OPENJPA-966: Support MySQL Replication Driver

git-svn-id: https://svn.apache.org/repos/asf/openjpa/trunk@751487 13f79535-47bb-0310-9956-ffa450edef68

openjpa-jdbc/src/main/java/org/apache/openjpa/jdbc/kernel/JDBCStoreManager.java

@@ -641,6 +641,11 @@ public class JDBCStoreManager
     }
 
     public Collection flush(Collection sms) {
+        try {
+            if (_conn != null && _conn.getInnermostDelegate().isReadOnly())
+                _conn.setReadOnly(false);
+        } catch (SQLException e) {
+        }
         return _conf.getUpdateManagerInstance().flush(sms, this);
     }
 

openjpa-jdbc/src/main/java/org/apache/openjpa/jdbc/sql/MySQLDictionary.java

@@ -146,6 +146,13 @@ public class MySQLDictionary
         }
     }
 
+    public Connection decorate(Connection conn)  throws SQLException {
+        String driver = conf.getConnectionDriverName();
+        if ("com.mysql.jdbc.ReplicationDriver".equals(driver))
+            conn.setReadOnly(true);
+        return conn;
+    }
+    
     private static int[] getMajorMinorVersions(String versionStr)
         throws IllegalArgumentException {
         int beginIndex = 0;

openjpa-project/src/doc/manual/ref_guide_dbsetup.xml

@@ -3216,6 +3216,37 @@ more info about <literal>deleteTableContents</literal>.) Defaults to
 <literal>false</literal>, since the statement may fail if using InnoDB
 tables and delete constraints.
                     </para>
+                    
+                </listitem>
+            </itemizedlist>
+            
+                    <para>
+Starting with Connector/J 3.1.7, MySQL supports a variant of the driver 
+<literal>com.mysql.jdbc.ReplicationDriver</literal> that automatically sends 
+queries to a read/write master, or a failover or round-robin load balanced set 
+of slaves based on the state of read-only status of the connection. 
+See  <ulink url="http://dev.mysql.com/doc/refman/5.1/en/connector-j-reference-replication-connection.html">
+MySQL Reference</ulink> for more details. 
+                    </para>
+                    <para>
+This replication feature can be used transparently with OpenJPA application by
+following configuration:
+                    </para>
+        <itemizedlist>
+           <listitem>
+             <para>
+<literal>openjpa.ConnectionDriverName: com.mysql.jdbc.ReplicationDriver</literal>
+             </para>
+           </listitem>
+           <listitem>
+             <para>
+<literal>openjpa.ConnectionFactoryProperties: autoReconnect=true,roundRobinLoadBalance=true</literal>
+             </para>
+             <para>
+OpenJPA will use a read-only connection with replicated database configuration
+and will automatically switch the connection to a non-readonly mode if the
+transaction is writing to the database.             
+             </para>
            </listitem>
          </itemizedlist>
         </section>