org.apache.avalon.excalibur.datasource.ids
Class TableIdGenerator

java.lang.Object
  org.apache.avalon.framework.logger.AbstractLogEnabled
      org.apache.avalon.excalibur.datasource.ids.AbstractIdGenerator
          org.apache.avalon.excalibur.datasource.ids.AbstractDataSourceIdGenerator
              org.apache.avalon.excalibur.datasource.ids.AbstractDataSourceBlockIdGenerator
                  org.apache.avalon.excalibur.datasource.ids.TableIdGenerator

All Implemented Interfaces:

Component, Configurable, Disposable, IdGenerator, Initializable, LogEnabled, Serviceable, ThreadSafe

public class TableIdGenerator

extends AbstractDataSourceBlockIdGenerator

The TableIdGenerator requests blocks of ids from a Database table. The table consists of two columns one called table_name of type CHAR or VARCHAR, and the second called next_id of an integer type large enough to hold your largest ids.

The Configuration to use a TableIdGenerator looks like the following:

   <id-generators>
       <table name="user-ids" big-decimals="true" block-size="1" table="ids"
           key-table="event-type" logger="cm.ids">
           <dbpool>user-db</dbpool>
       </table>
   </id-generators>
 

Where user-db is the name of a DataSource configured in a datasources element, block-size is the number if ids that are allocated with each query to the databse (defaults to "10"), table is the name of the table which contains the ids (defaults to "ids"), and key-table is the table_name of the row from which the block of ids are allocated (defaults to "id").

With the following roles declaration:

   <role name="org.apache.avalon.excalibur.datasource.ids.IdGeneratorSelector"
         shorthand="id-generators"
         default-class="org.apache.avalon.excalibur.component.ExcaliburComponentSelector">
       <hint shorthand="table"
             class="org.apache.avalon.excalibur.datasource.ids.TableIdGenerator"/>
   </role>
 

To configure your component to use the IdGenerator declared above, its configuration should look something like the following:

   <user-service logger="cm">
       <dbpool>user-db</dbpool>
       <id-generator>user-ids</id-generator>
   </user-service>
 

Your component obtains a reference to an IdGenerator using the same method as it obtains a DataSource, by making use of a ComponentSelector.

Depending on your database, the ids table should look something like the following:

   CREATE TABLE ids (
       table_name varchar(16) NOT NULL,
       next_id INTEGER NOT NULL,
       PRIMARY KEY (table_name)
   );
 

Since:

4.1

Version:

CVS $Revision: 1.4 $ $Date: 2004/02/28 11:47:17 $

Author:

Avalon Development Team

Field Summary

Fields inherited from class org.apache.avalon.excalibur.datasource.ids.AbstractDataSourceIdGenerator

m_dataSource, m_nextId

Fields inherited from interface org.apache.avalon.excalibur.datasource.ids.IdGenerator

ROLE

Constructor Summary

TableIdGenerator()

Method Summary

protected java.math.BigDecimal	allocateBigDecimalIdBlock(int blockSize) Allocates a block, of the given size, of ids from the database.
protected long	allocateLongIdBlock(int blockSize) Allocates a block, of the given size, of ids from the database.
void	configure(Configuration configuration) Called by the Container to configure the component.

Methods inherited from class org.apache.avalon.excalibur.datasource.ids.AbstractDataSourceBlockIdGenerator

getNextBigDecimalIdInner, getNextLongIdInner, initialize

Methods inherited from class org.apache.avalon.excalibur.datasource.ids.AbstractDataSourceIdGenerator

dispose, getConnection, service

Methods inherited from class org.apache.avalon.excalibur.datasource.ids.AbstractIdGenerator

getNextBigDecimalId, getNextByteId, getNextIntegerId, getNextLongId, getNextLongIdChecked, getNextShortId, isUsingBigDecimals, setUseBigDecimals

Methods inherited from class org.apache.avalon.framework.logger.AbstractLogEnabled

enableLogging, getLogger, setupLogger, setupLogger, setupLogger

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

TableIdGenerator

public TableIdGenerator()

Method Detail

allocateBigDecimalIdBlock

protected java.math.BigDecimal allocateBigDecimalIdBlock(int blockSize)
                                                  throws IdException

Allocates a block, of the given size, of ids from the database.

Specified by:

allocateBigDecimalIdBlock in class AbstractDataSourceBlockIdGenerator

Parameters:

blockSize - number of Ids which are to be allocated.

Returns:

The first id in the allocated block.

Throws:

IdException - if there it was not possible to allocate a block of ids.

allocateLongIdBlock

protected long allocateLongIdBlock(int blockSize)
                            throws IdException

Allocates a block, of the given size, of ids from the database.

Specified by:

allocateLongIdBlock in class AbstractDataSourceBlockIdGenerator

Parameters:

blockSize - number of Ids which are to be allocated.

Returns:

The first id in the allocated block.

Throws:

IdException - if there it was not possible to allocate a block of ids.

configure

public void configure(Configuration configuration)
               throws ConfigurationException

Called by the Container to configure the component.

Specified by:

configure in interface Configurable

Overrides:

configure in class AbstractDataSourceBlockIdGenerator

Parameters:

configuration - configuration info used to setup the component.

Throws:

ConfigurationException - if there are any problems with the configuration.