CreateTablePolicy


1   /**
2    * C-JDBC: Clustered JDBC.
3    * Copyright (C) 2002-2004 French National Institute For Research In Computer
4    * Science And Control (INRIA).
5    * Contact: c-jdbc@objectweb.org
6    * 
7    * This library is free software; you can redistribute it and/or modify it
8    * under the terms of the GNU Lesser General Public License as published by the
9    * Free Software Foundation; either version 2.1 of the License, or any later
10   * version.
11   * 
12   * This library is distributed in the hope that it will be useful, but WITHOUT
13   * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
14   * FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
15   * for more details.
16   * 
17   * You should have received a copy of the GNU Lesser General Public License
18   * along with this library; if not, write to the Free Software Foundation,
19   * Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
20   *
21   * Initial developer(s): Emmanuel Cecchet.
22   * Contributor(s): _______________________
23   */
24  
25  package org.objectweb.cjdbc.controller.loadbalancer.policies.createtable;
26  
27  import java.util.HashMap  ;
28  import java.util.Iterator  ;
29  
30  import org.objectweb.cjdbc.common.xml.DatabasesXmlTags;
31  import org.objectweb.cjdbc.common.xml.XmlComponent;
32  
33  /**
34   * Defines the policy to adopt when creating a new table.
35   * 
36   * @author <a HREF="mailto:Emmanuel.Cecchet@inria.fr">Emmanuel Cecchet</a>
37   * @version 1.0
38   */
39  public class CreateTablePolicy implements XmlComponent
40  {
41    /** Pickup a backend name randomly in the backend list. */
42    public static final int RANDOM = 0;
43  
44    /** Backends are chosen using a round-robin algorithm. */
45    public static final int ROUND_ROBIN = 1;
46  
47    /** Table is created on all backends in the backend list. */
48    public static final int ALL = 2;
49  
50    /** List of backends to wait for. */
51    private HashMap   ruleList = new HashMap  ();
52  
53    /**
54     * Adds a rule to this policy. <br>If the rule's table name is <code>null</code>,
55     * the rule is considered as the default rule
56     * 
57     * @param rule rule to add
58     */
59    public void addRule(CreateTableRule rule)
60    {
61      ruleList.put(rule.getTableName(), rule);
62    }
63  
64    /**
65     * Returns the rule Hashmap(table name,rule).
66     * 
67     * @return Hashmap
68     */
69    public HashMap   getRuleList()
70    {
71      return ruleList;
72    }
73  
74    /**
75     * Gets the rule corresponding to a table name.
76     * 
77     * @param tableName table name of the rule
78     * @return the rule or <code>null</code> if no specific rule has been
79     *         defined for this table
80     */
81    public CreateTableRule getTableRule(String   tableName)
82    {
83      return (CreateTableRule) ruleList.get(tableName);
84    }
85  
86    /**
87     * Returns the default rule or <code>null</code> if no default rule has
88     * been defined.
89     * 
90     * @return a <code>CreateTableRule</code>
91     */
92    public CreateTableRule getDefaultRule()
93    {
94      return (CreateTableRule) ruleList.get(null);
95    }
96  
97    /**
98     * Returns the xml attribute value for the given policy
99     * 
100    * @param policy the policy to convert
101    * @return xml attribute value or "" if not found
102    */
103   public static final String   getXmlValue(int policy)
104   {
105     switch (policy)
106     {
107       case RANDOM :
108         return DatabasesXmlTags.VAL_random;
109       case ROUND_ROBIN :
110         return DatabasesXmlTags.VAL_roundRobin;
111       case ALL :
112         return DatabasesXmlTags.VAL_all;
113       default :
114         return "";
115     }
116   }
117 
118   /**
119    * Returns xml formatted string containing information on all rules of the
120    * system
121    * 
122    * @return xml formatted string.
123    */
124   public String   getXml()
125   {
126     StringBuffer   info = new StringBuffer  ();
127     for (Iterator   iterator = ruleList.keySet().iterator(); iterator.hasNext();)
128       info.append(((CreateTableRule) ruleList.get(iterator.next())).getXml());
129     return info.toString();
130   }
131 
132 }
133
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