CreateTablePolicy


1   /**
2    * Sequoia: Database clustering technology.
3    * Copyright (C) 2002-2004 French National Institute For Research In Computer
4    * Science And Control (INRIA).
5    * Contact: sequoia@continuent.org
6    * 
7    * Licensed under the Apache License, Version 2.0 (the "License");
8    * you may not use this file except in compliance with the License.
9    * You may obtain a copy of the License at
10   * 
11   * http://www.apache.org/licenses/LICENSE-2.0
12   * 
13   * Unless required by applicable law or agreed to in writing, software
14   * distributed under the License is distributed on an "AS IS" BASIS,
15   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
16   * See the License for the specific language governing permissions and
17   * limitations under the License. 
18   *
19   * Initial developer(s): Emmanuel Cecchet.
20   * Contributor(s): _______________________
21   */
22  
23  package org.continuent.sequoia.controller.loadbalancer.policies.createtable;
24  
25  import java.util.HashMap  ;
26  import java.util.Iterator  ;
27  
28  import org.continuent.sequoia.common.xml.DatabasesXmlTags;
29  import org.continuent.sequoia.common.xml.XmlComponent;
30  
31  /**
32   * Defines the policy to adopt when creating a new table.
33   * 
34   * @author <a HREF="mailto:Emmanuel.Cecchet@inria.fr">Emmanuel Cecchet</a>
35   * @version 1.0
36   */
37  public class CreateTablePolicy implements XmlComponent
38  {
39    /** Pickup a backend name randomly in the backend list. */
40    public static final int RANDOM      = 0;
41  
42    /** Backends are chosen using a round-robin algorithm. */
43    public static final int ROUND_ROBIN = 1;
44  
45    /** Table is created on all backends in the backend list. */
46    public static final int ALL         = 2;
47  
48    /** List of backends to wait for. */
49    private HashMap           ruleList    = new HashMap  ();
50  
51    /**
52     * Adds a rule to this policy. <br>
53     * If the rule's table name is <code>null</code>, the rule is considered as
54     * the default rule
55     * 
56     * @param rule rule to add
57     */
58    public void addRule(CreateTableRule rule)
59    {
60      ruleList.put(rule.getTableName(), rule);
61    }
62  
63    /**
64     * Returns the rule Hashmap(table name,rule).
65     * 
66     * @return Hashmap
67     */
68    public HashMap   getRuleList()
69    {
70      return ruleList;
71    }
72  
73    /**
74     * Gets the rule corresponding to a table name.
75     * 
76     * @param tableName table name of the rule
77     * @return the rule or <code>null</code> if no specific rule has been
78     *         defined for this table
79     */
80    public CreateTableRule getTableRule(String   tableName)
81    {
82      return (CreateTableRule) ruleList.get(tableName);
83    }
84  
85    /**
86     * Returns the default rule or <code>null</code> if no default rule has been
87     * defined.
88     * 
89     * @return a <code>CreateTableRule</code>
90     */
91    public CreateTableRule getDefaultRule()
92    {
93      return (CreateTableRule) ruleList.get(null);
94    }
95  
96    /**
97     * Returns the xml attribute value for the given policy
98     * 
99     * @param policy the policy to convert
100    * @return xml attribute value or "" if not found
101    */
102   public static final String   getXmlValue(int policy)
103   {
104     switch (policy)
105     {
106       case RANDOM :
107         return DatabasesXmlTags.VAL_random;
108       case ROUND_ROBIN :
109         return DatabasesXmlTags.VAL_roundRobin;
110       case ALL :
111         return DatabasesXmlTags.VAL_all;
112       default :
113         return "";
114     }
115   }
116 
117   /**
118    * Returns xml formatted string containing information on all rules of the
119    * system
120    * 
121    * @return xml formatted string.
122    */
123   public String   getXml()
124   {
125     StringBuffer   info = new StringBuffer  ();
126     for (Iterator   iterator = ruleList.keySet().iterator(); iterator.hasNext();)
127       info.append(((CreateTableRule) ruleList.get(iterator.next())).getXml());
128     return info.toString();
129   }
130 
131 }
132
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