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

   1 // Copyright 2011 Google Inc. All Rights Reserved.
   2 package com.google.appengine.api.datastore;
   3
   4 import java.util.ArrayList;
   5 import java.util.List;
   6
   7 /**
   8  * Describes options for transactions, passed at transaction creation time.
   9  *
  10  * <p>{@code XG} is a boolean that enables or disables the use of cross-group
  11  * transactions.
  12  *
  13  * <p>Notes on usage:<br>
  14  * The recommended way to instantiate a {@code TransactionsOptions} object is to
  15  * statically import {@link Builder}.* and invoke a static
  16  * creation method followed by an instance mutator (if needed):
  17  *
  18  * <pre>
  19  * import static com.google.appengine.api.datastore.TransactionOptions.Builder.*;
  20  *
  21  * ...
  22  *
  23  * datastoreService.beginTransaction(withXG(true));
  24  * </pre>
  25  *
  26  */
  27 public final class TransactionOptions {
  28
  29   private boolean xg = false;
  30
  31   private TransactionOptions() {
  32   }
  33
  34   TransactionOptions(TransactionOptions original) {
  35     this.xg = original.xg;
  36   }
  37
  38   /**
  39    * Enable or disable the use of cross-group transactions.
  40    *
  41    * @param enable true to cross-group transactions, false to
  42    *   restrict transactions to a single entity group.
  43    * @return {@code this} (for chaining)
  44    */
  45   public TransactionOptions setXG(boolean enable) {
  46     this.xg = enable;
  47     return this;
  48   }
  49
  50   /**
  51    * Return the cross-group transaction setting to default (disabled).
  52    */
  53   public TransactionOptions clearXG() {
  54     this.xg = false;
  55     return this;
  56   }
  57
  58   /**
  59    * @return {@code true} if cross-group transactions are allowed,
  60    *   {@code false} if they are not allowed.
  61    */
  62   public boolean isXG() {
  63     return xg;
  64   }
  65
  66   /**
  67    * @deprecated
  68    * @see #setXG
  69    */
  70   @Deprecated public TransactionOptions multipleEntityGroups(boolean enable) {
  71     return setXG(enable);
  72   }
  73
  74   /**
  75    * @deprecated
  76    * @see #clearXG
  77    */
  78   @Deprecated public TransactionOptions clearMultipleEntityGroups() {
  79     return clearXG();
  80   }
  81
  82   /**
  83    * @deprecated
  84    * @see #isXG
  85    */
  86   @Deprecated public Boolean allowsMultipleEntityGroups() {
  87     return isXG();
  88   }
  89
  90   @Override
  91   public int hashCode() {
  92     int result = 0;
  93
  94     result = result * 31 + (xg ? 1 : 0);
  95
  96     return result;
  97   }
  98
  99   @Override
 100   public boolean equals(Object obj) {
 101     if (obj == null) {
 102       return false;
 103     }
 104
 105     if (obj.getClass() != this.getClass()) {
 106       return false;
 107     }
 108
 109     TransactionOptions that = (TransactionOptions) obj;
 110
 111     return xg == that.xg;
 112   }
 113
 114   @Override
 115   public String toString() {
 116     List<String> result = new ArrayList<String>();
 117
 118     result.add("XG=" + xg);
 119
 120     return "TransactionOptions" + result;
 121   }
 122
 123   /**
 124    * Contains static creation methods for {@link TransactionOptions}.
 125    */
 126   public static final class Builder {
 127     /**
 128      * Create a {@link TransactionOptions} that enables or disables the use of
 129      * cross-group transactions. Shorthand for
 130      * <code>TransactionOptions.withDefaults().setXG(...);</code>
 131      *
 132      * @param enable true to allow cross-group transactions, false to
 133      *   restrict transactions to a single entity group.
 134      * @return {@code this} (for chaining)
 135      */
 136     public static TransactionOptions withXG(boolean enable) {
 137       return withDefaults().setXG(enable);
 138     }
 139
 140     /**
 141      * @deprecated
 142      * @see #withXG
 143      */
 144     @Deprecated public static TransactionOptions allowMultipleEntityGroups(boolean enable) {
 145       return withDefaults().setXG(enable);
 146     }
 147
 148     /**
 149      * Helper method for creating a {@link TransactionOptions} instance with
 150      * default values.  The defaults is false (disabled) for XG.
 151      */
 152     public static TransactionOptions withDefaults() {
 153       return new TransactionOptions();
 154     }
 155
 156     private Builder() {}
 157   }
 158 }