalTransactionV3) o;
  94
  95     return getHandle() == that.getHandle();
  96   }
  97
  98   @Override
  99   public int hashCode() {
 100     return (int) (getHandle() ^ (getHandle() >>> 32));
 101   }
 102
 103   static DatastoreV3Pb.Transaction toProto(Transaction txn) {
 104     DatastoreV3Pb.Transaction txnProto = new DatastoreV3Pb.Transaction();
 105     txnProto.setApp(txn.getApp());
 106     txnProto.setHandle(Long.parseLong(txn.getId()));
 107     return txnProto;
 108   }
 109 }